Re: [RFC PATCH] regmap: mmio: add register clock support
From: Philipp Zabel
Date: Thu Feb 14 2013 - 07:38:48 EST
Hi Mark,
Am Donnerstag, den 14.02.2013, 11:56 +0000 schrieb Mark Brown:
> On Thu, Feb 14, 2013 at 10:49:14AM +0100, Philipp Zabel wrote:
>
> > 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.
>
> This is a good feature but a couple of concerns here.
>
> > + if (ctx->clk)
> > + clk_prepare_enable(ctx->clk);
> > +
>
> This is only going to work if prepare doesn't sleep. That's probably
> fine for the use cases we're interested in but doesn't fill me with joy.
Good point. I moved clk_prepare/unprepare into
regmap_mmio_gen_context/free_context.
> The other thing is that we ought to check the return value.
Done.
Are you ok with the way (devm_)regmap_mmio_init_clk are added?
Maybe (devm_)regmap_mmio_init should be turned into inlines.
thanks
Philipp
From: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
Subject: [PATCH] regmap: mmio: add register clock support
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 | 108 +++++++++++++++++++++++++++++++++++--
include/linux/regmap.h | 6 +++
2 files changed, 111 insertions(+), 3 deletions(-)
diff --git a/drivers/base/regmap/regmap-mmio.c b/drivers/base/regmap/regmap-mmio.c
index f05fc74..8ccac3f 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);
@@ -179,7 +210,27 @@ 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);
}
/**
@@ -198,7 +249,7 @@ struct regmap *regmap_init_mmio(struct device *dev,
{
struct regmap_mmio_context *ctx;
- ctx = regmap_mmio_gen_context(regs, config);
+ ctx = regmap_mmio_gen_context(dev, NULL, regs, config);
if (IS_ERR(ctx))
return ERR_CAST(ctx);
@@ -207,6 +258,31 @@ struct regmap *regmap_init_mmio(struct device *dev,
EXPORT_SYMBOL_GPL(regmap_init_mmio);
/**
+ * 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_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(dev, clk_id, regs, config);
+ if (IS_ERR(ctx))
+ return ERR_CAST(ctx);
+
+ return regmap_init(dev, ®map_mmio, ctx, config);
+}
+EXPORT_SYMBOL_GPL(regmap_init_mmio_clk);
+
+/**
* devm_regmap_init_mmio(): Initialise managed register map
*
* @dev: Device that will be interacted with
@@ -223,7 +299,7 @@ struct regmap *devm_regmap_init_mmio(struct device *dev,
{
struct regmap_mmio_context *ctx;
- ctx = regmap_mmio_gen_context(regs, config);
+ ctx = regmap_mmio_gen_context(dev, NULL, regs, config);
if (IS_ERR(ctx))
return ERR_CAST(ctx);
@@ -231,4 +307,30 @@ struct regmap *devm_regmap_init_mmio(struct device *dev,
}
EXPORT_SYMBOL_GPL(devm_regmap_init_mmio);
+/**
+ * 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
+ *
+ * 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.
+ */
+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(dev, clk_id, regs, config);
+ if (IS_ERR(ctx))
+ return ERR_CAST(ctx);
+
+ return devm_regmap_init(dev, ®map_mmio, ctx, config);
+}
+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..5850848 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -288,6 +288,9 @@ struct regmap *regmap_init_spi(struct spi_device *dev,
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,
@@ -300,6 +303,9 @@ struct regmap *devm_regmap_init_spi(struct spi_device *dev,
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);
void regmap_exit(struct regmap *map);
int regmap_reinit_cache(struct regmap *map,
--
1.7.10.4
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