[PATCH] sd: SD 4-bit bus
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>
diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 21d4fb3..6414f07 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -335,6 +335,40 @@
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 @@
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 @@
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);
}