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- // 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 *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,
- const struct i2c_device_id *id)
- {
- 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", 0},
- {}
- };
- 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 = {
- .class = I2C_CLASS_HWMON,
- .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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