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[PATCH] sd: SD 4-bit bus

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Infrastructure for 4-bit bus transfers with SD cards.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Pierre Ossman 2005-09-06 15:18:55 -07:00 committed by Linus Torvalds
parent a9c4342beb
commit f218278a45
3 changed files with 52 additions and 0 deletions
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36
drivers/mmc/mmc.c
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@ -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);
}

9
include/linux/mmc/host.h
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@ -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 */

7
include/linux/mmc/protocol.h
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@ -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 */