[PATCH v8 02/10] misc: amd-sbi: Move protocol functionality to core file

Akshay Gupta
2025-04-11T13:31:53Z

- This is done to utilize the protocol functionality into
other domains.
- Increase the scalability of the module with different bus(i2c/i3c)

Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>
---
Changes since v7:
- Add dependency on hwmon subsystem

Changes since v5:
- Address kernel test robot error:
- undefined reference to `devm_hwmon_device_register_with_info'
Changes since v4:
New patch: Patch split from v4 patch 1/9
- Update Copyright year to 2025

drivers/misc/amd-sbi/Kconfig | 9 +-
drivers/misc/amd-sbi/Makefile | 3 +-
drivers/misc/amd-sbi/rmi-core.c | 113 +++++++++++++
drivers/misc/amd-sbi/rmi-core.h | 63 ++++++++
drivers/misc/amd-sbi/{sbrmi.c => rmi-i2c.c} | 166 ++------------------
5 files changed, 192 insertions(+), 162 deletions(-)
create mode 100644 drivers/misc/amd-sbi/rmi-core.c
create mode 100644 drivers/misc/amd-sbi/rmi-core.h
rename drivers/misc/amd-sbi/{sbrmi.c => rmi-i2c.c} (53%)

diff --git a/drivers/misc/amd-sbi/Kconfig b/drivers/misc/amd-sbi/Kconfig
index be2d9e495eb7..0c8981f97f25 100644
--- a/drivers/misc/amd-sbi/Kconfig
+++ b/drivers/misc/amd-sbi/Kconfig
@@ -1,9 +1,10 @@
# SPDX-License-Identifier: GPL-2.0-only
config AMD_SBRMI_I2C
- tristate "AMD side band RMI support"
- depends on I2C
- help
- Side band RMI over I2C support for AMD out of band management.
+ tristate "AMD side band RMI support"
+ depends on I2C
+ depends on HWMON
+ help
+ Side band RMI over I2C support for AMD out of band management.

This driver can also be built as a module. If so, the module will
be called sbrmi-i2c.
diff --git a/drivers/misc/amd-sbi/Makefile b/drivers/misc/amd-sbi/Makefile
index 304394bf5e59..7cd8e0a1aa5d 100644
--- a/drivers/misc/amd-sbi/Makefile
+++ b/drivers/misc/amd-sbi/Makefile
@@ -1,2 +1,3 @@
# SPDX-License-Identifier: GPL-2.0-only
-obj-$(CONFIG_AMD_SBRMI_I2C) += sbrmi.o
+sbrmi-i2c-objs := rmi-i2c.o rmi-core.o
+obj-$(CONFIG_AMD_SBRMI_I2C) += sbrmi-i2c.o
diff --git a/drivers/misc/amd-sbi/rmi-core.c b/drivers/misc/amd-sbi/rmi-core.c
new file mode 100644
index 000000000000..74456756270c
--- /dev/null
+++ b/drivers/misc/amd-sbi/rmi-core.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * sbrmi-core.c - file defining SB-RMI protocols compliant
+ * AMD SoC device.
+ *
+ * Copyright (C) 2025 Advanced Micro Devices, Inc.
+ */
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+#include "rmi-core.h"
+
+/* Mask for Status Register bit[1] */
+#define SW_ALERT_MASK 0x2
+
+/* Software Interrupt for triggering */
+#define START_CMD 0x80
+#define TRIGGER_MAILBOX 0x01
+
+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;
+}
diff --git a/drivers/misc/amd-sbi/rmi-core.h b/drivers/misc/amd-sbi/rmi-core.h
new file mode 100644
index 000000000000..8e30a43ec714
--- /dev/null
+++ b/drivers/misc/amd-sbi/rmi-core.h
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2025 Advanced Micro Devices, Inc.
+ */
+
+#ifndef _SBRMI_CORE_H_
+#define _SBRMI_CORE_H_
+
+#include <linux/mutex.h>
+#include <linux/i2c.h>
+#include <linux/platform_device.h>
+
+/* 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,
+};
+
+/*
+ * 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,
+};
+
+/* 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;
+};
+
+int rmi_mailbox_xfer(struct sbrmi_data *data, struct sbrmi_mailbox_msg *msg);
+#endif /*_SBRMI_CORE_H_*/
diff --git a/drivers/misc/amd-sbi/sbrmi.c b/drivers/misc/amd-sbi/rmi-i2c.c
similarity index 53%
rename from drivers/misc/amd-sbi/sbrmi.c
rename to drivers/misc/amd-sbi/rmi-i2c.c
index d48d8e5460ff..6412f00eb381 100644
--- a/drivers/misc/amd-sbi/sbrmi.c
+++ b/drivers/misc/amd-sbi/rmi-i2c.c
@@ -1,9 +1,9 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/*
- * sbrmi.c - hwmon driver for a SB-RMI mailbox
- * compliant AMD SoC device.
+ * rmi-i2c.c - Side band RMI over I2C support for AMD out
+ * of band management
*
- * Copyright (C) 2020-2021 Advanced Micro Devices, Inc.
+ * Copyright (C) 2024 Advanced Micro Devices, Inc.
*/

#include <linux/delay.h>
@@ -14,64 +14,10 @@
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
+#include "rmi-core.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)
{
@@ -94,100 +40,6 @@ static int sbrmi_enable_alert(struct i2c_client *client)
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)
{
@@ -297,7 +149,7 @@ static int sbrmi_get_max_pwr_limit(struct sbrmi_data *data)
return ret;
}

-static int sbrmi_probe(struct i2c_client *client)
+static int sbrmi_i2c_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct device *hwmon_dev;
@@ -323,12 +175,11 @@ static int sbrmi_probe(struct i2c_client *client)

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"},
+ {"sbrmi-i2c"},
{}
};
MODULE_DEVICE_TABLE(i2c, sbrmi_id);
@@ -343,15 +194,16 @@ MODULE_DEVICE_TABLE(of, sbrmi_of_match);

static struct i2c_driver sbrmi_driver = {
.driver = {
- .name = "sbrmi",
+ .name = "sbrmi-i2c",
.of_match_table = of_match_ptr(sbrmi_of_match),
},
- .probe = sbrmi_probe,
+ .probe = sbrmi_i2c_probe,
.id_table = sbrmi_id,
};

module_i2c_driver(sbrmi_driver);

MODULE_AUTHOR("Akshay Gupta <akshay.gupta@amd.com>");
+MODULE_AUTHOR("Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>");
MODULE_DESCRIPTION("Hwmon driver for AMD SB-RMI emulated sensor");
MODULE_LICENSE("GPL");
--
2.25.1