Commit ad3868b2 authored by Pierre Ossman's avatar Pierre Ossman
Browse files

mmc,sdio: helper function for transfer padding 



There are a lot of crappy controllers out there that cannot handle
all the request sizes that the MMC/SD/SDIO specifications require.
In case the card driver can pad the data to overcome the problems,
this commit adds a helper that calculates how much that padding
should be.

A corresponding helper is also added for SDIO, but it can also deal
with all the complexities of splitting up a large transfer efficiently.

Signed-off-by: default avatarPierre Ossman <drzeus@drzeus.cx>
parent e2d26477

drivers/mmc/core/core.c

+28 −1
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ 
 *

 *  Copyright (C) 2003-2004 Russell King, All Rights Reserved.

 *  SD support Copyright (C) 2004 Ian Molton, All Rights Reserved.

 *  Copyright (C) 2005-2007 Pierre Ossman, All Rights Reserved.

 *  Copyright (C) 2005-2008 Pierre Ossman, All Rights Reserved.

 *  MMCv4 support Copyright (C) 2006 Philip Langdale, All Rights Reserved.

 *

 * This program is free software; you can redistribute it and/or modify
@@ -294,6 +294,33 @@ void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card) 
}

EXPORT_SYMBOL(mmc_set_data_timeout);



/**

 *	mmc_align_data_size - pads a transfer size to a more optimal value

 *	@card: the MMC card associated with the data transfer

 *	@sz: original transfer size

 *

 *	Pads the original data size with a number of extra bytes in

 *	order to avoid controller bugs and/or performance hits

 *	(e.g. some controllers revert to PIO for certain sizes).

 *

 *	Returns the improved size, which might be unmodified.

 *

 *	Note that this function is only relevant when issuing a

 *	single scatter gather entry.

 */

unsigned int mmc_align_data_size(struct mmc_card *card, unsigned int sz)

{

	/*

	 * FIXME: We don't have a system for the controller to tell

	 * the core about its problems yet, so for now we just 32-bit

	 * align the size.

	 */

	sz = ((sz + 3) / 4) * 4;



	return sz;

}

EXPORT_SYMBOL(mmc_align_data_size);



/**

 *	__mmc_claim_host - exclusively claim a host

 *	@host: mmc host to claim

drivers/mmc/core/sdio_io.c

+98 −1
Original line number Diff line number Diff line 
/*

 *  linux/drivers/mmc/core/sdio_io.c

 *

 *  Copyright 2007 Pierre Ossman

 *  Copyright 2007-2008 Pierre Ossman

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by
@@ -189,6 +189,103 @@ int sdio_set_block_size(struct sdio_func *func, unsigned blksz) 


EXPORT_SYMBOL_GPL(sdio_set_block_size);



/**

 *	sdio_align_size - pads a transfer size to a more optimal value

 *	@func: SDIO function

 *	@sz: original transfer size

 *

 *	Pads the original data size with a number of extra bytes in

 *	order to avoid controller bugs and/or performance hits

 *	(e.g. some controllers revert to PIO for certain sizes).

 *

 *	If possible, it will also adjust the size so that it can be

 *	handled in just a single request.

 *

 *	Returns the improved size, which might be unmodified.

 */

unsigned int sdio_align_size(struct sdio_func *func, unsigned int sz)

{

	unsigned int orig_sz;

	unsigned int blk_sz, byte_sz;

	unsigned chunk_sz;



	orig_sz = sz;



	/*

	 * Do a first check with the controller, in case it

	 * wants to increase the size up to a point where it

	 * might need more than one block.

	 */

	sz = mmc_align_data_size(func->card, sz);



	/*

	 * If we can still do this with just a byte transfer, then

	 * we're done.

	 */

	if ((sz <= func->cur_blksize) && (sz <= 512))

		return sz;



	if (func->card->cccr.multi_block) {

		/*

		 * Check if the transfer is already block aligned

		 */

		if ((sz % func->cur_blksize) == 0)

			return sz;



		/*

		 * Realign it so that it can be done with one request,

		 * and recheck if the controller still likes it.

		 */

		blk_sz = ((sz + func->cur_blksize - 1) /

			func->cur_blksize) * func->cur_blksize;

		blk_sz = mmc_align_data_size(func->card, blk_sz);



		/*

		 * This value is only good if it is still just

		 * one request.

		 */

		if ((blk_sz % func->cur_blksize) == 0)

			return blk_sz;



		/*

		 * We failed to do one request, but at least try to

		 * pad the remainder properly.

		 */

		byte_sz = mmc_align_data_size(func->card,

				sz % func->cur_blksize);

		if ((byte_sz <= func->cur_blksize) && (byte_sz <= 512)) {

			blk_sz = sz / func->cur_blksize;

			return blk_sz * func->cur_blksize + byte_sz;

		}

	} else {

		/*

		 * We need multiple requests, so first check that the

		 * controller can handle the chunk size;

		 */

		chunk_sz = mmc_align_data_size(func->card,

				min(func->cur_blksize, 512u));

		if (chunk_sz == min(func->cur_blksize, 512u)) {

			/*

			 * Fix up the size of the remainder (if any)

			 */

			byte_sz = orig_sz % chunk_sz;

			if (byte_sz) {

				byte_sz = mmc_align_data_size(func->card,

						byte_sz);

			}



			return (orig_sz / chunk_sz) * chunk_sz + byte_sz;

		}

	}



	/*

	 * The controller is simply incapable of transferring the size

	 * we want in decent manner, so just return the original size.

	 */

	return orig_sz;

}

EXPORT_SYMBOL_GPL(sdio_align_size);



/* Split an arbitrarily sized data transfer into several

 * IO_RW_EXTENDED commands. */

static int sdio_io_rw_ext_helper(struct sdio_func *func, int write,

drivers/net/wireless/libertas/if_sdio.c

+7 −13
Original line number Diff line number Diff line 
/*

 *  linux/drivers/net/wireless/libertas/if_sdio.c

 *

 *  Copyright 2007 Pierre Ossman

 *  Copyright 2007-2008 Pierre Ossman

 *

 * Inspired by if_cs.c, Copyright 2007 Holger Schurig

 *
@@ -266,13 +266,10 @@ static int if_sdio_card_to_host(struct if_sdio_card *card) 


	/*

	 * The transfer must be in one transaction or the firmware

	 * goes suicidal.

	 * goes suicidal. There's no way to guarantee that for all

	 * controllers, but we can at least try.

	 */

	chunk = size;

	if ((chunk > card->func->cur_blksize) || (chunk > 512)) {

		chunk = (chunk + card->func->cur_blksize - 1) /

			card->func->cur_blksize * card->func->cur_blksize;

	}

	chunk = sdio_align_size(card->func, size);



	ret = sdio_readsb(card->func, card->buffer, card->ioport, chunk);

	if (ret)
@@ -696,13 +693,10 @@ static int if_sdio_host_to_card(struct lbs_private *priv, 


	/*

	 * The transfer must be in one transaction or the firmware

	 * goes suicidal.

	 * goes suicidal. There's no way to guarantee that for all

	 * controllers, but we can at least try.

	 */

	size = nb + 4;

	if ((size > card->func->cur_blksize) || (size > 512)) {

		size = (size + card->func->cur_blksize - 1) /

			card->func->cur_blksize * card->func->cur_blksize;

	}

	size = sdio_align_size(card->func, nb + 4);



	packet = kzalloc(sizeof(struct if_sdio_packet) + size,

			GFP_ATOMIC);

include/linux/mmc/core.h

+1 −0
Original line number Diff line number Diff line
@@ -135,6 +135,7 @@ extern int mmc_wait_for_app_cmd(struct mmc_host *, struct mmc_card *, 
	struct mmc_command *, int);



extern void mmc_set_data_timeout(struct mmc_data *, const struct mmc_card *);

extern unsigned int mmc_align_data_size(struct mmc_card *, unsigned int);



extern int __mmc_claim_host(struct mmc_host *host, atomic_t *abort);

extern void mmc_release_host(struct mmc_host *host);

include/linux/mmc/sdio_func.h

+3 −1
Original line number Diff line number Diff line 
/*

 *  include/linux/mmc/sdio_func.h

 *

 *  Copyright 2007 Pierre Ossman

 *  Copyright 2007-2008 Pierre Ossman

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by
@@ -120,6 +120,8 @@ 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);



extern unsigned int sdio_align_size(struct sdio_func *func, unsigned int sz);



extern unsigned char sdio_readb(struct sdio_func *func,

	unsigned int addr, int *err_ret);

extern unsigned short sdio_readw(struct sdio_func *func,

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