This is a note to let you know that I've just added the patch titled
mfd: syscon: Add of_syscon_register_regmap() API
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mfd-syscon-add-of_syscon_register_regmap-api.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 441e05cd5625f7d1dc8cdcf18374f8f27d80c1b1
Author: Peter Griffin <peter.griffin@xxxxxxxxxx>
Date: Fri Jun 21 12:55:43 2024 +0100
mfd: syscon: Add of_syscon_register_regmap() API
[ Upstream commit 769cb63166d90f1fadafa4352f180cbd96b6cb77 ]
The of_syscon_register_regmap() API allows an externally created regmap
to be registered with syscon. This regmap can then be returned to client
drivers using the syscon_regmap_lookup_by_phandle() APIs.
The API is used by platforms where mmio access to the syscon registers is
not possible, and a underlying soc driver like exynos-pmu provides a SoC
specific regmap that can issue a SMC or hypervisor call to write the
register.
This approach keeps the SoC complexities out of syscon, but allows common
drivers such as syscon-poweroff, syscon-reboot and friends that are used
by many SoCs already to be re-used.
Signed-off-by: Peter Griffin <peter.griffin@xxxxxxxxxx>
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
Reviewed-by: Sam Protsenko <semen.protsenko@xxxxxxxxxx>
Tested-by: Will McVicker <willmcvicker@xxxxxxxxxx>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240621115544.1655458-2-peter.griffin@xxxxxxxxxx
Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
Stable-dep-of: 805f7aaf7fee ("mfd: syscon: Fix race in device_node_get_regmap()")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index 7d0e91164cbaa..33f1e07ab24dc 100644
--- a/drivers/mfd/syscon.c
+++ b/drivers/mfd/syscon.c
@@ -192,6 +192,54 @@ static struct regmap *device_node_get_regmap(struct device_node *np,
return syscon->regmap;
}
+/**
+ * of_syscon_register_regmap() - Register regmap for specified device node
+ * @np: Device tree node
+ * @regmap: Pointer to regmap object
+ *
+ * Register an externally created regmap object with syscon for the specified
+ * device tree node. This regmap will then be returned to client drivers using
+ * the syscon_regmap_lookup_by_phandle() API.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+int of_syscon_register_regmap(struct device_node *np, struct regmap *regmap)
+{
+ struct syscon *entry, *syscon = NULL;
+ int ret;
+
+ if (!np || !regmap)
+ return -EINVAL;
+
+ syscon = kzalloc(sizeof(*syscon), GFP_KERNEL);
+ if (!syscon)
+ return -ENOMEM;
+
+ /* check if syscon entry already exists */
+ spin_lock(&syscon_list_slock);
+
+ list_for_each_entry(entry, &syscon_list, list)
+ if (entry->np == np) {
+ ret = -EEXIST;
+ goto err_unlock;
+ }
+
+ syscon->regmap = regmap;
+ syscon->np = np;
+
+ /* register the regmap in syscon list */
+ list_add_tail(&syscon->list, &syscon_list);
+ spin_unlock(&syscon_list_slock);
+
+ return 0;
+
+err_unlock:
+ spin_unlock(&syscon_list_slock);
+ kfree(syscon);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(of_syscon_register_regmap);
+
struct regmap *device_node_to_regmap(struct device_node *np)
{
return device_node_get_regmap(np, false);
diff --git a/include/linux/mfd/syscon.h b/include/linux/mfd/syscon.h
index c315903f6dab3..aad9c6b504636 100644
--- a/include/linux/mfd/syscon.h
+++ b/include/linux/mfd/syscon.h
@@ -28,6 +28,8 @@ struct regmap *syscon_regmap_lookup_by_phandle_args(struct device_node *np,
unsigned int *out_args);
struct regmap *syscon_regmap_lookup_by_phandle_optional(struct device_node *np,
const char *property);
+int of_syscon_register_regmap(struct device_node *np,
+ struct regmap *regmap);
#else
static inline struct regmap *device_node_to_regmap(struct device_node *np)
{
@@ -67,6 +69,12 @@ static inline struct regmap *syscon_regmap_lookup_by_phandle_optional(
return NULL;
}
+static inline int of_syscon_register_regmap(struct device_node *np,
+ struct regmap *regmap)
+{
+ return -EOPNOTSUPP;
+}
+
#endif
#endif /* __LINUX_MFD_SYSCON_H__ */
