Commit 35ac2034 authored by Akshay Gupta's avatar Akshay Gupta Committed by Greg Kroah-Hartman
Browse files

misc: amd-sbi: Add support for AMD_SBI IOCTL 

The present sbrmi module only support reporting power via hwmon.
However, AMD data center range of processors support various
system management functionality using custom protocols defined in
Advanced Platform Management Link (APML) specification.

Register a miscdevice, which creates a device /dev/sbrmiX with an IOCTL
interface for the user space to invoke the APML Mailbox protocol, which
is already defined in sbrmi_mailbox_xfer().

The APML protocols depend on a set of RMI registers. Having an IOCTL
as a single entry point will help in providing synchronization among
these protocols as multiple transactions on RMI register set may
create race condition.
Support for other protocols will be added in subsequent patches.

APML mailbox protocol returns additional error codes written by
SMU firmware in the out-bound register 0x37. These errors include,
invalid core, message not supported over platform and
others. This additional error codes can be used to provide more
details to user space.

Open-sourced and widely used https://github.com/amd/esmi_oob_library


will continue to provide user-space programmable API.

Reviewed-by: default avatarNaveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: default avatarAkshay Gupta <akshay.gupta@amd.com>
Link: https://lore.kernel.org/r/20250428063034.2145566-7-akshay.gupta@amd.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 587d2c62

Documentation/misc-devices/index.rst

+1 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ fit into other categories. 
   :maxdepth: 2



   ad525x_dpot

   amd-sbi

   apds990x

   bh1770glc

   c2port

Documentation/userspace-api/ioctl/ioctl-number.rst

+2 −0
Original line number Diff line number Diff line
@@ -397,6 +397,8 @@ Code Seq# Include File Comments 
                                                                     <mailto:mathieu.desnoyers@efficios.com>

0xF8  all    arch/x86/include/uapi/asm/amd_hsmp.h                    AMD HSMP EPYC system management interface driver

                                                                     <mailto:nchatrad@amd.com>

0xF9  00-0F  uapi/misc/amd-apml.h		                     AMD side band system management interface driver

                                                                     <mailto:naveenkrishna.chatradhi@amd.com>

0xFD  all    linux/dm-ioctl.h

0xFE  all    linux/isst_if.h

====  =====  ======================================================= ================================================================

drivers/misc/amd-sbi/rmi-core.c

+79 −13
Original line number Diff line number Diff line
@@ -7,7 +7,10 @@ 
 */

#include <linux/delay.h>

#include <linux/err.h>

#include <linux/fs.h>

#include <linux/i2c.h>

#include <linux/miscdevice.h>

#include <linux/module.h>

#include <linux/mutex.h>

#include <linux/regmap.h>

#include "rmi-core.h"
@@ -20,15 +23,17 @@ 
#define TRIGGER_MAILBOX	0x01



int rmi_mailbox_xfer(struct sbrmi_data *data,

		     struct sbrmi_mailbox_msg *msg)

		     struct apml_mbox_msg *msg)

{

	unsigned int bytes;

	unsigned int bytes, ec;

	int i, ret;

	int sw_status;

	u8 byte;



	mutex_lock(&data->lock);



	msg->fw_ret_code = 0;



	/* Indicate firmware a command is to be serviced */

	ret = regmap_write(data->regmap, SBRMI_INBNDMSG7, START_CMD);

	if (ret < 0)
@@ -44,8 +49,8 @@ int rmi_mailbox_xfer(struct sbrmi_data *data, 
	 * Command Data In[31:0] to SBRMI::InBndMsg_inst[4:1]

	 * SBRMI_x3C(MSB):SBRMI_x39(LSB)

	 */

	for (i = 0; i < 4; i++) {

		byte = (msg->data_in >> i * 8) & 0xff;

	for (i = 0; i < AMD_SBI_MB_DATA_SIZE; i++) {

		byte = (msg->mb_in_out >> i * 8) & 0xff;

		ret = regmap_write(data->regmap, SBRMI_INBNDMSG1 + i, byte);

		if (ret < 0)

			goto exit_unlock;
@@ -69,29 +74,90 @@ int rmi_mailbox_xfer(struct sbrmi_data *data, 
	if (ret)

		goto exit_unlock;



	ret = regmap_read(data->regmap, SBRMI_OUTBNDMSG7, &ec);

	if (ret || ec)

		goto exit_clear_alert;

	/*

	 * For a read operation, the initiator (BMC) reads the firmware

	 * response Command Data Out[31:0] from SBRMI::OutBndMsg_inst[4:1]

	 * {SBRMI_x34(MSB):SBRMI_x31(LSB)}.

	 */

	if (msg->read) {

		for (i = 0; i < 4; i++) {

	for (i = 0; i < AMD_SBI_MB_DATA_SIZE; i++) {

		ret = regmap_read(data->regmap,

				  SBRMI_OUTBNDMSG1 + i, &bytes);

		if (ret < 0)

				goto exit_unlock;

			msg->data_out |= bytes << i * 8;

		}

			break;

		msg->mb_in_out |= bytes << i * 8;

	}



exit_clear_alert:

	/*

	 * BMC must write 1'b1 to SBRMI::Status[SwAlertSts] to clear the

	 * ALERT to initiator

	 */

	ret = regmap_write(data->regmap, SBRMI_STATUS,

			   sw_status | SW_ALERT_MASK);



	if (ec) {

		ret = -EPROTOTYPE;

		msg->fw_ret_code = ec;

	}

exit_unlock:

	mutex_unlock(&data->lock);

	return ret;

}



static int apml_mailbox_xfer(struct sbrmi_data *data, struct apml_mbox_msg __user *arg)

{

	struct apml_mbox_msg msg = { 0 };

	int ret;



	/* Copy the structure from user */

	if (copy_from_user(&msg, arg, sizeof(struct apml_mbox_msg)))

		return -EFAULT;



	/* Mailbox protocol */

	ret = rmi_mailbox_xfer(data, &msg);

	if (ret && ret != -EPROTOTYPE)

		return ret;



	return copy_to_user(arg, &msg, sizeof(struct apml_mbox_msg));

}



static long sbrmi_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)

{

	void __user *argp = (void __user *)arg;

	struct sbrmi_data *data;



	data = container_of(fp->private_data, struct sbrmi_data, sbrmi_misc_dev);

	switch (cmd) {

	case SBRMI_IOCTL_MBOX_CMD:

		return apml_mailbox_xfer(data, argp);

	default:

		return -ENOTTY;

	}

}



static const struct file_operations sbrmi_fops = {

	.owner		= THIS_MODULE,

	.unlocked_ioctl	= sbrmi_ioctl,

	.compat_ioctl	= compat_ptr_ioctl,

};



int create_misc_rmi_device(struct sbrmi_data *data,

			   struct device *dev)

{

	data->sbrmi_misc_dev.name	= devm_kasprintf(dev,

							 GFP_KERNEL,

							 "sbrmi-%x",

							 data->dev_static_addr);

	data->sbrmi_misc_dev.minor	= MISC_DYNAMIC_MINOR;

	data->sbrmi_misc_dev.fops	= &sbrmi_fops;

	data->sbrmi_misc_dev.parent	= dev;

	data->sbrmi_misc_dev.nodename	= devm_kasprintf(dev,

							 GFP_KERNEL,

							 "sbrmi-%x",

							 data->dev_static_addr);

	data->sbrmi_misc_dev.mode	= 0600;



	return misc_register(&data->sbrmi_misc_dev);

}

drivers/misc/amd-sbi/rmi-core.h

+7 −8
Original line number Diff line number Diff line
@@ -6,10 +6,12 @@ 
#ifndef _SBRMI_CORE_H_

#define _SBRMI_CORE_H_



#include <linux/miscdevice.h>

#include <linux/mutex.h>

#include <linux/i2c.h>

#include <linux/platform_device.h>

#include <linux/regmap.h>

#include <uapi/misc/amd-apml.h>



/* SB-RMI registers */

enum sbrmi_reg {
@@ -48,19 +50,15 @@ enum sbrmi_msg_id { 


/* Each client has this additional data */

struct sbrmi_data {

	struct miscdevice sbrmi_misc_dev;

	struct regmap *regmap;

	/* Mutex locking */

	struct mutex lock;

	u32 pwr_limit_max;

	u8 dev_static_addr;

};



struct sbrmi_mailbox_msg {

	u8 cmd;

	bool read;

	u32 data_in;

	u32 data_out;

};



int rmi_mailbox_xfer(struct sbrmi_data *data, struct sbrmi_mailbox_msg *msg);

int rmi_mailbox_xfer(struct sbrmi_data *data, struct apml_mbox_msg *msg);

#ifdef CONFIG_AMD_SBRMI_HWMON

int create_hwmon_sensor_device(struct device *dev, struct sbrmi_data *data);

#else
@@ -69,4 +67,5 @@ static inline int create_hwmon_sensor_device(struct device *dev, struct sbrmi_da 
	return 0;

}

#endif

int create_misc_rmi_device(struct sbrmi_data *data, struct device *dev);

#endif /*_SBRMI_CORE_H_*/

drivers/misc/amd-sbi/rmi-hwmon.c

+6 −7
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
 */

#include <linux/err.h>

#include <linux/hwmon.h>

#include <uapi/misc/amd-apml.h>

#include "rmi-core.h"



/* Do not allow setting negative power limit */
@@ -15,7 +16,7 @@ static int sbrmi_read(struct device *dev, enum hwmon_sensor_types type, 
		      u32 attr, int channel, long *val)

{

	struct sbrmi_data *data = dev_get_drvdata(dev);

	struct sbrmi_mailbox_msg msg = { 0 };

	struct apml_mbox_msg msg = { 0 };

	int ret;



	if (!data)
@@ -24,7 +25,6 @@ static int sbrmi_read(struct device *dev, enum hwmon_sensor_types type, 
	if (type != hwmon_power)

		return -EINVAL;



	msg.read = true;

	switch (attr) {

	case hwmon_power_input:

		msg.cmd = SBRMI_READ_PKG_PWR_CONSUMPTION;
@@ -35,7 +35,7 @@ static int sbrmi_read(struct device *dev, enum hwmon_sensor_types type, 
		ret = rmi_mailbox_xfer(data, &msg);

		break;

	case hwmon_power_cap_max:

		msg.data_out = data->pwr_limit_max;

		msg.mb_in_out = data->pwr_limit_max;

		ret = 0;

		break;

	default:
@@ -44,7 +44,7 @@ static int sbrmi_read(struct device *dev, enum hwmon_sensor_types type, 
	if (ret < 0)

		return ret;

	/* hwmon power attributes are in microWatt */

	*val = (long)msg.data_out * 1000;

	*val = (long)msg.mb_in_out * 1000;

	return ret;

}
@@ -52,7 +52,7 @@ static int sbrmi_write(struct device *dev, enum hwmon_sensor_types type, 
		       u32 attr, int channel, long val)

{

	struct sbrmi_data *data = dev_get_drvdata(dev);

	struct sbrmi_mailbox_msg msg = { 0 };

	struct apml_mbox_msg msg = { 0 };



	if (!data)

		return -ENODEV;
@@ -68,8 +68,7 @@ static int sbrmi_write(struct device *dev, enum hwmon_sensor_types type, 
	val = clamp_val(val, SBRMI_PWR_MIN, data->pwr_limit_max);



	msg.cmd = SBRMI_WRITE_PKG_PWR_LIMIT;

	msg.data_in = val;

	msg.read = false;

	msg.mb_in_out = val;



	return rmi_mailbox_xfer(data, &msg);

}