mmc: sh_mmcif: calculate best clock with parent clock

MMCIF IP on R-Car series has parent clock which can be set several rate,
and it was not implemented on old SH-Mobile series (= SH-Mobile series
parent clock was fixed rate) R-Car series MMCIF can use more high speed
access if it setups parent clock. This patch adds parent clock setup
method. It will be used if DT has "max-frequency", and then, this driver
assumes it is booted on R-Car Gen2 or later SoC. Because SH-Mobile series
(which doesn't boot from DT) and R-Car series (which boots from DT) have
different divider.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Keita Kobayashi <keita.kobayashi.ym@renesas.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
[Ulf: Silence compiler warning]

diff --git a/Documentation/devicetree/bindings/mmc/renesas,mmcif.txt b/Documentation/devicetree/bindings/mmc/renesas,mmcif.txt
index 299081f..d38942f 100644 (file)
--- a/Documentation/devicetree/bindings/mmc/renesas,mmcif.txt
+++ b/Documentation/devicetree/bindings/mmc/renesas,mmcif.txt
@@ -18,6 +18,8 @@ Required properties:
   dma-names property.
 - dma-names: must contain "tx" for the transmit DMA channel and "rx" for the
   receive DMA channel.
+- max-frequency: Maximum operating clock frequency, driver uses default clock
+  frequency if it is not set.
 
 
 Example: R8A7790 (R-Car H2) MMCIF0
@@ -29,4 +31,5 @@ Example: R8A7790 (R-Car H2) MMCIF0
                clocks = <&mstp3_clks R8A7790_CLK_MMCIF0>;
                dmas = <&dmac0 0xd1>, <&dmac0 0xd2>;
                dma-names = "tx", "rx";
+               max-frequency = <97500000>;
        };

diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c
index e13c5f4..5a1fdd4 100644 (file)
--- a/drivers/mmc/host/sh_mmcif.c
+++ b/drivers/mmc/host/sh_mmcif.c
@@ -57,6 +57,7 @@
 #include <linux/mmc/slot-gpio.h>
 #include <linux/mod_devicetable.h>
 #include <linux/mutex.h>
+#include <linux/of_device.h>
 #include <linux/pagemap.h>
 #include <linux/platform_device.h>
 #include <linux/pm_qos.h>
@@ -224,6 +225,9 @@ enum sh_mmcif_wait_for {
        MMCIF_WAIT_FOR_STOP,
 };
 
+/*
+ * difference for each SoC
+ */
 struct sh_mmcif_host {
        struct mmc_host *mmc;
        struct mmc_request *mrq;
@@ -248,6 +252,7 @@ struct sh_mmcif_host {
        bool ccs_enable;                /* Command Completion Signal support */
        bool clk_ctrl2_enable;
        struct mutex thread_lock;
+       u32 clkdiv_map;         /* see CE_CLK_CTRL::CLKDIV */
 
        /* DMA support */
        struct dma_chan         *chan_rx;
@@ -492,19 +497,55 @@ static void sh_mmcif_clock_control(struct sh_mmcif_host *host, unsigned int clk)
        struct sh_mmcif_plat_data *p = dev->platform_data;
        bool sup_pclk = p ? p->sup_pclk : false;
        unsigned int current_clk = clk_get_rate(host->clk);
+       unsigned int clkdiv;
 
        sh_mmcif_bitclr(host, MMCIF_CE_CLK_CTRL, CLK_ENABLE);
        sh_mmcif_bitclr(host, MMCIF_CE_CLK_CTRL, CLK_CLEAR);
 
        if (!clk)
                return;
-       if (sup_pclk && clk == current_clk)
-               sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_SUP_PCLK);
-       else
-               sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_CLEAR &
-                               ((fls(DIV_ROUND_UP(current_clk,
-                                                  clk) - 1) - 1) << 16));
 
+       if (host->clkdiv_map) {
+               unsigned int freq, best_freq, myclk, div, diff_min, diff;
+               int i;
+
+               clkdiv = 0;
+               diff_min = ~0;
+               best_freq = 0;
+               for (i = 31; i >= 0; i--) {
+                       if (!((1 << i) & host->clkdiv_map))
+                               continue;
+
+                       /*
+                        * clk = parent_freq / div
+                        * -> parent_freq = clk x div
+                        */
+
+                       div = 1 << (i + 1);
+                       freq = clk_round_rate(host->clk, clk * div);
+                       myclk = freq / div;
+                       diff = (myclk > clk) ? myclk - clk : clk - myclk;
+
+                       if (diff <= diff_min) {
+                               best_freq = freq;
+                               clkdiv = i;
+                               diff_min = diff;
+                       }
+               }
+
+               dev_dbg(dev, "clk %u/%u (%u, 0x%x)\n",
+                       (best_freq / (1 << (clkdiv + 1))), clk,
+                       best_freq, clkdiv);
+
+               clk_set_rate(host->clk, best_freq);
+               clkdiv = clkdiv << 16;
+       } else if (sup_pclk && clk == current_clk) {
+               clkdiv = CLK_SUP_PCLK;
+       } else {
+               clkdiv = (fls(DIV_ROUND_UP(current_clk, clk) - 1) - 1) << 16;
+       }
+
+       sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_CLEAR & clkdiv);
        sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_ENABLE);
 }
 
@@ -1000,10 +1041,35 @@ static void sh_mmcif_request(struct mmc_host *mmc, struct mmc_request *mrq)
 
 static void sh_mmcif_clk_setup(struct sh_mmcif_host *host)
 {
-       unsigned int clk = clk_get_rate(host->clk);
+       struct device *dev = sh_mmcif_host_to_dev(host);
+
+       if (host->mmc->f_max) {
+               unsigned int f_max, f_min = 0, f_min_old;
+
+               f_max = host->mmc->f_max;
+               for (f_min_old = f_max; f_min_old > 2;) {
+                       f_min = clk_round_rate(host->clk, f_min_old / 2);
+                       if (f_min == f_min_old)
+                               break;
+                       f_min_old = f_min;
+               }
+
+               /*
+                * This driver assumes this SoC is R-Car Gen2 or later
+                */
+               host->clkdiv_map = 0x3ff;
+
+               host->mmc->f_max = f_max / (1 << ffs(host->clkdiv_map));
+               host->mmc->f_min = f_min / (1 << fls(host->clkdiv_map));
+       } else {
+               unsigned int clk = clk_get_rate(host->clk);
+
+               host->mmc->f_max = clk / 2;
+               host->mmc->f_min = clk / 512;
+       }
 
-       host->mmc->f_max = clk / 2;
-       host->mmc->f_min = clk / 512;
+       dev_dbg(dev, "clk max/min = %d/%d\n",
+               host->mmc->f_max, host->mmc->f_min);
 }
 
 static void sh_mmcif_set_power(struct sh_mmcif_host *host, struct mmc_ios *ios)