sdhci: Add support for hosts that are only capable of 1-bit transfers
Some hosts (hardware configurations, or particular SD/MMC slots) may
not support 4-bit bus. For example, on MPC8569E-MDS boards we can
switch between serial (1-bit only) and nibble (4-bit) modes, thought
we have to disable more peripherals to work in 4-bit mode.
Along with some small core changes, this patch modifies sdhci-of
driver, so that now it looks for "sdhci,1-bit-only" property in the
device-tree, and if specified we enable a proper quirk.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Pierre Ossman <pierre@ossman.eu>
diff --git a/Documentation/powerpc/dts-bindings/fsl/esdhc.txt b/Documentation/powerpc/dts-bindings/fsl/esdhc.txt
index 5093ddf..3ed3797 100644
--- a/Documentation/powerpc/dts-bindings/fsl/esdhc.txt
+++ b/Documentation/powerpc/dts-bindings/fsl/esdhc.txt
@@ -10,6 +10,8 @@
- interrupts : should contain eSDHC interrupt.
- interrupt-parent : interrupt source phandle.
- clock-frequency : specifies eSDHC base clock frequency.
+ - sdhci,1-bit-only : (optional) specifies that a controller can
+ only handle 1-bit data transfers.
Example:
diff --git a/drivers/mmc/host/sdhci-of.c b/drivers/mmc/host/sdhci-of.c
index 128c614..d79fa55 100644
--- a/drivers/mmc/host/sdhci-of.c
+++ b/drivers/mmc/host/sdhci-of.c
@@ -250,6 +250,9 @@
host->ops = &sdhci_of_data->ops;
}
+ if (of_get_property(np, "sdhci,1-bit-only", NULL))
+ host->quirks |= SDHCI_QUIRK_FORCE_1_BIT_DATA;
+
clk = of_get_property(np, "clock-frequency", &size);
if (clk && size == sizeof(*clk) && *clk)
of_host->clock = *clk;
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 3856669..c758673 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1761,7 +1761,10 @@
mmc->ops = &sdhci_ops;
mmc->f_min = host->max_clk / 256;
mmc->f_max = host->max_clk;
- mmc->caps = MMC_CAP_4_BIT_DATA | MMC_CAP_SDIO_IRQ;
+ mmc->caps = MMC_CAP_SDIO_IRQ;
+
+ if (!(host->quirks & SDHCI_QUIRK_FORCE_1_BIT_DATA))
+ mmc->caps |= MMC_CAP_4_BIT_DATA;
if (caps & SDHCI_CAN_DO_HISPD)
mmc->caps |= MMC_CAP_SD_HIGHSPEED;
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 84d1490..5d37dd9 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -228,6 +228,8 @@
#define SDHCI_QUIRK_FORCE_BLK_SZ_2048 (1<<20)
/* Controller cannot do multi-block transfers */
#define SDHCI_QUIRK_NO_MULTIBLOCK (1<<21)
+/* Controller can only handle 1-bit data transfers */
+#define SDHCI_QUIRK_FORCE_1_BIT_DATA (1<<22)
int irq; /* Device IRQ */
void __iomem * ioaddr; /* Mapped address */