[PATCH v2 1/3] hwmon: sbrmi: Add support for sbrmi power module

Naveen Krishna Chatradhi
2021-07-07T15:59:41Z

From: Akshay Gupta <Akshay.Gupta@amd.com>

On AMD platforms the Out-of-band access is provided by
Advanced Platform Management Link (APML), APML is a
SMBus v2.0 compatible 2-wire processor client interface.
APML is also referred as the sideband interface (SBI).

APML is used to communicate with the
Side-Band Remote Management Interface (SB-RMI) which provides
Soft Mailbox messages to manage power consumption and
power limits of the CPU socket.

- This module add support to read power consumption,
power limit & max power limit and write power limit.
- To instantiate this driver on a Board Management Controller (BMC)
connected to an AMD CPU with SB-RMI support, the i2c bus number
would be the bus connected from the BMC to the CPU.

Signed-off-by: Akshay Gupta <Akshay.Gupta@amd.com>
Signed-off-by: Naveen Krishna Chatradhi <nchatrad@amd.com>
---

Changes since v1:
1. remove header file and move in alphabetical order
2. make all comments multiline
3. remove the pr_err, needed for debugging only
4. fix #define tab issue
5. uninitailize err,
- correct spelling & remove extra ()
- remove extra i2c functionality check
6. reduce call to data->client
7. remove usage of union

drivers/hwmon/Kconfig | 10 ++
drivers/hwmon/Makefile | 1 +
drivers/hwmon/sbrmi.c | 341 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 352 insertions(+)
create mode 100644 drivers/hwmon/sbrmi.c

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 87624902ea80..f489972a6309 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1551,6 +1551,16 @@ config SENSORS_SBTSI
This driver can also be built as a module. If so, the module will
be called sbtsi_temp.

+config SENSORS_SBRMI
+ tristate "Emulated SB-RMI sensor"
+ depends on I2C
+ help
+ If you say yes here you get support for emulated RMI
+ sensors on AMD SoCs with APML interface connected to a BMC device.
+
+ This driver can also be built as a module. If so, the module will
+ be called sbrmi.
+
config SENSORS_SHT15
tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
depends on GPIOLIB || COMPILE_TEST
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 59e78bc212cf..8031acf58936 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -164,6 +164,7 @@ obj-$(CONFIG_SENSORS_PWM_FAN) += pwm-fan.o
obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON) += raspberrypi-hwmon.o
obj-$(CONFIG_SENSORS_S3C) += s3c-hwmon.o
obj-$(CONFIG_SENSORS_SBTSI) += sbtsi_temp.o
+obj-$(CONFIG_SENSORS_SBRMI) += sbrmi.o
obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
obj-$(CONFIG_SENSORS_SCH5627) += sch5627.o
obj-$(CONFIG_SENSORS_SCH5636) += sch5636.o
diff --git a/drivers/hwmon/sbrmi.c b/drivers/hwmon/sbrmi.c
new file mode 100644
index 000000000000..10622b1f23f2
--- /dev/null
+++ b/drivers/hwmon/sbrmi.c
@@ -0,0 +1,341 @@
+// 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;
+};
+
+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);
+
+ ret = sbrmi_enable_alert(data->client);
+ if (ret < 0)
+ goto exit_unlock;
+
+ /* 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) {
+ pr_err("Firmware fail to indicate command completion\n");
+ ret = -1;
+ 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 & 0xff) << 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:
+ if (ret < 0)
+ pr_err("SMBUS translation failed\n");
+
+ 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.cmd = SBRMI_READ_PKG_MAX_PWR_LIMIT;
+ ret = rmi_mailbox_xfer(data, &msg);
+ break;
+ default:
+ return -EINVAL;
+ }
+ /* 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;
+
+ msg.cmd = SBRMI_READ_PKG_MAX_PWR_LIMIT;
+ msg.data_in = 0;
+ msg.read = true;
+ rmi_mailbox_xfer(data, &msg);
+
+ val = clamp_val(val, SBRMI_PWR_MIN, msg.data_out);
+
+ 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_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ struct device *hwmon_dev;
+ struct sbrmi_data *data;
+
+ data = devm_kzalloc(dev, sizeof(struct sbrmi_data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->client = client;
+ mutex_init(&data->lock);
+
+ 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 <akshay.gupta@amd.com>");
+MODULE_DESCRIPTION("Hwmon driver for AMD SB-RMI emulated sensor");
+MODULE_LICENSE("GPL");
--
2.17.1