[PATCH v8 04/10] misc: amd-sbi: Use regmap subsystem

Akshay Gupta
2025-04-11T13:32:02Z

- regmap subsystem provides multiple benefits over direct smbus APIs
- subsystem adds another abstraction layer on top of struct i2c_client to
make it easy to read or write registers.
- The subsystem can be helpful in following cases
- Different types of bus (i2c/i3c), we have plans to support i3c.
- Different Register address size (1byte/2byte)

Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>
---
Changes since v4:
- Previously patch 2
Changes since v1:
- Previously patch 3
- Remove "__packed" from data structure

drivers/misc/amd-sbi/rmi-core.c | 29 ++++++++++++-----------------
drivers/misc/amd-sbi/rmi-core.h | 3 ++-
drivers/misc/amd-sbi/rmi-i2c.c | 25 ++++++++++++++++---------
3 files changed, 30 insertions(+), 27 deletions(-)

diff --git a/drivers/misc/amd-sbi/rmi-core.c b/drivers/misc/amd-sbi/rmi-core.c
index 74456756270c..663ab9176d95 100644
--- a/drivers/misc/amd-sbi/rmi-core.c
+++ b/drivers/misc/amd-sbi/rmi-core.c
@@ -9,6 +9,7 @@
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/mutex.h>
+#include <linux/regmap.h>
#include "rmi-core.h"

/* Mask for Status Register bit[1] */
@@ -21,6 +22,7 @@
int rmi_mailbox_xfer(struct sbrmi_data *data,
struct sbrmi_mailbox_msg *msg)
{
+ unsigned int bytes;
int i, ret, retry = 10;
int sw_status;
u8 byte;
@@ -28,14 +30,12 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
mutex_lock(&data->lock);

/* Indicate firmware a command is to be serviced */
- ret = i2c_smbus_write_byte_data(data->client,
- SBRMI_INBNDMSG7, START_CMD);
+ ret = regmap_write(data->regmap, 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);
+ ret = regmap_write(data->regmap, SBRMI_INBNDMSG0, msg->cmd);
if (ret < 0)
goto exit_unlock;

@@ -46,8 +46,7 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
*/
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);
+ ret = regmap_write(data->regmap, SBRMI_INBNDMSG1 + i, byte);
if (ret < 0)
goto exit_unlock;
}
@@ -56,8 +55,7 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
* 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);
+ ret = regmap_write(data->regmap, SBRMI_SW_INTERRUPT, TRIGGER_MAILBOX);
if (ret < 0)
goto exit_unlock;

@@ -67,8 +65,7 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
* of the requested command
*/
do {
- sw_status = i2c_smbus_read_byte_data(data->client,
- SBRMI_STATUS);
+ ret = regmap_read(data->regmap, SBRMI_STATUS, &sw_status);
if (sw_status < 0) {
ret = sw_status;
goto exit_unlock;
@@ -79,8 +76,6 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
} while (retry--);

if (retry < 0) {
- dev_err(&data->client->dev,
- "Firmware fail to indicate command completion\n");
ret = -EIO;
goto exit_unlock;
}
@@ -92,11 +87,11 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
*/
if (msg->read) {
for (i = 0; i < 4; i++) {
- ret = i2c_smbus_read_byte_data(data->client,
- SBRMI_OUTBNDMSG1 + i);
+ ret = regmap_read(data->regmap,
+ SBRMI_OUTBNDMSG1 + i, &bytes);
if (ret < 0)
goto exit_unlock;
- msg->data_out |= ret << i * 8;
+ msg->data_out |= bytes << i * 8;
}
}

@@ -104,8 +99,8 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
* 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);
+ ret = regmap_write(data->regmap, SBRMI_STATUS,
+ sw_status | SW_ALERT_MASK);

exit_unlock:
mutex_unlock(&data->lock);
diff --git a/drivers/misc/amd-sbi/rmi-core.h b/drivers/misc/amd-sbi/rmi-core.h
index 977ee05af6a6..3a6028306d10 100644
--- a/drivers/misc/amd-sbi/rmi-core.h
+++ b/drivers/misc/amd-sbi/rmi-core.h
@@ -9,6 +9,7 @@
#include <linux/mutex.h>
#include <linux/i2c.h>
#include <linux/platform_device.h>
+#include <linux/regmap.h>

/* SB-RMI registers */
enum sbrmi_reg {
@@ -47,7 +48,7 @@ enum sbrmi_msg_id {

/* Each client has this additional data */
struct sbrmi_data {
- struct i2c_client *client;
+ struct regmap *regmap;
struct mutex lock;
u32 pwr_limit_max;
};
diff --git a/drivers/misc/amd-sbi/rmi-i2c.c b/drivers/misc/amd-sbi/rmi-i2c.c
index 9ad4c8093399..7a9801273a4c 100644
--- a/drivers/misc/amd-sbi/rmi-i2c.c
+++ b/drivers/misc/amd-sbi/rmi-i2c.c
@@ -13,24 +13,24 @@
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
+#include <linux/regmap.h>
#include "rmi-core.h"

-static int sbrmi_enable_alert(struct i2c_client *client)
+static int sbrmi_enable_alert(struct sbrmi_data *data)
{
- int ctrl;
+ int ctrl, ret;

/*
* 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;
+ ret = regmap_read(data->regmap, SBRMI_CTRL, &ctrl);
+ if (ret < 0)
+ return ret;

if (ctrl & 0x10) {
ctrl &= ~0x10;
- return i2c_smbus_write_byte_data(client,
- SBRMI_CTRL, ctrl);
+ return regmap_write(data->regmap, SBRMI_CTRL, ctrl);
}

return 0;
@@ -55,17 +55,24 @@ static int sbrmi_i2c_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct sbrmi_data *data;
+ struct regmap_config sbrmi_i2c_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ };
int ret;

data = devm_kzalloc(dev, sizeof(struct sbrmi_data), GFP_KERNEL);
if (!data)
return -ENOMEM;

- data->client = client;
mutex_init(&data->lock);

+ data->regmap = devm_regmap_init_i2c(client, &sbrmi_i2c_regmap_config);
+ if (IS_ERR(data->regmap))
+ return PTR_ERR(data->regmap);
+
/* Enable alert for SB-RMI sequence */
- ret = sbrmi_enable_alert(client);
+ ret = sbrmi_enable_alert(data);
if (ret < 0)
return ret;

--
2.25.1