From: Pierre Ossman <drzeus-list@drzeus.cx>
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>
---
drivers/mmc/mmc.c | 36 ++++++++++++++++++++++++++++++++++++
include/linux/mmc/host.h | 9 +++++++++
include/linux/mmc/protocol.h | 7 +++++++
3 files changed, 52 insertions(+)
diff -puN drivers/mmc/mmc.c~sd-4-bit-bus drivers/mmc/mmc.c
--- devel/drivers/mmc/mmc.c~sd-4-bit-bus 2005-07-30 00:17:00.000000000 -0700
+++ devel-akpm/drivers/mmc/mmc.c 2005-07-30 00:17:00.000000000 -0700
@@ -335,6 +335,40 @@ static int mmc_select_card(struct mmc_ho
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;
}
@@ -644,6 +678,7 @@ static void mmc_power_up(struct mmc_host
host->ios.vdd = bit;
host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
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);
@@ -661,6 +696,7 @@ static void mmc_power_off(struct mmc_hos
host->ios.vdd = 0;
host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
host->ios.power_mode = MMC_POWER_OFF;
+ host->ios.bus_width = MMC_BUS_WIDTH_1;
host->ops->set_ios(host, &host->ios);
}
diff -puN include/linux/mmc/host.h~sd-4-bit-bus include/linux/mmc/host.h
--- devel/include/linux/mmc/host.h~sd-4-bit-bus 2005-07-30 00:17:00.000000000 -0700
+++ devel-akpm/include/linux/mmc/host.h 2005-07-30 00:17:00.000000000 -0700
@@ -51,6 +51,11 @@ 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 {
@@ -70,6 +75,10 @@ struct mmc_host {
u32 ocr_avail;
char host_name[8];
+ 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 */
diff -puN include/linux/mmc/protocol.h~sd-4-bit-bus include/linux/mmc/protocol.h
--- devel/include/linux/mmc/protocol.h~sd-4-bit-bus 2005-07-30 00:17:00.000000000 -0700
+++ devel-akpm/include/linux/mmc/protocol.h 2005-07-30 00:17:00.000000000 -0700
@@ -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 */
_