mmc: sdhci-of-esdhc: add peripheral clock support

eSDHC could select peripheral clock or platform clock as clock source by
the PCS bit of eSDHC Control Register, and this bit couldn't be reset by
software reset for all. In default, the platform clock is used. But we have
to use peripheral clock since it has a higher frequency to support eMMC
HS200 mode and SD UHS-I mode. This patch is to add peripheral clock support
and use it instead of platform clock if it's declared in eSDHC dts node.
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-esdhc.h

@@ -54,6 +54,7 @@
 
 /* Control Register for DMA transfer */
 #define ESDHC_DMA_SYSCTL		0x40c
+#define ESDHC_PERIPHERAL_CLK_SEL	0x00080000
 #define ESDHC_DMA_SNOOP			0x00000040
 
 #endif /* _DRIVERS_MMC_SDHCI_ESDHC_H */

drivers/mmc/host/sdhci-of-esdhc.c

@@ -19,6 +19,8 @@
 #include <linux/delay.h>
 #include <linux/module.h>
 #include <linux/sys_soc.h>
+#include <linux/clk.h>
+#include <linux/ktime.h>
 #include <linux/mmc/host.h>
 #include "sdhci-pltfm.h"
 #include "sdhci-esdhc.h"
@@ -30,6 +32,7 @@ struct sdhci_esdhc {
 	u8 vendor_ver;
 	u8 spec_ver;
 	bool quirk_incorrect_hostver;
+	unsigned int peripheral_clock;
 };
 
 /**
@@ -414,15 +417,25 @@ static int esdhc_of_enable_dma(struct sdhci_host *host)
 static unsigned int esdhc_of_get_max_clock(struct sdhci_host *host)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_esdhc *esdhc = sdhci_pltfm_priv(pltfm_host);
 
-	return pltfm_host->clock;
+	if (esdhc->peripheral_clock)
+		return esdhc->peripheral_clock;
+	else
+		return pltfm_host->clock;
 }
 
 static unsigned int esdhc_of_get_min_clock(struct sdhci_host *host)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_esdhc *esdhc = sdhci_pltfm_priv(pltfm_host);
+	unsigned int clock;
 
-	return pltfm_host->clock / 256 / 16;
+	if (esdhc->peripheral_clock)
+		clock = esdhc->peripheral_clock;
+	else
+		clock = pltfm_host->clock;
+	return clock / 256 / 16;
 }
 
 static void esdhc_of_set_clock(struct sdhci_host *host, unsigned int clock)
@@ -512,6 +525,33 @@ static void esdhc_pltfm_set_bus_width(struct sdhci_host *host, int width)
 	sdhci_writel(host, ctrl, ESDHC_PROCTL);
 }
 
+static void esdhc_clock_enable(struct sdhci_host *host, bool enable)
+{
+	u32 val;
+	ktime_t timeout;
+
+	val = sdhci_readl(host, ESDHC_SYSTEM_CONTROL);
+
+	if (enable)
+		val |= ESDHC_CLOCK_SDCLKEN;
+	else
+		val &= ~ESDHC_CLOCK_SDCLKEN;
+
+	sdhci_writel(host, val, ESDHC_SYSTEM_CONTROL);
+
+	/* Wait max 20 ms */
+	timeout = ktime_add_ms(ktime_get(), 20);
+	val = ESDHC_CLOCK_STABLE;
+	while (!(sdhci_readl(host, ESDHC_PRSSTAT) & val)) {
+		if (ktime_after(ktime_get(), timeout)) {
+			pr_err("%s: Internal clock never stabilised.\n",
+				mmc_hostname(host->mmc));
+			break;
+		}
+		udelay(10);
+	}
+}
+
 static void esdhc_reset(struct sdhci_host *host, u8 mask)
 {
 	sdhci_reset(host, mask);
@@ -613,6 +653,9 @@ static void esdhc_init(struct platform_device *pdev, struct sdhci_host *host)
 {
 	struct sdhci_pltfm_host *pltfm_host;
 	struct sdhci_esdhc *esdhc;
+	struct device_node *np;
+	struct clk *clk;
+	u32 val;
 	u16 host_ver;
 
 	pltfm_host = sdhci_priv(host);
@@ -626,6 +669,32 @@ static void esdhc_init(struct platform_device *pdev, struct sdhci_host *host)
 		esdhc->quirk_incorrect_hostver = true;
 	else
 		esdhc->quirk_incorrect_hostver = false;
+
+	np = pdev->dev.of_node;
+	clk = of_clk_get(np, 0);
+	if (!IS_ERR(clk)) {
+		/*
+		 * esdhc->peripheral_clock would be assigned with a value
+		 * which is eSDHC base clock when use periperal clock.
+		 * For ls1046a, the clock value got by common clk API is
+		 * peripheral clock while the eSDHC base clock is 1/2
+		 * peripheral clock.
+		 */
+		if (of_device_is_compatible(np, "fsl,ls1046a-esdhc"))
+			esdhc->peripheral_clock = clk_get_rate(clk) / 2;
+		else
+			esdhc->peripheral_clock = clk_get_rate(clk);
+
+		clk_put(clk);
+	}
+
+	if (esdhc->peripheral_clock) {
+		esdhc_clock_enable(host, false);
+		val = sdhci_readl(host, ESDHC_DMA_SYSCTL);
+		val |= ESDHC_PERIPHERAL_CLK_SEL;
+		sdhci_writel(host, val, ESDHC_DMA_SYSCTL);
+		esdhc_clock_enable(host, true);
+	}
 }
 
 static int sdhci_esdhc_probe(struct platform_device *pdev)