sdio: set the functions' block size

Before a driver is probed, set the function's block size to the default so the
driver is sure the block size is something sensible and it needn't explicitly
set it.

The default block size is the largest that's supported by both the card and
the host, with a maximum of 512 to ensure aribitrarily sized transfer use the
optimal (least) number of commands.

See http://lkml.org/lkml/2007/8/7/150 for reasons for the block size choice.

Signed-off-by: David Vrabel <david.vrabel@csr.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

4 files changed, 63 insertions, 2 deletions

diff --git a/drivers/mmc/core/sdio_bus.c b/drivers/mmc/core/sdio_bus.c
index d229020db4a2..fcb13fb0daad 100644
--- a/drivers/mmc/core/sdio_bus.c
+++ b/drivers/mmc/core/sdio_bus.c
@@ -128,11 +128,20 @@ static int sdio_bus_probe(struct device *dev)
 	struct sdio_driver *drv = to_sdio_driver(dev->driver);
 	struct sdio_func *func = dev_to_sdio_func(dev);
 	const struct sdio_device_id *id;
+	int ret;
 
 	id = sdio_match_device(func, drv);
 	if (!id)
 		return -ENODEV;
 
+	/* Set the default block size so the driver is sure it's something
+	 * sensible. */
+	sdio_claim_host(func);
+	ret = sdio_set_block_size(func, 0);
+	sdio_release_host(func);
+	if (ret)
+		return ret;
+
 	return drv->probe(func, id);
 }
 
diff --git a/drivers/mmc/core/sdio_cis.c b/drivers/mmc/core/sdio_cis.c
index d050c40cf046..1d03f12bbb38 100644
--- a/drivers/mmc/core/sdio_cis.c
+++ b/drivers/mmc/core/sdio_cis.c
@@ -79,7 +79,7 @@ static int cistpl_funce_func(struct sdio_func *func,
 		return -EINVAL;
 
 	/* TPLFE_MAX_BLK_SIZE */
-	func->blksize = buf[12] | (buf[13] << 8);
+	func->max_blksize = buf[12] | (buf[13] << 8);
 
 	return 0;
 }
diff --git a/drivers/mmc/core/sdio_io.c b/drivers/mmc/core/sdio_io.c
index ecdb77242e98..c2bad1195e3b 100644
--- a/drivers/mmc/core/sdio_io.c
+++ b/drivers/mmc/core/sdio_io.c
@@ -141,6 +141,55 @@ err:
 EXPORT_SYMBOL_GPL(sdio_disable_func);
 
 /**
+ *	sdio_set_block_size - set the block size of an SDIO function
+ *	@func: SDIO function to change
+ *	@blksz: new block size or 0 to use the default.
+ *
+ *	The default block size is the largest supported by both the function
+ *	and the host, with a maximum of 512 to ensure that arbitrarily sized
+ *	data transfer use the optimal (least) number of commands.
+ *
+ *	A driver may call this to override the default block size set by the
+ *	core. This can be used to set a block size greater than the maximum
+ *	that reported by the card; it is the driver's responsibility to ensure
+ *	it uses a value that the card supports.
+ *
+ *	Returns 0 on success, -EINVAL if the host does not support the
+ *	requested block size, or -EIO (etc.) if one of the resultant FBR block
+ *	size register writes failed.
+ *
+ */
+int sdio_set_block_size(struct sdio_func *func, unsigned blksz)
+{
+	int ret;
+
+	if (blksz > func->card->host->max_blk_size)
+		return -EINVAL;
+
+	if (blksz == 0) {
+		blksz = min(min(
+			func->max_blksize,
+			func->card->host->max_blk_size),
+			512u);
+	}
+
+	ret = mmc_io_rw_direct(func->card, 1, 0,
+		SDIO_FBR_BASE(func->num) + SDIO_FBR_BLKSIZE,
+		blksz & 0xff, NULL);
+	if (ret)
+		return ret;
+	ret = mmc_io_rw_direct(func->card, 1, 0,
+		SDIO_FBR_BASE(func->num) + SDIO_FBR_BLKSIZE + 1,
+		(blksz >> 8) & 0xff, NULL);
+	if (ret)
+		return ret;
+	func->cur_blksize = blksz;
+	return 0;
+}
+
+EXPORT_SYMBOL_GPL(sdio_set_block_size);
+
+/**
  *	sdio_readb - read a single byte from a SDIO function
  *	@func: SDIO function to access
  *	@addr: address to read
diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h
index af813fffc4ac..f05757984e8d 100644
--- a/include/linux/mmc/sdio_func.h
+++ b/include/linux/mmc/sdio_func.h
@@ -43,7 +43,8 @@ struct sdio_func {
 	unsigned short		vendor;		/* vendor id */
 	unsigned short		device;		/* device id */
 
-	unsigned short		blksize;	/* maximum block size */
+	unsigned		max_blksize;	/* maximum block size */
+	unsigned		cur_blksize;	/* current block size */
 
 	unsigned int		state;		/* function state */
 #define SDIO_STATE_PRESENT	(1<<0)		/* present in sysfs */
@@ -111,6 +112,8 @@ extern void sdio_release_host(struct sdio_func *func);
 extern int sdio_enable_func(struct sdio_func *func);
 extern int sdio_disable_func(struct sdio_func *func);
 
+extern int sdio_set_block_size(struct sdio_func *func, unsigned blksz);
+
 extern int sdio_claim_irq(struct sdio_func *func, sdio_irq_handler_t *handler);
 extern int sdio_release_irq(struct sdio_func *func);