[PATCH v8 2/8] mfd: simple-mfd-i2c: specify max_register

Alex Elder
2025-07-10T17:51:14Z

All devices supported by simple MFD use the same 8-bit register 8-bit
value regmap configuration. There is an option available for a device
to specify a custom configuration, but no existing device uses it.

Rather than specify a "full" regmap configuration to change only
the max_register value, Lee Jones suggested allowing max_register
to be specified in the simple_mfd_data structure. If regmap_config
and max_register are both supplied, the max_register field is ignored.

Signed-off-by: Alex Elder <elder@riscstar.com>
Suggested-by: Lee Jones <lee@kernel.org>
---
v8: - Use regmap_config_8r_8v, modifying it if max_register supplied

drivers/mfd/simple-mfd-i2c.c | 8 ++++++--
drivers/mfd/simple-mfd-i2c.h | 3 ++-
2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/mfd/simple-mfd-i2c.c b/drivers/mfd/simple-mfd-i2c.c
index 22159913bea03..5138aa72140b5 100644
--- a/drivers/mfd/simple-mfd-i2c.c
+++ b/drivers/mfd/simple-mfd-i2c.c
@@ -24,15 +24,16 @@

#include "simple-mfd-i2c.h"

-static const struct regmap_config regmap_config_8r_8v = {
+static struct regmap_config regmap_config_8r_8v = {
.reg_bits = 8,
.val_bits = 8,
+ /* .max_register can be specified in simple_mfd_data */
};

static int simple_mfd_i2c_probe(struct i2c_client *i2c)
{
const struct simple_mfd_data *simple_mfd_data;
- const struct regmap_config *regmap_config;
+ struct regmap_config *regmap_config;
struct regmap *regmap;
int ret;

@@ -43,8 +44,11 @@ static int simple_mfd_i2c_probe(struct i2c_client *i2c)
regmap_config = &regmap_config_8r_8v;
else
regmap_config = simple_mfd_data->regmap_config;
+ if (simple_mfd_data && !simple_mfd_data->regmap_config)
+ regmap_config->max_register = simple_mfd_data->max_register;

regmap = devm_regmap_init_i2c(i2c, regmap_config);
+ regmap_config->max_register = 0;
if (IS_ERR(regmap))
return PTR_ERR(regmap);

diff --git a/drivers/mfd/simple-mfd-i2c.h b/drivers/mfd/simple-mfd-i2c.h
index 7cb2bdd347d97..ea2a96af8bce4 100644
--- a/drivers/mfd/simple-mfd-i2c.h
+++ b/drivers/mfd/simple-mfd-i2c.h
@@ -24,7 +24,8 @@
#include <linux/regmap.h>

struct simple_mfd_data {
- const struct regmap_config *regmap_config;
+ struct regmap_config *regmap_config;
+ unsigned int max_register; /* Ignored if regmap_config supplied */
const struct mfd_cell *mfd_cell;
size_t mfd_cell_size;
};
--
2.45.2