mmc: sh_mobile_sdhi: add support for 2 clocks

Some controllers have 2 clock sources instead of 1. The 2nd clock
is for the internal card detect logic and must be enabled/disabled
along with the main core clock for proper operation.

Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

diff --git a/drivers/mmc/host/sh_mobile_sdhi.c b/drivers/mmc/host/sh_mobile_sdhi.c
index 8bebf35..bc6be0d 100644 (file)
--- a/drivers/mmc/host/sh_mobile_sdhi.c
+++ b/drivers/mmc/host/sh_mobile_sdhi.c
@@ -143,6 +143,7 @@ MODULE_DEVICE_TABLE(of, sh_mobile_sdhi_of_match);
 
 struct sh_mobile_sdhi {
        struct clk *clk;
+       struct clk *clk_cd;
        struct tmio_mmc_data mmc_data;
        struct tmio_mmc_dma dma_priv;
        struct pinctrl *pinctrl;
@@ -190,6 +191,12 @@ static int sh_mobile_sdhi_clk_enable(struct tmio_mmc_host *host)
        if (ret < 0)
                return ret;
 
+       ret = clk_prepare_enable(priv->clk_cd);
+       if (ret < 0) {
+               clk_disable_unprepare(priv->clk);
+               return ret;
+       }
+
        /*
         * The clock driver may not know what maximum frequency
         * actually works, so it should be set with the max-frequency
@@ -255,6 +262,7 @@ static void sh_mobile_sdhi_clk_disable(struct tmio_mmc_host *host)
        struct sh_mobile_sdhi *priv = host_to_priv(host);
 
        clk_disable_unprepare(priv->clk);
+       clk_disable_unprepare(priv->clk_cd);
 }
 
 static int sh_mobile_sdhi_card_busy(struct mmc_host *mmc)
@@ -572,6 +580,21 @@ static int sh_mobile_sdhi_probe(struct platform_device *pdev)
                goto eprobe;
        }
 
+       /*
+        * Some controllers provide a 2nd clock just to run the internal card
+        * detection logic. Unfortunately, the existing driver architecture does
+        * not support a separation of clocks for runtime PM usage. When
+        * native hotplug is used, the tmio driver assumes that the core
+        * must continue to run for card detect to stay active, so we cannot
+        * disable it.
+        * Additionally, it is prohibited to supply a clock to the core but not
+        * to the card detect circuit. That leaves us with if separate clocks
+        * are presented, we must treat them both as virtually 1 clock.
+        */
+       priv->clk_cd = devm_clk_get(&pdev->dev, "cd");
+       if (IS_ERR(priv->clk_cd))
+               priv->clk_cd = NULL;
+
        priv->pinctrl = devm_pinctrl_get(&pdev->dev);
        if (!IS_ERR(priv->pinctrl)) {
                priv->pins_default = pinctrl_lookup_state(priv->pinctrl,