[PATCH] regmap: mmio: add register clock support

From: Philipp Zabel
Date: Thu Feb 14 2013 - 11:39:22 EST

Some mmio devices have a dedicated interface clock that needs
to be enabled to access their registers. This patch optionally
enables a clock before accessing registers in the regmap_bus
callbacks.

I added (devm_)regmap_init_mmio_clk variants of the init
functions that have an added clk_id string parameter. This
is passed to clk_get to request the clock from the clk
framework.

Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
---
drivers/base/regmap/regmap-mmio.c | 79 +++++++++++++++++++++++++++++++------
include/linux/regmap.h | 47 +++++++++++++++++++---
2 files changed, 107 insertions(+), 19 deletions(-)

diff --git a/drivers/base/regmap/regmap-mmio.c b/drivers/base/regmap/regmap-mmio.c
index f05fc74..98745dd 100644
--- a/drivers/base/regmap/regmap-mmio.c
+++ b/drivers/base/regmap/regmap-mmio.c
@@ -16,6 +16,7 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

+#include <linux/clk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/io.h>
@@ -26,6 +27,7 @@
struct regmap_mmio_context {
void __iomem *regs;
unsigned val_bytes;
+ struct clk *clk;
};

static int regmap_mmio_gather_write(void *context,
@@ -34,9 +36,16 @@ static int regmap_mmio_gather_write(void *context,
{
struct regmap_mmio_context *ctx = context;
u32 offset;
+ int ret;

BUG_ON(reg_size != 4);

+ if (ctx->clk) {
+ ret = clk_enable(ctx->clk);
+ if (ret < 0)
+ return ret;
+ }
+
offset = *(u32 *)reg;

while (val_size) {
@@ -64,6 +73,9 @@ static int regmap_mmio_gather_write(void *context,
offset += ctx->val_bytes;
}

+ if (ctx->clk)
+ clk_disable(ctx->clk);
+
return 0;
}

@@ -80,9 +92,16 @@ static int regmap_mmio_read(void *context,
{
struct regmap_mmio_context *ctx = context;
u32 offset;
+ int ret;

BUG_ON(reg_size != 4);

+ if (ctx->clk) {
+ ret = clk_enable(ctx->clk);
+ if (ret < 0)
+ return ret;
+ }
+
offset = *(u32 *)reg;

while (val_size) {
@@ -110,11 +129,20 @@ static int regmap_mmio_read(void *context,
offset += ctx->val_bytes;
}

+ if (ctx->clk)
+ clk_disable(ctx->clk);
+
return 0;
}

static void regmap_mmio_free_context(void *context)
{
+ struct regmap_mmio_context *ctx = context;
+
+ if (ctx->clk) {
+ clk_unprepare(ctx->clk);
+ clk_put(ctx->clk);
+ }
kfree(context);
}

@@ -128,11 +156,14 @@ static struct regmap_bus regmap_mmio = {
.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
};

-static struct regmap_mmio_context *regmap_mmio_gen_context(void __iomem *regs,
+static struct regmap_mmio_context *regmap_mmio_gen_context(struct device *dev,
+ const char *clk_id,
+ void __iomem *regs,
const struct regmap_config *config)
{
struct regmap_mmio_context *ctx;
int min_stride;
+ int ret;

if (config->reg_bits != 32)
return ERR_PTR(-EINVAL);
@@ -179,37 +210,59 @@ static struct regmap_mmio_context *regmap_mmio_gen_context(void __iomem *regs,
ctx->regs = regs;
ctx->val_bytes = config->val_bits / 8;

+ if (clk_id == NULL)
+ return ctx;
+
+ ctx->clk = clk_get(dev, clk_id);
+ if (IS_ERR(ctx->clk)) {
+ ret = PTR_ERR(ctx->clk);
+ goto err_free;
+ }
+
+ ret = clk_prepare(ctx->clk);
+ if (ret < 0) {
+ clk_put(ctx->clk);
+ goto err_free;
+ }
+
return ctx;
+
+err_free:
+ kfree(ctx);
+
+ return ERR_PTR(ret);
}

/**
- * regmap_init_mmio(): Initialise register map
+ * regmap_init_mmio_clk(): Initialise register map with register clock
*
* @dev: Device that will be interacted with
+ * @clk_id: register clock consumer ID
* @regs: Pointer to memory-mapped IO region
* @config: Configuration for register map
*
* The return value will be an ERR_PTR() on error or a valid pointer to
* a struct regmap.
*/
-struct regmap *regmap_init_mmio(struct device *dev,
- void __iomem *regs,
- const struct regmap_config *config)
+struct regmap *regmap_init_mmio_clk(struct device *dev, const char *clk_id,
+ void __iomem *regs,
+ const struct regmap_config *config)
{
struct regmap_mmio_context *ctx;

- ctx = regmap_mmio_gen_context(regs, config);
+ ctx = regmap_mmio_gen_context(dev, clk_id, regs, config);
if (IS_ERR(ctx))
return ERR_CAST(ctx);

return regmap_init(dev, &regmap_mmio, ctx, config);
}
-EXPORT_SYMBOL_GPL(regmap_init_mmio);
+EXPORT_SYMBOL_GPL(regmap_init_mmio_clk);

/**
- * devm_regmap_init_mmio(): Initialise managed register map
+ * devm_regmap_init_mmio_clk(): Initialise managed register map with clock
*
* @dev: Device that will be interacted with
+ * @clk_id: register clock consumer ID
* @regs: Pointer to memory-mapped IO region
* @config: Configuration for register map
*
@@ -217,18 +270,18 @@ EXPORT_SYMBOL_GPL(regmap_init_mmio);
* to a struct regmap. The regmap will be automatically freed by the
* device management code.
*/
-struct regmap *devm_regmap_init_mmio(struct device *dev,
- void __iomem *regs,
- const struct regmap_config *config)
+struct regmap *devm_regmap_init_mmio_clk(struct device *dev, const char *clk_id,
+ void __iomem *regs,
+ const struct regmap_config *config)
{
struct regmap_mmio_context *ctx;

- ctx = regmap_mmio_gen_context(regs, config);
+ ctx = regmap_mmio_gen_context(dev, clk_id, regs, config);
if (IS_ERR(ctx))
return ERR_CAST(ctx);

return devm_regmap_init(dev, &regmap_mmio, ctx, config);
}
-EXPORT_SYMBOL_GPL(devm_regmap_init_mmio);
+EXPORT_SYMBOL_GPL(devm_regmap_init_mmio_clk);

MODULE_LICENSE("GPL v2");
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index b7e95bf..f0480a3 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -285,9 +285,9 @@ struct regmap *regmap_init_i2c(struct i2c_client *i2c,
const struct regmap_config *config);
struct regmap *regmap_init_spi(struct spi_device *dev,
const struct regmap_config *config);
-struct regmap *regmap_init_mmio(struct device *dev,
- void __iomem *regs,
- const struct regmap_config *config);
+struct regmap *regmap_init_mmio_clk(struct device *dev, const char *clk_id,
+ void __iomem *regs,
+ const struct regmap_config *config);

struct regmap *devm_regmap_init(struct device *dev,
const struct regmap_bus *bus,
@@ -297,9 +297,44 @@ struct regmap *devm_regmap_init_i2c(struct i2c_client *i2c,
const struct regmap_config *config);
struct regmap *devm_regmap_init_spi(struct spi_device *dev,
const struct regmap_config *config);
-struct regmap *devm_regmap_init_mmio(struct device *dev,
- void __iomem *regs,
- const struct regmap_config *config);
+struct regmap *devm_regmap_init_mmio_clk(struct device *dev, const char *clk_id,
+ void __iomem *regs,
+ const struct regmap_config *config);
+
+/**
+ * regmap_init_mmio(): Initialise register map
+ *
+ * @dev: Device that will be interacted with
+ * @regs: Pointer to memory-mapped IO region
+ * @config: Configuration for register map
+ *
+ * The return value will be an ERR_PTR() on error or a valid pointer to
+ * a struct regmap.
+ */
+static inline struct regmap *regmap_init_mmio(struct device *dev,
+ void __iomem *regs,
+ const struct regmap_config *config)
+{
+ return regmap_init_mmio_clk(dev, NULL, regs, config);
+}
+
+/**
+ * devm_regmap_init_mmio(): Initialise managed register map
+ *
+ * @dev: Device that will be interacted with
+ * @regs: Pointer to memory-mapped IO region
+ * @config: Configuration for register map
+ *
+ * The return value will be an ERR_PTR() on error or a valid pointer
+ * to a struct regmap. The regmap will be automatically freed by the
+ * device management code.
+ */
+static inline struct regmap *devm_regmap_init_mmio(struct device *dev,
+ void __iomem *regs,
+ const struct regmap_config *config)
+{
+ return devm_regmap_init_mmio_clk(dev, NULL, regs, config);
+}

void regmap_exit(struct regmap *map);
int regmap_reinit_cache(struct regmap *map,
--
1.7.10.4

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