[PATCH V6 16/24] mmc: sdhci-uhs2: add clock operations

[Victor Shih]

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>
Signed-off-by: Victor Shih <victor.shih@xxxxxxxxxxxxxxxxxxx>
---
 drivers/mmc/host/sdhci-uhs2.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
index 52587025d5e3..c7e411fa0a6e 100644
--- a/drivers/mmc/host/sdhci-uhs2.c
+++ b/drivers/mmc/host/sdhci-uhs2.c
@@ -14,6 +14,7 @@
 #include <linux/module.h>
 #include <linux/iopoll.h>
 #include <linux/bitfield.h>
+#include <linux/ktime.h>
 
 #include "sdhci.h"
 #include "sdhci-uhs2.h"
@@ -329,6 +330,37 @@ int sdhci_uhs2_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 	return 0;
 }
 
+static int 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);
+
+	return 0;
+}
+
+static int sdhci_uhs2_enable_clk(struct mmc_host *mmc)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	u16 clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+	u32 val;
+	/* 20ms */
+	int timeout_us = 20000;
+
+	clk |= SDHCI_CLOCK_CARD_EN;
+	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+
+	if (read_poll_timeout_atomic(sdhci_readw, val, (val & SDHCI_CLOCK_INT_STABLE),
+				     10, timeout_us, true, host, SDHCI_CLOCK_CONTROL)) {
+		pr_err("%s: Internal clock never stabilised.\n", mmc_hostname(host->mmc));
+		sdhci_dumpregs(host);
+		return 1;
+	}
+	return 0;
+}
+
 /*****************************************************************************\
  *                                                                           *
  * Driver init/exit                                                          *
-- 
2.25.1