Commit bacdbe07 authored by Stephen Warren's avatar Stephen Warren Committed by Mark Brown
Browse files

regmap: introduce fast_io busses, and use a spinlock for them 



Some bus types have very fast IO. For these, acquiring a mutex for every
IO operation is a significant overhead. Allow busses to indicate their IO
is fast, and enhance regmap to use a spinlock for those busses.

[Currently limited to native endian registers -- broonie]

Signed-off-by: default avatarStephen Warren <swarren@nvidia.com>
Signed-off-by: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
parent 0135bbcc

drivers/base/regmap/internal.h

+7 −1
Original line number Diff line number Diff line
@@ -31,8 +31,14 @@ struct regmap_format { 
	unsigned int (*parse_val)(void *buf);

};



typedef void (*regmap_lock)(struct regmap *map);

typedef void (*regmap_unlock)(struct regmap *map);



struct regmap {

	struct mutex lock;

	struct mutex mutex;

	spinlock_t spinlock;

	regmap_lock lock;

	regmap_unlock unlock;



	struct device *dev; /* Device we do I/O on */

	void *work_buf;     /* Scratch buffer used to format I/O */

drivers/base/regmap/regcache-rbtree.c

+2 −2
Original line number Diff line number Diff line
@@ -139,7 +139,7 @@ static int rbtree_show(struct seq_file *s, void *ignored) 
	int nodes = 0;

	int registers = 0;



	mutex_lock(&map->lock);

	map->lock(map);



	for (node = rb_first(&rbtree_ctx->root); node != NULL;

	     node = rb_next(node)) {
@@ -155,7 +155,7 @@ static int rbtree_show(struct seq_file *s, void *ignored) 
	seq_printf(s, "%d nodes, %d registers, average %d registers\n",

		   nodes, registers, registers / nodes);



	mutex_unlock(&map->lock);

	map->unlock(map);



	return 0;

}

drivers/base/regmap/regcache.c

+10 −10
Original line number Diff line number Diff line
@@ -264,7 +264,7 @@ int regcache_sync(struct regmap *map) 


	BUG_ON(!map->cache_ops || !map->cache_ops->sync);



	mutex_lock(&map->lock);

	map->lock(map);

	/* Remember the initial bypass state */

	bypass = map->cache_bypass;

	dev_dbg(map->dev, "Syncing %s cache\n",
@@ -296,7 +296,7 @@ out: 
	trace_regcache_sync(map->dev, name, "stop");

	/* Restore the bypass state */

	map->cache_bypass = bypass;

	mutex_unlock(&map->lock);

	map->unlock(map);



	return ret;

}
@@ -323,7 +323,7 @@ int regcache_sync_region(struct regmap *map, unsigned int min, 


	BUG_ON(!map->cache_ops || !map->cache_ops->sync);



	mutex_lock(&map->lock);

	map->lock(map);



	/* Remember the initial bypass state */

	bypass = map->cache_bypass;
@@ -342,7 +342,7 @@ out: 
	trace_regcache_sync(map->dev, name, "stop region");

	/* Restore the bypass state */

	map->cache_bypass = bypass;

	mutex_unlock(&map->lock);

	map->unlock(map);



	return ret;

}
@@ -361,11 +361,11 @@ out: 
 */

void regcache_cache_only(struct regmap *map, bool enable)

{

	mutex_lock(&map->lock);

	map->lock(map);

	WARN_ON(map->cache_bypass && enable);

	map->cache_only = enable;

	trace_regmap_cache_only(map->dev, enable);

	mutex_unlock(&map->lock);

	map->unlock(map);

}

EXPORT_SYMBOL_GPL(regcache_cache_only);
@@ -380,9 +380,9 @@ EXPORT_SYMBOL_GPL(regcache_cache_only); 
 */

void regcache_mark_dirty(struct regmap *map)

{

	mutex_lock(&map->lock);

	map->lock(map);

	map->cache_dirty = true;

	mutex_unlock(&map->lock);

	map->unlock(map);

}

EXPORT_SYMBOL_GPL(regcache_mark_dirty);
@@ -399,11 +399,11 @@ EXPORT_SYMBOL_GPL(regcache_mark_dirty); 
 */

void regcache_cache_bypass(struct regmap *map, bool enable)

{

	mutex_lock(&map->lock);

	map->lock(map);

	WARN_ON(map->cache_only && enable);

	map->cache_bypass = enable;

	trace_regmap_cache_bypass(map->dev, enable);

	mutex_unlock(&map->lock);

	map->unlock(map);

}

EXPORT_SYMBOL_GPL(regcache_cache_bypass);

drivers/base/regmap/regmap.c

+45 −17
Original line number Diff line number Diff line
@@ -158,6 +158,26 @@ static unsigned int regmap_parse_32(void *buf) 
	return b[0];

}



static void regmap_lock_mutex(struct regmap *map)

{

	mutex_lock(&map->mutex);

}



static void regmap_unlock_mutex(struct regmap *map)

{

	mutex_unlock(&map->mutex);

}



static void regmap_lock_spinlock(struct regmap *map)

{

	spin_lock(&map->spinlock);

}



static void regmap_unlock_spinlock(struct regmap *map)

{

	spin_unlock(&map->spinlock);

}



/**

 * regmap_init(): Initialise register map

 *
@@ -187,7 +207,15 @@ struct regmap *regmap_init(struct device *dev, 
		goto err;

	}



	mutex_init(&map->lock);

	if (bus->fast_io) {

		spin_lock_init(&map->spinlock);

		map->lock = regmap_lock_spinlock;

		map->unlock = regmap_unlock_spinlock;

	} else {

		mutex_init(&map->mutex);

		map->lock = regmap_lock_mutex;

		map->unlock = regmap_unlock_mutex;

	}

	map->format.buf_size = (config->reg_bits + config->val_bits) / 8;

	map->format.reg_bytes = DIV_ROUND_UP(config->reg_bits, 8);

	map->format.pad_bytes = config->pad_bits / 8;
@@ -365,7 +393,7 @@ int regmap_reinit_cache(struct regmap *map, const struct regmap_config *config) 
{

	int ret;



	mutex_lock(&map->lock);

	map->lock(map);



	regcache_exit(map);

	regmap_debugfs_exit(map);
@@ -384,7 +412,7 @@ int regmap_reinit_cache(struct regmap *map, const struct regmap_config *config) 


	ret = regcache_init(map, config);



	mutex_unlock(&map->lock);

	map->unlock(map);



	return ret;

}
@@ -536,11 +564,11 @@ int regmap_write(struct regmap *map, unsigned int reg, unsigned int val) 
{

	int ret;



	mutex_lock(&map->lock);

	map->lock(map);



	ret = _regmap_write(map, reg, val);



	mutex_unlock(&map->lock);

	map->unlock(map);



	return ret;

}
@@ -567,11 +595,11 @@ int regmap_raw_write(struct regmap *map, unsigned int reg, 
{

	int ret;



	mutex_lock(&map->lock);

	map->lock(map);



	ret = _regmap_raw_write(map, reg, val, val_len);



	mutex_unlock(&map->lock);

	map->unlock(map);



	return ret;

}
@@ -601,7 +629,7 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val, 
	if (!map->format.parse_val)

		return -EINVAL;



	mutex_lock(&map->lock);

	map->lock(map);



	/* No formatting is require if val_byte is 1 */

	if (val_bytes == 1) {
@@ -622,7 +650,7 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val, 
		kfree(wval);



out:

	mutex_unlock(&map->lock);

	map->unlock(map);

	return ret;

}

EXPORT_SYMBOL_GPL(regmap_bulk_write);
@@ -696,11 +724,11 @@ int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val) 
{

	int ret;



	mutex_lock(&map->lock);

	map->lock(map);



	ret = _regmap_read(map, reg, val);



	mutex_unlock(&map->lock);

	map->unlock(map);



	return ret;

}
@@ -725,7 +753,7 @@ int regmap_raw_read(struct regmap *map, unsigned int reg, void *val, 
	unsigned int v;

	int ret, i;



	mutex_lock(&map->lock);

	map->lock(map);



	if (regmap_volatile_range(map, reg, val_count) || map->cache_bypass ||

	    map->cache_type == REGCACHE_NONE) {
@@ -746,7 +774,7 @@ int regmap_raw_read(struct regmap *map, unsigned int reg, void *val, 
	}



 out:

	mutex_unlock(&map->lock);

	map->unlock(map);



	return ret;

}
@@ -799,7 +827,7 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg, 
	int ret;

	unsigned int tmp, orig;



	mutex_lock(&map->lock);

	map->lock(map);



	ret = _regmap_read(map, reg, &orig);

	if (ret != 0)
@@ -816,7 +844,7 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg, 
	}



out:

	mutex_unlock(&map->lock);

	map->unlock(map);



	return ret;

}
@@ -883,7 +911,7 @@ int regmap_register_patch(struct regmap *map, const struct reg_default *regs, 
	if (map->patch)

		return -EBUSY;



	mutex_lock(&map->lock);

	map->lock(map);



	bypass = map->cache_bypass;
@@ -911,7 +939,7 @@ int regmap_register_patch(struct regmap *map, const struct reg_default *regs, 
out:

	map->cache_bypass = bypass;



	mutex_unlock(&map->lock);

	map->unlock(map);



	return ret;

}

include/linux/regmap.h

+3 −0
Original line number Diff line number Diff line
@@ -110,6 +110,8 @@ typedef void (*regmap_hw_free_context)(void *context); 
/**

 * Description of a hardware bus for the register map infrastructure.

 *

 * @fast_io: Register IO is fast. Use a spinlock instead of a mutex

 *           to perform locking.

 * @write: Write operation.

 * @gather_write: Write operation with split register/value, return -ENOTSUPP

 *                if not implemented  on a given device.
@@ -119,6 +121,7 @@ typedef void (*regmap_hw_free_context)(void *context); 
 *                  a read.

 */

struct regmap_bus {

	bool fast_io;

	regmap_hw_write write;

	regmap_hw_gather_write gather_write;

	regmap_hw_read read;

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