mmc: dw_mmc: exynos: adjust the clock rate with speed mode

Exynos's host has divider logic before 'cclk_in' to controller core.
It means that actual clock rate of ciu clock comes from this divider
value. So, source clock should be adjusted along with 'ciu_div' which
indicates the host's divider ratio. Setting clock rate basically fits
the required speed. Specially, 'cclk_in' should have double rate of
target speed in case of DDR 8-bit mode.

Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c
index b86f518..d42e664 100644 (file)
--- a/drivers/mmc/host/dw_mmc-exynos.c
+++ b/drivers/mmc/host/dw_mmc-exynos.c
@@ -56,6 +56,8 @@
 #define DWMCI_MPSCTRL_ENCRYPTION               BIT(1)
 #define DWMCI_MPSCTRL_VALID                    BIT(0)
 
+#define EXYNOS_CCLKIN_MIN      50000000        /* unit: HZ */
+
 /* Variations in Exynos specific dw-mshc controller */
 enum dw_mci_exynos_type {
        DW_MCI_TYPE_EXYNOS4210,
@@ -71,6 +73,7 @@ struct dw_mci_exynos_priv_data {
        u8                              ciu_div;
        u32                             sdr_timing;
        u32                             ddr_timing;
+       u32                             cur_speed;
 };
 
 static struct dw_mci_exynos_compatible {
@@ -114,16 +117,9 @@ static int dw_mci_exynos_priv_init(struct dw_mci *host)
 static int dw_mci_exynos_setup_clock(struct dw_mci *host)
 {
        struct dw_mci_exynos_priv_data *priv = host->priv;
+       unsigned long rate = clk_get_rate(host->ciu_clk);
 
-       if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS5250 ||
-           priv->ctrl_type == DW_MCI_TYPE_EXYNOS5420 ||
-           priv->ctrl_type == DW_MCI_TYPE_EXYNOS5420_SMU)
-               host->bus_hz /= (priv->ciu_div + 1);
-       else if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS4412)
-               host->bus_hz /= EXYNOS4412_FIXED_CIU_CLK_DIV;
-       else if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS4210)
-               host->bus_hz /= EXYNOS4210_FIXED_CIU_CLK_DIV;
-
+       host->bus_hz = rate / (priv->ciu_div + 1);
        return 0;
 }
 
@@ -187,11 +183,38 @@ static void dw_mci_exynos_prepare_command(struct dw_mci *host, u32 *cmdr)
 static void dw_mci_exynos_set_ios(struct dw_mci *host, struct mmc_ios *ios)
 {
        struct dw_mci_exynos_priv_data *priv = host->priv;
+       unsigned int wanted = ios->clock;
+       unsigned long actual;
+       u8 div = priv->ciu_div + 1;
 
-       if (ios->timing == MMC_TIMING_UHS_DDR50)
+       if (ios->timing == MMC_TIMING_UHS_DDR50) {
                mci_writel(host, CLKSEL, priv->ddr_timing);
-       else
+               /* Should be double rate for DDR mode */
+               if (ios->bus_width == MMC_BUS_WIDTH_8)
+                       wanted <<= 1;
+       } else {
                mci_writel(host, CLKSEL, priv->sdr_timing);
+       }
+
+       /* Don't care if wanted clock is zero */
+       if (!wanted)
+               return;
+
+       /* Guaranteed minimum frequency for cclkin */
+       if (wanted < EXYNOS_CCLKIN_MIN)
+               wanted = EXYNOS_CCLKIN_MIN;
+
+       if (wanted != priv->cur_speed) {
+               int ret = clk_set_rate(host->ciu_clk, wanted * div);
+               if (ret)
+                       dev_warn(host->dev,
+                               "failed to set clk-rate %u error: %d\n",
+                                wanted * div, ret);
+               actual = clk_get_rate(host->ciu_clk);
+               host->bus_hz = actual / div;
+               priv->cur_speed = wanted;
+               host->current_speed = 0;
+       }
 }
 
 static int dw_mci_exynos_parse_dt(struct dw_mci *host)
@@ -214,8 +237,14 @@ static int dw_mci_exynos_parse_dt(struct dw_mci *host)
                        priv->ctrl_type = exynos_compat[idx].ctrl_type;
        }
 
-       of_property_read_u32(np, "samsung,dw-mshc-ciu-div", &div);
-       priv->ciu_div = div;
+       if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS4412)
+               priv->ciu_div = EXYNOS4412_FIXED_CIU_CLK_DIV - 1;
+       else if (priv->ctrl_type == DW_MCI_TYPE_EXYNOS4210)
+               priv->ciu_div = EXYNOS4210_FIXED_CIU_CLK_DIV - 1;
+       else {
+               of_property_read_u32(np, "samsung,dw-mshc-ciu-div", &div);
+               priv->ciu_div = div;
+       }
 
        ret = of_property_read_u32_array(np,
                        "samsung,dw-mshc-sdr-timing", timing, 2);