/* * System Control and Management Interface (SCMI) Message Protocol driver * * SCMI Message Protocol is used between the System Control Processor(SCP) * and the Application Processors(AP). The Message Handling Unit(MHU) * provides a mechanism for inter-processor communication between SCP's * Cortex M3 and AP. * * SCP offers control and management of the core/cluster power states, * various power domain DVFS including the core/cluster, certain system * clocks configuration, thermal sensors and many others. * * Copyright (C) 2017 ARM Ltd. * * This program is free software; you can redistribute it and/or modify it * under the terms and conditions of the GNU General Public License, * version 2, as published by the Free Software Foundation. * * This program is distributed in the hope it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for * more details. * * You should have received a copy of the GNU General Public License along * with this program. If not, see . */ #include #include #include #include #include #include #include #include #include #include #include "common.h" #define MSG_ID_SHIFT 0 #define MSG_ID_MASK 0xff #define MSG_TYPE_SHIFT 8 #define MSG_TYPE_MASK 0x3 #define MSG_PROTOCOL_ID_SHIFT 10 #define MSG_PROTOCOL_ID_MASK 0xff #define MSG_TOKEN_ID_SHIFT 18 #define MSG_TOKEN_ID_MASK 0x3ff #define MSG_XTRACT_TOKEN(header) \ (((header) >> MSG_TOKEN_ID_SHIFT) & MSG_TOKEN_ID_MASK) enum scmi_error_codes { SCMI_SUCCESS = 0, /* Success */ SCMI_ERR_SUPPORT = -1, /* Not supported */ SCMI_ERR_PARAMS = -2, /* Invalid Parameters */ SCMI_ERR_ACCESS = -3, /* Invalid access/permission denied */ SCMI_ERR_ENTRY = -4, /* Not found */ SCMI_ERR_RANGE = -5, /* Value out of range */ SCMI_ERR_BUSY = -6, /* Device busy */ SCMI_ERR_COMMS = -7, /* Communication Error */ SCMI_ERR_GENERIC = -8, /* Generic Error */ SCMI_ERR_HARDWARE = -9, /* Hardware Error */ SCMI_ERR_PROTOCOL = -10,/* Protocol Error */ SCMI_ERR_MAX }; /* List of all SCMI devices active in system */ static LIST_HEAD(scmi_list); /* Protection for the entire list */ static DEFINE_MUTEX(scmi_list_mutex); /** * struct scmi_xfers_info - Structure to manage transfer information * * @sem_xfer_count: Counting Semaphore for managing max simultaneous * Messages. * @xfer_block: Preallocated Message array * @xfer_alloc_table: Bitmap table for allocated messages. * Index of this bitmap table is also used for message * sequence identifier. * @xfer_lock: Protection for message allocation */ struct scmi_xfers_info { struct semaphore sem_xfer_count; struct scmi_xfer *xfer_block; unsigned long *xfer_alloc_table; /* protect transfer allocation */ spinlock_t xfer_lock; }; /** * struct scmi_desc - Description of SoC integration * * @max_rx_timeout_ms: Timeout for communication with SoC (in Milliseconds) * @max_msg: Maximum number of messages that can be pending * simultaneously in the system * @max_msg_size: Maximum size of data per message that can be handled. */ struct scmi_desc { int max_rx_timeout_ms; int max_msg; int max_msg_size; }; /** * struct scmi_info - Structure representing a SCMI instance * * @dev: Device pointer * @desc: SoC description for this instance * @handle: Instance of SCMI handle to send to clients * @version: SCMI revision information containing protocol version, * implementation version and (sub-)vendor identification. * @cl: Mailbox Client * @tx_chan: Transmit mailbox channel * @rx_chan: Receive mailbox channel * @tx_payload: Transmit mailbox channel payload area * @rx_payload: Receive mailbox channel payload area * @minfo: Message info * @protocols_imp: list of protocols implemented * @node: list head * @users: Number of users of this instance */ struct scmi_info { struct device *dev; const struct scmi_desc *desc; struct scmi_revision_info version; struct scmi_handle handle; struct mbox_client cl; struct mbox_chan *tx_chan; struct mbox_chan *rx_chan; void __iomem *tx_payload; void __iomem *rx_payload; struct scmi_xfers_info minfo; u8 *protocols_imp; struct list_head node; int users; }; #define client_to_scmi_info(c) container_of(c, struct scmi_info, cl) #define handle_to_scmi_info(h) container_of(h, struct scmi_info, handle) /* * The SCP firmware providing SCM interface to OSPM and other agents must * execute only in little-endian mode as per SCMI specification, so any buffers * shared through SCMI should have their contents converted to little-endian */ struct scmi_shared_mem { __le32 reserved; __le32 channel_status; #define SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR BIT(1) #define SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE BIT(0) __le32 reserved1[2]; __le32 flags; #define SCMI_SHMEM_FLAG_INTR_ENABLED BIT(0) __le32 length; __le32 msg_header; u8 msg_payload[0]; }; struct scmi_protocol_match { u8 protocol_id; scmi_init_fn_t fn; char name[32]; }; static int scmi_linux_errmap[] = { /* better than switch case as long as return value is continuous */ 0, /* SCMI_SUCCESS */ -EOPNOTSUPP, /* SCMI_ERR_SUPPORT */ -EINVAL, /* SCMI_ERR_PARAM */ -EACCES, /* SCMI_ERR_ACCESS */ -ENOENT, /* SCMI_ERR_ENTRY */ -ERANGE, /* SCMI_ERR_RANGE */ -EBUSY, /* SCMI_ERR_BUSY */ -ECOMM, /* SCMI_ERR_COMMS */ -EIO, /* SCMI_ERR_GENERIC */ -EREMOTEIO, /* SCMI_ERR_HARDWARE */ -EPROTO, /* SCMI_ERR_PROTOCOL */ }; static inline int scmi_to_linux_errno(int errno) { if (errno < SCMI_SUCCESS && errno > SCMI_ERR_MAX) return scmi_linux_errmap[-errno]; return -EIO; } /** * scmi_dump_header_dbg() - Helper to dump a message header. * * @dev: Device pointer corresponding to the SCMI entity * @hdr: pointer to header. */ static inline void scmi_dump_header_dbg(struct device *dev, struct scmi_msg_hdr *hdr) { dev_dbg(dev, "Command ID: %x Sequence ID: %x Protocol: %x\n", hdr->id, hdr->seq, hdr->protocol_id); } /** * scmi_rx_callback() - mailbox client callback for receive messages * * @cl: client pointer * @m: mailbox message * * Processes one received message to appropriate transfer information and * signals completion of the transfer. * * NOTE: This function will be invoked in IRQ context, hence should be * as optimal as possible. */ static void scmi_rx_callback(struct mbox_client *cl, void *m) { u16 xfer_id; struct scmi_xfer *xfer; struct scmi_info *info = client_to_scmi_info(cl); struct scmi_xfers_info *minfo = &info->minfo; struct device *dev = info->dev; struct scmi_shared_mem *mem = info->tx_payload; xfer_id = MSG_XTRACT_TOKEN(mem->msg_header); /* * Are we even expecting this? */ if (!test_bit(xfer_id, minfo->xfer_alloc_table)) { dev_err(dev, "message for %d is not expected!\n", xfer_id); return; } xfer = &minfo->xfer_block[xfer_id]; scmi_dump_header_dbg(dev, &xfer->hdr); /* Is the message of valid length? */ if (xfer->rx.len > info->desc->max_msg_size) { dev_err(dev, "unable to handle %zu xfer(max %d)\n", xfer->rx.len, info->desc->max_msg_size); return; } xfer->hdr.status = le32_to_cpu(*(__le32 *)mem->msg_payload); /* Skip the length of header and statues in payload area i.e 8 bytes*/ xfer->rx.len = min_t(size_t, xfer->rx.len, mem->length - 8); /* Take a copy to the rx buffer.. */ memcpy_fromio(xfer->rx.buf, mem->msg_payload + 4, xfer->rx.len); complete(&xfer->done); } /** * pack_scmi_header() - packs and returns 32-bit header * * @hdr: pointer to header containing all the information on message id, * protocol id and sequence id. */ static inline u32 pack_scmi_header(struct scmi_msg_hdr *hdr) { return ((hdr->id & MSG_ID_MASK) << MSG_ID_SHIFT) | ((hdr->seq & MSG_TOKEN_ID_MASK) << MSG_TOKEN_ID_SHIFT) | ((hdr->protocol_id & MSG_PROTOCOL_ID_MASK) << MSG_PROTOCOL_ID_SHIFT); } /** * scmi_tx_prepare() - mailbox client callback to prepare for the transfer * * @cl: client pointer * @m: mailbox message * * This function prepares the shared memory which contains the header and the * payload. */ static void scmi_tx_prepare(struct mbox_client *cl, void *m) { struct scmi_xfer *t = m; struct scmi_info *info = client_to_scmi_info(cl); struct scmi_shared_mem *mem = info->tx_payload; mem->channel_status = 0x0; /* Mark channel busy + clear error */ mem->flags = t->hdr.poll_completion ? 0 : SCMI_SHMEM_FLAG_INTR_ENABLED; mem->length = sizeof(mem->msg_header) + t->tx.len; mem->msg_header = cpu_to_le32(pack_scmi_header(&t->hdr)); if (t->tx.buf) memcpy_toio(mem->msg_payload, t->tx.buf, t->tx.len); } /** * scmi_one_xfer_get() - Allocate one message * * @handle: SCMI entity handle * * Helper function which is used by various command functions that are * exposed to clients of this driver for allocating a message traffic event. * * This function can sleep depending on pending requests already in the system * for the SCMI entity. Further, this also holds a spinlock to maintain * integrity of internal data structures. * * Return: 0 if all went fine, else corresponding error. */ static struct scmi_xfer *scmi_one_xfer_get(const struct scmi_handle *handle) { u16 xfer_id; int ret, timeout; struct scmi_xfer *xfer; unsigned long flags, bit_pos; struct scmi_info *info = handle_to_scmi_info(handle); struct scmi_xfers_info *minfo = &info->minfo; /* * Ensure we have only controlled number of pending messages. * Ideally, we might just have to wait a single message, be * conservative and wait 5 times that.. */ timeout = msecs_to_jiffies(info->desc->max_rx_timeout_ms) * 5; ret = down_timeout(&minfo->sem_xfer_count, timeout); if (ret < 0) return ERR_PTR(ret); /* Keep the locked section as small as possible */ spin_lock_irqsave(&minfo->xfer_lock, flags); bit_pos = find_first_zero_bit(minfo->xfer_alloc_table, info->desc->max_msg); if (bit_pos == info->desc->max_msg) { spin_unlock_irqrestore(&minfo->xfer_lock, flags); return ERR_PTR(-ENOMEM); } set_bit(bit_pos, minfo->xfer_alloc_table); spin_unlock_irqrestore(&minfo->xfer_lock, flags); xfer_id = bit_pos; xfer = &minfo->xfer_block[xfer_id]; xfer->hdr.seq = xfer_id; reinit_completion(&xfer->done); return xfer; } /** * scmi_one_xfer_put() - Release a message * * @minfo: transfer info pointer * @xfer: message that was reserved by scmi_one_xfer_get * * This holds a spinlock to maintain integrity of internal data structures. */ void scmi_one_xfer_put(const struct scmi_handle *handle, struct scmi_xfer *xfer) { unsigned long flags; struct scmi_info *info = handle_to_scmi_info(handle); struct scmi_xfers_info *minfo = &info->minfo; /* * Keep the locked section as small as possible * NOTE: we might escape with smp_mb and no lock here.. * but just be conservative and symmetric. */ spin_lock_irqsave(&minfo->xfer_lock, flags); clear_bit(xfer->hdr.seq, minfo->xfer_alloc_table); spin_unlock_irqrestore(&minfo->xfer_lock, flags); /* Increment the count for the next user to get through */ up(&minfo->sem_xfer_count); } /** * scmi_do_xfer() - Do one transfer * * @info: Pointer to SCMI entity information * @xfer: Transfer to initiate and wait for response * * Return: -ETIMEDOUT in case of no response, if transmit error, * return corresponding error, else if all goes well, * return 0. */ int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer) { int ret; int timeout; struct scmi_info *info = handle_to_scmi_info(handle); struct device *dev = info->dev; ret = mbox_send_message(info->tx_chan, xfer); if (ret < 0) { dev_dbg(dev, "mbox send fail %d\n", ret); return ret; } /* mbox_send_message returns non-negative value on success, so reset */ ret = 0; /* And we wait for the response. */ timeout = msecs_to_jiffies(info->desc->max_rx_timeout_ms); if (!wait_for_completion_timeout(&xfer->done, timeout)) { dev_err(dev, "mbox timed out in resp(caller: %pF)\n", (void *)_RET_IP_); ret = -ETIMEDOUT; } else if (xfer->hdr.status) { ret = scmi_to_linux_errno(xfer->hdr.status); } /* * NOTE: we might prefer not to need the mailbox ticker to manage the * transfer queueing since the protocol layer queues things by itself. * Unfortunately, we have to kick the mailbox framework after we have * received our message. */ mbox_client_txdone(info->tx_chan, ret); return ret; } /** * scmi_one_xfer_init() - Allocate and initialise one message * * @handle: SCMI entity handle * @msg_id: Message identifier * @msg_prot_id: Protocol identifier for the message * @tx_size: transmit message size * @rx_size: receive message size * @p: pointer to the allocated and initialised message * * This function allocates the message using @scmi_one_xfer_get and * initialise the header. * * Return: 0 if all went fine with @p pointing to message, else * corresponding error. */ int scmi_one_xfer_init(const struct scmi_handle *handle, u8 msg_id, u8 prot_id, size_t tx_size, size_t rx_size, struct scmi_xfer **p) { int ret; struct scmi_xfer *xfer; struct scmi_info *info = handle_to_scmi_info(handle); struct device *dev = info->dev; /* Ensure we have sane transfer sizes */ if (rx_size > info->desc->max_msg_size || tx_size > info->desc->max_msg_size) return -ERANGE; xfer = scmi_one_xfer_get(handle); if (IS_ERR(xfer)) { ret = PTR_ERR(xfer); dev_err(dev, "failed to get free message slot(%d)\n", ret); return ret; } xfer->tx.len = tx_size; xfer->rx.len = rx_size ? : info->desc->max_msg_size; xfer->hdr.id = msg_id; xfer->hdr.protocol_id = prot_id; *p = xfer; return 0; } /** * scmi_version_get() - command to get the revision of the SCMI entity * * @handle: Handle to SCMI entity information * * Updates the SCMI information in the internal data structure. * * Return: 0 if all went fine, else return appropriate error. */ int scmi_version_get(const struct scmi_handle *handle, u8 protocol, u32 *version) { int ret; __le32 *rev_info; struct scmi_xfer *t; ret = scmi_one_xfer_init(handle, PROTOCOL_VERSION, protocol, 0, sizeof(*version), &t); if (ret) return ret; ret = scmi_do_xfer(handle, t); if (!ret) { rev_info = t->rx.buf; *version = le32_to_cpu(*rev_info); } scmi_one_xfer_put(handle, t); return ret; } void scmi_setup_protocol_implemented(const struct scmi_handle *handle, u8 *prot_imp) { struct scmi_info *info = handle_to_scmi_info(handle); info->protocols_imp = prot_imp; } static bool scmi_is_protocol_implemented(const struct scmi_handle *handle, u8 prot_id) { int i; struct scmi_info *info = handle_to_scmi_info(handle); if (!info->protocols_imp) return false; for (i = 0; i < MAX_PROTOCOLS_IMP; i++) if (info->protocols_imp[i] == prot_id) return true; return false; } /** * scmi_handle_get() - Get the SCMI handle for a device * * @dev: pointer to device for which we want SCMI handle * * NOTE: The function does not track individual clients of the framework * and is expected to be maintained by caller of SCMI protocol library. * scmi_handle_put must be balanced with successful scmi_handle_get * * Return: pointer to handle if successful, else: * -EPROBE_DEFER if the instance is not ready * -ENODEV if the required node handler is missing * -EINVAL if invalid conditions are encountered. */ const struct scmi_handle *scmi_handle_get(struct device *dev) { struct list_head *p; struct scmi_info *info; struct scmi_handle *handle = NULL; if (!dev || !dev->parent) { pr_err("missing device or parent pointer\n"); return ERR_PTR(-EINVAL); } mutex_lock(&scmi_list_mutex); list_for_each(p, &scmi_list) { info = list_entry(p, struct scmi_info, node); if (dev->parent == info->dev) { handle = &info->handle; info->users++; break; } } mutex_unlock(&scmi_list_mutex); if (!handle) return ERR_PTR(-EPROBE_DEFER); return handle; } EXPORT_SYMBOL_GPL(scmi_handle_get); /** * scmi_handle_put() - Release the handle acquired by scmi_handle_get * * @handle: handle acquired by scmi_handle_get * * NOTE: The function does not track individual clients of the framework * and is expected to be maintained by caller of SCMI protocol library. * scmi_handle_put must be balanced with successful scmi_handle_get * * Return: 0 is successfully released * if an error pointer was passed, it returns the error value back, * if null was passed, it returns -EINVAL; */ int scmi_handle_put(const struct scmi_handle *handle) { struct scmi_info *info; if (IS_ERR(handle)) return PTR_ERR(handle); if (!handle) return -EINVAL; info = handle_to_scmi_info(handle); mutex_lock(&scmi_list_mutex); if (!WARN_ON(!info->users)) info->users--; mutex_unlock(&scmi_list_mutex); return 0; } EXPORT_SYMBOL_GPL(scmi_handle_put); static void devm_scmi_release(struct device *dev, void *res) { const struct scmi_handle **ptr = res; const struct scmi_handle *handle = *ptr; int ret; ret = scmi_handle_put(handle); if (ret) dev_err(dev, "failed to put handle %d\n", ret); } /** * devm_scmi_handle_get() - Managed get handle * @dev: device for which we want SCMI handle for. * * NOTE: This releases the handle once the device resources are * no longer needed. MUST NOT BE released with scmi_handle_put. * The function does not track individual clients of the framework * and is expected to be maintained by caller of SCMI protocol library. * * Return: 0 if all went fine, else corresponding error. */ const struct scmi_handle *devm_scmi_handle_get(struct device *dev) { const struct scmi_handle **ptr; const struct scmi_handle *handle; ptr = devres_alloc(devm_scmi_release, sizeof(*ptr), GFP_KERNEL); if (!ptr) return ERR_PTR(-ENOMEM); handle = scmi_handle_get(dev); if (!IS_ERR(handle)) { *ptr = handle; devres_add(dev, ptr); } else { devres_free(ptr); } return handle; } EXPORT_SYMBOL_GPL(devm_scmi_handle_get); static const struct scmi_desc scmi_generic_desc = { .max_rx_timeout_ms = 30, /* we may increase this if required */ .max_msg = 20, /* Limited by MBOX_TX_QUEUE_LEN */ .max_msg_size = 128, }; /* Each compatible listed below must have descriptor associated with it */ static const struct of_device_id scmi_of_match[] = { { .compatible = "arm,scmi", .data = &scmi_generic_desc }, { /* Sentinel */ }, }; MODULE_DEVICE_TABLE(of, scmi_of_match); static int scmi_xfer_info_init(struct scmi_info *sinfo) { int i; struct scmi_xfer *xfer; struct device *dev = sinfo->dev; const struct scmi_desc *desc = sinfo->desc; struct scmi_xfers_info *info = &sinfo->minfo; /* Pre-allocated messages, no more than what hdr.seq can support */ if (WARN_ON(desc->max_msg >= (MSG_TOKEN_ID_MASK + 1))) { dev_err(dev, "Maximum message of %d exceeds supported %d\n", desc->max_msg, MSG_TOKEN_ID_MASK + 1); return -EINVAL; } info->xfer_block = devm_kcalloc(dev, desc->max_msg, sizeof(*info->xfer_block), GFP_KERNEL); if (!info->xfer_block) return -ENOMEM; info->xfer_alloc_table = devm_kcalloc(dev, BITS_TO_LONGS(desc->max_msg), sizeof(long), GFP_KERNEL); if (!info->xfer_alloc_table) return -ENOMEM; bitmap_zero(info->xfer_alloc_table, desc->max_msg); /* Pre-initialize the buffer pointer to pre-allocated buffers */ for (i = 0, xfer = info->xfer_block; i < desc->max_msg; i++, xfer++) { xfer->rx.buf = devm_kcalloc(dev, sizeof(u8), desc->max_msg_size, GFP_KERNEL); if (!xfer->rx.buf) return -ENOMEM; xfer->tx.buf = xfer->rx.buf; init_completion(&xfer->done); } spin_lock_init(&info->xfer_lock); sema_init(&info->sem_xfer_count, desc->max_msg); return 0; } static const struct scmi_protocol_match scmi_protocols[] = { { .protocol_id = SCMI_PROTOCOL_PERF, .fn = scmi_perf_protocol_init, .name = "scmi-cpufreq", }, { .protocol_id = SCMI_PROTOCOL_CLOCK, .fn = scmi_clock_protocol_init, .name = "scmi-clocks", }, { .protocol_id = SCMI_PROTOCOL_POWER, .fn = scmi_power_protocol_init, .name = "scmi-power-domain", }, { .protocol_id = SCMI_PROTOCOL_SENSOR, .fn = scmi_sensors_protocol_init, .name = "scmi-hwmon", }, {} }; static const struct scmi_protocol_match *scmi_protocol_match_get(u8 protocol_id) { int i; const struct scmi_protocol_match *match = NULL, *loop = scmi_protocols; for (i = 0; i < ARRAY_SIZE(scmi_protocols); i++, loop++) if (loop->protocol_id == protocol_id) { match = loop; break; } return match; } static int scmi_probe(struct platform_device *pdev) { int ret = -EINVAL; struct resource res; resource_size_t size; struct mbox_client *cl; struct scmi_handle *handle; const struct scmi_desc *desc; struct scmi_info *info = NULL; struct device *dev = &pdev->dev; struct device_node *child, *shmem, *np = dev->of_node; desc = of_match_device(scmi_of_match, dev)->data; if (of_property_match_string(np, "method", "mailbox-doorbell") < 0) { dev_err(dev, "invalid method property in %s\n", np->full_name); return -EINVAL; } info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL); if (!info) return -ENOMEM; info->dev = dev; info->desc = desc; INIT_LIST_HEAD(&info->node); ret = scmi_xfer_info_init(info); if (ret) return ret; platform_set_drvdata(pdev, info); cl = &info->cl; cl->dev = dev; cl->rx_callback = scmi_rx_callback; cl->tx_prepare = scmi_tx_prepare; cl->tx_block = false; cl->knows_txdone = true; shmem = of_parse_phandle(np, "shmem", 0); ret = of_address_to_resource(shmem, 0, &res); of_node_put(shmem); if (ret) { dev_err(dev, "failed to get SCMI Tx payload mem resource\n"); return ret; } size = resource_size(&res); info->tx_payload = devm_ioremap(dev, res.start, size); if (!info->tx_payload) { dev_err(dev, "failed to ioremap SCMI Tx payload\n"); ret = -EADDRNOTAVAIL; return ret; } info->tx_chan = mbox_request_channel_byname(cl, "tx"); if (IS_ERR(info->tx_chan)) { ret = PTR_ERR(info->tx_chan); goto out; } handle = &info->handle; handle->dev = info->dev; handle->version = &info->version; ret = scmi_base_protocol_init(handle); if (ret) { dev_err(dev, "unable to communicate with SCMI(%d)\n", ret); goto out; } mutex_lock(&scmi_list_mutex); list_add_tail(&info->node, &scmi_list); mutex_unlock(&scmi_list_mutex); for_each_available_child_of_node(np, child) { int init_ret; u32 protocol_id; const struct scmi_protocol_match *match; if (of_property_read_u32(child, "reg", &protocol_id)) continue; protocol_id &= MSG_PROTOCOL_ID_MASK; if (!scmi_is_protocol_implemented(handle, protocol_id)) { dev_err(dev, "SCMI protocol %d not implemented\n", protocol_id); continue; } match = scmi_protocol_match_get(protocol_id); if (match) { init_ret = match->fn(handle); if (!init_ret) of_platform_device_create(child, match->name, dev); else dev_err(dev, "SCMI protocol %d init error %d\n", protocol_id, init_ret); } } return 0; out: if (!IS_ERR(info->tx_chan)) mbox_free_channel(info->tx_chan); return ret; } static int scmi_remove(struct platform_device *pdev) { int ret = 0; struct scmi_info *info = platform_get_drvdata(pdev); of_platform_depopulate(&pdev->dev); mutex_lock(&scmi_list_mutex); if (info->users) ret = -EBUSY; else list_del(&info->node); mutex_unlock(&scmi_list_mutex); if (!ret) /* Safe to free channels since no more users */ mbox_free_channel(info->tx_chan); return ret; } static struct platform_driver scmi_driver = { .driver = { .name = "arm-scmi", .of_match_table = of_match_ptr(scmi_of_match), }, .probe = scmi_probe, .remove = scmi_remove, }; module_platform_driver(scmi_driver); MODULE_ALIAS("platform: arm-scmi"); MODULE_AUTHOR("Sudeep Holla "); MODULE_DESCRIPTION("ARM SCMI protocol driver"); MODULE_LICENSE("GPL v2");