[PATCH 2/3] hwmon: xgene: Adds hwmon driver

[Hoan Tran]

This patch adds hardware temperature and power reading support for
APM X-Gene SoC's using the mailbox communication interface.

Signed-off-by: Hoan Tran <hotran@xxxxxxx>
---
 Documentation/hwmon/xgene-hwmon |  32 ++
 drivers/hwmon/Kconfig           |   7 +
 drivers/hwmon/Makefile          |   1 +
 drivers/hwmon/xgene-hwmon.c     | 801 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 841 insertions(+)
 create mode 100644 Documentation/hwmon/xgene-hwmon
 create mode 100644 drivers/hwmon/xgene-hwmon.c

diff --git a/Documentation/hwmon/xgene-hwmon b/Documentation/hwmon/xgene-hwmon
new file mode 100644
index 0000000..040a7f2
--- /dev/null
+++ b/Documentation/hwmon/xgene-hwmon
@@ -0,0 +1,32 @@
+Kernel driver xgene-hwmon
+========================
+
+Supported chips:
+ * APM X-Gene SoC
+
+Description
+-----------
+
+This driver adds hardware temperature and power reading support for
+APM X-Gene SoC's using the mailbox communication interface.
+For device tree, it is the standard DT mailbox.
+For ACPI, it is the PCC mailbox.
+
+The following sensors are supported
+
+  * Temperature
+    - SoC on-die temperature in milli-degree
+    - Alarm when high/over temperature occurs
+  * Power
+    - CPU power in uW
+    - IO power in uW
+    - CPU and IO power in uW
+
+sysfs-Interface
+---------------
+
+temp1_input - SoC on-die temperature (milli-degree C)
+temp1_critical_alarm - An 1 would indicates on-die temperature exceeded threshold
+power1_input - CPU power in (uW)
+power2_input - IO power in (uW)
+power3_input - CPU and IO power in (uW)
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 5c2d13a..91c3056 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1776,6 +1776,13 @@ config SENSORS_ULTRA45
 	  This driver provides support for the Ultra45 workstation environmental
 	  sensors.
 
+config SENSORS_XGENE
+	tristate "APM X-Gene SoC hardware monitoring driver"
+	depends on XGENE_SLIMPRO_MBOX || PCC
+	help
+	  If you say yes here you get support for the temperature
+	  and power sensors for APM X-Gene SoC.
+
 if ACPI
 
 comment "ACPI drivers"
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 58cc3ac..668d0f1 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -161,6 +161,7 @@ obj-$(CONFIG_SENSORS_W83L785TS)	+= w83l785ts.o
 obj-$(CONFIG_SENSORS_W83L786NG)	+= w83l786ng.o
 obj-$(CONFIG_SENSORS_WM831X)	+= wm831x-hwmon.o
 obj-$(CONFIG_SENSORS_WM8350)	+= wm8350-hwmon.o
+obj-$(CONFIG_SENSORS_XGENE)	+= xgene-hwmon.o
 
 obj-$(CONFIG_PMBUS)		+= pmbus/
 
diff --git a/drivers/hwmon/xgene-hwmon.c b/drivers/hwmon/xgene-hwmon.c
new file mode 100644
index 0000000..bc4ad29
--- /dev/null
+++ b/drivers/hwmon/xgene-hwmon.c
@@ -0,0 +1,801 @@
+/*
+ * APM X-Gene SoC Hardware Monitoring Driver
+ *
+ * Copyright (c) 2016, Applied Micro Circuits Corporation
+ * Author: Loc Ho <lho@xxxxxxx>
+ *         Hoan Tran <hotran@xxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that 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 <http://www.gnu.org/licenses/>.
+ *
+ * This driver provides the following features:
+ *  - Retrieve CPU's total power (uW)
+ *  - Retrieve IO's total power (uW)
+ *  - Retrieve SoC total power (uW)
+ *  - Retrieve SoC temperature (milli-degree C) and alarm
+ */
+#include <linux/acpi.h>
+#include <linux/dma-mapping.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/kfifo.h>
+#include <linux/interrupt.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <acpi/cppc_acpi.h>
+
+/* SLIMpro message defines */
+#define SLIMPRO_MSG_TYPE_DBG_ID		0
+#define SLIMPRO_MSG_TYPE_ERR_ID		7
+#define SLIMPRO_MSG_TYPE_PWRMGMT_ID	9
+
+#define SLIMPRO_MSG_TYPE(v)		(((v) & 0xF0000000) >> 28)
+#define SLIMPRO_MSG_TYPE_SET(v)		(((v) << 28) & 0xF0000000)
+#define SLIMPRO_MSG_SUBTYPE(v)		(((v) & 0x0F000000) >> 24)
+#define SLIMPRO_MSG_SUBTYPE_SET(v)	(((v) << 24) & 0x0F000000)
+
+#define SLIMPRO_DBG_SUBTYPE_SENSOR_READ	4
+#define SLIMPRO_SENSOR_READ_MSG		0x04FFE902
+#define SLIMPRO_SENSOR_READ_ENCODE_ADDR(a) \
+	((a) & 0x000FFFFF)
+#define PMD_PWR_MW_REG			0x26
+#define SOC_PWR_REG			0x21
+#define SOC_TEMP_REG			0x10
+
+#define SLIMPRO_PWRMGMT_SUBTYPE_TPC	1
+#define SLIMPRO_TPC_ALARM		2
+#define SLIMPRO_TPC_GET_ALARM		3
+#define SLIMPRO_TPC_CMD(v)		(((v) & 0x00FF0000) >> 16)
+#define SLIMPRO_TPC_CMD_SET(v)		(((v) << 16) & 0x00FF0000)
+#define SLIMPRO_TPC_ENCODE_MSG(hndl, cmd, type) \
+	(SLIMPRO_MSG_TYPE_SET(SLIMPRO_MSG_TYPE_PWRMGMT_ID) | \
+	SLIMPRO_MSG_SUBTYPE_SET(hndl) | \
+	SLIMPRO_TPC_CMD_SET(cmd) | \
+	type)
+
+/* PCC defines */
+#define SLIMPRO_MSG_PCC_SUBSPACE	7
+#define PCC_SIGNATURE_MASK		0x50424300
+#define PCCC_GENERATE_DB_INT		BIT(15)
+#define PCCS_CMD_COMPLETE		BIT(0)
+#define PCCS_SCI_DOORBEL		BIT(1)
+#define PCCS_PLATFORM_NOTIFICATION	BIT(3)
+/*
+ * Arbitrary retries in case the remote processor is slow to respond
+ * to PCC commands
+ */
+#define PCC_NUM_RETRIES			500
+
+#define ASYNC_MSG_FIFO_SIZE		16
+#define MBOX_HWMON_INDEX		0
+#define MBOX_OP_TIMEOUTMS		1000
+
+#define SOC_TEMP			0
+#define CPU_POWER			0
+#define IO_POWER			1
+#define SOC_POWER			2
+
+#define WATT_TO_mWATT(x)		((x) * 1000)
+#define mWATT_TO_uWATT(x)		((x) * 1000)
+#define WATT_TO_uWATT(x)		((x) * 1000000)
+#define CELSIUS_TO_mCELSIUS(x)		((x) * 1000)
+
+#define to_xgene_hwmon_dev(cl)		\
+	container_of(cl, struct xgene_hwmon_dev, mbox_client)
+
+struct slimpro_resp_msg {
+	u32 msg;
+	u32 param1;
+	u32 param2;
+} __packed;
+
+struct xgene_hwmon_dev {
+	struct device		*dev;
+	struct mbox_chan	*mbox_chan;
+	struct mbox_client	mbox_client;
+
+	spinlock_t		lock;
+	struct completion	rd_complete;
+	int			resp_pending;
+	struct slimpro_resp_msg sync_msg;
+
+	struct work_struct	workq;
+	struct kfifo_rec_ptr_1	async_msg_fifo;
+
+	struct device		*hwmon_dev;
+	bool			temp_critical_alarm;
+
+	phys_addr_t		comm_base_addr;
+	void			*pcc_comm_addr;
+	u64			usecs_lat;
+};
+
+/*
+ * This function tests and clears a bitmask then returns its old value
+ */
+static u16 xgene_word_tst_and_clr(u16 *addr, u16 mask)
+{
+	u16 ret, val;
+
+	val = readw_relaxed(addr);
+	ret = val & mask;
+	val &= ~mask;
+	writew_relaxed(val, addr);
+
+	return ret;
+}
+
+static int xgene_hwmon_pcc_rd(struct xgene_hwmon_dev *ctx, u32 *msg)
+{
+	struct acpi_pcct_shared_memory *generic_comm_base = ctx->pcc_comm_addr;
+	void *ptr = generic_comm_base + 1;
+	unsigned long flags;
+	u16 val;
+	int rc;
+
+	spin_lock_irqsave(&ctx->lock, flags);
+	if (ctx->resp_pending) {
+		spin_unlock_irqrestore(&ctx->lock, flags);
+		return -EAGAIN;
+	}
+
+	init_completion(&ctx->rd_complete);
+	ctx->resp_pending = true;
+
+	/* Write signature for subspace */
+	writel_relaxed(PCC_SIGNATURE_MASK | SLIMPRO_MSG_PCC_SUBSPACE,
+		       &generic_comm_base->signature);
+
+	/* Write to the shared command region */
+	writew_relaxed(SLIMPRO_MSG_TYPE(msg[0]) | PCCC_GENERATE_DB_INT,
+		       &generic_comm_base->command);
+
+	/* Flip CMD COMPLETE bit */
+	val = readw_relaxed(&generic_comm_base->status);
+	val &= ~PCCS_CMD_COMPLETE;
+	writew_relaxed(val, &generic_comm_base->status);
+
+	/* Copy the message to the PCC comm space */
+	memcpy(ptr, msg, sizeof(struct slimpro_resp_msg));
+
+	/* Ring the doorbell */
+	rc = mbox_send_message(ctx->mbox_chan, msg);
+	if (rc < 0) {
+		dev_err(ctx->dev, "Mailbox send error %d\n", rc);
+		goto err;
+	}
+	spin_unlock_irqrestore(&ctx->lock, flags);
+	if (!wait_for_completion_timeout(&ctx->rd_complete,
+					 usecs_to_jiffies(ctx->usecs_lat))) {
+		spin_lock_irqsave(&ctx->lock, flags);
+		dev_err(ctx->dev, "Mailbox operation timed out\n");
+		rc = -EIO;
+		goto err;
+	}
+	spin_lock_irqsave(&ctx->lock, flags);
+
+	/* Check for invalid data or no device */
+	if (SLIMPRO_MSG_TYPE(ctx->sync_msg.msg) == SLIMPRO_MSG_TYPE_ERR_ID ||
+	    ctx->sync_msg.msg == 0xffffffff) {
+		rc = -ENODEV;
+		goto err;
+	}
+
+	msg[0] = ctx->sync_msg.msg;
+	msg[1] = ctx->sync_msg.param1;
+	msg[2] = ctx->sync_msg.param2;
+
+err:
+	mbox_chan_txdone(ctx->mbox_chan, 0);
+	ctx->resp_pending = false;
+	spin_unlock_irqrestore(&ctx->lock, flags);
+	return rc;
+}
+
+static int xgene_hwmon_rd(struct xgene_hwmon_dev *ctx, u32 *msg)
+{
+	unsigned long flags;
+	int rc;
+
+	spin_lock_irqsave(&ctx->lock, flags);
+	if (ctx->resp_pending) {
+		spin_unlock_irqrestore(&ctx->lock, flags);
+		return -EAGAIN;
+	}
+
+	init_completion(&ctx->rd_complete);
+	ctx->resp_pending = true;
+	rc = mbox_send_message(ctx->mbox_chan, msg);
+	if (rc < 0) {
+		dev_err(ctx->dev, "Mailbox send error %d\n", rc);
+		goto err;
+	}
+	spin_unlock_irqrestore(&ctx->lock, flags);
+
+	if (!wait_for_completion_timeout(&ctx->rd_complete,
+					 msecs_to_jiffies(MBOX_OP_TIMEOUTMS))) {
+		spin_lock_irqsave(&ctx->lock, flags);
+		dev_err(ctx->dev, "Mailbox operation timed out\n");
+		rc = -EIO;
+		goto err;
+	}
+	spin_lock_irqsave(&ctx->lock, flags);
+
+	/* Check for invalid data or no device */
+	if (SLIMPRO_MSG_TYPE(ctx->sync_msg.msg) == SLIMPRO_MSG_TYPE_ERR_ID ||
+	    ctx->sync_msg.msg == 0xffffffff) {
+		rc = -ENODEV;
+		goto err;
+	}
+
+	msg[0] = ctx->sync_msg.msg;
+	msg[1] = ctx->sync_msg.param1;
+	msg[2] = ctx->sync_msg.param2;
+
+err:
+	ctx->resp_pending = false;
+	spin_unlock_irqrestore(&ctx->lock, flags);
+	return rc;
+}
+
+static int xgene_hwmon_reg_map_rd(struct xgene_hwmon_dev *ctx, u32 addr,
+				  u32 *data)
+{
+	u32 msg[3];
+	int rc;
+
+	msg[0] = SLIMPRO_SENSOR_READ_MSG;
+	msg[1] = SLIMPRO_SENSOR_READ_ENCODE_ADDR(addr);
+	msg[2] = 0;
+
+	if (ACPI_COMPANION(ctx->dev))
+		rc = xgene_hwmon_pcc_rd(ctx, msg);
+	else
+		rc = xgene_hwmon_rd(ctx, msg);
+	if (rc < 0) {
+		/* To support compatibility with firmware, return 0 */
+		dev_err(ctx->dev, "SLIMpro register 0x%02X read error %d\n",
+			addr, rc);
+		*data = 0;
+		return rc;
+	}
+	*data = msg[1];
+
+	return rc;
+}
+
+static int xgene_hwmon_get_notification_msg(struct xgene_hwmon_dev *ctx,
+					    u32 *amsg)
+{
+	u32 msg[3];
+	int rc;
+
+	msg[0] = SLIMPRO_TPC_ENCODE_MSG(SLIMPRO_PWRMGMT_SUBTYPE_TPC,
+					SLIMPRO_TPC_GET_ALARM, 0);
+	msg[1] = 0;
+	msg[2] = 0;
+
+	rc = xgene_hwmon_pcc_rd(ctx, msg);
+	if (rc < 0) {
+		dev_err(ctx->dev, "PCC Alarm read error %d\n", rc);
+		return rc;
+	}
+	amsg[0] = msg[0];
+	amsg[1] = msg[1];
+	amsg[2] = msg[2];
+
+	return rc;
+}
+
+static int xgene_hwmon_get_cpu_pwr(struct xgene_hwmon_dev *ctx, u32 *val)
+{
+	return xgene_hwmon_reg_map_rd(ctx, PMD_PWR_MW_REG, val);
+}
+
+static int xgene_hwmon_get_io_pwr(struct xgene_hwmon_dev *ctx, u32 *val)
+{
+	return xgene_hwmon_reg_map_rd(ctx, SOC_PWR_REG, val);
+}
+
+static int xgene_hwmon_get_soc_power(struct xgene_hwmon_dev *ctx, u32 *val)
+{
+	u32 pmd_vrm_power;
+	u32 io_vrm_power;
+	int rc;
+
+	rc = xgene_hwmon_get_cpu_pwr(ctx, &pmd_vrm_power);
+	if (rc < 0)
+		return rc;
+
+	rc = xgene_hwmon_get_io_pwr(ctx, &io_vrm_power);
+	if (rc < 0)
+		return rc;
+
+	*val = pmd_vrm_power + WATT_TO_mWATT(io_vrm_power);
+
+	return 0;
+}
+
+static int xgene_hwmon_get_temp(struct xgene_hwmon_dev *ctx, u32 *val)
+{
+	return xgene_hwmon_reg_map_rd(ctx, SOC_TEMP_REG, val);
+}
+
+/*
+ * Sensor temperature/power functions
+ */
+static const char * const sensor_temp_input_names[] = {
+	[SOC_TEMP] = "SoC Temperature",
+};
+
+static const char * const sensor_pwr_input_names[] = {
+	[CPU_POWER] = "CPU's power",
+	[IO_POWER] = "IO's power",
+	[SOC_POWER] = "SoC power"
+};
+
+static ssize_t xgene_hwmon_show_name(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "APM X-Gene\n");
+}
+
+static ssize_t xgene_hwmon_show_temp(struct device *dev,
+				     struct device_attribute *attr,
+				     char *buf)
+{
+	struct xgene_hwmon_dev *ctx = dev_get_drvdata(dev);
+	u32 val;
+	int rc;
+
+	rc = xgene_hwmon_get_temp(ctx, &val);
+	if (rc < 0)
+		return rc;
+
+	val = CELSIUS_TO_mCELSIUS(val);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+
+static ssize_t xgene_hwmon_show_temp_label(struct device *dev,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	int channel = to_sensor_dev_attr(attr)->index - 1;
+
+	return snprintf(buf, PAGE_SIZE, "%s\n",
+			sensor_temp_input_names[channel]);
+}
+
+static ssize_t xgene_hwmon_show_temp_critical_alarm(struct device *dev,
+						    struct device_attribute *devattr,
+						    char *buf)
+{
+	struct xgene_hwmon_dev *ctx = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", ctx->temp_critical_alarm);
+}
+
+static ssize_t xgene_hwmon_show_pwr_label(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	int channel = to_sensor_dev_attr(attr)->index - 1;
+
+	return snprintf(buf, PAGE_SIZE, "%s\n",
+			sensor_pwr_input_names[channel]);
+}
+
+static ssize_t xgene_hwmon_show_pwr(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct xgene_hwmon_dev *ctx = dev_get_drvdata(dev);
+	int channel = to_sensor_dev_attr(attr)->index - 1;
+	u32 val;
+	int rc;
+
+	switch (channel) {
+	case CPU_POWER:
+		rc = xgene_hwmon_get_cpu_pwr(ctx, &val);
+		break;
+	case IO_POWER:
+		rc = xgene_hwmon_get_io_pwr(ctx, &val);
+		break;
+	case SOC_POWER:
+		rc = xgene_hwmon_get_soc_power(ctx, &val);
+		break;
+	default:
+		rc = -EINVAL;
+		break;
+	}
+	if (rc < 0)
+		return rc;
+
+	if (channel == IO_POWER)
+		val = WATT_TO_uWATT(val);
+	else
+		val = mWATT_TO_uWATT(val);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+
+/* Chip name, required by hwmon */
+static DEVICE_ATTR(name, S_IRUGO, xgene_hwmon_show_name, NULL);
+
+#define SENSOR_ATTR_TEMP(index) \
+	static SENSOR_DEVICE_ATTR(temp##index##_label, S_IRUGO, \
+				  xgene_hwmon_show_temp_label, NULL, index); \
+	static SENSOR_DEVICE_ATTR(temp##index##_input, S_IRUGO, \
+				  xgene_hwmon_show_temp, NULL, index); \
+	static SENSOR_DEVICE_ATTR(temp##index##_critical_alarm, S_IRUGO, \
+				  xgene_hwmon_show_temp_critical_alarm, NULL, \
+				  index);
+#define SENSOR_ATTR_PWR(index) \
+	static SENSOR_DEVICE_ATTR(power##index##_label, S_IRUGO, \
+				  xgene_hwmon_show_pwr_label, NULL, index); \
+	static SENSOR_DEVICE_ATTR(power##index##_input, S_IRUGO, \
+				  xgene_hwmon_show_pwr, NULL, index);
+
+#define APM_TEMP_SENSOR_ATTR(index) \
+	&sensor_dev_attr_temp##index##_input.dev_attr.attr, \
+	&sensor_dev_attr_temp##index##_label.dev_attr.attr, \
+	&sensor_dev_attr_temp##index##_critical_alarm.dev_attr.attr
+#define APM_PWR_SENSOR_ATTR(index) \
+	&sensor_dev_attr_power##index##_input.dev_attr.attr, \
+	&sensor_dev_attr_power##index##_label.dev_attr.attr
+
+SENSOR_ATTR_TEMP(1); /* SoC temperature */
+SENSOR_ATTR_PWR(1);  /* CPU power */
+SENSOR_ATTR_PWR(2);  /* IO power */
+SENSOR_ATTR_PWR(3);  /* SoC power */
+
+static struct attribute *xgene_hwmon_attributes[] = {
+	&dev_attr_name.attr,
+	APM_TEMP_SENSOR_ATTR(1),
+	APM_PWR_SENSOR_ATTR(1),
+	APM_PWR_SENSOR_ATTR(2),
+	APM_PWR_SENSOR_ATTR(3),
+	NULL,
+};
+
+static const struct attribute_group xgene_hwmon_attr_group = {
+	.attrs	= xgene_hwmon_attributes,
+};
+
+static int xgene_hwmon_tpc_alarm(struct xgene_hwmon_dev *ctx,
+				 struct slimpro_resp_msg *amsg)
+{
+	char name[40];
+
+	ctx->temp_critical_alarm = amsg->param2 ? true : false;
+	snprintf(name, sizeof(name), "temp%d_critical_alarm", SOC_TEMP + 1);
+	sysfs_notify(&ctx->dev->kobj, NULL, name);
+	dev_alert(ctx->dev, "SoC temperature alarm at %d degree\n",
+		  amsg->param1);
+	return 0;
+}
+
+static void xgene_hwmon_process_pwrmsg(struct xgene_hwmon_dev *ctx,
+				       struct slimpro_resp_msg *amsg)
+{
+	switch (SLIMPRO_MSG_SUBTYPE(amsg->msg)) {
+	case SLIMPRO_PWRMGMT_SUBTYPE_TPC:
+		switch (SLIMPRO_TPC_CMD(amsg->msg)) {
+		case SLIMPRO_TPC_ALARM:
+			xgene_hwmon_tpc_alarm(ctx, amsg);
+			break;
+		default:
+			dev_warn(ctx->dev,
+				 "Un-supported TPC message received 0x%08X\n",
+				 amsg->msg);
+			break;
+		}
+		break;
+	default:
+		dev_warn(ctx->dev, "Un-supported message received 0x%08X\n",
+			 amsg->msg);
+		break;
+	}
+}
+
+/*
+ * This function is called to process async work queue
+ */
+static void xgene_hwmon_evt_work(struct work_struct *work)
+{
+	struct slimpro_resp_msg amsg;
+	struct xgene_hwmon_dev *ctx;
+	int ret;
+
+	ctx = container_of(work, struct xgene_hwmon_dev, workq);
+	while (kfifo_out_spinlocked(&ctx->async_msg_fifo, &amsg,
+				    sizeof(struct slimpro_resp_msg),
+				    &ctx->lock)) {
+		/*
+		 * If PCC, send a consumer command to Platform to get info
+		 * If Slimpro Mailbox, get message from specific FIFO
+		 */
+		if (ACPI_COMPANION(ctx->dev)) {
+			ret = xgene_hwmon_get_notification_msg(ctx,
+							       (u32 *)&amsg);
+			if (ret < 0)
+				continue;
+		}
+		switch (SLIMPRO_MSG_TYPE(amsg.msg)) {
+		case SLIMPRO_MSG_TYPE_PWRMGMT_ID:
+			xgene_hwmon_process_pwrmsg(ctx, &amsg);
+			break;
+		default:
+			dev_warn(ctx->dev,
+				 "Invalid mailbox msg received 0x%08X 0x%08X 0x%08X\n",
+				 amsg.msg, amsg.param1, amsg.param2);
+			break;
+		}
+	}
+}
+
+/*
+ * This function is called when the SLIMpro/PCC Mailbox received a message
+ */
+static void xgene_hwmon_rx_cb(struct mbox_client *cl, void *msg)
+{
+	struct xgene_hwmon_dev *ctx = to_xgene_hwmon_dev(cl);
+	struct acpi_pcct_shared_memory *generic_comm_base = ctx->pcc_comm_addr;
+	struct slimpro_resp_msg amsg;
+
+	/* If PCC mailbox controller, get msg from shared memory */
+	if (ACPI_COMPANION(ctx->dev)) {
+		msg = generic_comm_base + 1;
+		/* Check if platform sends interrupt */
+		if (!xgene_word_tst_and_clr(&generic_comm_base->status,
+					    PCCS_SCI_DOORBEL))
+			return;
+	}
+
+	/*
+	 * Response message format:
+	 * msg[0] is the return code of the operation
+	 * msg[1] is the first parameter word
+	 * msg[2] is the second parameter word
+	 *
+	 * As message only supports dword size, just assign it.
+	 */
+
+	/* Check for sync query */
+	if (ctx->resp_pending &&
+	    ((SLIMPRO_MSG_TYPE(((u32 *) msg)[0]) == SLIMPRO_MSG_TYPE_ERR_ID) ||
+	     (SLIMPRO_MSG_TYPE(((u32 *) msg)[0]) == SLIMPRO_MSG_TYPE_DBG_ID &&
+	      SLIMPRO_MSG_SUBTYPE(((u32 *) msg)[0]) == SLIMPRO_DBG_SUBTYPE_SENSOR_READ) ||
+	     (SLIMPRO_MSG_TYPE(((u32 *) msg)[0]) == SLIMPRO_MSG_TYPE_PWRMGMT_ID &&
+	      SLIMPRO_MSG_SUBTYPE(((u32 *) msg)[0]) == SLIMPRO_PWRMGMT_SUBTYPE_TPC &&
+	      SLIMPRO_TPC_CMD(((u32 *) msg)[0]) == SLIMPRO_TPC_ALARM))) {
+		if (ACPI_COMPANION(ctx->dev)) {
+			/* Check if platform completes command */
+			if (!xgene_word_tst_and_clr(&generic_comm_base->status,
+						    PCCS_CMD_COMPLETE))
+				goto notify;
+		}
+		ctx->sync_msg.msg = ((u32 *) msg)[0];
+		ctx->sync_msg.param1 = ((u32 *) msg)[1];
+		ctx->sync_msg.param2 = ((u32 *) msg)[2];
+
+		/* Operation waiting for response */
+		complete(&ctx->rd_complete);
+
+		return;
+	}
+
+	/*
+	 * If PCC, platform notifies interrupt to OSPM.
+	 * OPSM schedules a consumer command to get this information
+	 * in a workqueue. Platform must wait until OSPM has issued
+	 * a consumer command that serves this notification.
+	 */
+notify:
+	if (ACPI_COMPANION(ctx->dev)) {
+		/* Check and clear Platform Notification bit */
+		if (!xgene_word_tst_and_clr(&generic_comm_base->status,
+					    PCCS_PLATFORM_NOTIFICATION))
+			return;
+	} else {
+		amsg.msg   = ((u32 *) msg)[0];
+		amsg.param1 = ((u32 *) msg)[1];
+		amsg.param2 = ((u32 *) msg)[2];
+	}
+
+	/* Enqueue to the FIFO */
+	kfifo_in_spinlocked(&ctx->async_msg_fifo, &amsg,
+			    sizeof(struct slimpro_resp_msg), &ctx->lock);
+	/* Schedule the bottom handler */
+	schedule_work(&ctx->workq);
+}
+
+static void xgene_hwmon_tx_done(struct mbox_client *cl, void *msg, int ret)
+{
+	if (ret) {
+		dev_dbg(cl->dev, "TX did not complete: CMD sent:%x, ret:%d\n",
+			*(u16 *) msg, ret);
+	} else {
+		dev_dbg(cl->dev, "TX completed. CMD sent:%x, ret:%d\n",
+			*(u16 *) msg, ret);
+	}
+}
+
+static int __init xgene_hwmon_probe(struct platform_device *pdev)
+{
+	struct xgene_hwmon_dev *ctx;
+	struct mbox_client *cl;
+	int rc;
+
+	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	ctx->dev = &pdev->dev;
+	platform_set_drvdata(pdev, ctx);
+	cl = &ctx->mbox_client;
+
+	/* Request mailbox channel */
+	cl->dev = &pdev->dev;
+	cl->rx_callback = xgene_hwmon_rx_cb;
+	cl->tx_done = xgene_hwmon_tx_done;
+	cl->tx_block = false;
+	cl->tx_tout = MBOX_OP_TIMEOUTMS;
+	cl->knows_txdone = false;
+	if (!ACPI_COMPANION(cl->dev)) {
+		ctx->mbox_chan = mbox_request_channel(cl, MBOX_HWMON_INDEX);
+		if (IS_ERR(ctx->mbox_chan)) {
+			dev_err(&pdev->dev,
+				"SLIMpro mailbox channel request failed\n");
+			return PTR_ERR(ctx->mbox_chan);
+		}
+	} else {
+		struct acpi_pcct_hw_reduced *cppc_ss;
+
+		ctx->mbox_chan =
+			pcc_mbox_request_channel(cl, SLIMPRO_MSG_PCC_SUBSPACE);
+		if (IS_ERR(ctx->mbox_chan)) {
+			dev_err(&pdev->dev,
+				"PPC channel request failed\n");
+			return PTR_ERR(ctx->mbox_chan);
+		}
+
+		/*
+		 * The PCC mailbox controller driver should
+		 * have parsed the PCCT (global table of all
+		 * PCC channels) and stored pointers to the
+		 * subspace communication region in con_priv.
+		 */
+		cppc_ss = ctx->mbox_chan->con_priv;
+		if (!cppc_ss) {
+			dev_err(&pdev->dev, "PPC subspace not found\n");
+			rc = -ENODEV;
+			goto out_mbox_free;
+		}
+
+		if (!ctx->mbox_chan->mbox->txdone_irq) {
+			dev_err(&pdev->dev, "PCC IRQ not supported\n");
+			rc = -ENODEV;
+			goto out_mbox_free;
+		}
+
+		/*
+		 * This is the shared communication region
+		 * for the OS and Platform to communicate over.
+		 */
+		ctx->comm_base_addr = cppc_ss->base_address;
+		if (ctx->comm_base_addr) {
+			ctx->pcc_comm_addr =
+					acpi_os_ioremap(ctx->comm_base_addr,
+							cppc_ss->length);
+		} else {
+			dev_err(&pdev->dev, "Failed to get PCC comm region\n");
+			rc = -ENODEV;
+			goto out_mbox_free;
+		}
+
+		if (!ctx->pcc_comm_addr) {
+			dev_err(&pdev->dev,
+				"Failed to ioremap PCC comm region\n");
+			rc = -ENOMEM;
+			goto out_mbox_free;
+		}
+
+		/*
+		 * cppc_ss->latency is just a Nominal value. In reality
+		 * the remote processor could be much slower to reply.
+		 * So add an arbitrary amount of wait on top of Nominal.
+		 */
+		ctx->usecs_lat = PCC_NUM_RETRIES * cppc_ss->latency;
+	}
+
+	spin_lock_init(&ctx->lock);
+
+	rc = kfifo_alloc(&ctx->async_msg_fifo,
+			 sizeof(struct slimpro_resp_msg) * ASYNC_MSG_FIFO_SIZE,
+			 GFP_KERNEL);
+	if (rc)
+		goto out_mbox_free;
+
+	INIT_WORK(&ctx->workq, xgene_hwmon_evt_work);
+
+	/* Hook up sysfs for sensor monitor */
+	rc = sysfs_create_group(&pdev->dev.kobj, &xgene_hwmon_attr_group);
+	if (rc) {
+		dev_err(&pdev->dev, "Fail to create sysfs\n");
+		goto out_kfifo_free;
+	}
+
+	ctx->hwmon_dev = hwmon_device_register(ctx->dev);
+	if (IS_ERR(ctx->hwmon_dev)) {
+		dev_err(&pdev->dev, "Failed to register HW monitor device\n");
+		rc = PTR_ERR(ctx->hwmon_dev);
+		goto out;
+	}
+
+	dev_info(&pdev->dev, "APM X-Gene SoC HW monitor driver registered\n");
+
+	return rc;
+
+out:
+	sysfs_remove_group(&pdev->dev.kobj, &xgene_hwmon_attr_group);
+out_kfifo_free:
+	kfifo_free(&ctx->async_msg_fifo);
+out_mbox_free:
+	mbox_free_channel(ctx->mbox_chan);
+
+	return rc;
+}
+
+static int xgene_hwmon_remove(struct platform_device *pdev)
+{
+	struct xgene_hwmon_dev *ctx = platform_get_drvdata(pdev);
+
+	hwmon_device_unregister(ctx->hwmon_dev);
+	sysfs_remove_group(&pdev->dev.kobj, &xgene_hwmon_attr_group);
+	kfifo_free(&ctx->async_msg_fifo);
+	mbox_free_channel(ctx->mbox_chan);
+
+	return 0;
+}
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id xgene_hwmon_acpi_match[] = {
+	{"APMC0D29", 0},
+	{},
+};
+MODULE_DEVICE_TABLE(acpi, xgene_hwmon_acpi_match);
+#endif
+
+static const struct of_device_id xgene_hwmon_of_match[] = {
+	{.compatible = "apm,xgene-slimpro-hwmon"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, xgene_hwmon_of_match);
+
+static struct platform_driver xgene_hwmon_driver __refdata = {
+	.probe = xgene_hwmon_probe,
+	.remove = xgene_hwmon_remove,
+	.driver = {
+		.name = "xgene-slimpro-hwmon",
+		.of_match_table = xgene_hwmon_of_match,
+		.acpi_match_table = ACPI_PTR(xgene_hwmon_acpi_match),
+	},
+};
+module_platform_driver(xgene_hwmon_driver);
+
+MODULE_DESCRIPTION("APM X-Gene SoC hardware monitor");
+MODULE_LICENSE("GPL");
-- 
1.9.1