regmap: reg_default_cb for flat cache defaults

Merge series from "Sheetal ." <sheetal@nvidia.com>:

This series adds a reg_default_cb callback for REGCACHE_FLAT to provide
defaults for registers not listed in reg_defaults. Defaults are loaded
eagerly during regcache init and the callback can use writeable_reg to
filter valid addresses and avoid holes.

Tegra ASoC drivers set reg_default_cb and add writeable_reg filtering for
AHUB RX holes to prevent invalid addresses from being marked valid.

Author: broonie

drivers/base/regmap/internal.h

@@ -117,6 +117,9 @@ struct regmap {
 		    void *val_buf, size_t val_size);
 	int (*write)(void *context, const void *data, size_t count);
 
+	int (*reg_default_cb)(struct device *dev, unsigned int reg,
+			      unsigned int *val);
+
 	unsigned long read_flag_mask;
 	unsigned long write_flag_mask;
 

drivers/base/regmap/regcache-flat.c

@@ -79,6 +79,25 @@ static int regcache_flat_populate(struct regmap *map)
 		__set_bit(index, cache->valid);
 	}
 
+	if (map->reg_default_cb) {
+		dev_dbg(map->dev,
+			"Populating regcache_flat using reg_default_cb callback\n");
+
+		for (i = 0; i <= map->max_register; i += map->reg_stride) {
+			unsigned int index = regcache_flat_get_index(map, i);
+			unsigned int value;
+
+			if (test_bit(index, cache->valid))
+				continue;
+
+			if (map->reg_default_cb(map->dev, i, &value))
+				continue;
+
+			cache->data[index] = value;
+			__set_bit(index, cache->valid);
+		}
+	}
+
 	return 0;
 }
 

drivers/base/regmap/regcache.c

@@ -223,7 +223,8 @@ int regcache_init(struct regmap *map, const struct regmap_config *config)
 			goto err_free;
 	}
 
-	if (map->num_reg_defaults && map->cache_ops->populate) {
+	if (map->cache_ops->populate &&
+	    (map->num_reg_defaults || map->reg_default_cb)) {
 		dev_dbg(map->dev, "Populating %s cache\n", map->cache_ops->name);
 		map->lock(map->lock_arg);
 		ret = map->cache_ops->populate(map);

drivers/base/regmap/regmap-kunit.c

@@ -15,6 +15,8 @@ KUNIT_DEFINE_ACTION_WRAPPER(regmap_exit_action, regmap_exit, struct regmap *);
 
 struct regmap_test_priv {
 	struct device *dev;
+	bool *reg_default_called;
+	unsigned int reg_default_max;
 };
 
 struct regmap_test_param {
@@ -118,6 +120,14 @@ static const struct regmap_test_param real_cache_types_only_list[] = {
 
 KUNIT_ARRAY_PARAM(real_cache_types_only, real_cache_types_only_list, param_to_desc);
 
+static const struct regmap_test_param flat_cache_types_list[] = {
+	{ .cache = REGCACHE_FLAT, .from_reg = 0 },
+	{ .cache = REGCACHE_FLAT, .from_reg = 0, .fast_io = true },
+	{ .cache = REGCACHE_FLAT, .from_reg = 0x2001 },
+};
+
+KUNIT_ARRAY_PARAM(flat_cache_types, flat_cache_types_list, param_to_desc);
+
 static const struct regmap_test_param real_cache_types_list[] = {
 	{ .cache = REGCACHE_FLAT,   .from_reg = 0 },
 	{ .cache = REGCACHE_FLAT,   .from_reg = 0, .fast_io = true },
@@ -248,6 +258,37 @@ static bool reg_5_false(struct device *dev, unsigned int reg)
 	return reg != (param->from_reg + 5);
 }
 
+static unsigned int reg_default_expected(unsigned int reg)
+{
+	return 0x5a5a0000 | (reg & 0xffff);
+}
+
+static int reg_default_test_cb(struct device *dev, unsigned int reg,
+			       unsigned int *def)
+{
+	struct kunit *test = dev_get_drvdata(dev);
+	struct regmap_test_priv *priv = test->priv;
+
+	if (priv && priv->reg_default_called && reg <= priv->reg_default_max)
+		priv->reg_default_called[reg] = true;
+
+	*def = reg_default_expected(reg);
+	return 0;
+}
+
+static void expect_reg_default_value(struct kunit *test, struct regmap *map,
+				     struct regmap_ram_data *data,
+				     struct regmap_test_priv *priv,
+				     unsigned int reg)
+{
+	unsigned int val;
+
+	KUNIT_EXPECT_TRUE(test, priv->reg_default_called[reg]);
+	KUNIT_EXPECT_EQ(test, 0, regmap_read(map, reg, &val));
+	KUNIT_EXPECT_EQ(test, reg_default_expected(reg), val);
+	KUNIT_EXPECT_FALSE(test, data->read[reg]);
+}
+
 static void basic_read_write(struct kunit *test)
 {
 	struct regmap *map;
@@ -628,6 +669,54 @@ static void reg_defaults(struct kunit *test)
 		KUNIT_EXPECT_EQ(test, config.cache_type == REGCACHE_NONE, data->read[i]);
 }
 
+static void reg_default_callback_populates_flat_cache(struct kunit *test)
+{
+	const struct regmap_test_param *param = test->param_value;
+	struct regmap_test_priv *priv = test->priv;
+	struct regmap *map;
+	struct regmap_config config;
+	struct regmap_ram_data *data;
+	unsigned int reg, val;
+	unsigned int defaults_end;
+
+	config = test_regmap_config;
+	config.num_reg_defaults = 3;
+	config.max_register = param->from_reg + BLOCK_TEST_SIZE - 1;
+	config.reg_default_cb = reg_default_test_cb;
+
+	priv->reg_default_max = config.max_register;
+	priv->reg_default_called = kunit_kcalloc(test, config.max_register + 1,
+						 sizeof(*priv->reg_default_called),
+						 GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, priv->reg_default_called);
+
+	map = gen_regmap(test, &config, &data);
+	KUNIT_ASSERT_FALSE(test, IS_ERR(map));
+	if (IS_ERR(map))
+		return;
+
+	for (reg = 0; reg <= config.max_register; reg++)
+		data->read[reg] = false;
+
+	defaults_end = param->from_reg + config.num_reg_defaults - 1;
+
+	for (reg = param->from_reg; reg <= defaults_end; reg++) {
+		KUNIT_EXPECT_FALSE(test, priv->reg_default_called[reg]);
+		KUNIT_EXPECT_EQ(test, 0, regmap_read(map, reg, &val));
+		KUNIT_EXPECT_EQ(test, data->vals[reg], val);
+		KUNIT_EXPECT_FALSE(test, data->read[reg]);
+	}
+
+	if (param->from_reg > 0)
+		expect_reg_default_value(test, map, data, priv, 0);
+
+	if (defaults_end + 1 <= config.max_register)
+		expect_reg_default_value(test, map, data, priv, defaults_end + 1);
+
+	if (config.max_register > defaults_end + 1)
+		expect_reg_default_value(test, map, data, priv, config.max_register);
+}
+
 static void reg_defaults_read_dev(struct kunit *test)
 {
 	struct regmap *map;
@@ -2058,6 +2147,8 @@ static struct kunit_case regmap_test_cases[] = {
 	KUNIT_CASE_PARAM(write_readonly, regcache_types_gen_params),
 	KUNIT_CASE_PARAM(read_writeonly, regcache_types_gen_params),
 	KUNIT_CASE_PARAM(reg_defaults, regcache_types_gen_params),
+	KUNIT_CASE_PARAM(reg_default_callback_populates_flat_cache,
+			 flat_cache_types_gen_params),
 	KUNIT_CASE_PARAM(reg_defaults_read_dev, regcache_types_gen_params),
 	KUNIT_CASE_PARAM(register_patch, regcache_types_gen_params),
 	KUNIT_CASE_PARAM(stride, regcache_types_gen_params),

drivers/base/regmap/regmap.c

@@ -813,6 +813,7 @@ struct regmap *__regmap_init(struct device *dev,
 	map->precious_reg = config->precious_reg;
 	map->writeable_noinc_reg = config->writeable_noinc_reg;
 	map->readable_noinc_reg = config->readable_noinc_reg;
+	map->reg_default_cb = config->reg_default_cb;
 	map->cache_type = config->cache_type;
 
 	spin_lock_init(&map->async_lock);
@@ -1435,6 +1436,7 @@ int regmap_reinit_cache(struct regmap *map, const struct regmap_config *config)
 	map->precious_reg = config->precious_reg;
 	map->writeable_noinc_reg = config->writeable_noinc_reg;
 	map->readable_noinc_reg = config->readable_noinc_reg;
+	map->reg_default_cb = config->reg_default_cb;
 	map->cache_type = config->cache_type;
 
 	ret = regmap_set_name(map, config);

include/linux/regmap.h

@@ -359,6 +359,10 @@ typedef void (*regmap_unlock)(void *);
  * @reg_defaults: Power on reset values for registers (for use with
  *                register cache support).
  * @num_reg_defaults: Number of elements in reg_defaults.
+ * @reg_default_cb: Optional callback to return default values for registers
+ *                  not listed in reg_defaults. This is only used for
+ *                  REGCACHE_FLAT population; drivers must ensure the readable_reg/
+ *                  writeable_reg callbacks are defined to handle holes.
  *
  * @read_flag_mask: Mask to be set in the top bytes of the register when doing
  *                  a read.
@@ -449,6 +453,8 @@ struct regmap_config {
 	const struct regmap_access_table *rd_noinc_table;
 	const struct reg_default *reg_defaults;
 	unsigned int num_reg_defaults;
+	int (*reg_default_cb)(struct device *dev, unsigned int reg,
+			      unsigned int *def);
 	enum regcache_type cache_type;
 	const void *reg_defaults_raw;
 	unsigned int num_reg_defaults_raw;
@@ -1349,6 +1355,14 @@ static inline int regmap_write_bits(struct regmap *map, unsigned int reg,
 	return regmap_update_bits_base(map, reg, mask, val, NULL, false, true);
 }
 
+static inline int regmap_default_zero_cb(struct device *dev,
+					 unsigned int reg,
+					 unsigned int *def)
+{
+	*def = 0;
+	return 0;
+}
+
 int regmap_get_val_bytes(struct regmap *map);
 int regmap_get_max_register(struct regmap *map);
 int regmap_get_reg_stride(struct regmap *map);

sound/soc/tegra/tegra186_asrc.c

@@ -950,6 +950,7 @@ static const struct regmap_config tegra186_asrc_regmap_config = {
 	.volatile_reg		= tegra186_asrc_volatile_reg,
 	.reg_defaults		= tegra186_asrc_reg_defaults,
 	.num_reg_defaults	= ARRAY_SIZE(tegra186_asrc_reg_defaults),
+	.reg_default_cb		= regmap_default_zero_cb,
 	.cache_type		= REGCACHE_FLAT,
 };
 

sound/soc/tegra/tegra186_dspk.c

@@ -467,6 +467,7 @@ static const struct regmap_config tegra186_dspk_regmap = {
 	.volatile_reg		= tegra186_dspk_volatile_reg,
 	.reg_defaults		= tegra186_dspk_reg_defaults,
 	.num_reg_defaults	= ARRAY_SIZE(tegra186_dspk_reg_defaults),
+	.reg_default_cb		= regmap_default_zero_cb,
 	.cache_type		= REGCACHE_FLAT,
 };
 

sound/soc/tegra/tegra210_admaif.c

@@ -241,6 +241,7 @@ static const struct regmap_config tegra210_admaif_regmap_config = {
 	.volatile_reg		= tegra_admaif_volatile_reg,
 	.reg_defaults		= tegra210_admaif_reg_defaults,
 	.num_reg_defaults	= TEGRA210_ADMAIF_CHANNEL_COUNT * 6 + 1,
+	.reg_default_cb		= regmap_default_zero_cb,
 	.cache_type		= REGCACHE_FLAT,
 };
 
@@ -254,6 +255,7 @@ static const struct regmap_config tegra186_admaif_regmap_config = {
 	.volatile_reg		= tegra_admaif_volatile_reg,
 	.reg_defaults		= tegra186_admaif_reg_defaults,
 	.num_reg_defaults	= TEGRA186_ADMAIF_CHANNEL_COUNT * 6 + 1,
+	.reg_default_cb		= regmap_default_zero_cb,
 	.cache_type		= REGCACHE_FLAT,
 };
 
@@ -267,6 +269,7 @@ static const struct regmap_config tegra264_admaif_regmap_config = {
 	.volatile_reg		= tegra_admaif_volatile_reg,
 	.reg_defaults		= tegra264_admaif_reg_defaults,
 	.num_reg_defaults	= TEGRA264_ADMAIF_CHANNEL_COUNT * 6 + 1,
+	.reg_default_cb		= regmap_default_zero_cb,
 	.cache_type		= REGCACHE_FLAT,
 };
 

sound/soc/tegra/tegra210_adx.c

@@ -625,6 +625,7 @@ static const struct regmap_config tegra210_adx_regmap_config = {
 	.volatile_reg		= tegra210_adx_volatile_reg,
 	.reg_defaults		= tegra210_adx_reg_defaults,
 	.num_reg_defaults	= ARRAY_SIZE(tegra210_adx_reg_defaults),
+	.reg_default_cb		= regmap_default_zero_cb,
 	.cache_type		= REGCACHE_FLAT,
 };
 
@@ -638,6 +639,7 @@ static const struct regmap_config tegra264_adx_regmap_config = {
 	.volatile_reg		= tegra264_adx_volatile_reg,
 	.reg_defaults		= tegra264_adx_reg_defaults,
 	.num_reg_defaults	= ARRAY_SIZE(tegra264_adx_reg_defaults),
+	.reg_default_cb		= regmap_default_zero_cb,
 	.cache_type		= REGCACHE_FLAT,
 };