linux-kernel - [PATCH v8 2/8] mfd: simple-mfd-i2c: specify max

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Message-ID: <20250710175107.1280221-3-elder@riscstar.com>
Date: Thu, 10 Jul 2025 12:51:00 -0500
From: Alex Elder <elder@...cstar.com>
To: lee@...nel.org,
	lgirdwood@...il.com,
	broonie@...nel.org,
	alexandre.belloni@...tlin.com,
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Cc: mat.jonczyk@...pl,
	dlan@...too.org,
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	aou@...s.berkeley.edu,
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Subject: [PATCH v8 2/8] mfd: simple-mfd-i2c: specify max_register

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@...cstar.com>
Suggested-by: Lee Jones <lee@...nel.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