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>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/mmc/host/sdhci-of.c b/drivers/mmc/host/sdhci-of.c
index 128c614d11aa..d79fa55c3b89 100644
--- a/drivers/mmc/host/sdhci-of.c
+++ b/drivers/mmc/host/sdhci-of.c
@@ -250,6 +250,9 @@ static int __devinit sdhci_of_probe(struct of_device *ofdev,
                 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;