text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * System Control and Power Interface (SCPI) Message Protocol driver
   *
   * SCPI 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) 2015 ARM Ltd.
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/bitmap.h>
  #include <linux/bitfield.h>
  #include <linux/device.h>
  #include <linux/err.h>
  #include <linux/export.h>
  #include <linux/io.h>
  #include <linux/kernel.h>
  #include <linux/list.h>
  #include <linux/mailbox_client.h>
  #include <linux/module.h>
  #include <linux/of_address.h>
  #include <linux/of_platform.h>
  #include <linux/printk.h>
  #include <linux/pm_opp.h>
  #include <linux/scpi_protocol.h>
  #include <linux/slab.h>
  #include <linux/sort.h>
  #include <linux/spinlock.h>
  
  #define CMD_ID_MASK		GENMASK(6, 0)
  #define CMD_TOKEN_ID_MASK	GENMASK(15, 8)
  #define CMD_DATA_SIZE_MASK	GENMASK(24, 16)
  #define CMD_LEGACY_DATA_SIZE_MASK	GENMASK(28, 20)
  #define PACK_SCPI_CMD(cmd_id, tx_sz)		\
  	(FIELD_PREP(CMD_ID_MASK, cmd_id) |	\
  	FIELD_PREP(CMD_DATA_SIZE_MASK, tx_sz))
  #define PACK_LEGACY_SCPI_CMD(cmd_id, tx_sz)	\
  	(FIELD_PREP(CMD_ID_MASK, cmd_id) |	\
  	FIELD_PREP(CMD_LEGACY_DATA_SIZE_MASK, tx_sz))
  
  #define CMD_SIZE(cmd)	FIELD_GET(CMD_DATA_SIZE_MASK, cmd)
  #define CMD_UNIQ_MASK	(CMD_TOKEN_ID_MASK | CMD_ID_MASK)
  #define CMD_XTRACT_UNIQ(cmd)	((cmd) & CMD_UNIQ_MASK)
  
  #define SCPI_SLOT		0
  
  #define MAX_DVFS_DOMAINS	8
  #define MAX_DVFS_OPPS		16
  
  #define PROTO_REV_MAJOR_MASK	GENMASK(31, 16)
  #define PROTO_REV_MINOR_MASK	GENMASK(15, 0)
  
  #define FW_REV_MAJOR_MASK	GENMASK(31, 24)
  #define FW_REV_MINOR_MASK	GENMASK(23, 16)
  #define FW_REV_PATCH_MASK	GENMASK(15, 0)
  
  #define MAX_RX_TIMEOUT		(msecs_to_jiffies(30))
  
  enum scpi_error_codes {
  	SCPI_SUCCESS = 0, /* Success */
  	SCPI_ERR_PARAM = 1, /* Invalid parameter(s) */
  	SCPI_ERR_ALIGN = 2, /* Invalid alignment */
  	SCPI_ERR_SIZE = 3, /* Invalid size */
  	SCPI_ERR_HANDLER = 4, /* Invalid handler/callback */
  	SCPI_ERR_ACCESS = 5, /* Invalid access/permission denied */
  	SCPI_ERR_RANGE = 6, /* Value out of range */
  	SCPI_ERR_TIMEOUT = 7, /* Timeout has occurred */
  	SCPI_ERR_NOMEM = 8, /* Invalid memory area or pointer */
  	SCPI_ERR_PWRSTATE = 9, /* Invalid power state */
  	SCPI_ERR_SUPPORT = 10, /* Not supported or disabled */
  	SCPI_ERR_DEVICE = 11, /* Device error */
  	SCPI_ERR_BUSY = 12, /* Device busy */
  	SCPI_ERR_MAX
  };
  
  /* SCPI Standard commands */
  enum scpi_std_cmd {
  	SCPI_CMD_INVALID		= 0x00,
  	SCPI_CMD_SCPI_READY		= 0x01,
  	SCPI_CMD_SCPI_CAPABILITIES	= 0x02,
  	SCPI_CMD_SET_CSS_PWR_STATE	= 0x03,
  	SCPI_CMD_GET_CSS_PWR_STATE	= 0x04,
  	SCPI_CMD_SET_SYS_PWR_STATE	= 0x05,
  	SCPI_CMD_SET_CPU_TIMER		= 0x06,
  	SCPI_CMD_CANCEL_CPU_TIMER	= 0x07,
  	SCPI_CMD_DVFS_CAPABILITIES	= 0x08,
  	SCPI_CMD_GET_DVFS_INFO		= 0x09,
  	SCPI_CMD_SET_DVFS		= 0x0a,
  	SCPI_CMD_GET_DVFS		= 0x0b,
  	SCPI_CMD_GET_DVFS_STAT		= 0x0c,
  	SCPI_CMD_CLOCK_CAPABILITIES	= 0x0d,
  	SCPI_CMD_GET_CLOCK_INFO		= 0x0e,
  	SCPI_CMD_SET_CLOCK_VALUE	= 0x0f,
  	SCPI_CMD_GET_CLOCK_VALUE	= 0x10,
  	SCPI_CMD_PSU_CAPABILITIES	= 0x11,
  	SCPI_CMD_GET_PSU_INFO		= 0x12,
  	SCPI_CMD_SET_PSU		= 0x13,
  	SCPI_CMD_GET_PSU		= 0x14,
  	SCPI_CMD_SENSOR_CAPABILITIES	= 0x15,
  	SCPI_CMD_SENSOR_INFO		= 0x16,
  	SCPI_CMD_SENSOR_VALUE		= 0x17,
  	SCPI_CMD_SENSOR_CFG_PERIODIC	= 0x18,
  	SCPI_CMD_SENSOR_CFG_BOUNDS	= 0x19,
  	SCPI_CMD_SENSOR_ASYNC_VALUE	= 0x1a,
  	SCPI_CMD_SET_DEVICE_PWR_STATE	= 0x1b,
  	SCPI_CMD_GET_DEVICE_PWR_STATE	= 0x1c,
  	SCPI_CMD_COUNT
  };
  
  /* SCPI Legacy Commands */
  enum legacy_scpi_std_cmd {
  	LEGACY_SCPI_CMD_INVALID			= 0x00,
  	LEGACY_SCPI_CMD_SCPI_READY		= 0x01,
  	LEGACY_SCPI_CMD_SCPI_CAPABILITIES	= 0x02,
  	LEGACY_SCPI_CMD_EVENT			= 0x03,
  	LEGACY_SCPI_CMD_SET_CSS_PWR_STATE	= 0x04,
  	LEGACY_SCPI_CMD_GET_CSS_PWR_STATE	= 0x05,
  	LEGACY_SCPI_CMD_CFG_PWR_STATE_STAT	= 0x06,
  	LEGACY_SCPI_CMD_GET_PWR_STATE_STAT	= 0x07,
  	LEGACY_SCPI_CMD_SYS_PWR_STATE		= 0x08,
  	LEGACY_SCPI_CMD_L2_READY		= 0x09,
  	LEGACY_SCPI_CMD_SET_AP_TIMER		= 0x0a,
  	LEGACY_SCPI_CMD_CANCEL_AP_TIME		= 0x0b,
  	LEGACY_SCPI_CMD_DVFS_CAPABILITIES	= 0x0c,
  	LEGACY_SCPI_CMD_GET_DVFS_INFO		= 0x0d,
  	LEGACY_SCPI_CMD_SET_DVFS		= 0x0e,
  	LEGACY_SCPI_CMD_GET_DVFS		= 0x0f,
  	LEGACY_SCPI_CMD_GET_DVFS_STAT		= 0x10,
  	LEGACY_SCPI_CMD_SET_RTC			= 0x11,
  	LEGACY_SCPI_CMD_GET_RTC			= 0x12,
  	LEGACY_SCPI_CMD_CLOCK_CAPABILITIES	= 0x13,
  	LEGACY_SCPI_CMD_SET_CLOCK_INDEX		= 0x14,
  	LEGACY_SCPI_CMD_SET_CLOCK_VALUE		= 0x15,
  	LEGACY_SCPI_CMD_GET_CLOCK_VALUE		= 0x16,
  	LEGACY_SCPI_CMD_PSU_CAPABILITIES	= 0x17,
  	LEGACY_SCPI_CMD_SET_PSU			= 0x18,
  	LEGACY_SCPI_CMD_GET_PSU			= 0x19,
  	LEGACY_SCPI_CMD_SENSOR_CAPABILITIES	= 0x1a,
  	LEGACY_SCPI_CMD_SENSOR_INFO		= 0x1b,
  	LEGACY_SCPI_CMD_SENSOR_VALUE		= 0x1c,
  	LEGACY_SCPI_CMD_SENSOR_CFG_PERIODIC	= 0x1d,
  	LEGACY_SCPI_CMD_SENSOR_CFG_BOUNDS	= 0x1e,
  	LEGACY_SCPI_CMD_SENSOR_ASYNC_VALUE	= 0x1f,
  	LEGACY_SCPI_CMD_COUNT
  };
  
  /* List all commands that are required to go through the high priority link */
  static int legacy_hpriority_cmds[] = {
  	LEGACY_SCPI_CMD_GET_CSS_PWR_STATE,
  	LEGACY_SCPI_CMD_CFG_PWR_STATE_STAT,
  	LEGACY_SCPI_CMD_GET_PWR_STATE_STAT,
  	LEGACY_SCPI_CMD_SET_DVFS,
  	LEGACY_SCPI_CMD_GET_DVFS,
  	LEGACY_SCPI_CMD_SET_RTC,
  	LEGACY_SCPI_CMD_GET_RTC,
  	LEGACY_SCPI_CMD_SET_CLOCK_INDEX,
  	LEGACY_SCPI_CMD_SET_CLOCK_VALUE,
  	LEGACY_SCPI_CMD_GET_CLOCK_VALUE,
  	LEGACY_SCPI_CMD_SET_PSU,
  	LEGACY_SCPI_CMD_GET_PSU,
  	LEGACY_SCPI_CMD_SENSOR_CFG_PERIODIC,
  	LEGACY_SCPI_CMD_SENSOR_CFG_BOUNDS,
  };
  
  /* List all commands used by this driver, used as indexes */
  enum scpi_drv_cmds {
  	CMD_SCPI_CAPABILITIES = 0,
  	CMD_GET_CLOCK_INFO,
  	CMD_GET_CLOCK_VALUE,
  	CMD_SET_CLOCK_VALUE,
  	CMD_GET_DVFS,
  	CMD_SET_DVFS,
  	CMD_GET_DVFS_INFO,
  	CMD_SENSOR_CAPABILITIES,
  	CMD_SENSOR_INFO,
  	CMD_SENSOR_VALUE,
  	CMD_SET_DEVICE_PWR_STATE,
  	CMD_GET_DEVICE_PWR_STATE,
  	CMD_MAX_COUNT,
  };
  
  static int scpi_std_commands[CMD_MAX_COUNT] = {
  	SCPI_CMD_SCPI_CAPABILITIES,
  	SCPI_CMD_GET_CLOCK_INFO,
  	SCPI_CMD_GET_CLOCK_VALUE,
  	SCPI_CMD_SET_CLOCK_VALUE,
  	SCPI_CMD_GET_DVFS,
  	SCPI_CMD_SET_DVFS,
  	SCPI_CMD_GET_DVFS_INFO,
  	SCPI_CMD_SENSOR_CAPABILITIES,
  	SCPI_CMD_SENSOR_INFO,
  	SCPI_CMD_SENSOR_VALUE,
  	SCPI_CMD_SET_DEVICE_PWR_STATE,
  	SCPI_CMD_GET_DEVICE_PWR_STATE,
  };
  
  static int scpi_legacy_commands[CMD_MAX_COUNT] = {
  	LEGACY_SCPI_CMD_SCPI_CAPABILITIES,
  	-1, /* GET_CLOCK_INFO */
  	LEGACY_SCPI_CMD_GET_CLOCK_VALUE,
  	LEGACY_SCPI_CMD_SET_CLOCK_VALUE,
  	LEGACY_SCPI_CMD_GET_DVFS,
  	LEGACY_SCPI_CMD_SET_DVFS,
  	LEGACY_SCPI_CMD_GET_DVFS_INFO,
  	LEGACY_SCPI_CMD_SENSOR_CAPABILITIES,
  	LEGACY_SCPI_CMD_SENSOR_INFO,
  	LEGACY_SCPI_CMD_SENSOR_VALUE,
  	-1, /* SET_DEVICE_PWR_STATE */
  	-1, /* GET_DEVICE_PWR_STATE */
  };
  
  struct scpi_xfer {
  	u32 slot; /* has to be first element */
  	u32 cmd;
  	u32 status;
  	const void *tx_buf;
  	void *rx_buf;
  	unsigned int tx_len;
  	unsigned int rx_len;
  	struct list_head node;
  	struct completion done;
  };
  
  struct scpi_chan {
  	struct mbox_client cl;
  	struct mbox_chan *chan;
  	void __iomem *tx_payload;
  	void __iomem *rx_payload;
  	struct list_head rx_pending;
  	struct list_head xfers_list;
  	struct scpi_xfer *xfers;
  	spinlock_t rx_lock; /* locking for the rx pending list */
  	struct mutex xfers_lock;
  	u8 token;
  };
  
  struct scpi_drvinfo {
  	u32 protocol_version;
  	u32 firmware_version;
  	bool is_legacy;
  	int num_chans;
  	int *commands;
  	DECLARE_BITMAP(cmd_priority, LEGACY_SCPI_CMD_COUNT);
  	atomic_t next_chan;
  	struct scpi_ops *scpi_ops;
  	struct scpi_chan *channels;
  	struct scpi_dvfs_info *dvfs[MAX_DVFS_DOMAINS];
  };
  
  /*
   * The SCP firmware only executes in little-endian mode, so any buffers
   * shared through SCPI should have their contents converted to little-endian
   */
  struct scpi_shared_mem {
  	__le32 command;
  	__le32 status;
  	u8 payload[0];
  } __packed;
  
  struct legacy_scpi_shared_mem {
  	__le32 status;
  	u8 payload[0];
  } __packed;
  
  struct scp_capabilities {
  	__le32 protocol_version;
  	__le32 event_version;
  	__le32 platform_version;
  	__le32 commands[4];
  } __packed;
  
  struct clk_get_info {
  	__le16 id;
  	__le16 flags;
  	__le32 min_rate;
  	__le32 max_rate;
  	u8 name[20];
  } __packed;
  
  struct clk_set_value {
  	__le16 id;
  	__le16 reserved;
  	__le32 rate;
  } __packed;
  
  struct legacy_clk_set_value {
  	__le32 rate;
  	__le16 id;
  	__le16 reserved;
  } __packed;
  
  struct dvfs_info {
  	u8 domain;
  	u8 opp_count;
  	__le16 latency;
  	struct {
  		__le32 freq;
  		__le32 m_volt;
  	} opps[MAX_DVFS_OPPS];
  } __packed;
  
  struct dvfs_set {
  	u8 domain;
  	u8 index;
  } __packed;
  
  struct _scpi_sensor_info {
  	__le16 sensor_id;
  	u8 class;
  	u8 trigger_type;
  	char name[20];
  };
  
  struct dev_pstate_set {
  	__le16 dev_id;
  	u8 pstate;
  } __packed;
  
  static struct scpi_drvinfo *scpi_info;
  
  static int scpi_linux_errmap[SCPI_ERR_MAX] = {
  	/* better than switch case as long as return value is continuous */
  	0, /* SCPI_SUCCESS */
  	-EINVAL, /* SCPI_ERR_PARAM */
  	-ENOEXEC, /* SCPI_ERR_ALIGN */
  	-EMSGSIZE, /* SCPI_ERR_SIZE */
  	-EINVAL, /* SCPI_ERR_HANDLER */
  	-EACCES, /* SCPI_ERR_ACCESS */
  	-ERANGE, /* SCPI_ERR_RANGE */
  	-ETIMEDOUT, /* SCPI_ERR_TIMEOUT */
  	-ENOMEM, /* SCPI_ERR_NOMEM */
  	-EINVAL, /* SCPI_ERR_PWRSTATE */
  	-EOPNOTSUPP, /* SCPI_ERR_SUPPORT */
  	-EIO, /* SCPI_ERR_DEVICE */
  	-EBUSY, /* SCPI_ERR_BUSY */
  };
  
  static inline int scpi_to_linux_errno(int errno)
  {
  	if (errno >= SCPI_SUCCESS && errno < SCPI_ERR_MAX)
  		return scpi_linux_errmap[errno];
  	return -EIO;
  }
  
  static void scpi_process_cmd(struct scpi_chan *ch, u32 cmd)
  {
  	unsigned long flags;
  	struct scpi_xfer *t, *match = NULL;
  
  	spin_lock_irqsave(&ch->rx_lock, flags);
  	if (list_empty(&ch->rx_pending)) {
  		spin_unlock_irqrestore(&ch->rx_lock, flags);
  		return;
  	}
  
  	/* Command type is not replied by the SCP Firmware in legacy Mode
  	 * We should consider that command is the head of pending RX commands
  	 * if the list is not empty. In TX only mode, the list would be empty.
  	 */
  	if (scpi_info->is_legacy) {
  		match = list_first_entry(&ch->rx_pending, struct scpi_xfer,
  					 node);
  		list_del(&match->node);
  	} else {
  		list_for_each_entry(t, &ch->rx_pending, node)
  			if (CMD_XTRACT_UNIQ(t->cmd) == CMD_XTRACT_UNIQ(cmd)) {
  				list_del(&t->node);
  				match = t;
  				break;
  			}
  	}
  	/* check if wait_for_completion is in progress or timed-out */
  	if (match && !completion_done(&match->done)) {
  		unsigned int len;
  
  		if (scpi_info->is_legacy) {
  			struct legacy_scpi_shared_mem __iomem *mem =
  							ch->rx_payload;
  
  			/* RX Length is not replied by the legacy Firmware */
  			len = match->rx_len;
  
  			match->status = ioread32(&mem->status);
  			memcpy_fromio(match->rx_buf, mem->payload, len);
  		} else {
  			struct scpi_shared_mem __iomem *mem = ch->rx_payload;
  
  			len = min_t(unsigned int, match->rx_len, CMD_SIZE(cmd));
  
  			match->status = ioread32(&mem->status);
  			memcpy_fromio(match->rx_buf, mem->payload, len);
  		}
  
  		if (match->rx_len > len)
  			memset(match->rx_buf + len, 0, match->rx_len - len);
  		complete(&match->done);
  	}
  	spin_unlock_irqrestore(&ch->rx_lock, flags);
  }
  
  static void scpi_handle_remote_msg(struct mbox_client *c, void *msg)
  {
  	struct scpi_chan *ch = container_of(c, struct scpi_chan, cl);
  	struct scpi_shared_mem __iomem *mem = ch->rx_payload;
  	u32 cmd = 0;
  
  	if (!scpi_info->is_legacy)
  		cmd = ioread32(&mem->command);
  
  	scpi_process_cmd(ch, cmd);
  }
  
  static void scpi_tx_prepare(struct mbox_client *c, void *msg)
  {
  	unsigned long flags;
  	struct scpi_xfer *t = msg;
  	struct scpi_chan *ch = container_of(c, struct scpi_chan, cl);
  	struct scpi_shared_mem __iomem *mem = ch->tx_payload;
  
  	if (t->tx_buf) {
  		if (scpi_info->is_legacy)
  			memcpy_toio(ch->tx_payload, t->tx_buf, t->tx_len);
  		else
  			memcpy_toio(mem->payload, t->tx_buf, t->tx_len);
  	}
  
  	if (t->rx_buf) {
  		if (!(++ch->token))
  			++ch->token;
  		t->cmd |= FIELD_PREP(CMD_TOKEN_ID_MASK, ch->token);
  		spin_lock_irqsave(&ch->rx_lock, flags);
  		list_add_tail(&t->node, &ch->rx_pending);
  		spin_unlock_irqrestore(&ch->rx_lock, flags);
  	}
  
  	if (!scpi_info->is_legacy)
  		iowrite32(t->cmd, &mem->command);
  }
  
  static struct scpi_xfer *get_scpi_xfer(struct scpi_chan *ch)
  {
  	struct scpi_xfer *t;
  
  	mutex_lock(&ch->xfers_lock);
  	if (list_empty(&ch->xfers_list)) {
  		mutex_unlock(&ch->xfers_lock);
  		return NULL;
  	}
  	t = list_first_entry(&ch->xfers_list, struct scpi_xfer, node);
  	list_del(&t->node);
  	mutex_unlock(&ch->xfers_lock);
  	return t;
  }
  
  static void put_scpi_xfer(struct scpi_xfer *t, struct scpi_chan *ch)
  {
  	mutex_lock(&ch->xfers_lock);
  	list_add_tail(&t->node, &ch->xfers_list);
  	mutex_unlock(&ch->xfers_lock);
  }
  
  static int scpi_send_message(u8 idx, void *tx_buf, unsigned int tx_len,
  			     void *rx_buf, unsigned int rx_len)
  {
  	int ret;
  	u8 chan;
  	u8 cmd;
  	struct scpi_xfer *msg;
  	struct scpi_chan *scpi_chan;
  
  	if (scpi_info->commands[idx] < 0)
  		return -EOPNOTSUPP;
  
  	cmd = scpi_info->commands[idx];
  
  	if (scpi_info->is_legacy)
  		chan = test_bit(cmd, scpi_info->cmd_priority) ? 1 : 0;
  	else
  		chan = atomic_inc_return(&scpi_info->next_chan) %
  			scpi_info->num_chans;
  	scpi_chan = scpi_info->channels + chan;
  
  	msg = get_scpi_xfer(scpi_chan);
  	if (!msg)
  		return -ENOMEM;
  
  	if (scpi_info->is_legacy) {
  		msg->cmd = PACK_LEGACY_SCPI_CMD(cmd, tx_len);
  		msg->slot = msg->cmd;
  	} else {
  		msg->slot = BIT(SCPI_SLOT);
  		msg->cmd = PACK_SCPI_CMD(cmd, tx_len);
  	}
  	msg->tx_buf = tx_buf;
  	msg->tx_len = tx_len;
  	msg->rx_buf = rx_buf;
  	msg->rx_len = rx_len;
  	reinit_completion(&msg->done);
  
  	ret = mbox_send_message(scpi_chan->chan, msg);
  	if (ret < 0 || !rx_buf)
  		goto out;
  
  	if (!wait_for_completion_timeout(&msg->done, MAX_RX_TIMEOUT))
  		ret = -ETIMEDOUT;
  	else
  		/* first status word */
  		ret = msg->status;
  out:
  	if (ret < 0 && rx_buf) /* remove entry from the list if timed-out */
  		scpi_process_cmd(scpi_chan, msg->cmd);
  
  	put_scpi_xfer(msg, scpi_chan);
  	/* SCPI error codes > 0, translate them to Linux scale*/
  	return ret > 0 ? scpi_to_linux_errno(ret) : ret;
  }
  
  static u32 scpi_get_version(void)
  {
  	return scpi_info->protocol_version;
  }
  
  static int
  scpi_clk_get_range(u16 clk_id, unsigned long *min, unsigned long *max)
  {
  	int ret;
  	struct clk_get_info clk;
  	__le16 le_clk_id = cpu_to_le16(clk_id);
  
  	ret = scpi_send_message(CMD_GET_CLOCK_INFO, &le_clk_id,
  				sizeof(le_clk_id), &clk, sizeof(clk));
  	if (!ret) {
  		*min = le32_to_cpu(clk.min_rate);
  		*max = le32_to_cpu(clk.max_rate);
  	}
  	return ret;
  }
  
  static unsigned long scpi_clk_get_val(u16 clk_id)
  {
  	int ret;
  	__le32 rate;
  	__le16 le_clk_id = cpu_to_le16(clk_id);
  
  	ret = scpi_send_message(CMD_GET_CLOCK_VALUE, &le_clk_id,
  				sizeof(le_clk_id), &rate, sizeof(rate));
  
  	return ret ? ret : le32_to_cpu(rate);
  }
  
  static int scpi_clk_set_val(u16 clk_id, unsigned long rate)
  {
  	int stat;
  	struct clk_set_value clk = {
  		.id = cpu_to_le16(clk_id),
  		.rate = cpu_to_le32(rate)
  	};
  
  	return scpi_send_message(CMD_SET_CLOCK_VALUE, &clk, sizeof(clk),
  				 &stat, sizeof(stat));
  }
  
  static int legacy_scpi_clk_set_val(u16 clk_id, unsigned long rate)
  {
  	int stat;
  	struct legacy_clk_set_value clk = {
  		.id = cpu_to_le16(clk_id),
  		.rate = cpu_to_le32(rate)
  	};
  
  	return scpi_send_message(CMD_SET_CLOCK_VALUE, &clk, sizeof(clk),
  				 &stat, sizeof(stat));
  }
  
  static int scpi_dvfs_get_idx(u8 domain)
  {
  	int ret;
  	u8 dvfs_idx;
  
  	ret = scpi_send_message(CMD_GET_DVFS, &domain, sizeof(domain),
  				&dvfs_idx, sizeof(dvfs_idx));
  
  	return ret ? ret : dvfs_idx;
  }
  
  static int scpi_dvfs_set_idx(u8 domain, u8 index)
  {
  	int stat;
  	struct dvfs_set dvfs = {domain, index};
  
  	return scpi_send_message(CMD_SET_DVFS, &dvfs, sizeof(dvfs),
  				 &stat, sizeof(stat));
  }
  
  static int opp_cmp_func(const void *opp1, const void *opp2)
  {
  	const struct scpi_opp *t1 = opp1, *t2 = opp2;
  
  	return t1->freq - t2->freq;
  }
  
  static struct scpi_dvfs_info *scpi_dvfs_get_info(u8 domain)
  {
  	struct scpi_dvfs_info *info;
  	struct scpi_opp *opp;
  	struct dvfs_info buf;
  	int ret, i;
  
  	if (domain >= MAX_DVFS_DOMAINS)
  		return ERR_PTR(-EINVAL);
  
  	if (scpi_info->dvfs[domain])	/* data already populated */
  		return scpi_info->dvfs[domain];
  
  	ret = scpi_send_message(CMD_GET_DVFS_INFO, &domain, sizeof(domain),
  				&buf, sizeof(buf));
  	if (ret)
  		return ERR_PTR(ret);
  
  	info = kmalloc(sizeof(*info), GFP_KERNEL);
  	if (!info)
  		return ERR_PTR(-ENOMEM);
  
  	info->count = buf.opp_count;
  	info->latency = le16_to_cpu(buf.latency) * 1000; /* uS to nS */
  
  	info->opps = kcalloc(info->count, sizeof(*opp), GFP_KERNEL);
  	if (!info->opps) {
  		kfree(info);
  		return ERR_PTR(-ENOMEM);
  	}
  
  	for (i = 0, opp = info->opps; i < info->count; i++, opp++) {
  		opp->freq = le32_to_cpu(buf.opps[i].freq);
  		opp->m_volt = le32_to_cpu(buf.opps[i].m_volt);
  	}
  
  	sort(info->opps, info->count, sizeof(*opp), opp_cmp_func, NULL);
  
  	scpi_info->dvfs[domain] = info;
  	return info;
  }
  
  static int scpi_dev_domain_id(struct device *dev)
  {
  	struct of_phandle_args clkspec;
  
  	if (of_parse_phandle_with_args(dev->of_node, "clocks", "#clock-cells",
  				       0, &clkspec))
  		return -EINVAL;
  
  	return clkspec.args[0];
  }
  
  static struct scpi_dvfs_info *scpi_dvfs_info(struct device *dev)
  {
  	int domain = scpi_dev_domain_id(dev);
  
  	if (domain < 0)
  		return ERR_PTR(domain);
  
  	return scpi_dvfs_get_info(domain);
  }
  
  static int scpi_dvfs_get_transition_latency(struct device *dev)
  {
  	struct scpi_dvfs_info *info = scpi_dvfs_info(dev);
  
  	if (IS_ERR(info))
  		return PTR_ERR(info);
  
  	return info->latency;
  }
  
  static int scpi_dvfs_add_opps_to_device(struct device *dev)
  {
  	int idx, ret;
  	struct scpi_opp *opp;
  	struct scpi_dvfs_info *info = scpi_dvfs_info(dev);
  
  	if (IS_ERR(info))
  		return PTR_ERR(info);
  
  	if (!info->opps)
  		return -EIO;
  
  	for (opp = info->opps, idx = 0; idx < info->count; idx++, opp++) {
  		ret = dev_pm_opp_add(dev, opp->freq, opp->m_volt * 1000);
  		if (ret) {
  			dev_warn(dev, "failed to add opp %uHz %umV\n",
  				 opp->freq, opp->m_volt);
  			while (idx-- > 0)
  				dev_pm_opp_remove(dev, (--opp)->freq);
  			return ret;
  		}
  	}
  	return 0;
  }
  
  static int scpi_sensor_get_capability(u16 *sensors)
  {
  	__le16 cap;
  	int ret;
  
  	ret = scpi_send_message(CMD_SENSOR_CAPABILITIES, NULL, 0, &cap,
  				sizeof(cap));
  	if (!ret)
  		*sensors = le16_to_cpu(cap);
  
  	return ret;
  }
  
  static int scpi_sensor_get_info(u16 sensor_id, struct scpi_sensor_info *info)
  {
  	__le16 id = cpu_to_le16(sensor_id);
  	struct _scpi_sensor_info _info;
  	int ret;
  
  	ret = scpi_send_message(CMD_SENSOR_INFO, &id, sizeof(id),
  				&_info, sizeof(_info));
  	if (!ret) {
  		memcpy(info, &_info, sizeof(*info));
  		info->sensor_id = le16_to_cpu(_info.sensor_id);
  	}
  
  	return ret;
  }
  
  static int scpi_sensor_get_value(u16 sensor, u64 *val)
  {
  	__le16 id = cpu_to_le16(sensor);
  	__le64 value;
  	int ret;
  
  	ret = scpi_send_message(CMD_SENSOR_VALUE, &id, sizeof(id),
  				&value, sizeof(value));
  	if (ret)
  		return ret;
  
  	if (scpi_info->is_legacy)
  		/* only 32-bits supported, upper 32 bits can be junk */
  		*val = le32_to_cpup((__le32 *)&value);
  	else
  		*val = le64_to_cpu(value);
  
  	return 0;
  }
  
  static int scpi_device_get_power_state(u16 dev_id)
  {
  	int ret;
  	u8 pstate;
  	__le16 id = cpu_to_le16(dev_id);
  
  	ret = scpi_send_message(CMD_GET_DEVICE_PWR_STATE, &id,
  				sizeof(id), &pstate, sizeof(pstate));
  	return ret ? ret : pstate;
  }
  
  static int scpi_device_set_power_state(u16 dev_id, u8 pstate)
  {
  	int stat;
  	struct dev_pstate_set dev_set = {
  		.dev_id = cpu_to_le16(dev_id),
  		.pstate = pstate,
  	};
  
  	return scpi_send_message(CMD_SET_DEVICE_PWR_STATE, &dev_set,
  				 sizeof(dev_set), &stat, sizeof(stat));
  }
  
  static struct scpi_ops scpi_ops = {
  	.get_version = scpi_get_version,
  	.clk_get_range = scpi_clk_get_range,
  	.clk_get_val = scpi_clk_get_val,
  	.clk_set_val = scpi_clk_set_val,
  	.dvfs_get_idx = scpi_dvfs_get_idx,
  	.dvfs_set_idx = scpi_dvfs_set_idx,
  	.dvfs_get_info = scpi_dvfs_get_info,
  	.device_domain_id = scpi_dev_domain_id,
  	.get_transition_latency = scpi_dvfs_get_transition_latency,
  	.add_opps_to_device = scpi_dvfs_add_opps_to_device,
  	.sensor_get_capability = scpi_sensor_get_capability,
  	.sensor_get_info = scpi_sensor_get_info,
  	.sensor_get_value = scpi_sensor_get_value,
  	.device_get_power_state = scpi_device_get_power_state,
  	.device_set_power_state = scpi_device_set_power_state,
  };
  
  struct scpi_ops *get_scpi_ops(void)
  {
  	return scpi_info ? scpi_info->scpi_ops : NULL;
  }
  EXPORT_SYMBOL_GPL(get_scpi_ops);
  
  static int scpi_init_versions(struct scpi_drvinfo *info)
  {
  	int ret;
  	struct scp_capabilities caps;
  
  	ret = scpi_send_message(CMD_SCPI_CAPABILITIES, NULL, 0,
  				&caps, sizeof(caps));
  	if (!ret) {
  		info->protocol_version = le32_to_cpu(caps.protocol_version);
  		info->firmware_version = le32_to_cpu(caps.platform_version);
  	}
  	/* Ignore error if not implemented */
  	if (scpi_info->is_legacy && ret == -EOPNOTSUPP)
  		return 0;
  
  	return ret;
  }
  
  static ssize_t protocol_version_show(struct device *dev,
  				     struct device_attribute *attr, char *buf)
  {
  	struct scpi_drvinfo *scpi_info = dev_get_drvdata(dev);
  
  	return sprintf(buf, "%lu.%lu\n",
  		FIELD_GET(PROTO_REV_MAJOR_MASK, scpi_info->protocol_version),
  		FIELD_GET(PROTO_REV_MINOR_MASK, scpi_info->protocol_version));
  }
  static DEVICE_ATTR_RO(protocol_version);
  
  static ssize_t firmware_version_show(struct device *dev,
  				     struct device_attribute *attr, char *buf)
  {
  	struct scpi_drvinfo *scpi_info = dev_get_drvdata(dev);
  
  	return sprintf(buf, "%lu.%lu.%lu\n",
  		FIELD_GET(FW_REV_MAJOR_MASK, scpi_info->firmware_version),
  		FIELD_GET(FW_REV_MINOR_MASK, scpi_info->firmware_version),
  		FIELD_GET(FW_REV_PATCH_MASK, scpi_info->firmware_version));
  }
  static DEVICE_ATTR_RO(firmware_version);
  
  static struct attribute *versions_attrs[] = {
  	&dev_attr_firmware_version.attr,
  	&dev_attr_protocol_version.attr,
  	NULL,
  };
  ATTRIBUTE_GROUPS(versions);
  
  static void scpi_free_channels(void *data)
  {
  	struct scpi_drvinfo *info = data;
  	int i;
  
  	for (i = 0; i < info->num_chans; i++)
  		mbox_free_channel(info->channels[i].chan);
  }
  
  static int scpi_remove(struct platform_device *pdev)
  {
  	int i;
  	struct scpi_drvinfo *info = platform_get_drvdata(pdev);
  
  	scpi_info = NULL; /* stop exporting SCPI ops through get_scpi_ops */
  
  	for (i = 0; i < MAX_DVFS_DOMAINS && info->dvfs[i]; i++) {
  		kfree(info->dvfs[i]->opps);
  		kfree(info->dvfs[i]);
  	}
  
  	return 0;
  }
  
  #define MAX_SCPI_XFERS		10
  static int scpi_alloc_xfer_list(struct device *dev, struct scpi_chan *ch)
  {
  	int i;
  	struct scpi_xfer *xfers;
  
  	xfers = devm_kcalloc(dev, MAX_SCPI_XFERS, sizeof(*xfers), GFP_KERNEL);
  	if (!xfers)
  		return -ENOMEM;
  
  	ch->xfers = xfers;
  	for (i = 0; i < MAX_SCPI_XFERS; i++, xfers++) {
  		init_completion(&xfers->done);
  		list_add_tail(&xfers->node, &ch->xfers_list);
  	}
  
  	return 0;
  }
  
  static const struct of_device_id legacy_scpi_of_match[] = {
  	{.compatible = "arm,scpi-pre-1.0"},
  	{},
  };
  
  static int scpi_probe(struct platform_device *pdev)
  {
  	int count, idx, ret;
  	struct resource res;
  	struct device *dev = &pdev->dev;
  	struct device_node *np = dev->of_node;
  
  	scpi_info = devm_kzalloc(dev, sizeof(*scpi_info), GFP_KERNEL);
  	if (!scpi_info)
  		return -ENOMEM;
  
  	if (of_match_device(legacy_scpi_of_match, &pdev->dev))
  		scpi_info->is_legacy = true;
  
  	count = of_count_phandle_with_args(np, "mboxes", "#mbox-cells");
  	if (count < 0) {
  		dev_err(dev, "no mboxes property in '%pOF'\n", np);
  		return -ENODEV;
  	}
  
  	scpi_info->channels = devm_kcalloc(dev, count, sizeof(struct scpi_chan),
  					   GFP_KERNEL);
  	if (!scpi_info->channels)
  		return -ENOMEM;
  
  	ret = devm_add_action(dev, scpi_free_channels, scpi_info);
  	if (ret)
  		return ret;
  
  	for (; scpi_info->num_chans < count; scpi_info->num_chans++) {
  		resource_size_t size;
  		int idx = scpi_info->num_chans;
  		struct scpi_chan *pchan = scpi_info->channels + idx;
  		struct mbox_client *cl = &pchan->cl;
  		struct device_node *shmem = of_parse_phandle(np, "shmem", idx);
  
  		ret = of_address_to_resource(shmem, 0, &res);
  		of_node_put(shmem);
  		if (ret) {
  			dev_err(dev, "failed to get SCPI payload mem resource\n");
  			return ret;
  		}
  
  		size = resource_size(&res);
  		pchan->rx_payload = devm_ioremap(dev, res.start, size);
  		if (!pchan->rx_payload) {
  			dev_err(dev, "failed to ioremap SCPI payload\n");
  			return -EADDRNOTAVAIL;
  		}
  		pchan->tx_payload = pchan->rx_payload + (size >> 1);
  
  		cl->dev = dev;
  		cl->rx_callback = scpi_handle_remote_msg;
  		cl->tx_prepare = scpi_tx_prepare;
  		cl->tx_block = true;
  		cl->tx_tout = 20;
  		cl->knows_txdone = false; /* controller can't ack */
  
  		INIT_LIST_HEAD(&pchan->rx_pending);
  		INIT_LIST_HEAD(&pchan->xfers_list);
  		spin_lock_init(&pchan->rx_lock);
  		mutex_init(&pchan->xfers_lock);
  
  		ret = scpi_alloc_xfer_list(dev, pchan);
  		if (!ret) {
  			pchan->chan = mbox_request_channel(cl, idx);
  			if (!IS_ERR(pchan->chan))
  				continue;
  			ret = PTR_ERR(pchan->chan);
  			if (ret != -EPROBE_DEFER)
  				dev_err(dev, "failed to get channel%d err %d\n",
  					idx, ret);
  		}
  		return ret;
  	}
  
  	scpi_info->commands = scpi_std_commands;
  
  	platform_set_drvdata(pdev, scpi_info);
  
  	if (scpi_info->is_legacy) {
  		/* Replace with legacy variants */
  		scpi_ops.clk_set_val = legacy_scpi_clk_set_val;
  		scpi_info->commands = scpi_legacy_commands;
  
  		/* Fill priority bitmap */
  		for (idx = 0; idx < ARRAY_SIZE(legacy_hpriority_cmds); idx++)
  			set_bit(legacy_hpriority_cmds[idx],
  				scpi_info->cmd_priority);
  	}
  
  	ret = scpi_init_versions(scpi_info);
  	if (ret) {
  		dev_err(dev, "incorrect or no SCP firmware found\n");
  		return ret;
  	}
  
  	if (scpi_info->is_legacy && !scpi_info->protocol_version &&
  	    !scpi_info->firmware_version)
  		dev_info(dev, "SCP Protocol legacy pre-1.0 firmware\n");
  	else
  		dev_info(dev, "SCP Protocol %lu.%lu Firmware %lu.%lu.%lu version\n",
  			 FIELD_GET(PROTO_REV_MAJOR_MASK,
  				   scpi_info->protocol_version),
  			 FIELD_GET(PROTO_REV_MINOR_MASK,
  				   scpi_info->protocol_version),
  			 FIELD_GET(FW_REV_MAJOR_MASK,
  				   scpi_info->firmware_version),
  			 FIELD_GET(FW_REV_MINOR_MASK,
  				   scpi_info->firmware_version),
  			 FIELD_GET(FW_REV_PATCH_MASK,
  				   scpi_info->firmware_version));
  	scpi_info->scpi_ops = &scpi_ops;
  
  	return devm_of_platform_populate(dev);
  }
  
  static const struct of_device_id scpi_of_match[] = {
  	{.compatible = "arm,scpi"},
  	{.compatible = "arm,scpi-pre-1.0"},
  	{},
  };
  
  MODULE_DEVICE_TABLE(of, scpi_of_match);
  
  static struct platform_driver scpi_driver = {
  	.driver = {
  		.name = "scpi_protocol",
  		.of_match_table = scpi_of_match,
  		.dev_groups = versions_groups,
  	},
  	.probe = scpi_probe,
  	.remove = scpi_remove,
  };
  module_platform_driver(scpi_driver);
  
  MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
  MODULE_DESCRIPTION("ARM SCPI mailbox protocol driver");
  MODULE_LICENSE("GPL v2");
  