diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-pci | 10 | ||||
| -rw-r--r-- | Documentation/DocBook/uio-howto.tmpl | 163 | ||||
| -rw-r--r-- | Documentation/PCI/pci-error-recovery.txt | 119 | ||||
| -rw-r--r-- | Documentation/arm/OMAP/omap_pm | 129 | ||||
| -rw-r--r-- | Documentation/cpu-freq/user-guide.txt | 9 | ||||
| -rw-r--r-- | Documentation/dontdiff | 1 | ||||
| -rw-r--r-- | Documentation/feature-removal-schedule.txt | 10 | ||||
| -rw-r--r-- | Documentation/hwmon/pcf8591 | 28 | ||||
| -rw-r--r-- | Documentation/hwmon/tmp421 | 36 | ||||
| -rw-r--r-- | Documentation/hwmon/wm831x | 37 | ||||
| -rw-r--r-- | Documentation/hwmon/wm8350 | 26 | ||||
| -rw-r--r-- | Documentation/kernel-parameters.txt | 4 | ||||
| -rw-r--r-- | Documentation/trace/events.txt | 208 | ||||
| -rw-r--r-- | Documentation/trace/ftrace-design.txt | 233 | ||||
| -rw-r--r-- | Documentation/trace/ftrace.txt | 6 | ||||
| -rw-r--r-- | Documentation/vgaarbiter.txt | 194 |
16 files changed, 1132 insertions, 81 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index 6bf68053e4b..25be3250f7d 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -84,6 +84,16 @@ Description: from this part of the device tree. Depends on CONFIG_HOTPLUG. +What: /sys/bus/pci/devices/.../reset +Date: July 2009 +Contact: Michael S. Tsirkin <mst@redhat.com> +Description: + Some devices allow an individual function to be reset + without affecting other functions in the same device. + For devices that have this support, a file named reset + will be present in sysfs. Writing 1 to this file + will perform reset. + What: /sys/bus/pci/devices/.../vpd Date: February 2008 Contact: Ben Hutchings <bhutchings@solarflare.com> diff --git a/Documentation/DocBook/uio-howto.tmpl b/Documentation/DocBook/uio-howto.tmpl index 8f6e3b2403c..4d4ce0e61e4 100644 --- a/Documentation/DocBook/uio-howto.tmpl +++ b/Documentation/DocBook/uio-howto.tmpl @@ -25,6 +25,10 @@ <year>2006-2008</year> <holder>Hans-Jürgen Koch.</holder> </copyright> +<copyright> + <year>2009</year> + <holder>Red Hat Inc, Michael S. Tsirkin (mst@redhat.com)</holder> +</copyright> <legalnotice> <para> @@ -42,6 +46,13 @@ GPL version 2. <revhistory> <revision> + <revnumber>0.9</revnumber> + <date>2009-07-16</date> + <authorinitials>mst</authorinitials> + <revremark>Added generic pci driver + </revremark> + </revision> + <revision> <revnumber>0.8</revnumber> <date>2008-12-24</date> <authorinitials>hjk</authorinitials> @@ -809,6 +820,158 @@ framework to set up sysfs files for this region. Simply leave it alone. </chapter> +<chapter id="uio_pci_generic" xreflabel="Using Generic driver for PCI cards"> +<?dbhtml filename="uio_pci_generic.html"?> +<title>Generic PCI UIO driver</title> + <para> + The generic driver is a kernel module named uio_pci_generic. + It can work with any device compliant to PCI 2.3 (circa 2002) and + any compliant PCI Express device. Using this, you only need to + write the userspace driver, removing the need to write + a hardware-specific kernel module. + </para> + +<sect1 id="uio_pci_generic_binding"> +<title>Making the driver recognize the device</title> + <para> +Since the driver does not declare any device ids, it will not get loaded +automatically and will not automatically bind to any devices, you must load it +and allocate id to the driver yourself. For example: + <programlisting> + modprobe uio_pci_generic + echo "8086 10f5" > /sys/bus/pci/drivers/uio_pci_generic/new_id + </programlisting> + </para> + <para> +If there already is a hardware specific kernel driver for your device, the +generic driver still won't bind to it, in this case if you want to use the +generic driver (why would you?) you'll have to manually unbind the hardware +specific driver and bind the generic driver, like this: + <programlisting> + echo -n 0000:00:19.0 > /sys/bus/pci/drivers/e1000e/unbind + echo -n 0000:00:19.0 > /sys/bus/pci/drivers/uio_pci_generic/bind + </programlisting> + </para> + <para> +You can verify that the device has been bound to the driver +by looking for it in sysfs, for example like the following: + <programlisting> + ls -l /sys/bus/pci/devices/0000:00:19.0/driver + </programlisting> +Which if successful should print + <programlisting> + .../0000:00:19.0/driver -> ../../../bus/pci/drivers/uio_pci_generic + </programlisting> +Note that the generic driver will not bind to old PCI 2.2 devices. +If binding the device failed, run the following command: + <programlisting> + dmesg + </programlisting> +and look in the output for failure reasons + </para> +</sect1> + +<sect1 id="uio_pci_generic_internals"> +<title>Things to know about uio_pci_generic</title> + <para> +Interrupts are handled using the Interrupt Disable bit in the PCI command +register and Interrupt Status bit in the PCI status register. All devices +compliant to PCI 2.3 (circa 2002) and all compliant PCI Express devices should +support these bits. uio_pci_generic detects this support, and won't bind to +devices which do not support the Interrupt Disable Bit in the command register. + </para> + <para> +On each interrupt, uio_pci_generic sets the Interrupt Disable bit. +This prevents the device from generating further interrupts +until the bit is cleared. The userspace driver should clear this +bit before blocking and waiting for more interrupts. + </para> +</sect1> +<sect1 id="uio_pci_generic_userspace"> +<title>Writing userspace driver using uio_pci_generic</title> + <para> +Userspace driver can use pci sysfs interface, or the +libpci libray that wraps it, to talk to the device and to +re-enable interrupts by writing to the command register. + </para> +</sect1> +<sect1 id="uio_pci_generic_example"> +<title>Example code using uio_pci_generic</title> + <para> +Here is some sample userspace driver code using uio_pci_generic: +<programlisting> +#include <stdlib.h> +#include <stdio.h> +#include <unistd.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <errno.h> + +int main() +{ + int uiofd; + int configfd; + int err; + int i; + unsigned icount; + unsigned char command_high; + + uiofd = open("/dev/uio0", O_RDONLY); + if (uiofd < 0) { + perror("uio open:"); + return errno; + } + configfd = open("/sys/class/uio/uio0/device/config", O_RDWR); + if (uiofd < 0) { + perror("config open:"); + return errno; + } + + /* Read and cache command value */ + err = pread(configfd, &command_high, 1, 5); + if (err != 1) { + perror("command config read:"); + return errno; + } + command_high &= ~0x4; + + for(i = 0;; ++i) { + /* Print out a message, for debugging. */ + if (i == 0) + fprintf(stderr, "Started uio test driver.\n"); + else + fprintf(stderr, "Interrupts: %d\n", icount); + + /****************************************/ + /* Here we got an interrupt from the + device. Do something to it. */ + /****************************************/ + + /* Re-enable interrupts. */ + err = pwrite(configfd, &command_high, 1, 5); + if (err != 1) { + perror("config write:"); + break; + } + + /* Wait for next interrupt. */ + err = read(uiofd, &icount, 4); + if (err != 4) { + perror("uio read:"); + break; + } + + } + return errno; +} + +</programlisting> + </para> +</sect1> + +</chapter> + <appendix id="app1"> <title>Further information</title> <itemizedlist> diff --git a/Documentation/PCI/pci-error-recovery.txt b/Documentation/PCI/pci-error-recovery.txt index 6650af43252..e83f2ea7641 100644 --- a/Documentation/PCI/pci-error-recovery.txt +++ b/Documentation/PCI/pci-error-recovery.txt @@ -4,15 +4,17 @@ February 2, 2006 Current document maintainer: - Linas Vepstas <linas@austin.ibm.com> + Linas Vepstas <linasvepstas@gmail.com> + updated by Richard Lary <rlary@us.ibm.com> + and Mike Mason <mmlnx@us.ibm.com> on 27-Jul-2009 Many PCI bus controllers are able to detect a variety of hardware PCI errors on the bus, such as parity errors on the data and address busses, as well as SERR and PERR errors. Some of the more advanced chipsets are able to deal with these errors; these include PCI-E chipsets, -and the PCI-host bridges found on IBM Power4 and Power5-based pSeries -boxes. A typical action taken is to disconnect the affected device, +and the PCI-host bridges found on IBM Power4, Power5 and Power6-based +pSeries boxes. A typical action taken is to disconnect the affected device, halting all I/O to it. The goal of a disconnection is to avoid system corruption; for example, to halt system memory corruption due to DMA's to "wild" addresses. Typically, a reconnection mechanism is also @@ -37,10 +39,11 @@ is forced by the need to handle multi-function devices, that is, devices that have multiple device drivers associated with them. In the first stage, each driver is allowed to indicate what type of reset it desires, the choices being a simple re-enabling of I/O -or requesting a hard reset (a full electrical #RST of the PCI card). -If any driver requests a full reset, that is what will be done. +or requesting a slot reset. -After a full reset and/or a re-enabling of I/O, all drivers are +If any driver requests a slot reset, that is what will be done. + +After a reset and/or a re-enabling of I/O, all drivers are again notified, so that they may then perform any device setup/config that may be required. After these have all completed, a final "resume normal operations" event is sent out. @@ -101,7 +104,7 @@ if it implements any, it must implement error_detected(). If a callback is not implemented, the corresponding feature is considered unsupported. For example, if mmio_enabled() and resume() aren't there, then it is assumed that the driver is not doing any direct recovery and requires -a reset. If link_reset() is not implemented, the card is assumed as +a slot reset. If link_reset() is not implemented, the card is assumed to not care about link resets. Typically a driver will want to know about a slot_reset(). @@ -111,7 +114,7 @@ sequence described below. STEP 0: Error Event ------------------- -PCI bus error is detect by the PCI hardware. On powerpc, the slot +A PCI bus error is detected by the PCI hardware. On powerpc, the slot is isolated, in that all I/O is blocked: all reads return 0xffffffff, all writes are ignored. @@ -139,7 +142,7 @@ The driver must return one of the following result codes: a chance to extract some diagnostic information (see mmio_enable, below). - PCI_ERS_RESULT_NEED_RESET: - Driver returns this if it can't recover without a hard + Driver returns this if it can't recover without a slot reset. - PCI_ERS_RESULT_DISCONNECT: Driver returns this if it doesn't want to recover at all. @@ -169,11 +172,11 @@ is STEP 6 (Permanent Failure). >>> The current powerpc implementation doesn't much care if the device >>> attempts I/O at this point, or not. I/O's will fail, returning ->>> a value of 0xff on read, and writes will be dropped. If the device ->>> driver attempts more than 10K I/O's to a frozen adapter, it will ->>> assume that the device driver has gone into an infinite loop, and ->>> it will panic the kernel. There doesn't seem to be any other ->>> way of stopping a device driver that insists on spinning on I/O. +>>> a value of 0xff on read, and writes will be dropped. If more than +>>> EEH_MAX_FAILS I/O's are attempted to a frozen adapter, EEH +>>> assumes that the device driver has gone into an infinite loop +>>> and prints an error to syslog. A reboot is then required to +>>> get the device working again. STEP 2: MMIO Enabled ------------------- @@ -182,15 +185,14 @@ DMA), and then calls the mmio_enabled() callback on all affected device drivers. This is the "early recovery" call. IOs are allowed again, but DMA is -not (hrm... to be discussed, I prefer not), with some restrictions. This -is NOT a callback for the driver to start operations again, only to -peek/poke at the device, extract diagnostic information, if any, and -eventually do things like trigger a device local reset or some such, -but not restart operations. This is callback is made if all drivers on -a segment agree that they can try to recover and if no automatic link reset -was performed by the HW. If the platform can't just re-enable IOs without -a slot reset or a link reset, it wont call this callback, and instead -will have gone directly to STEP 3 (Link Reset) or STEP 4 (Slot Reset) +not, with some restrictions. This is NOT a callback for the driver to +start operations again, only to peek/poke at the device, extract diagnostic +information, if any, and eventually do things like trigger a device local +reset or some such, but not restart operations. This callback is made if +all drivers on a segment agree that they can try to recover and if no automatic +link reset was performed by the HW. If the platform can't just re-enable IOs +without a slot reset or a link reset, it will not call this callback, and +instead will have gone directly to STEP 3 (Link Reset) or STEP 4 (Slot Reset) >>> The following is proposed; no platform implements this yet: >>> Proposal: All I/O's should be done _synchronously_ from within @@ -228,9 +230,6 @@ proceeds to either STEP3 (Link Reset) or to STEP 5 (Resume Operations). If any driver returned PCI_ERS_RESULT_NEED_RESET, then the platform proceeds to STEP 4 (Slot Reset) ->>> The current powerpc implementation does not implement this callback. - - STEP 3: Link Reset ------------------ The platform resets the link, and then calls the link_reset() callback @@ -253,16 +252,33 @@ The platform then proceeds to either STEP 4 (Slot Reset) or STEP 5 >>> The current powerpc implementation does not implement this callback. - STEP 4: Slot Reset ------------------ -The platform performs a soft or hard reset of the device, and then -calls the slot_reset() callback. -A soft reset consists of asserting the adapter #RST line and then +In response to a return value of PCI_ERS_RESULT_NEED_RESET, the +the platform will peform a slot reset on the requesting PCI device(s). +The actual steps taken by a platform to perform a slot reset +will be platform-dependent. Upon completion of slot reset, the +platform will call the device slot_reset() callback. + +Powerpc platforms implement two levels of slot reset: +soft reset(default) and fundamental(optional) reset. + +Powerpc soft reset consists of asserting the adapter #RST line and then restoring the PCI BAR's and PCI configuration header to a state that is equivalent to what it would be after a fresh system power-on followed by power-on BIOS/system firmware initialization. +Soft reset is also known as hot-reset. + +Powerpc fundamental reset is supported by PCI Express cards only +and results in device's state machines, hardware logic, port states and +configuration registers to initialize to their default conditions. + +For most PCI devices, a soft reset will be sufficient for recovery. +Optional fundamental reset is provided to support a limited number +of PCI Express PCI devices for which a soft reset is not sufficient +for recovery. + If the platform supports PCI hotplug, then the reset might be performed by toggling the slot electrical power off/on. @@ -274,10 +290,12 @@ may result in hung devices, kernel panics, or silent data corruption. This call gives drivers the chance to re-initialize the hardware (re-download firmware, etc.). At this point, the driver may assume -that he card is in a fresh state and is fully functional. In -particular, interrupt generation should work normally. +that the card is in a fresh state and is fully functional. The slot +is unfrozen and the driver has full access to PCI config space, +memory mapped I/O space and DMA. Interrupts (Legacy, MSI, or MSI-X) +will also be available. -Drivers should not yet restart normal I/O processing operations +Drivers should not restart normal I/O processing operations at this point. If all device drivers report success on this callback, the platform will call resume() to complete the sequence, and let the driver restart normal I/O processing. @@ -302,11 +320,21 @@ driver performs device init only from PCI function 0: - PCI_ERS_RESULT_DISCONNECT Same as above. +Drivers for PCI Express cards that require a fundamental reset must +set the needs_freset bit in the pci_dev structure in their probe function. +For example, the QLogic qla2xxx driver sets the needs_freset bit for certain +PCI card types: + ++ /* Set EEH reset type to fundamental if required by hba */ ++ if (IS_QLA24XX(ha) || IS_QLA25XX(ha) || IS_QLA81XX(ha)) ++ pdev->needs_freset = 1; ++ + Platform proceeds either to STEP 5 (Resume Operations) or STEP 6 (Permanent Failure). ->>> The current powerpc implementation does not currently try a ->>> power-cycle reset if the driver returned PCI_ERS_RESULT_DISCONNECT. +>>> The current powerpc implementation does not try a power-cycle +>>> reset if the driver returned PCI_ERS_RESULT_DISCONNECT. >>> However, it probably should. @@ -348,7 +376,7 @@ software errors. Conclusion; General Remarks --------------------------- -The way those callbacks are called is platform policy. A platform with +The way the callbacks are called is platform policy. A platform with no slot reset capability may want to just "ignore" drivers that can't recover (disconnect them) and try to let other cards on the same segment recover. Keep in mind that in most real life cases, though, there will @@ -361,8 +389,8 @@ That is, the recovery API only requires that: - There is no guarantee that interrupt delivery can proceed from any device on the segment starting from the error detection and until the -resume callback is sent, at which point interrupts are expected to be -fully operational. +slot_reset callback is called, at which point interrupts are expected +to be fully operational. - There is no guarantee that interrupt delivery is stopped, that is, a driver that gets an interrupt after detecting an error, or that detects @@ -381,16 +409,23 @@ anyway :) >>> Implementation details for the powerpc platform are discussed in >>> the file Documentation/powerpc/eeh-pci-error-recovery.txt ->>> As of this writing, there are six device drivers with patches ->>> implementing error recovery. Not all of these patches are in +>>> As of this writing, there is a growing list of device drivers with +>>> patches implementing error recovery. Not all of these patches are in >>> mainline yet. These may be used as "examples": >>> ->>> drivers/scsi/ipr.c ->>> drivers/scsi/sym53cxx_2 +>>> drivers/scsi/ipr +>>> drivers/scsi/sym53c8xx_2 +>>> drivers/scsi/qla2xxx +>>> drivers/scsi/lpfc +>>> drivers/next/bnx2.c >>> drivers/next/e100.c >>> drivers/net/e1000 +>>> drivers/net/e1000e >>> drivers/net/ixgb +>>> drivers/net/ixgbe +>>> drivers/net/cxgb3 >>> drivers/net/s2io.c +>>> drivers/net/qlge The End ------- diff --git a/Documentation/arm/OMAP/omap_pm b/Documentation/arm/OMAP/omap_pm new file mode 100644 index 00000000000..5389440aade --- /dev/null +++ b/Documentation/arm/OMAP/omap_pm @@ -0,0 +1,129 @@ + +The OMAP PM interface +===================== + +This document describes the temporary OMAP PM interface. Driver +authors use these functions to communicate minimum latency or +throughput constraints to the kernel power management code. +Over time, the intention is to merge features from the OMAP PM +interface into the Linux PM QoS code. + +Drivers need to express PM parameters which: + +- support the range of power management parameters present in the TI SRF; + +- separate the drivers from the underlying PM parameter + implementation, whether it is the TI SRF or Linux PM QoS or Linux + latency framework or something else; + +- specify PM parameters in terms of fundamental units, such as + latency and throughput, rather than units which are specific to OMAP + or to particular OMAP variants; + +- allow drivers which are shared with other architectures (e.g., + DaVinci) to add these constraints in a way which won't affect non-OMAP + systems, + +- can be implemented immediately with minimal disruption of other + architectures. + + +This document proposes the OMAP PM interface, including the following +five power management functions for driver code: + +1. Set the maximum MPU wakeup latency: + (*pdata->set_max_mpu_wakeup_lat)(struct device *dev, unsigned long t) + +2. Set the maximum device wakeup latency: + (*pdata->set_max_dev_wakeup_lat)(struct device *dev, unsigned long t) + +3. Set the maximum system DMA transfer start latency (CORE pwrdm): + (*pdata->set_max_sdma_lat)(struct device *dev, long t) + +4. Set the minimum bus throughput needed by a device: + (*pdata->set_min_bus_tput)(struct device *dev, u8 agent_id, unsigned long r) + +5. Return the number of times the device has lost context + (*pdata->get_dev_context_loss_count)(struct device *dev) + + +Further documentation for all OMAP PM interface functions can be +found in arch/arm/plat-omap/include/mach/omap-pm.h. + + +The OMAP PM layer is intended to be temporary +--------------------------------------------- + +The intention is that eventually the Linux PM QoS layer should support +the range of power management features present in OMAP3. As this +happens, existing drivers using the OMAP PM interface can be modified +to use the Linux PM QoS code; and the OMAP PM interface can disappear. + + +Driver usage of the OMAP PM functions +------------------------------------- + +As the 'pdata' in the above examples indicates, these functions are +exposed to drivers through function pointers in driver .platform_data +structures. The function pointers are initialized by the board-*.c +files to point to the corresponding OMAP PM functions: +.set_max_dev_wakeup_lat will point to +omap_pm_set_max_dev_wakeup_lat(), etc. Other architectures which do +not support these functions should leave these function pointers set +to NULL. Drivers should use the following idiom: + + if (pdata->set_max_dev_wakeup_lat) + (*pdata->set_max_dev_wakeup_lat)(dev, t); + +The most common usage of these functions will probably be to specify +the maximum time from when an interrupt occurs, to when the device +becomes accessible. To accomplish this, driver writers should use the +set_max_mpu_wakeup_lat() function to to constrain the MPU wakeup +latency, and the set_max_dev_wakeup_lat() function to constrain the +device wakeup latency (from clk_enable() to accessibility). For +example, + + /* Limit MPU wakeup latency */ + if (pdata->set_max_mpu_wakeup_lat) + (*pdata->set_max_mpu_wakeup_lat)(dev, tc); + + /* Limit device powerdomain wakeup latency */ + if (pdata->set_max_dev_wakeup_lat) + (*pdata->set_max_dev_wakeup_lat)(dev, td); + + /* total wakeup latency in this example: (tc + td) */ + +The PM parameters can be overwritten by calling the function again +with the new value. The settings can be removed by calling the +function with a t argument of -1 (except in the case of +set_max_bus_tput(), which should be called with an r argument of 0). + +The fifth function above, omap_pm_get_dev_context_loss_count(), +is intended as an optimization to allow drivers to determine whether the +device has lost its internal context. If context has been lost, the +driver must restore its internal context before proceeding. + + +Other specialized interface functions +------------------------------------- + +The five functions listed above are intended to be usable by any +device driver. DSPBridge and CPUFreq have a few special requirements. +DSPBridge expresses target DSP performance levels in terms of OPP IDs. +CPUFreq expresses target MPU performance levels in terms of MPU +frequency. The OMAP PM interface contains functions for these +specialized cases to convert that input information (OPPs/MPU +frequency) into the form that the underlying power management +implementation needs: + +6. (*pdata->dsp_get_opp_table)(void) + +7. (*pdata->dsp_set_min_opp)(u8 opp_id) + +8. (*pdata->dsp_get_opp)(void) + +9. (*pdata->cpu_get_freq_table)(void) + +10. (*pdata->cpu_set_freq)(unsigned long f) + +11. (*pdata->cpu_get_freq)(void) diff --git a/Documentation/cpu-freq/user-guide.txt b/Documentation/cpu-freq/user-guide.txt index 5d5f5fadd1c..2a5b850847c 100644 --- a/Documentation/cpu-freq/user-guide.txt +++ b/Documentation/cpu-freq/user-guide.txt @@ -176,7 +176,9 @@ scaling_governor, and by "echoing" the name of another work on some specific architectures or processors. -cpuinfo_cur_freq : Current speed of the CPU, in KHz. +cpuinfo_cur_freq : Current frequency of the CPU as obtained from + the hardware, in KHz. This is the frequency + the CPU actually runs at. scaling_available_frequencies : List of available frequencies, in KHz. @@ -196,7 +198,10 @@ related_cpus : List of CPUs that need some sort of frequency scaling_driver : Hardware driver for cpufreq. -scaling_cur_freq : Current frequency of the CPU, in KHz. +scaling_cur_freq : Current frequency of the CPU as determined by + the governor and cpufreq core, in KHz. This is + the frequency the kernel thinks the CPU runs + at. If you have selected the "userspace" governor which allows you to set the CPU operating frequency to a specific value, you can read out diff --git a/Documentation/dontdiff b/Documentation/dontdiff index 88519daab6e..e1efc400bed 100644 --- a/Documentation/dontdiff +++ b/Documentation/dontdiff @@ -152,7 +152,6 @@ piggy.gz piggyback pnmtologo ppc_defs.h* -promcon_tbl.c pss_boot.h qconf raid6altivec*.c diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 503d21216d5..fa75220f8d3 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -428,16 +428,6 @@ Who: Johannes Berg <johannes@sipsolutions.net> ---------------------------- -What: CONFIG_X86_OLD_MCE -When: 2.6.32 -Why: Remove the old legacy 32bit machine check code. This has been - superseded by the newer machine check code from the 64bit port, - but the old version has been kept around for easier testing. Note this - doesn't impact the old P5 and WinChip machine check handlers. -Who: Andi Kleen <andi@firstfloor.org> - ----------------------------- - What: lock_policy_rwsem_* and unlock_policy_rwsem_* will not be exported interface anymore. When: 2.6.33 diff --git a/Documentation/hwmon/pcf8591 b/Documentation/hwmon/pcf8591 index 5628fcf4207..e76a7892f68 100644 --- a/Documentation/hwmon/pcf8591 +++ b/Documentation/hwmon/pcf8591 @@ -2,11 +2,11 @@ Kernel driver pcf8591 ===================== Supported chips: - * Philips PCF8591 + * Philips/NXP PCF8591 Prefix: 'pcf8591' Addresses scanned: I2C 0x48 - 0x4f - Datasheet: Publicly available at the Philips Semiconductor website - http://www.semiconductors.philips.com/pip/PCF8591P.html + Datasheet: Publicly available at the NXP website + http://www.nxp.com/pip/PCF8591_6.html Authors: Aurelien Jarno <aurelien@aurel32.net> @@ -16,9 +16,10 @@ Authors: Description ----------- + The PCF8591 is an 8-bit A/D and D/A converter (4 analog inputs and one -analog output) for the I2C bus produced by Philips Semiconductors. It -is designed to provide a byte I2C interface to up to 4 separate devices. +analog output) for the I2C bus produced by Philips Semiconductors (now NXP). +It is designed to provide a byte I2C interface to up to 4 separate devices. The PCF8591 has 4 analog inputs programmable as single-ended or differential inputs : @@ -58,8 +59,8 @@ Accessing PCF8591 via /sys interface ------------------------------------- ! Be careful ! -The PCF8591 is plainly impossible to detect ! Stupid chip. -So every chip with address in the interval [48..4f] is +The PCF8591 is plainly impossible to detect! Stupid chip. +So every chip with address in the interval [0x48..0x4f] is detected as PCF8591. If you have other chips in this address range, the workaround is to load this module after the one for your others chips. @@ -67,19 +68,20 @@ for your others chips. On detection (i.e. insmod, modprobe et al.), directories are being created for each detected PCF8591: -/sys/bus/devices/<0>-<1>/ +/sys/bus/i2c/devices/<0>-<1>/ where <0> is the bus the chip was detected on (e. g. i2c-0) and <1> the chip address ([48..4f]) Inside these directories, there are such files: -in0, in1, in2, in3, out0_enable, out0_output, name +in0_input, in1_input, in2_input, in3_input, out0_enable, out0_output, name Name contains chip name. -The in0, in1, in2 and in3 files are RO. Reading gives the value of the -corresponding channel. Depending on the current analog inputs configuration, -files in2 and/or in3 do not exist. Values range are from 0 to 255 for single -ended inputs and -128 to +127 for differential inputs (8-bit ADC). +The in0_input, in1_input, in2_input and in3_input files are RO. Reading gives +the value of the corresponding channel. Depending on the current analog inputs +configuration, files in2_input and in3_input may not exist. Values range +from 0 to 255 for single ended inputs and -128 to +127 for differential inputs +(8-bit ADC). The out0_enable file is RW. Reading gives "1" for analog output enabled and "0" for analog output disabled. Writing accepts "0" and "1" accordingly. diff --git a/Documentation/hwmon/tmp421 b/Documentation/hwmon/tmp421 new file mode 100644 index 00000000000..0cf07f82474 --- /dev/null +++ b/Documentation/hwmon/tmp421 @@ -0,0 +1,36 @@ +Kernel driver tmp421 +==================== + +Supported chips: + * Texas Instruments TMP421 + Prefix: 'tmp421' + Addresses scanned: I2C 0x2a, 0x4c, 0x4d, 0x4e and 0x4f + Datasheet: http://focus.ti.com/docs/prod/folders/print/tmp421.html + * Texas Instruments TMP422 + Prefix: 'tmp422' + Addresses scanned: I2C 0x2a, 0x4c, 0x4d, 0x4e and 0x4f + Datasheet: http://focus.ti.com/docs/prod/folders/print/tmp421.html + * Texas Instruments TMP423 + Prefix: 'tmp423' + Addresses scanned: I2C 0x2a, 0x4c, 0x4d, 0x4e and 0x4f + Datasheet: http://focus.ti.com/docs/prod/folders/print/tmp421.html + +Authors: + Andre Prendel <andre.prendel@gmx.de> + +Description +----------- + +This driver implements support for Texas Instruments TMP421, TMP422 +and TMP423 temperature sensor chips. These chips implement one local +and up to one (TMP421), up to two (TMP422) or up to three (TMP423) +remote sensors. Temperature is measured in degrees Celsius. The chips +are wired over I2C/SMBus and specified over a temperature range of -40 +to +125 degrees Celsius. Resolution for both the local and remote +channels is 0.0625 degree C. + +The chips support only temperature measurement. The driver exports +the temperature values via the following sysfs files: + +temp[1-4]_input +temp[2-4]_fault diff --git a/Documentation/hwmon/wm831x b/Documentation/hwmon/wm831x new file mode 100644 index 00000000000..24f47d8f6a4 --- /dev/null +++ b/Documentation/hwmon/wm831x @@ -0,0 +1,37 @@ +Kernel driver wm831x-hwmon +========================== + +Supported chips: + * Wolfson Microelectronics WM831x PMICs + Prefix: 'wm831x' + Datasheet: + http://www.wolfsonmicro.com/products/WM8310 + http://www.wolfsonmicro.com/products/WM8311 + http://www.wolfsonmicro.com/products/WM8312 + +Authors: Mark Brown <broonie@opensource.wolfsonmicro.com> + +Description +----------- + +The WM831x series of PMICs include an AUXADC which can be used to +monitor a range of system operating parameters, including the voltages +of the major supplies within the system. Currently the driver provides +reporting of all the input values but does not provide any alarms. + +Voltage Monitoring +------------------ + +Voltages are sampled by a 12 bit ADC. Voltages in milivolts are 1.465 +times the ADC value. + +Temperature Monitoring +---------------------- + +Temperatures are sampled by a 12 bit ADC. Chip and battery temperatures +are available. The chip temperature is calculated as: + + Degrees celsius = (512.18 - data) / 1.0983 + +while the battery temperature calculation will depend on the NTC +thermistor component. diff --git a/Documentation/hwmon/wm8350 b/Documentation/hwmon/wm8350 new file mode 100644 index 00000000000..98f923bd2e9 --- /dev/null +++ b/Documentation/hwmon/wm8350 @@ -0,0 +1,26 @@ +Kernel driver wm8350-hwmon +========================== + +Supported chips: + * Wolfson Microelectronics WM835x PMICs + Prefix: 'wm8350' + Datasheet: + http://www.wolfsonmicro.com/products/WM8350 + http://www.wolfsonmicro.com/products/WM8351 + http://www.wolfsonmicro.com/products/WM8352 + +Authors: Mark Brown <broonie@opensource.wolfsonmicro.com> + +Description +----------- + +The WM835x series of PMICs include an AUXADC which can be used to +monitor a range of system operating parameters, including the voltages +of the major supplies within the system. Currently the driver provides +simple access to these major supplies. + +Voltage Monitoring +------------------ + +Voltages are sampled by a 12 bit ADC. For the internal supplies the ADC +is referenced to the system VRTC. diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 574ee67b618..0f17d16dc10 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1286,6 +1286,10 @@ and is between 256 and 4096 characters. It is defined in the file (machvec) in a generic kernel. Example: machvec=hpzx1_swiotlb + machtype= [Loongson] Share the same kernel image file between different + yeeloong laptop. + Example: machtype=lemote-yeeloong-2f-7inch + max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than or equal to this physical address is ignored. diff --git a/Documentation/trace/events.txt b/Documentation/trace/events.txt index 2bcc8d4dea2..78c45a87be5 100644 --- a/Documentation/trace/events.txt +++ b/Documentation/trace/events.txt @@ -1,7 +1,7 @@ Event Tracing Documentation written by Theodore Ts'o - Updated by Li Zefan + Updated by Li Zefan and Tom Zanussi 1. Introduction =============== @@ -22,12 +22,12 @@ tracing information should be printed. --------------------------------- The events which are available for tracing can be found in the file -/debug/tracing/available_events. +/sys/kernel/debug/tracing/available_events. To enable a particular event, such as 'sched_wakeup', simply echo it -to /debug/tracing/set_event. For example: +to /sys/kernel/debug/tracing/set_event. For example: - # echo sched_wakeup >> /debug/tracing/set_event + # echo sched_wakeup >> /sys/kernel/debug/tracing/set_event [ Note: '>>' is necessary, otherwise it will firstly disable all the events. ] @@ -35,15 +35,15 @@ to /debug/tracing/set_event. For example: To disable an event, echo the event name to the set_event file prefixed with an exclamation point: - # echo '!sched_wakeup' >> /debug/tracing/set_event + # echo '!sched_wakeup' >> /sys/kernel/debug/tracing/set_event To disable all events, echo an empty line to the set_event file: - # echo > /debug/tracing/set_event + # echo > /sys/kernel/debug/tracing/set_event To enable all events, echo '*:*' or '*:' to the set_event file: - # echo *:* > /debug/tracing/set_event + # echo *:* > /sys/kernel/debug/tracing/set_event The events are organized into subsystems, such as ext4, irq, sched, etc., and a full event name looks like this: <subsystem>:<event>. The @@ -52,29 +52,29 @@ file. All of the events in a subsystem can be specified via the syntax "<subsystem>:*"; for example, to enable all irq events, you can use the command: - # echo 'irq:*' > /debug/tracing/set_event + # echo 'irq:*' > /sys/kernel/debug/tracing/set_event 2.2 Via the 'enable' toggle --------------------------- -The events available are also listed in /debug/tracing/events/ hierarchy +The events available are also listed in /sys/kernel/debug/tracing/events/ hierarchy of directories. To enable event 'sched_wakeup': - # echo 1 > /debug/tracing/events/sched/sched_wakeup/enable + # echo 1 > /sys/kernel/debug/tracing/events/sched/sched_wakeup/enable To disable it: - # echo 0 > /debug/tracing/events/sched/sched_wakeup/enable + # echo 0 > /sys/kernel/debug/tracing/events/sched/sched_wakeup/enable To enable all events in sched subsystem: - # echo 1 > /debug/tracing/events/sched/enable + # echo 1 > /sys/kernel/debug/tracing/events/sched/enable To eanble all events: - # echo 1 > /debug/tracing/events/enable + # echo 1 > /sys/kernel/debug/tracing/events/enable When reading one of these enable files, there are four results: @@ -97,3 +97,185 @@ The format of this boot option is the same as described in section 2.1. See The example provided in samples/trace_events +4. Event formats +================ + +Each trace event has a 'format' file associated with it that contains +a description of each field in a logged event. This information can +be used to parse the binary trace stream, and is also the place to +find the field names that can be used in event filters (see section 5). + +It also displays the format string that will be used to print the +event in text mode, along with the event name and ID used for +profiling. + +Every event has a set of 'common' fields associated with it; these are +the fields prefixed with 'common_'. The other fields vary between +events and correspond to the fields defined in the TRACE_EVENT +definition for that event. + +Each field in the format has the form: + + field:field-type field-name; offset:N; size:N; + +where offset is the offset of the field in the trace record and size +is the size of the data item, in bytes. + +For example, here's the information displayed for the 'sched_wakeup' +event: + +# cat /debug/tracing/events/sched/sched_wakeup/format + +name: sched_wakeup +ID: 60 +format: + field:unsigned short common_type; offset:0; size:2; + field:unsigned char common_flags; offset:2; size:1; + field:unsigned char common_preempt_count; offset:3; size:1; + field:int common_pid; offset:4; size:4; + field:int common_tgid; offset:8; size:4; + + field:char comm[TASK_COMM_LEN]; offset:12; size:16; + field:pid_t pid; offset:28; size:4; + field:int prio; offset:32; size:4; + field:int success; offset:36; size:4; + field:int cpu; offset:40; size:4; + +print fmt: "task %s:%d [%d] success=%d [%03d]", REC->comm, REC->pid, + REC->prio, REC->success, REC->cpu + +This event contains 10 fields, the first 5 common and the remaining 5 +event-specific. All the fields for this event are numeric, except for +'comm' which is a string, a distinction important for event filtering. + +5. Event filtering +================== + +Trace events can be filtered in the kernel by associating boolean +'filter expressions' with them. As soon as an event is logged into +the trace buffer, its fields are checked against the filter expression +associated with that event type. An event with field values that +'match' the filter will appear in the trace output, and an event whose +values don't match will be discarded. An event with no filter +associated with it matches everything, and is the default when no +filter has been set for an event. + +5.1 Expression syntax +--------------------- + +A filter expression consists of one or more 'predicates' that can be +combined using the logical operators '&&' and '||'. A predicate is +simply a clause that compares the value of a field contained within a +logged event with a constant value and returns either 0 or 1 depending +on whether the field value matched (1) or didn't match (0): + + field-name relational-operator value + +Parentheses can be used to provide arbitrary logical groupings and +double-quotes can be used to prevent the shell from interpreting +operators as shell metacharacters. + +The field-names available for use in filters can be found in the +'format' files for trace events (see section 4). + +The relational-operators depend on the type of the field being tested: + +The operators available for numeric fields are: + +==, !=, <, <=, >, >= + +And for string fields they are: + +==, != + +Currently, only exact string matches are supported. + +Currently, the maximum number of predicates in a filter is 16. + +5.2 Setting filters +------------------- + +A filter for an individual event is set by writing a filter expression +to the 'filter' file for the given event. + +For example: + +# cd /debug/tracing/events/sched/sched_wakeup +# echo "common_preempt_count > 4" > filter + +A slightly more involved example: + +# cd /debug/tracing/events/sched/sched_signal_send +# echo "((sig >= 10 && sig < 15) || sig == 17) && comm != bash" > filter + +If there is an error in the expression, you'll get an 'Invalid +argument' error when setting it, and the erroneous string along with +an error message can be seen by looking at the filter e.g.: + +# cd /debug/tracing/events/sched/sched_signal_send +# echo "((sig >= 10 && sig < 15) || dsig == 17) && comm != bash" > filter +-bash: echo: write error: Invalid argument +# cat filter +((sig >= 10 && sig < 15) || dsig == 17) && comm != bash +^ +parse_error: Field not found + +Currently the caret ('^') for an error always appears at the beginning of +the filter string; the error message should still be useful though +even without more accurate position info. + +5.3 Clearing filters +-------------------- + +To clear the filter for an event, write a '0' to the event's filter +file. + +To clear the filters for all events in a subsystem, write a '0' to the +subsystem's filter file. + +5.3 Subsystem filters +--------------------- + +For convenience, filters for every event in a subsystem can be set or +cleared as a group by writing a filter expression into the filter file +at the root of the subsytem. Note however, that if a filter for any +event within the subsystem lacks a field specified in the subsystem +filter, or if the filter can't be applied for any other reason, the +filter for that event will retain its previous setting. This can +result in an unintended mixture of filters which could lead to +confusing (to the user who might think different filters are in +effect) trace output. Only filters that reference just the common +fields can be guaranteed to propagate successfully to all events. + +Here are a few subsystem filter examples that also illustrate the +above points: + +Clear the filters on all events in the sched subsytem: + +# cd /sys/kernel/debug/tracing/events/sched +# echo 0 > filter +# cat sched_switch/filter +none +# cat sched_wakeup/filter +none + +Set a filter using only common fields for all events in the sched +subsytem (all events end up with the same filter): + +# cd /sys/kernel/debug/tracing/events/sched +# echo common_pid == 0 > filter +# cat sched_switch/filter +common_pid == 0 +# cat sched_wakeup/filter +common_pid == 0 + +Attempt to set a filter using a non-common field for all events in the +sched subsytem (all events but those that have a prev_pid field retain +their old filters): + +# cd /sys/kernel/debug/tracing/events/sched +# echo prev_pid == 0 > filter +# cat sched_switch/filter +prev_pid == 0 +# cat sched_wakeup/filter +common_pid == 0 diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt new file mode 100644 index 00000000000..7003e10f10f --- /dev/null +++ b/Documentation/trace/ftrace-design.txt @@ -0,0 +1,233 @@ + function tracer guts + ==================== + +Introduction +------------ + +Here we will cover the architecture pieces that the common function tracing +code relies on for proper functioning. Things are broken down into increasing +complexity so that you can start simple and at least get basic functionality. + +Note that this focuses on architecture implementation details only. If you +want more explanation of a feature in terms of common code, review the common +ftrace.txt file. + + +Prerequisites +------------- + +Ftrace relies on these features being implemented: + STACKTRACE_SUPPORT - implement save_stack_trace() + TRACE_IRQFLAGS_SUPPORT - implement include/asm/irqflags.h + + +HAVE_FUNCTION_TRACER +-------------------- + +You will need to implement the mcount and the ftrace_stub functions. + +The exact mcount symbol name will depend on your toolchain. Some call it +"mcount", "_mcount", or even "__mcount". You can probably figure it out by +running something like: + $ echo 'main(){}' | gcc -x c -S -o - - -pg | grep mcount + call mcount +We'll make the assumption below that the symbol is "mcount" just to keep things +nice and simple in the examples. + +Keep in mind that the ABI that is in effect inside of the mcount function is +*highly* architecture/toolchain specific. We cannot help you in this regard, +sorry. Dig up some old documentation and/or find someone more familiar than +you to bang ideas off of. Typically, register usage (argument/scratch/etc...) +is a major issue at this point, especially in relation to the location of the +mcount call (before/after function prologue). You might also want to look at +how glibc has implemented the mcount function for your architecture. It might +be (semi-)relevant. + +The mcount function should check the function pointer ftrace_trace_function +to see if it is set to ftrace_stub. If it is, there is nothing for you to do, +so return immediately. If it isn't, then call that function in the same way +the mcount function normally calls __mcount_internal -- the first argument is +the "frompc" while the second argument is the "selfpc" (adjusted to remove the +size of the mcount call that is embedded in the function). + +For example, if the function foo() calls bar(), when the bar() function calls +mcount(), the arguments mcount() will pass to the tracer are: + "frompc" - the address bar() will use to return to foo() + "selfpc" - the address bar() (with _mcount() size adjustment) + +Also keep in mind that this mcount function will be called *a lot*, so +optimizing for the default case of no tracer will help the smooth running of +your system when tracing is disabled. So the start of the mcount function is +typically the bare min with checking things before returning. That also means +the code flow should usually kept linear (i.e. no branching in the nop case). +This is of course an optimization and not a hard requirement. + +Here is some pseudo code that should help (these functions should actually be +implemented in assembly): + +void ftrace_stub(void) +{ + return; +} + +void mcount(void) +{ + /* save any bare state needed in order to do initial checking */ + + extern void (*ftrace_trace_function)(unsigned long, unsigned long); + if (ftrace_trace_function != ftrace_stub) + goto do_trace; + + /* restore any bare state */ + + return; + +do_trace: + + /* save all state needed by the ABI (see paragraph above) */ + + unsigned long frompc = ...; + unsigned long selfpc = <return address> - MCOUNT_INSN_SIZE; + ftrace_trace_function(frompc, selfpc); + + /* restore all state needed by the ABI */ +} + +Don't forget to export mcount for modules ! +extern void mcount(void); +EXPORT_SYMBOL(mcount); + + +HAVE_FUNCTION_TRACE_MCOUNT_TEST +------------------------------- + +This is an optional optimization for the normal case when tracing is turned off +in the system. If you do not enable this Kconfig option, the common ftrace +code will take care of doing the checking for you. + +To support this feature, you only need to check the function_trace_stop +variable in the mcount function. If it is non-zero, there is no tracing to be +done at all, so you can return. + +This additional pseudo code would simply be: +void mcount(void) +{ + /* save any bare state needed in order to do initial checking */ + ++ if (function_trace_stop) ++ return; + + extern void (*ftrace_trace_function)(unsigned long, unsigned long); + if (ftrace_trace_function != ftrace_stub) +... + + +HAVE_FUNCTION_GRAPH_TRACER +-------------------------- + +Deep breath ... time to do some real work. Here you will need to update the +mcount function to check ftrace graph function pointers, as well as implement +some functions to save (hijack) and restore the return address. + +The mcount function should check the function pointers ftrace_graph_return +(compare to ftrace_stub) and ftrace_graph_entry (compare to +ftrace_graph_entry_stub). If either of those are not set to the relevant stub +function, call the arch-specific function ftrace_graph_caller which in turn +calls the arch-specific function prepare_ftrace_return. Neither of these +function names are strictly required, but you should use them anyways to stay +consistent across the architecture ports -- easier to compare & contrast +things. + +The arguments to prepare_ftrace_return are slightly different than what are +passed to ftrace_trace_function. The second argument "selfpc" is the same, +but the first argument should be a pointer to the "frompc". Typically this is +located on the stack. This allows the function to hijack the return address +temporarily to have it point to the arch-specific function return_to_handler. +That function will simply call the common ftrace_return_to_handler function and +that will return the original return address with which, you can return to the +original call site. + +Here is the updated mcount pseudo code: +void mcount(void) +{ +... + if (ftrace_trace_function != ftrace_stub) + goto do_trace; + ++#ifdef CONFIG_FUNCTION_GRAPH_TRACER ++ extern void (*ftrace_graph_return)(...); ++ extern void (*ftrace_graph_entry)(...); ++ if (ftrace_graph_return != ftrace_stub || ++ ftrace_graph_entry != ftrace_graph_entry_stub) ++ ftrace_graph_caller(); ++#endif + + /* restore any bare state */ +... + +Here is the pseudo code for the new ftrace_graph_caller assembly function: +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +void ftrace_graph_caller(void) +{ + /* save all state needed by the ABI */ + + unsigned long *frompc = &...; + unsigned long selfpc = <return address> - MCOUNT_INSN_SIZE; + prepare_ftrace_return(frompc, selfpc); + + /* restore all state needed by the ABI */ +} +#endif + +For information on how to implement prepare_ftrace_return(), simply look at +the x86 version. The only architecture-specific piece in it is the setup of +the fault recovery table (the asm(...) code). The rest should be the same +across architectures. + +Here is the pseudo code for the new return_to_handler assembly function. Note +that the ABI that applies here is different from what applies to the mcount +code. Since you are returning from a function (after the epilogue), you might +be able to skimp on things saved/restored (usually just registers used to pass +return values). + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +void return_to_handler(void) +{ + /* save all state needed by the ABI (see paragraph above) */ + + void (*original_return_point)(void) = ftrace_return_to_handler(); + + /* restore all state needed by the ABI */ + + /* this is usually either a return or a jump */ + original_return_point(); +} +#endif + + +HAVE_FTRACE_NMI_ENTER +--------------------- + +If you can't trace NMI functions, then skip this option. + +<details to be filled> + + +HAVE_FTRACE_SYSCALLS +--------------------- + +<details to be filled> + + +HAVE_FTRACE_MCOUNT_RECORD +------------------------- + +See scripts/recordmcount.pl for more info. + +<details to be filled> + + +HAVE_DYNAMIC_FTRACE +--------------------- + +<details to be filled> diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 355d0f1f8c5..1b6292bbdd6 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -26,6 +26,12 @@ disabled, and more (ftrace allows for tracer plugins, which means that the list of tracers can always grow). +Implementation Details +---------------------- + +See ftrace-design.txt for details for arch porters and such. + + The File System --------------- diff --git a/Documentation/vgaarbiter.txt b/Documentation/vgaarbiter.txt new file mode 100644 index 00000000000..987f9b0a5ec --- /dev/null +++ b/Documentation/vgaarbiter.txt @@ -0,0 +1,194 @@ + +VGA Arbiter +=========== + +Graphic devices are accessed through ranges in I/O or memory space. While most +modern devices allow relocation of such ranges, some "Legacy" VGA devices +implemented on PCI will typically have the same "hard-decoded" addresses as +they did on ISA. For more details see "PCI Bus Binding to IEEE Std 1275-1994 +Standard for Boot (Initialization Configuration) Firmware Revision 2.1" +Section 7, Legacy Devices. + +The Resource Access Control (RAC) module inside the X server [0] existed for +the legacy VGA arbitration task (besides other bus management tasks) when more +than one legacy device co-exists on the same machine. But the problem happens +when these devices are trying to be accessed by different userspace clients +(e.g. two server in parallel). Their address assignments conflict. Moreover, +ideally, being an userspace application, it is not the role of the the X +server to control bus resources. Therefore an arbitration scheme outside of +the X server is needed to control the sharing of these resources. This +document introduces the operation of the VGA arbiter implemented for Linux +kernel. + +---------------------------------------------------------------------------- + +I. Details and Theory of Operation + I.1 vgaarb + I.2 libpciaccess + I.3 xf86VGAArbiter (X server implementation) +II. Credits +III.References + + +I. Details and Theory of Operation +================================== + +I.1 vgaarb +---------- + +The vgaarb is a module of the Linux Kernel. When it is initially loaded, it +scans all PCI devices and adds the VGA ones inside the arbitration. The +arbiter then enables/disables the decoding on different devices of the VGA +legacy instructions. Device which do not want/need to use the arbiter may +explicitly tell it by calling vga_set_legacy_decoding(). + +The kernel exports a char device interface (/dev/vga_arbiter) to the clients, +which has the following semantics: + + open : open user instance of the arbiter. By default, it's attached to + the default VGA device of the system. + + close : close user instance. Release locks made by the user + + read : return a string indicating the status of the target like: + + "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)" + + An IO state string is of the form {io,mem,io+mem,none}, mc and + ic are respectively mem and io lock counts (for debugging/ + diagnostic only). "decodes" indicate what the card currently + decodes, "owns" indicates what is currently enabled on it, and + "locks" indicates what is locked by this card. If the card is + unplugged, we get "invalid" then for card_ID and an -ENODEV + error is returned for any command until a new card is targeted. + + + write : write a command to the arbiter. List of commands: + + target <card_ID> : switch target to card <card_ID> (see below) + lock <io_state> : acquires locks on target ("none" is an invalid io_state) + trylock <io_state> : non-blocking acquire locks on target (returns EBUSY if + unsuccessful) + unlock <io_state> : release locks on target + unlock all : release all locks on target held by this user (not + implemented yet) + decodes <io_state> : set the legacy decoding attributes for the card + + poll : event if something changes on any card (not just the + target) + + card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default" + to go back to the system default card (TODO: not implemented yet). Currently, + only PCI is supported as a prefix, but the userland API may support other bus + types in the future, even if the current kernel implementation doesn't. + +Note about locks: + +The driver keeps track of which user has which locks on which card. It +supports stacking, like the kernel one. This complexifies the implementation +a bit, but makes the arbiter more tolerant to user space problems and able +to properly cleanup in all cases when a process dies. +Currently, a max of 16 cards can have locks simultaneously issued from +user space for a given user (file descriptor instance) of the arbiter. + +In the case of devices hot-{un,}plugged, there is a hook - pci_notify() - to +notify them being added/removed in the system and automatically added/removed +in the arbiter. + +There's also a in-kernel API of the arbiter in the case of DRM, vgacon and +others which may use the arbiter. + + +I.2 libpciaccess +---------------- + +To use the vga arbiter char device it was implemented an API inside the +libpciaccess library. One fieldd was added to struct pci_device (each device +on the system): + + /* the type of resource decoded by the device */ + int vgaarb_rsrc; + +Besides it, in pci_system were added: + + int vgaarb_fd; + int vga_count; + struct pci_device *vga_target; + struct pci_device *vga_default_dev; + + +The vga_count is usually need to keep informed how many cards are being +arbitrated, so for instance if there's only one then it can totally escape the +scheme. + + +These functions below acquire VGA resources for the given card and mark those +resources as locked. If the resources requested are "normal" (and not legacy) +resources, the arbiter will first check whether the card is doing legacy +decoding for that type of resource. If yes, the lock is "converted" into a +legacy resource lock. The arbiter will first look for all VGA cards that +might conflict and disable their IOs and/or Memory access, including VGA +forwarding on P2P bridges if necessary, so that the requested resources can +be used. Then, the card is marked as locking these resources and the IO and/or +Memory access is enabled on the card (including VGA forwarding on parent +P2P bridges if any). In the case of vga_arb_lock(), the function will block +if some conflicting card is already locking one of the required resources (or +any resource on a different bus segment, since P2P bridges don't differentiate +VGA memory and IO afaik). If the card already owns the resources, the function +succeeds. vga_arb_trylock() will return (-EBUSY) instead of blocking. Nested +calls are supported (a per-resource counter is maintained). + + +Set the target device of this client. + int pci_device_vgaarb_set_target (struct pci_device *dev); + + +For instance, in x86 if two devices on the same bus want to lock different +resources, both will succeed (lock). If devices are in different buses and +trying to lock different resources, only the first who tried succeeds. + int pci_device_vgaarb_lock (void); + int pci_device_vgaarb_trylock (void); + +Unlock resources of device. + int pci_device_vgaarb_unlock (void); + +Indicates to the arbiter if the card decodes legacy VGA IOs, legacy VGA +Memory, both, or none. All cards default to both, the card driver (fbdev for +example) should tell the arbiter if it has disabled legacy decoding, so the +card can be left out of the arbitration process (and can be safe to take +interrupts at any time. + int pci_device_vgaarb_decodes (int new_vgaarb_rsrc); + +Connects to the arbiter device, allocates the struct + int pci_device_vgaarb_init (void); + +Close the connection + void pci_device_vgaarb_fini (void); + + +I.3 xf86VGAArbiter (X server implementation) +-------------------------------------------- + +(TODO) + +X server basically wraps all the functions that touch VGA registers somehow. + + +II. Credits +=========== + +Benjamin Herrenschmidt (IBM?) started this work when he discussed such design +with the Xorg community in 2005 [1, 2]. In the end of 2007, Paulo Zanoni and +Tiago Vignatti (both of C3SL/Federal University of Paran�) proceeded his work +enhancing the kernel code to adapt as a kernel module and also did the +implementation of the user space side [3]. Now (2009) Tiago Vignatti and Dave +Airlie finally put this work in shape and queued to Jesse Barnes' PCI tree. + + +III. References +============== + +[0] http://cgit.freedesktop.org/xorg/xserver/commit/?id=4b42448a2388d40f257774fbffdccaea87bd0347 +[1] http://lists.freedesktop.org/archives/xorg/2005-March/006663.html +[2] http://lists.freedesktop.org/archives/xorg/2005-March/006745.html +[3] http://lists.freedesktop.org/archives/xorg/2007-October/029507.html |