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Commit f218278a authored by Pierre Ossman's avatar Pierre Ossman Committed by Linus Torvalds
Browse files

[PATCH] sd: SD 4-bit bus 



Infrastructure for 4-bit bus transfers with SD cards.

Signed-off-by: default avatarPierre Ossman <drzeus@drzeus.cx>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent a9c4342b

drivers/mmc/mmc.c

+36 −0
Original line number Diff line number Diff line
@@ -335,6 +335,40 @@ static int mmc_select_card(struct mmc_host *host, struct mmc_card *card) 
	if (err != MMC_ERR_NONE)

		return err;



	/*

	 * Default bus width is 1 bit.

	 */

	host->ios.bus_width = MMC_BUS_WIDTH_1;



	/*

	 * We can only change the bus width of the selected

	 * card so therefore we have to put the handling

	 * here.

	 */

	if (host->caps & MMC_CAP_4_BIT_DATA) {

		/*

		 * The card is in 1 bit mode by default so

		 * we only need to change if it supports the

		 * wider version.

		 */

		if (mmc_card_sd(card) &&

			(card->scr.bus_widths & SD_SCR_BUS_WIDTH_4)) {

			struct mmc_command cmd;

			cmd.opcode = SD_APP_SET_BUS_WIDTH;

			cmd.arg = SD_BUS_WIDTH_4;

			cmd.flags = MMC_RSP_R1;



			err = mmc_wait_for_app_cmd(host, card->rca, &cmd,

				CMD_RETRIES);

			if (err != MMC_ERR_NONE)

				return err;



			host->ios.bus_width = MMC_BUS_WIDTH_4;

		}

	}



	host->ops->set_ios(host, &host->ios);



	return MMC_ERR_NONE;

}
@@ -653,6 +687,7 @@ static void mmc_power_up(struct mmc_host *host) 
	host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;

	host->ios.chip_select = MMC_CS_DONTCARE;

	host->ios.power_mode = MMC_POWER_UP;

	host->ios.bus_width = MMC_BUS_WIDTH_1;

	host->ops->set_ios(host, &host->ios);



	mmc_delay(1);
@@ -671,6 +706,7 @@ static void mmc_power_off(struct mmc_host *host) 
	host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;

	host->ios.chip_select = MMC_CS_DONTCARE;

	host->ios.power_mode = MMC_POWER_OFF;

	host->ios.bus_width = MMC_BUS_WIDTH_1;

	host->ops->set_ios(host, &host->ios);

}

include/linux/mmc/host.h

+9 −0
Original line number Diff line number Diff line
@@ -57,6 +57,11 @@ struct mmc_ios { 
#define MMC_POWER_OFF		0

#define MMC_POWER_UP		1

#define MMC_POWER_ON		2



	unsigned char	bus_width;		/* data bus width */



#define MMC_BUS_WIDTH_1		0

#define MMC_BUS_WIDTH_4		2

};



struct mmc_host_ops {
@@ -77,6 +82,10 @@ struct mmc_host { 
	unsigned int		f_max;

	u32			ocr_avail;



	unsigned long		caps;		/* Host capabilities */



#define MMC_CAP_4_BIT_DATA	(1 << 0)	/* Can the host do 4 bit transfers */



	/* host specific block data */

	unsigned int		max_seg_size;	/* see blk_queue_max_segment_size */

	unsigned short		max_hw_segs;	/* see blk_queue_max_hw_segments */

include/linux/mmc/protocol.h

+7 −0
Original line number Diff line number Diff line
@@ -236,5 +236,12 @@ struct _mmc_csd { 
#define CSD_SPEC_VER_2      2           /* Implements system specification 2.0 - 2.2 */

#define CSD_SPEC_VER_3      3           /* Implements system specification 3.1 */





/*

 * SD bus widths

 */

#define SD_BUS_WIDTH_1      0

#define SD_BUS_WIDTH_4      2



#endif  /* MMC_MMC_PROTOCOL_H */