| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20260123095346.1258556-3-sheetal@nvidia.com>
Date: Fri, 23 Jan 2026 15:23:44 +0530
From: "Sheetal ." <sheetal@...dia.com>
To: Mark Brown <broonie@...nel.org>
CC: Sander Vanheule <sander@...nheule.net>, Greg Kroah-Hartman
<gregkh@...uxfoundation.org>, "Rafael J . Wysocki" <rafael@...nel.org>,
Danilo Krummrich <dakr@...nel.org>, Liam Girdwood <lgirdwood@...il.com>,
Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>, "Thierry
Reding" <thierry.reding@...il.com>, Jonathan Hunter <jonathanh@...dia.com>,
Mohan kumar <mkumard@...dia.com>, <linux-kernel@...r.kernel.org>,
<linux-sound@...r.kernel.org>, <linux-tegra@...r.kernel.org>, Sheetal
<sheetal@...dia.com>
Subject: [RFC PATCH v3 2/4] regmap: Add reg_default_cb callback for flat cache defaults
From: Sheetal <sheetal@...dia.com>
Commit e062bdfdd6ad ("regmap: warn users about uninitialized flat cache")
warns when REGCACHE_FLAT is used without full defaults. This causes
false positives on hardware where many registers reset to zero but are
not listed in reg_defaults, forcing drivers to maintain large tables
just to silence the warning.
Add a reg_default_cb() hook so drivers can supply defaults for registers
not present in reg_defaults when populating REGCACHE_FLAT. This keeps
the warning quiet for known zero-reset registers without bloating
tables. Provide a generic regmap_default_zero_cb() helper for drivers
that need zero defaults.
The hook is only used for REGCACHE_FLAT; the core does not
check readable/writeable access, so drivers must provide readable_reg/
writeable_reg callbacks and handle holes in the register map.
Signed-off-by: Sheetal <sheetal@...dia.com>
---
drivers/base/regmap/internal.h | 3 +++
drivers/base/regmap/regcache-flat.c | 19 +++++++++++++++++++
drivers/base/regmap/regcache.c | 3 ++-
drivers/base/regmap/regmap.c | 2 ++
include/linux/regmap.h | 14 ++++++++++++++
5 files changed, 40 insertions(+), 1 deletion(-)
diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 1477329410ec..5bf993165438 100644
--- a/drivers/base/regmap/internal.h
+++ b/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;
diff --git a/drivers/base/regmap/regcache-flat.c b/drivers/base/regmap/regcache-flat.c
index 53cc59c84e2f..c924817e19b1 100644
--- a/drivers/base/regmap/regcache-flat.c
+++ b/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;
}
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 319c342bf5a0..31bdbf37dbed 100644
--- a/drivers/base/regmap/regcache.c
+++ b/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);
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index ce9be3989a21..57c5551044ed 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -811,6 +811,7 @@ 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);
@@ -1433,6 +1434,7 @@ 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);
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index b0b9be750d93..51940eeff872 100644
--- a/include/linux/regmap.h
+++ b/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);
--
2.34.1
Powered by blists - more mailing lists