// SPDX-License-Identifier: GPL-2.0-or-later
/*
* sbrmi.c - hwmon driver for a SB-RMI mailbox
* compliant AMD SoC device.
*
* Copyright (C) 2020-2021 Advanced Micro Devices, Inc.
*/
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
/* Do not allow setting negative power limit */
#define SBRMI_PWR_MIN 0
/* Mask for Status Register bit[1] */
#define SW_ALERT_MASK 0x2
/* Software Interrupt for triggering */
#define START_CMD 0x80
#define TRIGGER_MAILBOX 0x01
/*
* SB-RMI supports soft mailbox service request to MP1 (power management
* firmware) through SBRMI inbound/outbound message registers.
* SB-RMI message IDs
*/
enum sbrmi_msg_id {
SBRMI_READ_PKG_PWR_CONSUMPTION = 0x1,
SBRMI_WRITE_PKG_PWR_LIMIT,
SBRMI_READ_PKG_PWR_LIMIT,
SBRMI_READ_PKG_MAX_PWR_LIMIT,
};
/* SB-RMI registers */
enum sbrmi_reg {
SBRMI_CTRL = 0x01,
SBRMI_STATUS,
SBRMI_OUTBNDMSG0 = 0x30,
SBRMI_OUTBNDMSG1,
SBRMI_OUTBNDMSG2,
SBRMI_OUTBNDMSG3,
SBRMI_OUTBNDMSG4,
SBRMI_OUTBNDMSG5,
SBRMI_OUTBNDMSG6,
SBRMI_OUTBNDMSG7,
SBRMI_INBNDMSG0,
SBRMI_INBNDMSG1,
SBRMI_INBNDMSG2,
SBRMI_INBNDMSG3,
SBRMI_INBNDMSG4,
SBRMI_INBNDMSG5,
SBRMI_INBNDMSG6,
SBRMI_INBNDMSG7,
SBRMI_SW_INTERRUPT,
};
/* Each client has this additional data */
struct sbrmi_data {
struct i2c_client *client;
struct mutex lock;
u32 pwr_limit_max;
};
struct sbrmi_mailbox_msg {
u8 cmd;
bool read;
u32 data_in;
u32 data_out;
};
static int sbrmi_enable_alert(struct i2c_client *client)
{
int ctrl;
/*
* Enable the SB-RMI Software alert status
* by writing 0 to bit 4 of Control register(0x1)
*/
ctrl = i2c_smbus_read_byte_data(client, SBRMI_CTRL);
if (ctrl < 0)
return ctrl;
if (ctrl & 0x10) {
ctrl &= ~0x10;
return i2c_smbus_write_byte_data(client,
SBRMI_CTRL, ctrl);
}
return 0;
}
static int rmi_mailbox_xfer(struct sbrmi_data *data,
struct sbrmi_mailbox_msg *msg)
{
int i, ret, retry = 10;
int sw_status;
u8 byte;
mutex_lock(&data->lock);
/* Indicate firmware a command is to be serviced */
ret = i2c_smbus_write_byte_data(data->client,
SBRMI_INBNDMSG7, START_CMD);
if (ret < 0)
goto exit_unlock;
/* Write the command to SBRMI::InBndMsg_inst0 */
ret = i2c_smbus_write_byte_data(data->client,
SBRMI_INBNDMSG0, msg->cmd);
if (ret < 0)
goto exit_unlock;
/*
* For both read and write the initiator (BMC) writes
* 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;
ret = i2c_smbus_write_byte_data(data->client,
SBRMI_INBNDMSG1 + i, byte);
if (ret < 0)
goto exit_unlock;
}
/*
* Write 0x01 to SBRMI::SoftwareInterrupt to notify firmware to
* perform the requested read or write command
*/
ret = i2c_smbus_write_byte_data(data->client,
SBRMI_SW_INTERRUPT, TRIGGER_MAILBOX);
if (ret < 0)
goto exit_unlock;
/*
* Firmware will write SBRMI::Status[SwAlertSts]=1 to generate
* an ALERT (if enabled) to initiator (BMC) to indicate completion
* of the requested command
*/
do {
sw_status = i2c_smbus_read_byte_data(data->client,
SBRMI_STATUS);
if (sw_status < 0) {
ret = sw_status;
goto exit_unlock;
}
if (sw_status & SW_ALERT_MASK)
break;
usleep_range(50, 100);
} while (retry--);
if (retry < 0) {
dev_err(&data->client->dev,
"Firmware fail to indicate command completion\n");
ret = -EIO;
goto exit_unlock;
}
/*
* 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++) {
ret = i2c_smbus_read_byte_data(data->client,
SBRMI_OUTBNDMSG1 + i);
if (ret < 0)
goto exit_unlock;
msg->data_out |= ret << i * 8;
}
}
/*
* BMC must write 1'b1 to SBRMI::Status[SwAlertSts] to clear the
* ALERT to initiator
*/
ret = i2c_smbus_write_byte_data(data->client, SBRMI_STATUS,
sw_status | SW_ALERT_MASK);
exit_unlock:
mutex_unlock(&data->lock);
return ret;
}
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 };
int ret;
if (type != hwmon_power)
return -EINVAL;
msg.read = true;
switch (attr) {
case hwmon_power_input:
msg.cmd = SBRMI_READ_PKG_PWR_CONSUMPTION;
ret = rmi_mailbox_xfer(data, &msg);
break;
case hwmon_power_cap:
msg.cmd = SBRMI_READ_PKG_PWR_LIMIT;
ret = rmi_mailbox_xfer(data, &msg);
break;
case hwmon_power_cap_max:
msg.data_out = data->pwr_limit_max;
ret = 0;
break;
default:
return -EINVAL;
}
if (ret < 0)
return ret;
/* hwmon power attributes are in microWatt */
*val = (long)msg.data_out * 1000;
return ret;
}
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 };
if (type != hwmon_power && attr != hwmon_power_cap)
return -EINVAL;
/*
* hwmon power attributes are in microWatt
* mailbox read/write is in mWatt
*/
val /= 1000;
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;
return rmi_mailbox_xfer(data, &msg);
}
static umode_t sbrmi_is_visible(const void *data,
enum hwmon_sensor_types type,
u32 attr, int channel)
{
switch (type) {
case hwmon_power:
switch (attr) {
case hwmon_power_input:
case hwmon_power_cap_max:
return 0444;
case hwmon_power_cap:
return 0644;
}
break;
default:
break;
}
return 0;
}
static const struct hwmon_channel_info * const sbrmi_info[] = {
HWMON_CHANNEL_INFO(power,
HWMON_P_INPUT | HWMON_P_CAP | HWMON_P_CAP_MAX),
NULL
};
static const struct hwmon_ops sbrmi_hwmon_ops = {
.is_visible = sbrmi_is_visible,
.read = sbrmi_read,
.write = sbrmi_write,
};
static const struct hwmon_chip_info sbrmi_chip_info = {
.ops = &sbrmi_hwmon_ops,
.info = sbrmi_info,
};
static int sbrmi_get_max_pwr_limit(struct sbrmi_data *data)
{
struct sbrmi_mailbox_msg msg = { 0 };
int ret;
msg.cmd = SBRMI_READ_PKG_MAX_PWR_LIMIT;
msg.read = true;
ret = rmi_mailbox_xfer(data, &msg);
if (ret < 0)
return ret;
data->pwr_limit_max = msg.data_out;
return ret;
}
static int sbrmi_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct device *hwmon_dev;
struct sbrmi_data *data;
int ret;
data = devm_kzalloc(dev, sizeof(struct sbrmi_data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->client = client;
mutex_init(&data->lock);
/* Enable alert for SB-RMI sequence */
ret = sbrmi_enable_alert(client);
if (ret < 0)
return ret;
/* Cache maximum power limit */
ret = sbrmi_get_max_pwr_limit(data);
if (ret < 0)
return ret;
hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data,
&sbrmi_chip_info, NULL);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static const struct i2c_device_id sbrmi_id[] = {
{"sbrmi"},
{}
};
MODULE_DEVICE_TABLE(i2c, sbrmi_id);
static const struct of_device_id __maybe_unused sbrmi_of_match[] = {
{
.compatible = "amd,sbrmi",
},
{ },
};
MODULE_DEVICE_TABLE(of, sbrmi_of_match);
static struct i2c_driver sbrmi_driver = {
.driver = {
.name = "sbrmi",
.of_match_table = of_match_ptr(sbrmi_of_match),
},
.probe = sbrmi_probe,
.id_table = sbrmi_id,
};
module_i2c_driver(sbrmi_driver);
MODULE_AUTHOR("Akshay Gupta <[email protected]>");
MODULE_DESCRIPTION("Hwmon driver for AMD SB-RMI emulated sensor");
MODULE_LICENSE("GPL");
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