mmc: esdhc-imx: parse max-frequency from devicetree

In order to make it possible to reduce the SD bus frequency,
parse the optional "max-frequency" attribute as documented in
devicetree/bindings/mmc/mmc.txt

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

2 files changed, 18 insertions, 1 deletions

diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index eb1310ca021e..1dd5ba858754 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -384,6 +384,20 @@ static void esdhc_writeb_le(struct sdhci_host *host, u8 val, int reg)
         }
 }
 
+static unsigned int esdhc_pltfm_get_max_clock(struct sdhci_host *host)
+{
+        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+        struct pltfm_imx_data *imx_data = pltfm_host->priv;
+        struct esdhc_platform_data *boarddata = &imx_data->boarddata;
+
+        u32 f_host = clk_get_rate(pltfm_host->clk);
+
+        if (boarddata->f_max && (boarddata->f_max < f_host))
+                return boarddata->f_max;
+        else
+                return f_host;
+}
+
 static unsigned int esdhc_pltfm_get_min_clock(struct sdhci_host *host)
 {
         struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
@@ -447,7 +461,7 @@ static const struct sdhci_ops sdhci_esdhc_ops = {
         .write_w = esdhc_writew_le,
         .write_b = esdhc_writeb_le,
         .set_clock = esdhc_pltfm_set_clock,
-        .get_max_clock = sdhci_pltfm_clk_get_max_clock,
+        .get_max_clock = esdhc_pltfm_get_max_clock,
         .get_min_clock = esdhc_pltfm_get_min_clock,
         .get_ro = esdhc_pltfm_get_ro,
         .platform_bus_width = esdhc_pltfm_bus_width,
@@ -490,6 +504,8 @@ sdhci_esdhc_imx_probe_dt(struct platform_device *pdev,
 
         of_property_read_u32(np, "bus-width", &boarddata->max_bus_width);
 
+        of_property_read_u32(np, "max-frequency", &boarddata->f_max);
+
         return 0;
 }
 #else
diff --git a/include/linux/platform_data/mmc-esdhc-imx.h b/include/linux/platform_data/mmc-esdhc-imx.h
index b4a0521ce411..d44912d81578 100644
--- a/include/linux/platform_data/mmc-esdhc-imx.h
+++ b/include/linux/platform_data/mmc-esdhc-imx.h
@@ -40,5 +40,6 @@ struct esdhc_platform_data {
         enum wp_types wp_type;
         enum cd_types cd_type;
         int max_bus_width;
+        unsigned int f_max;
 };
 #endif /* __ASM_ARCH_IMX_ESDHC_H */