regmap: Provide async single register operations

This helps make it easier for users to take advantage of async I/O by
 allowing single register writes to be inserted into sequences.
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Merge tag 'regmap-async-reg' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap into asoc-dapm

regmap: Provide async single register operations

This helps make it easier for users to take advantage of async I/O by
allowing single register writes to be inserted into sequences.

drivers/base/regmap/internal.h

@@ -44,7 +44,6 @@ struct regmap_format {
 
 struct regmap_async {
 	struct list_head list;
-	struct work_struct cleanup;
 	struct regmap *map;
 	void *work_buf;
 };
@@ -64,9 +63,11 @@ struct regmap {
 	void *bus_context;
 	const char *name;
 
+	bool async;
 	spinlock_t async_lock;
 	wait_queue_head_t async_waitq;
 	struct list_head async_list;
+	struct list_head async_free;
 	int async_ret;
 
 #ifdef CONFIG_DEBUG_FS
@@ -218,7 +219,7 @@ bool regcache_set_val(struct regmap *map, void *base, unsigned int idx,
 int regcache_lookup_reg(struct regmap *map, unsigned int reg);
 
 int _regmap_raw_write(struct regmap *map, unsigned int reg,
-		      const void *val, size_t val_len, bool async);
+		      const void *val, size_t val_len);
 
 void regmap_async_complete_cb(struct regmap_async *async, int ret);
 

drivers/base/regmap/regcache.c

@@ -631,8 +631,7 @@ static int regcache_sync_block_raw_flush(struct regmap *map, const void **data,
 
 	map->cache_bypass = 1;
 
-	ret = _regmap_raw_write(map, base, *data, count * val_bytes,
+	ret = _regmap_raw_write(map, base, *data, count * val_bytes);
-				false);
 
 	map->cache_bypass = 0;
 

drivers/base/regmap/regmap.c

@@ -42,15 +42,6 @@ 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)
@@ -465,6 +456,7 @@ struct regmap *regmap_init(struct device *dev,
 
 	spin_lock_init(&map->async_lock);
 	INIT_LIST_HEAD(&map->async_list);
+	INIT_LIST_HEAD(&map->async_free);
 	init_waitqueue_head(&map->async_waitq);
 
 	if (config->read_flag_mask || config->write_flag_mask) {
@@ -942,12 +934,22 @@ EXPORT_SYMBOL_GPL(regmap_reinit_cache);
  */
 void regmap_exit(struct regmap *map)
 {
+	struct regmap_async *async;
+
 	regcache_exit(map);
 	regmap_debugfs_exit(map);
 	regmap_range_exit(map);
 	if (map->bus && map->bus->free_context)
 		map->bus->free_context(map->bus_context);
 	kfree(map->work_buf);
+	while (!list_empty(&map->async_free)) {
+		async = list_first_entry_or_null(&map->async_free,
+						 struct regmap_async,
+						 list);
+		list_del(&async->list);
+		kfree(async->work_buf);
+		kfree(async);
+	}
 	kfree(map);
 }
 EXPORT_SYMBOL_GPL(regmap_exit);
@@ -1039,7 +1041,7 @@ static int _regmap_select_page(struct regmap *map, unsigned int *reg,
 }
 
 int _regmap_raw_write(struct regmap *map, unsigned int reg,
-		      const void *val, size_t val_len, bool async)
+		      const void *val, size_t val_len)
 {
 	struct regmap_range_node *range;
 	unsigned long flags;
@@ -1091,7 +1093,7 @@ 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, async);
+						map->format.val_bytes);
 			if (ret != 0)
 				return ret;
 
@@ -1114,21 +1116,42 @@ 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();
+	 * Essentially all I/O mechanisms will be faster with a single
-		if (!async)
+	 * buffer to write.  Since register syncs often generate raw
-			return -ENOMEM;
+	 * writes of single registers optimise that case.
+	 */
+	if (val != work_val && val_len == map->format.val_bytes) {
+		memcpy(work_val, val, map->format.val_bytes);
+		val = work_val;
+	}
+
+	if (map->async && map->bus->async_write) {
+		struct regmap_async *async;
 
 		trace_regmap_async_write_start(map->dev, reg, val_len);
 
-		async->work_buf = kzalloc(map->format.buf_size,
+		spin_lock_irqsave(&map->async_lock, flags);
-					  GFP_KERNEL | GFP_DMA);
+		async = list_first_entry_or_null(&map->async_free,
-		if (!async->work_buf) {
+						 struct regmap_async,
-			kfree(async);
+						 list);
-			return -ENOMEM;
+		if (async)
+			list_del(&async->list);
+		spin_unlock_irqrestore(&map->async_lock, flags);
+
+		if (!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. */
@@ -1152,11 +1175,8 @@ int _regmap_raw_write(struct regmap *map, unsigned int reg,
 				ret);
 
 			spin_lock_irqsave(&map->async_lock, flags);
-			list_del(&async->list);
+			list_move(&async->list, &map->async_free);
 			spin_unlock_irqrestore(&map->async_lock, flags);
-
-			kfree(async->work_buf);
-			kfree(async);
 		}
 
 		return ret;
@@ -1253,7 +1273,7 @@ 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, false);
+				 map->format.val_bytes);
 }
 
 static inline void *_regmap_map_get_context(struct regmap *map)
@@ -1317,6 +1337,37 @@ int regmap_write(struct regmap *map, unsigned int reg, unsigned int val)
 }
 EXPORT_SYMBOL_GPL(regmap_write);
 
+/**
+ * regmap_write_async(): Write a value to a single register asynchronously
+ *
+ * @map: Register map to write to
+ * @reg: Register to write to
+ * @val: Value to be written
+ *
+ * A value of zero will be returned on success, a negative errno will
+ * be returned in error cases.
+ */
+int regmap_write_async(struct regmap *map, unsigned int reg, unsigned int val)
+{
+	int ret;
+
+	if (reg % map->reg_stride)
+		return -EINVAL;
+
+	map->lock(map->lock_arg);
+
+	map->async = true;
+
+	ret = _regmap_write(map, reg, val);
+
+	map->async = false;
+
+	map->unlock(map->lock_arg);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(regmap_write_async);
+
 /**
  * regmap_raw_write(): Write raw values to one or more registers
  *
@@ -1345,7 +1396,7 @@ int regmap_raw_write(struct regmap *map, unsigned int reg,
 
 	map->lock(map->lock_arg);
 
-	ret = _regmap_raw_write(map, reg, val, val_len, false);
+	ret = _regmap_raw_write(map, reg, val, val_len);
 
 	map->unlock(map->lock_arg);
 
@@ -1426,8 +1477,7 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
 				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)
@@ -1473,7 +1523,11 @@ int regmap_raw_write_async(struct regmap *map, unsigned int reg,
 
 	map->lock(map->lock_arg);
 
-	ret = _regmap_raw_write(map, reg, val, val_len, true);
+	map->async = true;
+
+	ret = _regmap_raw_write(map, reg, val, val_len);
+
+	map->async = false;
 
 	map->unlock(map->lock_arg);
 
@@ -1787,6 +1841,41 @@ int regmap_update_bits(struct regmap *map, unsigned int reg,
 }
 EXPORT_SYMBOL_GPL(regmap_update_bits);
 
+/**
+ * regmap_update_bits_async: Perform a read/modify/write cycle on the register
+ *                           map asynchronously
+ *
+ * @map: Register map to update
+ * @reg: Register to update
+ * @mask: Bitmask to change
+ * @val: New value for bitmask
+ *
+ * With most buses the read must be done synchronously so this is most
+ * useful for devices with a cache which do not need to interact with
+ * the hardware to determine the current register value.
+ *
+ * Returns zero for success, a negative number on error.
+ */
+int regmap_update_bits_async(struct regmap *map, unsigned int reg,
+			     unsigned int mask, unsigned int val)
+{
+	bool change;
+	int ret;
+
+	map->lock(map->lock_arg);
+
+	map->async = true;
+
+	ret = _regmap_update_bits(map, reg, mask, val, &change);
+
+	map->async = false;
+
+	map->unlock(map->lock_arg);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(regmap_update_bits_async);
+
 /**
  * regmap_update_bits_check: Perform a read/modify/write cycle on the
  *                           register map and report if updated
@@ -1812,6 +1901,43 @@ int regmap_update_bits_check(struct regmap *map, unsigned int reg,
 }
 EXPORT_SYMBOL_GPL(regmap_update_bits_check);
 
+/**
+ * regmap_update_bits_check_async: Perform a read/modify/write cycle on the
+ *                                 register map asynchronously and report if
+ *                                 updated
+ *
+ * @map: Register map to update
+ * @reg: Register to update
+ * @mask: Bitmask to change
+ * @val: New value for bitmask
+ * @change: Boolean indicating if a write was done
+ *
+ * With most buses the read must be done synchronously so this is most
+ * useful for devices with a cache which do not need to interact with
+ * the hardware to determine the current register value.
+ *
+ * Returns zero for success, a negative number on error.
+ */
+int regmap_update_bits_check_async(struct regmap *map, unsigned int reg,
+				   unsigned int mask, unsigned int val,
+				   bool *change)
+{
+	int ret;
+
+	map->lock(map->lock_arg);
+
+	map->async = true;
+
+	ret = _regmap_update_bits(map, reg, mask, val, change);
+
+	map->async = false;
+
+	map->unlock(map->lock_arg);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(regmap_update_bits_check_async);
+
 void regmap_async_complete_cb(struct regmap_async *async, int ret)
 {
 	struct regmap *map = async->map;
@@ -1820,8 +1946,7 @@ void regmap_async_complete_cb(struct regmap_async *async, int ret)
 	trace_regmap_async_io_complete(map->dev);
 
 	spin_lock(&map->async_lock);
-
+	list_move(&async->list, &map->async_free);
-	list_del(&async->list);
 	wake = list_empty(&map->async_list);
 
 	if (ret != 0)
@@ -1829,8 +1954,6 @@ void regmap_async_complete_cb(struct regmap_async *async, int ret)
 
 	spin_unlock(&map->async_lock);
 
-	schedule_work(&async->cleanup);
-
 	if (wake)
 		wake_up(&map->async_waitq);
 }

include/linux/regmap.h

@@ -374,6 +374,7 @@ int regmap_reinit_cache(struct regmap *map,
 			const struct regmap_config *config);
 struct regmap *dev_get_regmap(struct device *dev, const char *name);
 int regmap_write(struct regmap *map, unsigned int reg, unsigned int val);
+int regmap_write_async(struct regmap *map, unsigned int reg, unsigned int val);
 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,
@@ -387,9 +388,14 @@ int regmap_bulk_read(struct regmap *map, unsigned int reg, void *val,
 		     size_t val_count);
 int regmap_update_bits(struct regmap *map, unsigned int reg,
 		       unsigned int mask, unsigned int val);
+int regmap_update_bits_async(struct regmap *map, unsigned int reg,
+			     unsigned int mask, unsigned int val);
 int regmap_update_bits_check(struct regmap *map, unsigned int reg,
 			     unsigned int mask, unsigned int val,
 			     bool *change);
+int regmap_update_bits_check_async(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);
 bool regmap_can_raw_write(struct regmap *map);
@@ -527,6 +533,13 @@ static inline int regmap_write(struct regmap *map, unsigned int reg,
 	return -EINVAL;
 }
 
+static inline int regmap_write_async(struct regmap *map, unsigned int reg,
+				     unsigned int val)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+	return -EINVAL;
+}
+
 static inline int regmap_raw_write(struct regmap *map, unsigned int reg,
 				   const void *val, size_t val_len)
 {
@@ -576,6 +589,14 @@ static inline int regmap_update_bits(struct regmap *map, unsigned int reg,
 	return -EINVAL;
 }
 
+static inline int regmap_update_bits_async(struct regmap *map,
+					   unsigned int reg,
+					   unsigned int mask, unsigned int val)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+	return -EINVAL;
+}
+
 static inline int regmap_update_bits_check(struct regmap *map,
 					   unsigned int reg,
 					   unsigned int mask, unsigned int val,
@@ -585,6 +606,16 @@ static inline int regmap_update_bits_check(struct regmap *map,
 	return -EINVAL;
 }
 
+static inline int regmap_update_bits_check_async(struct regmap *map,
+						 unsigned int reg,
+						 unsigned int mask,
+						 unsigned int val,
+						 bool *change)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+	return -EINVAL;
+}
+
 static inline int regmap_get_val_bytes(struct regmap *map)
 {
 	WARN_ONCE(1, "regmap API is disabled");