regmap: Allow a base register to be specified for the RAM regmap

To allow testing of register maps with very large register values add
support for specifying base address to the RAM regmap.  Since the config
struct is shared with the raw RAM regmap also update that, though we
will not use it.

Link: https://patch.msgid.link/20260818-regmap-kunit-cache-high-bit-v1-1-7e790676dea3@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>

3 files changed, 34 insertions, 14 deletions

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index a6e4689000af..c73036744468 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -322,6 +322,7 @@ static inline unsigned int regcache_get_index_by_order(const struct regmap *map,
 }
 
 struct regmap_ram_data {
+	unsigned int base_reg;
 	unsigned int *vals;  /* Allocatd by caller */
 	bool *read;
 	bool *written;
diff --git a/drivers/base/regmap/regmap-ram.c b/drivers/base/regmap/regmap-ram.c
index c7356b0d8c83..a666bfb4d667 100644
--- a/drivers/base/regmap/regmap-ram.c
+++ b/drivers/base/regmap/regmap-ram.c
@@ -20,8 +20,11 @@ static int regmap_ram_write(void *context, unsigned int reg, unsigned int val)
 {
 	struct regmap_ram_data *data = context;
 
-	data->vals[reg] = val;
-	data->written[reg] = true;
+	if (reg < data->base_reg)
+		return -EINVAL;
+
+	data->vals[reg - data->base_reg] = val;
+	data->written[reg - data->base_reg] = true;
 
 	return 0;
 }
@@ -30,8 +33,11 @@ static int regmap_ram_read(void *context, unsigned int reg, unsigned int *val)
 {
 	struct regmap_ram_data *data = context;
 
-	*val = data->vals[reg];
-	data->read[reg] = true;
+	if (reg < data->base_reg)
+		return -EINVAL;
+
+	*val = data->vals[reg - data->base_reg];
+	data->read[reg - data->base_reg] = true;
 
 	return 0;
 }
@@ -60,17 +66,25 @@ struct regmap *__regmap_init_ram(struct device *dev,
 				 const char *lock_name)
 {
 	struct regmap *map;
+	unsigned int num_regs;
 
 	if (!config->max_register) {
 		pr_crit("No max_register specified for RAM regmap\n");
 		return ERR_PTR(-EINVAL);
 	}
 
-	data->read = kzalloc_objs(bool, config->max_register + 1);
+	if (data->base_reg > config->max_register) {
+		pr_crit("base_reg above max_register for RAM regmap\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	num_regs = config->max_register - data->base_reg + 1;
+
+	data->read = kzalloc_objs(bool, num_regs);
 	if (!data->read)
 		return ERR_PTR(-ENOMEM);
 
-	data->written = kzalloc_objs(bool, config->max_register + 1);
+	data->written = kzalloc_objs(bool, num_regs);
 	if (!data->written) {
 		kfree(data->read);
 		return ERR_PTR(-ENOMEM);
diff --git a/drivers/base/regmap/regmap-raw-ram.c b/drivers/base/regmap/regmap-raw-ram.c
index 60d6e95cdd1b..c63c464549f9 100644
--- a/drivers/base/regmap/regmap-raw-ram.c
+++ b/drivers/base/regmap/regmap-raw-ram.c
@@ -16,14 +16,17 @@
 
 #include "internal.h"
 
-static unsigned int decode_reg(enum regmap_endian endian, const void *reg)
+static unsigned int decode_reg(struct regmap_ram_data *data, const void *reg)
 {
 	const u16 *r = reg;
+	unsigned int decode;
 
-	if (endian == REGMAP_ENDIAN_BIG)
-		return be16_to_cpu(*r);
+	if (data->reg_endian == REGMAP_ENDIAN_BIG)
+		decode = be16_to_cpu(*r);
 	else
-		return le16_to_cpu(*r);
+		decode = le16_to_cpu(*r);
+
+	return decode - data->base_reg;
 }
 
 static int regmap_raw_ram_gather_write(void *context,
@@ -40,7 +43,7 @@ static int regmap_raw_ram_gather_write(void *context,
 	if (val_len % 2)
 		return -EINVAL;
 
-	r = decode_reg(data->reg_endian, reg);
+	r = decode_reg(data, reg);
 	if (data->noinc_reg && data->noinc_reg(data, r)) {
 		memcpy(&our_buf[r], val + val_len - 2, 2);
 		data->written[r] = true;
@@ -74,7 +77,7 @@ static int regmap_raw_ram_read(void *context,
 	if (val_len % 2)
 		return -EINVAL;
 
-	r = decode_reg(data->reg_endian, reg);
+	r = decode_reg(data, reg);
 	if (data->noinc_reg && data->noinc_reg(data, r)) {
 		for (i = 0; i < val_len; i += 2)
 			memcpy(val + i, &our_buf[r], 2);
@@ -114,6 +117,7 @@ struct regmap *__regmap_init_raw_ram(struct device *dev,
 				     const char *lock_name)
 {
 	struct regmap *map;
+	unsigned int regs;
 
 	if (config->reg_bits != 16)
 		return ERR_PTR(-EINVAL);
@@ -123,11 +127,12 @@ struct regmap *__regmap_init_raw_ram(struct device *dev,
 		return ERR_PTR(-EINVAL);
 	}
 
-	data->read = kzalloc_objs(bool, config->max_register + 1);
+	regs = config->max_register - data->base_reg + 1;
+	data->read = kzalloc_objs(bool, regs);
 	if (!data->read)
 		return ERR_PTR(-ENOMEM);
 
-	data->written = kzalloc_objs(bool, config->max_register + 1);
+	data->written = kzalloc_objs(bool, regs);
 	if (!data->written)
 		return ERR_PTR(-ENOMEM);