Message-ID: <578A6257.1050204@roeck-us.net>
Date:	Sat, 16 Jul 2016 09:35:35 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Hoan Tran <hotran@....com>, Jean Delvare <jdelvare@...e.com>,
	Jonathan Corbet <corbet@....net>,
	Rob Herring <robh+dt@...nel.org>
Cc:	Jassi Brar <jassisinghbrar@...il.com>,
	Ashwin Chaugule <ashwin.chaugule@...aro.org>,
	linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	devicetree@...r.kernel.org, Duc Dang <dhdang@....com>, lho@....com
Subject: Re: [PATCH v2 2/3] hwmon: xgene: Add hwmon driver

On 07/11/2016 05:30 PM, Hoan Tran wrote:
> This patch adds hardware temperature and power reading support for
> APM X-Gene SoC using the mailbox communication interface.
>
> Signed-off-by: Hoan Tran <hotran@....com>
> ---
>   Documentation/hwmon/xgene-hwmon |  30 ++
>   drivers/hwmon/Kconfig           |   7 +
>   drivers/hwmon/Makefile          |   1 +
>   drivers/hwmon/xgene-hwmon.c     | 772 ++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 810 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..6ec50ed
> --- /dev/null
> +++ b/Documentation/hwmon/xgene-hwmon
> @@ -0,0 +1,30 @@
> +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 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 C
> +    - Alarm when high/over temperature occurs
> +  * Power
> +    - CPU power in uW
> +    - IO power in uW
> +
> +sysfs-Interface
> +---------------
> +
> +temp0_input - SoC on-die temperature (milli-degree C)
> +temp0_critical_alarm - An 1 would indicates on-die temperature exceeded threshold
> +power0_input - CPU power in (uW)
> +power1_input - IO power in (uW)
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index ff94007..55218c6 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1787,6 +1787,13 @@ 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 2ef5b7c..a2460dd 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -162,6 +162,7 @@ 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..03917e3
> --- /dev/null
> +++ b/drivers/hwmon/xgene-hwmon.c
> @@ -0,0 +1,772 @@
> +/*
> + * APM X-Gene SoC Hardware Monitoring Driver
> + *
> + * Copyright (c) 2016, Applied Micro Circuits Corporation
> + * Author: Loc Ho <lho@....com>
> + *         Hoan Tran <hotran@....com>
> + *
> + * 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 total power (uW)
> + *  - Retrieve IO 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_controller.h>
> +#include <linux/mailbox_client.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <acpi/acpi_io.h>
> +#include <acpi/pcc.h>
> +
Please order include files alphabetically.

> +/* SLIMpro message defines */
> +#define MSG_TYPE_DBG			0
> +#define MSG_TYPE_ERR			7
> +#define MSG_TYPE_PWRMGMT		9

Are those only used in this driver ?

> +#define MSG_TYPE(v)			(((v) & 0xF0000000) >> 28)
> +#define MSG_TYPE_SET(v)			(((v) << 28) & 0xF0000000)
> +#define MSG_SUBTYPE(v)			(((v) & 0x0F000000) >> 24)
> +#define MSG_SUBTYPE_SET(v)		(((v) << 24) & 0x0F000000)
> +
> +#define DBG_SUBTYPE_SENSOR_READ		4
> +#define SENSOR_RD_MSG			0x04FFE902
> +#define SENSOR_RD_EN_ADDR(a)		((a) & 0x000FFFFF)
> +#define PMD_PWR_REG			0x20
> +#define PMD_PWR_MW_REG			0x26
> +#define SOC_PWR_REG			0x21
> +#define SOC_PWR_MW_REG			0x27
> +#define SOC_TEMP_REG			0x10
> +
> +#define TEMP_NEGATIVE_BIT		8
> +
> +#define PWRMGMT_SUBTYPE_TPC		1
> +#define TPC_ALARM			2
> +#define TPC_GET_ALARM			3
> +#define TPC_CMD(v)			(((v) & 0x00FF0000) >> 16)
> +#define TPC_CMD_SET(v)			(((v) << 16) & 0x00FF0000)
> +#define TPC_EN_MSG(hndl, cmd, type) \
> +	(MSG_TYPE_SET(MSG_TYPE_PWRMGMT) | \
> +	MSG_SUBTYPE_SET(hndl) | TPC_CMD_SET(cmd) | type)
> +
> +/* PCC defines */
> +#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_OP_TIMEOUTMS		1000
> +
> +#define WATT_TO_mWATT(x)		((x) * 1000)
> +#define mWATT_TO_uWATT(x)		((x) * 1000)
> +#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;
> +	int			mbox_idx;
> +
> +	spinlock_t		kfifo_lock;
> +	struct mutex		rd_mutex;
> +	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_decode_temp(u32 val)

The "hwmon" in the function names does not really add any value.
I would suggest to drop it.

> +{
> +	unsigned long temp = val;
> +
> +	/* Convert 9 bit signed temperature to integer */
> +	if (test_and_clear_bit(TEMP_NEGATIVE_BIT, &temp))
> +		return (temp - 256);
> +	else

else after return is unnecessary.
I would suggest to use sign_extend32(val, TEMP_NEGATIVE_BIT).

> +		return temp;
> +}
> +
> +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;
> +	int rc, i;
> +	u16 val;
> +
> +	mutex_lock(&ctx->rd_mutex);
> +	init_completion(&ctx->rd_complete);
> +	ctx->resp_pending = true;
> +
> +	/* Write signature for subspace */
> +	writel_relaxed(PCC_SIGNATURE_MASK | ctx->mbox_idx,
> +		       &generic_comm_base->signature);
> +
> +	/* Write to the shared command region */
> +	writew_relaxed(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 */
> +	for (i = 0; i < sizeof(struct slimpro_resp_msg) / 4; i++)
> +		writel_relaxed(msg[i], ptr + i * 4);
> +
> +	/* 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;
> +	}
> +	if (!wait_for_completion_timeout(&ctx->rd_complete,
> +					 usecs_to_jiffies(ctx->usecs_lat))) {
> +		dev_err(ctx->dev, "Mailbox operation timed out\n");
> +		rc = -ETIMEDOUT;
> +		goto err;
> +	}
> +
> +	/* Check for invalid data */
> +	if (MSG_TYPE(ctx->sync_msg.msg) == MSG_TYPE_ERR) {
> +		rc = -EINVAL;
> +		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;
> +	mutex_unlock(&ctx->rd_mutex);
> +	return rc;
> +}
> +
> +static int xgene_hwmon_rd(struct xgene_hwmon_dev *ctx, u32 *msg)
> +{
> +	int rc;
> +
> +	mutex_lock(&ctx->rd_mutex);
> +	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;
> +	}
> +
> +	if (!wait_for_completion_timeout(&ctx->rd_complete,
> +					 msecs_to_jiffies(MBOX_OP_TIMEOUTMS))) {
> +		dev_err(ctx->dev, "Mailbox operation timed out\n");
> +		rc = -ETIMEDOUT;
> +		goto err;
> +	}
> +
> +	/* Check for invalid data */
> +	if (MSG_TYPE(ctx->sync_msg.msg) == MSG_TYPE_ERR) {
> +		rc = -EINVAL;
> +		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;
> +	mutex_unlock(&ctx->rd_mutex);
> +	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] = SENSOR_RD_MSG;
> +	msg[1] = SENSOR_RD_EN_ADDR(addr);
> +	msg[2] = 0;
> +
> +	if (acpi_disabled)
> +		rc = xgene_hwmon_rd(ctx, msg);
> +	else
> +		rc = xgene_hwmon_pcc_rd(ctx, msg);
> +
> +	if (rc < 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] = TPC_EN_MSG(PWRMGMT_SUBTYPE_TPC, TPC_GET_ALARM, 0);
> +	msg[1] = 0;
> +	msg[2] = 0;
> +
> +	rc = xgene_hwmon_pcc_rd(ctx, msg);
> +	if (rc < 0)
> +		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)
> +{
> +	u32 watt, mwatt;
> +	int rc;
> +
> +	rc = xgene_hwmon_reg_map_rd(ctx, PMD_PWR_REG, &watt);
> +	if (rc < 0)
> +		return rc;
> +
> +	rc = xgene_hwmon_reg_map_rd(ctx, PMD_PWR_MW_REG, &mwatt);
> +	if (rc < 0)
> +		return rc;
> +
> +	*val = WATT_TO_mWATT(watt) + mwatt;
> +	return 0;
> +}
> +
> +static int xgene_hwmon_get_io_pwr(struct xgene_hwmon_dev *ctx, u32 *val)
> +{
> +	u32 watt, mwatt;
> +	int rc;
> +
> +	rc = xgene_hwmon_reg_map_rd(ctx, SOC_PWR_REG, &watt);
> +	if (rc < 0)
> +		return rc;
> +
> +	rc = xgene_hwmon_reg_map_rd(ctx, SOC_PWR_MW_REG, &mwatt);
> +	if (rc < 0)
> +		return rc;
> +
> +	*val = WATT_TO_mWATT(watt) + mwatt;
> +	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 ssize_t xgene_hwmon_show_temp(struct device *dev,
> +				     struct device_attribute *attr,
> +				     char *buf)
> +{
> +	struct xgene_hwmon_dev *ctx = dev_get_drvdata(dev);
> +	int rc, temp;
> +	u32 val;
> +
> +	rc = xgene_hwmon_get_temp(ctx, &val);
> +	if (rc < 0)
> +		return rc;
> +
> +	temp = xgene_hwmon_decode_temp(val);
> +
> +	return snprintf(buf, PAGE_SIZE, "%d\n", CELSIUS_TO_mCELSIUS(temp));
> +}
> +
> +static ssize_t xgene_hwmon_show_temp_label(struct device *dev,
> +					   struct device_attribute *attr,
> +					   char *buf)
> +{
> +	return snprintf(buf, PAGE_SIZE, "SoC Temperature\n");
> +}
> +
> +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_cpu_pwr_label(struct device *dev,
> +					      struct device_attribute *attr,
> +					      char *buf)
> +{
> +	return snprintf(buf, PAGE_SIZE, "CPU power\n");
> +}
> +
> +static ssize_t xgene_hwmon_show_io_pwr_label(struct device *dev,
> +					      struct device_attribute *attr,
> +					      char *buf)
> +{
> +	return snprintf(buf, PAGE_SIZE, "IO power\n");
> +}
> +
> +static ssize_t xgene_hwmon_show_cpu_pwr(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_cpu_pwr(ctx, &val);
> +	if (rc < 0)
> +		return rc;
> +
> +	return snprintf(buf, PAGE_SIZE, "%u\n", mWATT_TO_uWATT(val));
> +}
> +
> +static ssize_t xgene_hwmon_show_io_pwr(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_io_pwr(ctx, &val);
> +	if (rc < 0)
> +		return rc;
> +
> +	return snprintf(buf, PAGE_SIZE, "%u\n", mWATT_TO_uWATT(val));
> +}
> +
> +static SENSOR_DEVICE_ATTR(temp0_label, S_IRUGO, xgene_hwmon_show_temp_label,
> +			  NULL, 0);
> +static SENSOR_DEVICE_ATTR(temp0_input, S_IRUGO, xgene_hwmon_show_temp,
> +			  NULL, 0);
> +static SENSOR_DEVICE_ATTR(temp0_critical_alarm, S_IRUGO,
> +			  xgene_hwmon_show_temp_critical_alarm, NULL, 0);
> +
> +static SENSOR_DEVICE_ATTR(power0_label, S_IRUGO,
> +			  xgene_hwmon_show_cpu_pwr_label, NULL, 0);
> +static SENSOR_DEVICE_ATTR(power0_input, S_IRUGO, xgene_hwmon_show_cpu_pwr,
> +			  NULL, 0);
> +
> +static SENSOR_DEVICE_ATTR(power1_label, S_IRUGO,
> +			  xgene_hwmon_show_io_pwr_label, NULL, 1);
> +static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, xgene_hwmon_show_io_pwr,
> +			  NULL, 1);
> +

Temperature and power attributes start with index 1. You don't use the index value in
SENSOR_DEVICE_ATTR(), so DEVCIE_ATTR_RO() might be a better choice.

> +static struct attribute *xgene_hwmon_attrs[] = {
> +	&sensor_dev_attr_temp0_label.dev_attr.attr,
> +	&sensor_dev_attr_temp0_input.dev_attr.attr,
> +	&sensor_dev_attr_temp0_critical_alarm.dev_attr.attr,
> +	&sensor_dev_attr_power0_label.dev_attr.attr,
> +	&sensor_dev_attr_power0_input.dev_attr.attr,
> +	&sensor_dev_attr_power1_label.dev_attr.attr,
> +	&sensor_dev_attr_power1_input.dev_attr.attr,
> +	NULL,
> +};
> +ATTRIBUTE_GROUPS(xgene_hwmon);
> +
> +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;

You could use !!amsg->param2, or simply rely on the compiler and C standard
to auto-convert the integer to boolean.

> +	snprintf(name, sizeof(name), "temp0_critical_alarm");
> +	sysfs_notify(&ctx->dev->kobj, NULL, name);

Why not just use "temp0_critical_alarm" (or rather "temp1_critical_alarm")
as parameter to sysfs_notify() ?

> +
> +	return 0;
> +}
> +
> +static void xgene_hwmon_process_pwrmsg(struct xgene_hwmon_dev *ctx,
> +				       struct slimpro_resp_msg *amsg)
> +{
> +	if ((MSG_SUBTYPE(amsg->msg) == PWRMGMT_SUBTYPE_TPC) &&
> +	    (TPC_CMD(amsg->msg) == TPC_ALARM))
> +		xgene_hwmon_tpc_alarm(ctx, amsg);
> +}
> +
> +/*
> + * 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->kfifo_lock)) {
> +		/*
> +		 * If PCC, send a consumer command to Platform to get info
> +		 * If Slimpro Mailbox, get message from specific FIFO
> +		 */
> +		if (!acpi_disabled) {
> +			ret = xgene_hwmon_get_notification_msg(ctx,
> +							       (u32 *)&amsg);
> +			if (ret < 0)
> +				continue;
> +		}
> +
> +		if (MSG_TYPE(amsg.msg) == MSG_TYPE_PWRMGMT)
> +			xgene_hwmon_process_pwrmsg(ctx, &amsg);
> +	}
> +}
> +
> +/*
> + * This function is called when the SLIMpro 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 slimpro_resp_msg amsg;
> +
> +	/*
> +	 * 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 &&
> +	    ((MSG_TYPE(((u32 *) msg)[0]) == MSG_TYPE_ERR) ||
> +	     (MSG_TYPE(((u32 *) msg)[0]) == MSG_TYPE_DBG &&
> +	      MSG_SUBTYPE(((u32 *) msg)[0]) == DBG_SUBTYPE_SENSOR_READ) ||
> +	     (MSG_TYPE(((u32 *) msg)[0]) == MSG_TYPE_PWRMGMT &&
> +	      MSG_SUBTYPE(((u32 *) msg)[0]) == PWRMGMT_SUBTYPE_TPC &&
> +	      TPC_CMD(((u32 *) msg)[0]) == TPC_ALARM))) {
> +		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;
> +	}
> +
> +	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->kfifo_lock);
> +	/* Schedule the bottom handler */
> +	schedule_work(&ctx->workq);
> +}
> +
> +/*
> + * This function is called when the PCC Mailbox received a message
> + */
> +static void xgene_hwmon_pcc_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;
> +
> +	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 &&
> +	    ((MSG_TYPE(((u32 *) msg)[0]) == MSG_TYPE_ERR) ||
> +	     (MSG_TYPE(((u32 *) msg)[0]) == MSG_TYPE_DBG &&
> +	      MSG_SUBTYPE(((u32 *) msg)[0]) == DBG_SUBTYPE_SENSOR_READ) ||
> +	     (MSG_TYPE(((u32 *) msg)[0]) == MSG_TYPE_PWRMGMT &&
> +	      MSG_SUBTYPE(((u32 *) msg)[0]) == PWRMGMT_SUBTYPE_TPC &&
> +	      TPC_CMD(((u32 *) msg)[0]) == TPC_ALARM))) {
> +
> +		/* Check if platform completes command */
> +		if (xgene_word_tst_and_clr(&generic_comm_base->status,
> +					    PCCS_CMD_COMPLETE)) {
> +			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;
> +		}
> +	}
> +
> +	/*
> +	 * 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.
> +	 */
> +
> +	/* Enqueue to the FIFO */
> +	kfifo_in_spinlocked(&ctx->async_msg_fifo, &amsg,
> +			    sizeof(struct slimpro_resp_msg), &ctx->kfifo_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);

Please run your patch through checkoatch --strict. I would like to see
at least the following messages resolved.

"No space is necessary after a cast"
"Blank lines aren't necessary after an open brace '{'"
"Please don't use multiple blank lines"
"Alignment should match open parenthesis"
"line over 80 characters" (with precedence over continuation line alignment)

> +	}
> +}
> +
> +static int 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->tx_done = xgene_hwmon_tx_done;
> +	cl->tx_block = false;
> +	cl->tx_tout = MBOX_OP_TIMEOUTMS;
> +	cl->knows_txdone = false;
> +	if (acpi_disabled) {
> +		cl->rx_callback = xgene_hwmon_rx_cb;
> +		ctx->mbox_chan = mbox_request_channel(cl, 0);
> +		if (IS_ERR(ctx->mbox_chan)) {
> +			dev_err(&pdev->dev,
> +				"SLIMpro mailbox channel request failed\n");
> +			return -ENODEV;
> +		}
> +	} else {
> +		struct acpi_pcct_hw_reduced *cppc_ss;
> +
> +		if (device_property_read_u32(&pdev->dev, "pcc-channel",
> +					     &ctx->mbox_idx)) {
> +			dev_err(&pdev->dev, "no pcc-channel property\n");
> +			return -ENODEV;
> +		}
> +
> +		cl->rx_callback = xgene_hwmon_pcc_rx_cb;
> +		ctx->mbox_chan = pcc_mbox_request_channel(cl, ctx->mbox_idx);
> +		if (IS_ERR(ctx->mbox_chan)) {
> +			dev_err(&pdev->dev,
> +				"PPC channel request failed\n");
> +			return -ENODEV;
> +		}
> +
> +		/*
> +		 * 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->kfifo_lock);
> +	mutex_init(&ctx->rd_mutex);
> +
> +	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);
> +
> +	ctx->hwmon_dev = devm_hwmon_device_register_with_groups(ctx->dev,
> +								"apm_xgene",
> +								ctx,
> +								xgene_hwmon_groups);

Using the devm_ function here would, on remove, result in the mailbox and kfifo
being removed before the hwmon driver is removed. This might result in race
conditions. You have two options: Use devm_add_action() to remove those in sequence,
or use hwmon_device_register_with_groups() and remove the hwmon device explicitly
(and first) in the remove function.

Note that you don't have to store hwmon_dev in ctx if you use devm_add_action()
and devm_hwmon_device_register_with_groups().

> +	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:
> +	kfifo_free(&ctx->async_msg_fifo);
> +out_mbox_free:
> +	if (acpi_disabled)
> +		mbox_free_channel(ctx->mbox_chan);
> +	else
> +		pcc_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);
> +
> +	kfifo_free(&ctx->async_msg_fifo);
> +	if (acpi_disabled)
> +		mbox_free_channel(ctx->mbox_chan);
> +	else
> +		pcc_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");
>

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