[RFC PATCH v3.1 18/27] mmc: sdhci-uhs2: add clock operations

[AKASHI Takahiro]

This is a sdhci version of mmc's uhs2_[enable|disable]_clk operations.

Signed-off-by: Ben Chuang <ben.chuang@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
---
 drivers/mmc/host/sdhci-uhs2.c | 41 +++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
index 994dff967e85..55362ace1857 100644
--- a/drivers/mmc/host/sdhci-uhs2.c
+++ b/drivers/mmc/host/sdhci-uhs2.c
@@ -11,6 +11,7 @@
  */
 
 #include <linux/delay.h>
+#include <linux/ktime.h>
 #include <linux/module.h>
 
 #include "sdhci.h"
@@ -385,6 +386,42 @@ void sdhci_uhs2_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 	__sdhci_uhs2_set_ios(mmc, ios);
 }
 
+static void sdhci_uhs2_disable_clk(struct mmc_host *mmc)
+{
+        struct sdhci_host *host = mmc_priv(mmc);
+	u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+
+	clk &= ~SDHCI_CLOCK_CARD_EN;
+	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+}
+
+static void sdhci_uhs2_enable_clk(struct mmc_host *mmc)
+{
+        struct sdhci_host *host = mmc_priv(mmc);
+	u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+	ktime_t timeout;
+
+	clk |= SDHCI_CLOCK_CARD_EN;
+	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+
+	/* Wait max 20 ms */
+	timeout = ktime_add_ms(ktime_get(), 20);
+	while (1) {
+		bool timedout = ktime_after(ktime_get(), timeout);
+
+		clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+		if (clk & SDHCI_CLOCK_INT_STABLE)
+			break;
+		if (timedout) {
+			pr_err("%s: Internal clock never stabilised.\n",
+			       mmc_hostname(host->mmc));
+			sdhci_dumpregs(host);
+			return;
+		}
+		udelay(10);
+	}
+}
+
 /*****************************************************************************\
  *                                                                           *
  * Driver init/exit                                                          *
@@ -556,6 +593,10 @@ static int sdhci_uhs2_host_ops_init(struct sdhci_host *host)
 
 	if (!host->mmc_host_ops.uhs2_detect_init)
 		host->mmc_host_ops.uhs2_detect_init = sdhci_uhs2_do_detect_init;
+	if (!host->mmc_host_ops.uhs2_disable_clk)
+		host->mmc_host_ops.uhs2_disable_clk = sdhci_uhs2_disable_clk;
+	if (!host->mmc_host_ops.uhs2_enable_clk)
+		host->mmc_host_ops.uhs2_enable_clk = sdhci_uhs2_enable_clk;
 
 	return 0;
 }
-- 
2.28.0