diff options
Diffstat (limited to 'arch/arm/mach-vexpress/tc2_pm_psci.c')
-rw-r--r-- | arch/arm/mach-vexpress/tc2_pm_psci.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/arch/arm/mach-vexpress/tc2_pm_psci.c b/arch/arm/mach-vexpress/tc2_pm_psci.c new file mode 100644 index 000000000000..c2fdc22e4c06 --- /dev/null +++ b/arch/arm/mach-vexpress/tc2_pm_psci.c @@ -0,0 +1,173 @@ +/* + * arch/arm/mach-vexpress/tc2_pm_psci.c - TC2 PSCI support + * + * Created by: Achin Gupta, December 2012 + * Copyright: (C) 2012 ARM Limited + * + * Some portions of this file were originally written by Nicolas Pitre + * Copyright: (C) 2012 Linaro Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/spinlock.h> +#include <linux/errno.h> + +#include <asm/mcpm.h> +#include <asm/proc-fns.h> +#include <asm/cacheflush.h> +#include <asm/psci.h> +#include <asm/atomic.h> +#include <asm/cputype.h> +#include <asm/cp15.h> + +#include <mach/motherboard.h> +#include <mach/tc2.h> + +#include <linux/vexpress.h> + +/* + * Platform specific state id understood by the firmware and used to + * program the power controller + */ +#define PSCI_POWER_STATE_ID 0 + +static atomic_t tc2_pm_use_count[TC2_MAX_CPUS][TC2_MAX_CLUSTERS]; + +static int tc2_pm_psci_power_up(unsigned int cpu, unsigned int cluster) +{ + unsigned int mpidr = (cluster << 8) | cpu; + int ret = 0; + + BUG_ON(!psci_ops.cpu_on); + + switch (atomic_inc_return(&tc2_pm_use_count[cpu][cluster])) { + case 1: + /* + * This is a request to power up a cpu that linux thinks has + * been powered down. Retries are needed if the firmware has + * seen the power down request as yet. + */ + do + ret = psci_ops.cpu_on(mpidr, + virt_to_phys(mcpm_entry_point)); + while (ret == -EAGAIN); + + return ret; + case 2: + /* This power up request has overtaken a power down request */ + return ret; + default: + /* Any other value is a bug */ + BUG(); + } +} + +static void tc2_pm_psci_power_down(void) +{ + struct psci_power_state power_state; + unsigned int mpidr, cpu, cluster; + + mpidr = read_cpuid_mpidr(); + cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); + cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); + + BUG_ON(!psci_ops.cpu_off); + + switch (atomic_dec_return(&tc2_pm_use_count[cpu][cluster])) { + case 1: + /* + * Overtaken by a power up. Flush caches, exit coherency, + * return & fake a reset + */ + set_cr(get_cr() & ~CR_C); + + flush_cache_louis(); + + asm volatile ("clrex"); + set_auxcr(get_auxcr() & ~(1 << 6)); + + return; + case 0: + /* A normal request to possibly power down the cluster */ + power_state.id = PSCI_POWER_STATE_ID; + power_state.type = PSCI_POWER_STATE_TYPE_POWER_DOWN; + power_state.affinity_level = PSCI_POWER_STATE_AFFINITY_LEVEL1; + + psci_ops.cpu_off(power_state); + + /* On success this function never returns */ + default: + /* Any other value is a bug */ + BUG(); + } +} + +static void tc2_pm_psci_suspend(u64 unused) +{ + struct psci_power_state power_state; + + BUG_ON(!psci_ops.cpu_suspend); + + /* On TC2 always attempt to power down the cluster */ + power_state.id = PSCI_POWER_STATE_ID; + power_state.type = PSCI_POWER_STATE_TYPE_POWER_DOWN; + power_state.affinity_level = PSCI_POWER_STATE_AFFINITY_LEVEL1; + + psci_ops.cpu_suspend(power_state, virt_to_phys(mcpm_entry_point)); + + /* On success this function never returns */ + BUG(); +} + +static const struct mcpm_platform_ops tc2_pm_power_ops = { + .power_up = tc2_pm_psci_power_up, + .power_down = tc2_pm_psci_power_down, + .suspend = tc2_pm_psci_suspend, +}; + +static void __init tc2_pm_usage_count_init(void) +{ + unsigned int mpidr, cpu, cluster; + + mpidr = read_cpuid_mpidr(); + cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0); + cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1); + + pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster); + BUG_ON(cluster >= TC2_MAX_CLUSTERS || + cpu >= vexpress_spc_get_nb_cpus(cluster)); + + atomic_set(&tc2_pm_use_count[cpu][cluster], 1); +} + +static int __init tc2_pm_psci_init(void) +{ + int ret; + + ret = psci_probe(); + if (ret) { + pr_debug("psci not found. Aborting psci init\n"); + return -ENODEV; + } + + if (!vexpress_spc_check_loaded()) { + pr_debug("spc not found. Aborting psci init\n"); + return -ENODEV; + } + + tc2_pm_usage_count_init(); + + ret = mcpm_platform_register(&tc2_pm_power_ops); + if (!ret) + ret = mcpm_sync_init(NULL); + if (!ret) + pr_info("TC2 power management initialized\n"); + return ret; +} + +early_initcall(tc2_pm_psci_init); |