[PATCH 1/2] regmap: Add asynchronous I/O support

[PATCH 1/2] regmap: Add asynchronous I/O support

[Mark Brown]

Some use cases like firmware download can transfer a lot of data in quick
succession. With high speed buses these use cases can benefit from having
multiple transfers scheduled at once since this allows the bus to minimise
the delay between transfers.

Support this by adding regmap_raw_write_async(), allowing raw transfers to
be scheduled, and regmap_async_complete() to wait for them to finish.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---
 drivers/base/regmap/internal.h |   15 ++++
 drivers/base/regmap/regmap.c   |  183 +++++++++++++++++++++++++++++++++++++---
 include/linux/regmap.h         |   26 ++++++
 3 files changed, 214 insertions(+), 10 deletions(-)

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index ba6532c..855eb4f 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -16,6 +16,7 @@
 #include <linux/regmap.h>
 #include <linux/fs.h>
 #include <linux/list.h>
+#include <linux/wait.h>
 
 struct regmap;
 struct regcache_ops;
@@ -39,6 +40,13 @@ struct regmap_format {
 	unsigned int (*parse_val)(void *buf);
 };
 
+struct regmap_async {
+	struct list_head list;
+	struct work_struct cleanup;
+	struct regmap *map;
+	void *work_buf;
+};
+
 struct regmap {
 	struct mutex mutex;
 	spinlock_t spinlock;
@@ -53,6 +61,11 @@ struct regmap {
 	void *bus_context;
 	const char *name;
 
+	spinlock_t async_lock;
+	wait_queue_head_t async_waitq;
+	struct list_head async_list;
+	int async_ret;
+
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *debugfs;
 	const char *debugfs_name;
@@ -178,6 +191,8 @@ bool regcache_set_val(void *base, unsigned int idx,
 		      unsigned int val, unsigned int word_size);
 int regcache_lookup_reg(struct regmap *map, unsigned int reg);
 
+void regmap_async_complete_cb(struct regmap_async *async, int ret);
+
 extern struct regcache_ops regcache_rbtree_ops;
 extern struct regcache_ops regcache_lzo_ops;
 extern struct regcache_ops regcache_flat_ops;
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index dc51e80..61818cc 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -41,6 +41,15 @@ static int _regmap_bus_formatted_write(void *context, unsigned int reg,
 static int _regmap_bus_raw_write(void *context, unsigned int reg,
 				 unsigned int val);
 
+static void async_cleanup(struct work_struct *work)
+{
+	struct regmap_async *async = container_of(work, struct regmap_async,
+						  cleanup);
+
+	kfree(async->work_buf);
+	kfree(async);
+}
+
 bool regmap_reg_in_ranges(unsigned int reg,
 			  const struct regmap_range *ranges,
 			  unsigned int nranges)
@@ -430,6 +439,10 @@ struct regmap *regmap_init(struct device *dev,
 	map->cache_type = config->cache_type;
 	map->name = config->name;
 
+	spin_lock_init(&map->async_lock);
+	INIT_LIST_HEAD(&map->async_list);
+	init_waitqueue_head(&map->async_waitq);
+
 	if (config->read_flag_mask || config->write_flag_mask) {
 		map->read_flag_mask = config->read_flag_mask;
 		map->write_flag_mask = config->write_flag_mask;
@@ -890,10 +903,13 @@ static int _regmap_select_page(struct regmap *map, unsigned int *reg,
 }
 
 static int _regmap_raw_write(struct regmap *map, unsigned int reg,
-			     const void *val, size_t val_len)
+			     const void *val, size_t val_len, bool async)
 {
 	struct regmap_range_node *range;
+	unsigned long flags;
 	u8 *u8 = map->work_buf;
+	void *work_val = map->work_buf + map->format.reg_bytes +
+		map->format.pad_bytes;
 	void *buf;
 	int ret = -ENOTSUPP;
 	size_t len;
@@ -938,7 +954,7 @@ static int _regmap_raw_write(struct regmap *map, unsigned int reg,
 			dev_dbg(map->dev, "Writing window %d/%zu\n",
 				win_residue, val_len / map->format.val_bytes);
 			ret = _regmap_raw_write(map, reg, val, win_residue *
-						map->format.val_bytes);
+						map->format.val_bytes, async);
 			if (ret != 0)
 				return ret;
 
@@ -961,6 +977,51 @@ static int _regmap_raw_write(struct regmap *map, unsigned int reg,
 
 	u8[0] |= map->write_flag_mask;
 
+	if (async && map->bus->async_write) {
+		struct regmap_async *async = kzalloc(map->bus->async_size,
+						     GFP_KERNEL);
+		if (!async)
+			return -ENOMEM;
+
+		async->work_buf = kzalloc(map->format.buf_size,
+					  GFP_KERNEL | GFP_DMA);
+		if (!async->work_buf) {
+			kfree(async);
+			return -ENOMEM;
+		}
+
+		INIT_WORK(&async->cleanup, async_cleanup);
+		async->map = map;
+
+		/* If the caller supplied the value we can use it safely. */
+		memcpy(async->work_buf, map->work_buf, map->format.pad_bytes +
+		       map->format.reg_bytes + map->format.val_bytes);
+		if (val == work_val)
+			val = async->work_buf + map->format.pad_bytes +
+				map->format.reg_bytes;
+
+		spin_lock_irqsave(&map->async_lock, flags);
+		list_add_tail(&async->list, &map->async_list);
+		spin_unlock_irqrestore(&map->async_lock, flags);
+
+		ret = map->bus->async_write(map->bus_context, async->work_buf,
+					    map->format.reg_bytes +
+					    map->format.pad_bytes,
+					    val, val_len, async);
+
+		if (ret != 0) {
+			dev_err(map->dev, "Failed to schedule write: %d\n",
+				ret);
+
+			spin_lock_irqsave(&map->async_lock, flags);
+			list_del(&async->list);
+			spin_unlock_irqrestore(&map->async_lock, flags);
+
+			kfree(async->work_buf);
+			kfree(async);
+		}
+	}
+
 	trace_regmap_hw_write_start(map->dev, reg,
 				    val_len / map->format.val_bytes);
 
@@ -968,8 +1029,7 @@ static int _regmap_raw_write(struct regmap *map, unsigned int reg,
 	 * send the work_buf directly, otherwise try to do a gather
 	 * write.
 	 */
-	if (val == (map->work_buf + map->format.pad_bytes +
-		    map->format.reg_bytes))
+	if (val == work_val)
 		ret = map->bus->write(map->bus_context, map->work_buf,
 				      map->format.reg_bytes +
 				      map->format.pad_bytes +
@@ -1042,7 +1102,7 @@ static int _regmap_bus_raw_write(void *context, unsigned int reg,
 				 map->work_buf +
 				 map->format.reg_bytes +
 				 map->format.pad_bytes,
-				 map->format.val_bytes);
+				 map->format.val_bytes, false);
 }
 
 int _regmap_write(struct regmap *map, unsigned int reg,
@@ -1125,7 +1185,7 @@ int regmap_raw_write(struct regmap *map, unsigned int reg,
 
 	map->lock(map->lock_arg);
 
-	ret = _regmap_raw_write(map, reg, val, val_len);
+	ret = _regmap_raw_write(map, reg, val, val_len, false);
 
 	map->unlock(map->lock_arg);
 
@@ -1181,14 +1241,15 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
 	if (map->use_single_rw) {
 		for (i = 0; i < val_count; i++) {
 			ret = regmap_raw_write(map,
-						reg + (i * map->reg_stride),
-						val + (i * val_bytes),
-						val_bytes);
+					       reg + (i * map->reg_stride),
+					       val + (i * val_bytes),
+					       val_bytes);
 			if (ret != 0)
 				return ret;
 		}
 	} else {
-		ret = _regmap_raw_write(map, reg, wval, val_bytes * val_count);
+		ret = _regmap_raw_write(map, reg, wval, val_bytes * val_count,
+					false);
 	}
 
 	if (val_bytes != 1)
@@ -1200,6 +1261,48 @@ out:
 }
 EXPORT_SYMBOL_GPL(regmap_bulk_write);
 
+/**
+ * regmap_raw_write_async(): Write raw values to one or more registers
+ *                           asynchronously
+ *
+ * @map: Register map to write to
+ * @reg: Initial register to write to
+ * @val: Block of data to be written, laid out for direct transmission to the
+ *       device.  Must be valid until regmap_async_complete() is called.
+ * @val_len: Length of data pointed to by val.
+ *
+ * This function is intended to be used for things like firmware
+ * download where a large block of data needs to be transferred to the
+ * device.  No formatting will be done on the data provided.
+ *
+ * If supported by the underlying bus the write will be scheduled
+ * asynchronously, helping maximise I/O speed on higher speed buses
+ * like SPI.  regmap_async_complete() can be called to ensure that all
+ * asynchrnous writes have been completed.
+ *
+ * A value of zero will be returned on success, a negative errno will
+ * be returned in error cases.
+ */
+int regmap_raw_write_async(struct regmap *map, unsigned int reg,
+			   const void *val, size_t val_len)
+{
+	int ret;
+
+	if (val_len % map->format.val_bytes)
+		return -EINVAL;
+	if (reg % map->reg_stride)
+		return -EINVAL;
+
+	map->lock(map->lock_arg);
+
+	ret = _regmap_raw_write(map, reg, val, val_len, true);
+
+	map->unlock(map->lock_arg);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(regmap_raw_write_async);
+
 static int _regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
 			    unsigned int val_len)
 {
@@ -1498,6 +1601,66 @@ int regmap_update_bits_check(struct regmap *map, unsigned int reg,
 }
 EXPORT_SYMBOL_GPL(regmap_update_bits_check);
 
+void regmap_async_complete_cb(struct regmap_async *async, int ret)
+{
+	struct regmap *map = async->map;
+	bool wake;
+
+	spin_lock(&map->async_lock);
+
+	list_del(&async->list);
+	wake = list_empty(&map->async_list);
+
+	if (ret != 0)
+		map->async_ret = ret;
+
+	spin_unlock(&map->async_lock);
+
+	schedule_work(&async->cleanup);
+
+	if (wake)
+		wake_up(&map->async_waitq);
+}
+
+static int regmap_async_is_done(struct regmap *map)
+{
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&map->async_lock, flags);
+	ret = list_empty(&map->async_list);
+	spin_unlock_irqrestore(&map->async_lock, flags);
+
+	return ret;
+}
+
+/**
+ * regmap_async_complete: Ensure all asynchronous I/O has completed.
+ *
+ * @map: Map to operate on.
+ *
+ * Blocks until any pending asynchronous I/O has completed.  Returns
+ * an error code for any failed I/O operations.
+ */
+int regmap_async_complete(struct regmap *map)
+{
+	unsigned long flags;
+	int ret;
+
+	/* Nothing to do with no async support */
+	if (!map->bus->async_write)
+		return 0;
+
+	wait_event(map->async_waitq, regmap_async_is_done(map));
+
+	spin_lock_irqsave(&map->async_lock, flags);
+	ret = map->async_ret;
+	map->async_ret = 0;
+	spin_unlock_irqrestore(&map->async_lock, flags);
+
+	return ret;
+}
+
 /**
  * regmap_register_patch: Register and apply register updates to be applied
  *                        on device initialistion
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 5e81abf..c8e9024 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -236,11 +236,17 @@ struct regmap_range_cfg {
 	unsigned int window_len;
 };
 
+struct regmap_async;
+
 typedef int (*regmap_hw_write)(void *context, const void *data,
 			       size_t count);
 typedef int (*regmap_hw_gather_write)(void *context,
 				      const void *reg, size_t reg_len,
 				      const void *val, size_t val_len);
+typedef int (*regmap_hw_async_write)(void *context,
+				     const void *reg, size_t reg_len,
+				     const void *val, size_t val_len,
+				     struct regmap_async *async);
 typedef int (*regmap_hw_read)(void *context,
 			      const void *reg_buf, size_t reg_size,
 			      void *val_buf, size_t val_size);
@@ -256,6 +262,8 @@ typedef void (*regmap_hw_free_context)(void *context);
  * @write: Write operation.
  * @gather_write: Write operation with split register/value, return -ENOTSUPP
  *                if not implemented  on a given device.
+ * @async_write: Write operation which completes asynchronously, optional and
+ *               must serialise with respect to non-async I/O.
  * @read: Read operation.  Data is returned in the buffer used to transmit
  *         data.
  * @read_flag_mask: Mask to be set in the top byte of the register when doing
@@ -266,16 +274,19 @@ typedef void (*regmap_hw_free_context)(void *context);
  * @val_format_endian_default: Default endianness for formatted register
  *     values. Used when the regmap_config specifies DEFAULT. If this is
  *     DEFAULT, BIG is assumed.
+ * @async_size: Size of struct used for async work.
  */
 struct regmap_bus {
 	bool fast_io;
 	regmap_hw_write write;
 	regmap_hw_gather_write gather_write;
+	regmap_hw_async_write async_write;
 	regmap_hw_read read;
 	regmap_hw_free_context free_context;
 	u8 read_flag_mask;
 	enum regmap_endian reg_format_endian_default;
 	enum regmap_endian val_format_endian_default;
+	size_t async_size;
 };
 
 struct regmap *regmap_init(struct device *dev,
@@ -311,6 +322,8 @@ int regmap_raw_write(struct regmap *map, unsigned int reg,
 		     const void *val, size_t val_len);
 int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
 			size_t val_count);
+int regmap_raw_write_async(struct regmap *map, unsigned int reg,
+			   const void *val, size_t val_len);
 int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val);
 int regmap_raw_read(struct regmap *map, unsigned int reg,
 		    void *val, size_t val_len);
@@ -322,6 +335,7 @@ int regmap_update_bits_check(struct regmap *map, unsigned int reg,
 			     unsigned int mask, unsigned int val,
 			     bool *change);
 int regmap_get_val_bytes(struct regmap *map);
+int regmap_async_complete(struct regmap *map);
 
 int regcache_sync(struct regmap *map);
 int regcache_sync_region(struct regmap *map, unsigned int min,
@@ -424,6 +438,13 @@ static inline int regmap_raw_write(struct regmap *map, unsigned int reg,
 	return -EINVAL;
 }
 
+static inline int regmap_raw_write_async(struct regmap *map, unsigned int reg,
+					 const void *val, size_t val_len)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+	return -EINVAL;
+}
+
 static inline int regmap_bulk_write(struct regmap *map, unsigned int reg,
 				    const void *val, size_t val_count)
 {
@@ -502,6 +523,11 @@ static inline void regcache_mark_dirty(struct regmap *map)
 	WARN_ONCE(1, "regmap API is disabled");
 }
 
+static inline void regmap_async_complete(struct regmap *map)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+}
+
 static inline int regmap_register_patch(struct regmap *map,
 					const struct reg_default *regs,
 					int num_regs)
-- 
1.7.10.4

[PATCH 2/2] regmap: spi: Support asynchronous I/O for SPI

[Mark Brown]

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---
 drivers/base/regmap/regmap-spi.c |   41 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/drivers/base/regmap/regmap-spi.c b/drivers/base/regmap/regmap-spi.c
index ffa46a9..bb19592 100644
--- a/drivers/base/regmap/regmap-spi.c
+++ b/drivers/base/regmap/regmap-spi.c
@@ -15,6 +15,21 @@
 #include <linux/init.h>
 #include <linux/module.h>
 
+#include "internal.h"
+
+struct regmap_async_spi {
+	struct regmap_async core;
+	struct spi_message m;
+	struct spi_transfer t[2];
+};
+
+static void regmap_spi_complete(void *data)
+{
+	struct regmap_async_spi *async = data;
+
+	regmap_async_complete_cb(&async->core, async->m.status);
+}
+
 static int regmap_spi_write(void *context, const void *data, size_t count)
 {
 	struct device *dev = context;
@@ -40,6 +55,30 @@ static int regmap_spi_gather_write(void *context,
 	return spi_sync(spi, &m);
 }
 
+static int regmap_spi_async_write(void *context,
+				  const void *reg, size_t reg_len,
+				  const void *val, size_t val_len,
+				  struct regmap_async *a)
+{
+	struct regmap_async_spi *async = (void *)a;
+	struct device *dev = context;
+	struct spi_device *spi = to_spi_device(dev);
+
+	async->t[0].tx_buf = reg;
+	async->t[0].len = reg_len;
+	async->t[1].tx_buf = val;
+	async->t[1].len = val_len;
+
+	spi_message_init(&async->m);
+	spi_message_add_tail(&async->t[0], &async->m);
+	spi_message_add_tail(&async->t[1], &async->m);
+
+	async->m.complete = regmap_spi_complete;
+	async->m.context = async;
+
+	return spi_async(spi, &async->m);
+}
+
 static int regmap_spi_read(void *context,
 			   const void *reg, size_t reg_size,
 			   void *val, size_t val_size)
@@ -53,8 +92,10 @@ static int regmap_spi_read(void *context,
 static struct regmap_bus regmap_spi = {
 	.write = regmap_spi_write,
 	.gather_write = regmap_spi_gather_write,
+	.async_write = regmap_spi_async_write,
 	.read = regmap_spi_read,
 	.read_flag_mask = 0x80,
+	.async_size = sizeof(struct regmap_async_spi),
 };
 
 /**
-- 
1.7.10.4

Re: [PATCH 2/2] regmap: spi: Support asynchronous I/O for SPI

[Stephen Boyd]

On 01/27/13 06:12, Mark Brown wrote:
> diff --git a/drivers/base/regmap/regmap-spi.c b/drivers/base/regmap/regmap-spi.c
> index ffa46a9..bb19592 100644
> --- a/drivers/base/regmap/regmap-spi.c
> +++ b/drivers/base/regmap/regmap-spi.c
> @@ -15,6 +15,21 @@
>  #include <linux/init.h>
>  #include <linux/module.h>
>  
> +#include "internal.h"
> +
> +struct regmap_async_spi {
> +	struct regmap_async core;
> +	struct spi_message m;
> +	struct spi_transfer t[2];
> +};
> +
> +static void regmap_spi_complete(void *data)
> +{
> +	struct regmap_async_spi *async = data;
> +
> +	regmap_async_complete_cb(&async->core, async->m.status);
> +}
> +
>  static int regmap_spi_write(void *context, const void *data, size_t count)
>  {
>  	struct device *dev = context;
> @@ -40,6 +55,30 @@ static int regmap_spi_gather_write(void *context,
>  	return spi_sync(spi, &m);
>  }
>  
> +static int regmap_spi_async_write(void *context,
> +				  const void *reg, size_t reg_len,
> +				  const void *val, size_t val_len,
> +				  struct regmap_async *a)
> +{
> +	struct regmap_async_spi *async = (void *)a;

Can you use container_of() here?

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH 2/2] regmap: spi: Support asynchronous I/O for SPI

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 471 bytes --]

On Mon, Jan 28, 2013 at 11:38:50AM -0800, Stephen Boyd wrote:
> On 01/27/13 06:12, Mark Brown wrote:

> > +static int regmap_spi_async_write(void *context,
> > +				  const void *reg, size_t reg_len,
> > +				  const void *val, size_t val_len,
> > +				  struct regmap_async *a)
> > +{
> > +	struct regmap_async_spi *async = (void *)a;

> Can you use container_of() here?

We could but I tend not to if the interface strictly requires that the
pointers be type punnable.

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Re: [PATCH 2/2] regmap: spi: Support asynchronous I/O for SPI

[Stephen Boyd]

On 01/28/13 17:39, Mark Brown wrote:
> On Mon, Jan 28, 2013 at 11:38:50AM -0800, Stephen Boyd wrote:
>> On 01/27/13 06:12, Mark Brown wrote:
>>> +static int regmap_spi_async_write(void *context,
>>> +				  const void *reg, size_t reg_len,
>>> +				  const void *val, size_t val_len,
>>> +				  struct regmap_async *a)
>>> +{
>>> +	struct regmap_async_spi *async = (void *)a;
>> Can you use container_of() here?
> We could but I tend not to if the interface strictly requires that the
> pointers be type punnable.

What is the interface requiring strict type punning here? async_write?

I just hope we don't move the fields around in the regmap_async_spi
struct and then this code silently breaks. I hope the compiler is smart
enough to skip doing any math if we used container_of() with the current
struct layout.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH 2/2] regmap: spi: Support asynchronous I/O for SPI

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 912 bytes --]

On Mon, Jan 28, 2013 at 05:47:36PM -0800, Stephen Boyd wrote:
> On 01/28/13 17:39, Mark Brown wrote:

> > We could but I tend not to if the interface strictly requires that the
> > pointers be type punnable.

> What is the interface requiring strict type punning here? async_write?

Yes, the async data must always be the first member of the bus specific
struct.  This is to avoid having to do an additional allocation for the
bus specific private data.

> I just hope we don't move the fields around in the regmap_async_spi
> struct and then this code silently breaks. I hope the compiler is smart
> enough to skip doing any math if we used container_of() with the current
> struct layout.

It would break anyway, like I say the interface relies on it currently.
The other option is to do a callback into the bus code and return the
contained structure but it seemed more involved and this is fairly
idiomatic.

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Re: [PATCH 2/2] regmap: spi: Support asynchronous I/O for SPI

[Mark Brown]

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On Tue, Jan 29, 2013 at 09:54:11AM +0800, Mark Brown wrote:

> It would break anyway, like I say the interface relies on it currently.
> The other option is to do a callback into the bus code and return the
> contained structure but it seemed more involved and this is fairly
> idiomatic.

Actually I'll just do that, we have to provide the size to the core
anyway.  Thanks.

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[PATCH 1/2] regmap: Add asynchronous I/O support

[Mark Brown]

Some use cases like firmware download can transfer a lot of data in quick
succession. With high speed buses these use cases can benefit from having
multiple transfers scheduled at once since this allows the bus to minimise
the delay between transfers.

Support this by adding regmap_raw_write_async(), allowing raw transfers to
be scheduled, and regmap_async_complete() to wait for them to finish.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---
 drivers/base/regmap/internal.h |   15 ++++
 drivers/base/regmap/regmap.c   |  182 +++++++++++++++++++++++++++++++++++++---
 include/linux/regmap.h         |   28 +++++++
 3 files changed, 215 insertions(+), 10 deletions(-)

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 51f0574..2025186 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -16,6 +16,7 @@
 #include <linux/regmap.h>
 #include <linux/fs.h>
 #include <linux/list.h>
+#include <linux/wait.h>
 
 struct regmap;
 struct regcache_ops;
@@ -39,6 +40,13 @@ struct regmap_format {
 	unsigned int (*parse_val)(void *buf);
 };
 
+struct regmap_async {
+	struct list_head list;
+	struct work_struct cleanup;
+	struct regmap *map;
+	void *work_buf;
+};
+
 struct regmap {
 	struct mutex mutex;
 	spinlock_t spinlock;
@@ -53,6 +61,11 @@ struct regmap {
 	void *bus_context;
 	const char *name;
 
+	spinlock_t async_lock;
+	wait_queue_head_t async_waitq;
+	struct list_head async_list;
+	int async_ret;
+
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *debugfs;
 	const char *debugfs_name;
@@ -178,6 +191,8 @@ bool regcache_set_val(void *base, unsigned int idx,
 		      unsigned int val, unsigned int word_size);
 int regcache_lookup_reg(struct regmap *map, unsigned int reg);
 
+void regmap_async_complete_cb(struct regmap_async *async, int ret);
+
 extern struct regcache_ops regcache_rbtree_ops;
 extern struct regcache_ops regcache_lzo_ops;
 
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 6845a07..e57b7bc 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -41,6 +41,15 @@ static int _regmap_bus_formatted_write(void *context, unsigned int reg,
 static int _regmap_bus_raw_write(void *context, unsigned int reg,
 				 unsigned int val);
 
+static void async_cleanup(struct work_struct *work)
+{
+	struct regmap_async *async = container_of(work, struct regmap_async,
+						  cleanup);
+
+	kfree(async->work_buf);
+	kfree(async);
+}
+
 bool regmap_reg_in_ranges(unsigned int reg,
 			  const struct regmap_range *ranges,
 			  unsigned int nranges)
@@ -430,6 +439,10 @@ struct regmap *regmap_init(struct device *dev,
 	map->cache_type = config->cache_type;
 	map->name = config->name;
 
+	spin_lock_init(&map->async_lock);
+	INIT_LIST_HEAD(&map->async_list);
+	init_waitqueue_head(&map->async_waitq);
+
 	if (config->read_flag_mask || config->write_flag_mask) {
 		map->read_flag_mask = config->read_flag_mask;
 		map->write_flag_mask = config->write_flag_mask;
@@ -884,10 +897,13 @@ static int _regmap_select_page(struct regmap *map, unsigned int *reg,
 }
 
 static int _regmap_raw_write(struct regmap *map, unsigned int reg,
-			     const void *val, size_t val_len)
+			     const void *val, size_t val_len, bool async)
 {
 	struct regmap_range_node *range;
+	unsigned long flags;
 	u8 *u8 = map->work_buf;
+	void *work_val = map->work_buf + map->format.reg_bytes +
+		map->format.pad_bytes;
 	void *buf;
 	int ret = -ENOTSUPP;
 	size_t len;
@@ -932,7 +948,7 @@ static int _regmap_raw_write(struct regmap *map, unsigned int reg,
 			dev_dbg(map->dev, "Writing window %d/%zu\n",
 				win_residue, val_len / map->format.val_bytes);
 			ret = _regmap_raw_write(map, reg, val, win_residue *
-						map->format.val_bytes);
+						map->format.val_bytes, async);
 			if (ret != 0)
 				return ret;
 
@@ -955,6 +971,50 @@ static int _regmap_raw_write(struct regmap *map, unsigned int reg,
 
 	u8[0] |= map->write_flag_mask;
 
+	if (async && map->bus->async_write) {
+		struct regmap_async *async = map->bus->async_alloc();
+		if (!async)
+			return -ENOMEM;
+
+		async->work_buf = kzalloc(map->format.buf_size,
+					  GFP_KERNEL | GFP_DMA);
+		if (!async->work_buf) {
+			kfree(async);
+			return -ENOMEM;
+		}
+
+		INIT_WORK(&async->cleanup, async_cleanup);
+		async->map = map;
+
+		/* If the caller supplied the value we can use it safely. */
+		memcpy(async->work_buf, map->work_buf, map->format.pad_bytes +
+		       map->format.reg_bytes + map->format.val_bytes);
+		if (val == work_val)
+			val = async->work_buf + map->format.pad_bytes +
+				map->format.reg_bytes;
+
+		spin_lock_irqsave(&map->async_lock, flags);
+		list_add_tail(&async->list, &map->async_list);
+		spin_unlock_irqrestore(&map->async_lock, flags);
+
+		ret = map->bus->async_write(map->bus_context, async->work_buf,
+					    map->format.reg_bytes +
+					    map->format.pad_bytes,
+					    val, val_len, async);
+
+		if (ret != 0) {
+			dev_err(map->dev, "Failed to schedule write: %d\n",
+				ret);
+
+			spin_lock_irqsave(&map->async_lock, flags);
+			list_del(&async->list);
+			spin_unlock_irqrestore(&map->async_lock, flags);
+
+			kfree(async->work_buf);
+			kfree(async);
+		}
+	}
+
 	trace_regmap_hw_write_start(map->dev, reg,
 				    val_len / map->format.val_bytes);
 
@@ -962,8 +1022,7 @@ static int _regmap_raw_write(struct regmap *map, unsigned int reg,
 	 * send the work_buf directly, otherwise try to do a gather
 	 * write.
 	 */
-	if (val == (map->work_buf + map->format.pad_bytes +
-		    map->format.reg_bytes))
+	if (val == work_val)
 		ret = map->bus->write(map->bus_context, map->work_buf,
 				      map->format.reg_bytes +
 				      map->format.pad_bytes +
@@ -1036,7 +1095,7 @@ static int _regmap_bus_raw_write(void *context, unsigned int reg,
 				 map->work_buf +
 				 map->format.reg_bytes +
 				 map->format.pad_bytes,
-				 map->format.val_bytes);
+				 map->format.val_bytes, false);
 }
 
 int _regmap_write(struct regmap *map, unsigned int reg,
@@ -1119,7 +1178,7 @@ int regmap_raw_write(struct regmap *map, unsigned int reg,
 
 	map->lock(map->lock_arg);
 
-	ret = _regmap_raw_write(map, reg, val, val_len);
+	ret = _regmap_raw_write(map, reg, val, val_len, false);
 
 	map->unlock(map->lock_arg);
 
@@ -1175,14 +1234,15 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
 	if (map->use_single_rw) {
 		for (i = 0; i < val_count; i++) {
 			ret = regmap_raw_write(map,
-						reg + (i * map->reg_stride),
-						val + (i * val_bytes),
-						val_bytes);
+					       reg + (i * map->reg_stride),
+					       val + (i * val_bytes),
+					       val_bytes);
 			if (ret != 0)
 				return ret;
 		}
 	} else {
-		ret = _regmap_raw_write(map, reg, wval, val_bytes * val_count);
+		ret = _regmap_raw_write(map, reg, wval, val_bytes * val_count,
+					false);
 	}
 
 	if (val_bytes != 1)
@@ -1194,6 +1254,48 @@ out:
 }
 EXPORT_SYMBOL_GPL(regmap_bulk_write);
 
+/**
+ * regmap_raw_write_async(): Write raw values to one or more registers
+ *                           asynchronously
+ *
+ * @map: Register map to write to
+ * @reg: Initial register to write to
+ * @val: Block of data to be written, laid out for direct transmission to the
+ *       device.  Must be valid until regmap_async_complete() is called.
+ * @val_len: Length of data pointed to by val.
+ *
+ * This function is intended to be used for things like firmware
+ * download where a large block of data needs to be transferred to the
+ * device.  No formatting will be done on the data provided.
+ *
+ * If supported by the underlying bus the write will be scheduled
+ * asynchronously, helping maximise I/O speed on higher speed buses
+ * like SPI.  regmap_async_complete() can be called to ensure that all
+ * asynchrnous writes have been completed.
+ *
+ * A value of zero will be returned on success, a negative errno will
+ * be returned in error cases.
+ */
+int regmap_raw_write_async(struct regmap *map, unsigned int reg,
+			   const void *val, size_t val_len)
+{
+	int ret;
+
+	if (val_len % map->format.val_bytes)
+		return -EINVAL;
+	if (reg % map->reg_stride)
+		return -EINVAL;
+
+	map->lock(map->lock_arg);
+
+	ret = _regmap_raw_write(map, reg, val, val_len, true);
+
+	map->unlock(map->lock_arg);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(regmap_raw_write_async);
+
 static int _regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
 			    unsigned int val_len)
 {
@@ -1492,6 +1594,66 @@ int regmap_update_bits_check(struct regmap *map, unsigned int reg,
 }
 EXPORT_SYMBOL_GPL(regmap_update_bits_check);
 
+void regmap_async_complete_cb(struct regmap_async *async, int ret)
+{
+	struct regmap *map = async->map;
+	bool wake;
+
+	spin_lock(&map->async_lock);
+
+	list_del(&async->list);
+	wake = list_empty(&map->async_list);
+
+	if (ret != 0)
+		map->async_ret = ret;
+
+	spin_unlock(&map->async_lock);
+
+	schedule_work(&async->cleanup);
+
+	if (wake)
+		wake_up(&map->async_waitq);
+}
+
+static int regmap_async_is_done(struct regmap *map)
+{
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&map->async_lock, flags);
+	ret = list_empty(&map->async_list);
+	spin_unlock_irqrestore(&map->async_lock, flags);
+
+	return ret;
+}
+
+/**
+ * regmap_async_complete: Ensure all asynchronous I/O has completed.
+ *
+ * @map: Map to operate on.
+ *
+ * Blocks until any pending asynchronous I/O has completed.  Returns
+ * an error code for any failed I/O operations.
+ */
+int regmap_async_complete(struct regmap *map)
+{
+	unsigned long flags;
+	int ret;
+
+	/* Nothing to do with no async support */
+	if (!map->bus->async_write)
+		return 0;
+
+	wait_event(map->async_waitq, regmap_async_is_done(map));
+
+	spin_lock_irqsave(&map->async_lock, flags);
+	ret = map->async_ret;
+	map->async_ret = 0;
+	spin_unlock_irqrestore(&map->async_lock, flags);
+
+	return ret;
+}
+
 /**
  * regmap_register_patch: Register and apply register updates to be applied
  *                        on device initialistion
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index b7e95bf..f9b7fbe 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -235,14 +235,21 @@ struct regmap_range_cfg {
 	unsigned int window_len;
 };
 
+struct regmap_async;
+
 typedef int (*regmap_hw_write)(void *context, const void *data,
 			       size_t count);
 typedef int (*regmap_hw_gather_write)(void *context,
 				      const void *reg, size_t reg_len,
 				      const void *val, size_t val_len);
+typedef int (*regmap_hw_async_write)(void *context,
+				     const void *reg, size_t reg_len,
+				     const void *val, size_t val_len,
+				     struct regmap_async *async);
 typedef int (*regmap_hw_read)(void *context,
 			      const void *reg_buf, size_t reg_size,
 			      void *val_buf, size_t val_size);
+typedef struct regmap_async *(*regmap_hw_async_alloc)(void);
 typedef void (*regmap_hw_free_context)(void *context);
 
 /**
@@ -255,8 +262,11 @@ typedef void (*regmap_hw_free_context)(void *context);
  * @write: Write operation.
  * @gather_write: Write operation with split register/value, return -ENOTSUPP
  *                if not implemented  on a given device.
+ * @async_write: Write operation which completes asynchronously, optional and
+ *               must serialise with respect to non-async I/O.
  * @read: Read operation.  Data is returned in the buffer used to transmit
  *         data.
+ * @async_alloc: Allocate a regmap_async() structure.
  * @read_flag_mask: Mask to be set in the top byte of the register when doing
  *                  a read.
  * @reg_format_endian_default: Default endianness for formatted register
@@ -265,13 +275,16 @@ typedef void (*regmap_hw_free_context)(void *context);
  * @val_format_endian_default: Default endianness for formatted register
  *     values. Used when the regmap_config specifies DEFAULT. If this is
  *     DEFAULT, BIG is assumed.
+ * @async_size: Size of struct used for async work.
  */
 struct regmap_bus {
 	bool fast_io;
 	regmap_hw_write write;
 	regmap_hw_gather_write gather_write;
+	regmap_hw_async_write async_write;
 	regmap_hw_read read;
 	regmap_hw_free_context free_context;
+	regmap_hw_async_alloc async_alloc;
 	u8 read_flag_mask;
 	enum regmap_endian reg_format_endian_default;
 	enum regmap_endian val_format_endian_default;
@@ -310,6 +323,8 @@ int regmap_raw_write(struct regmap *map, unsigned int reg,
 		     const void *val, size_t val_len);
 int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
 			size_t val_count);
+int regmap_raw_write_async(struct regmap *map, unsigned int reg,
+			   const void *val, size_t val_len);
 int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val);
 int regmap_raw_read(struct regmap *map, unsigned int reg,
 		    void *val, size_t val_len);
@@ -321,6 +336,7 @@ int regmap_update_bits_check(struct regmap *map, unsigned int reg,
 			     unsigned int mask, unsigned int val,
 			     bool *change);
 int regmap_get_val_bytes(struct regmap *map);
+int regmap_async_complete(struct regmap *map);
 
 int regcache_sync(struct regmap *map);
 int regcache_sync_region(struct regmap *map, unsigned int min,
@@ -422,6 +438,13 @@ static inline int regmap_raw_write(struct regmap *map, unsigned int reg,
 	return -EINVAL;
 }
 
+static inline int regmap_raw_write_async(struct regmap *map, unsigned int reg,
+					 const void *val, size_t val_len)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+	return -EINVAL;
+}
+
 static inline int regmap_bulk_write(struct regmap *map, unsigned int reg,
 				    const void *val, size_t val_count)
 {
@@ -500,6 +523,11 @@ static inline void regcache_mark_dirty(struct regmap *map)
 	WARN_ONCE(1, "regmap API is disabled");
 }
 
+static inline void regmap_async_complete(struct regmap *map)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+}
+
 static inline int regmap_register_patch(struct regmap *map,
 					const struct reg_default *regs,
 					int num_regs)
-- 
1.7.10.4