[PATCH 3/5] mmc: dw_mmc: Add exynos resume callback to clear WAKEUP_INT

[Doug Anderson]

If the WAKEUP_INT is asserted at wakeup and not cleared, we'll end up
looping around forever.

Signed-off-by: Doug Anderson <dianders at chromium.org>
---
 drivers/mmc/host/dw_mmc-exynos.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c
index f013e7e..84d3b78 100644
--- a/drivers/mmc/host/dw_mmc-exynos.c
+++ b/drivers/mmc/host/dw_mmc-exynos.c
@@ -30,6 +30,7 @@
 #define SDMMC_CLKSEL_TIMING(x, y, z)	(SDMMC_CLKSEL_CCLK_SAMPLE(x) |	\
 					SDMMC_CLKSEL_CCLK_DRIVE(y) |	\
 					SDMMC_CLKSEL_CCLK_DIVIDER(z))
+#define SDMMC_CLKSEL_WAKEUP_INT		BIT(11)
 
 #define SDMMC_CMD_USE_HOLD_REG		BIT(29)
 
@@ -102,6 +103,27 @@ static int dw_mci_exynos_setup_clock(struct dw_mci *host)
 	return 0;
 }
 
+/**
+ * dw_mci_exynos_resume - Exynos-specific resume code
+ *
+ * We have seen cases (at least on the exynos5420) where turning off the INT
+ * power rail during suspend will leave the WAKEUP_INT bit in the CLKSEL
+ * register asserted.  This bit is 1 to indicate that it fired and we can
+ * clear it by writing a 1 back.  Clear it to prevent interrupts from going off
+ * constantly.
+ */
+
+static int dw_mci_exynos_resume(struct dw_mci *host)
+{
+	u32 clksel;
+
+	clksel = mci_readl(host, CLKSEL);
+	if (clksel & SDMMC_CLKSEL_WAKEUP_INT)
+		mci_writel(host, CLKSEL, clksel);
+
+	return 0;
+}
+
 static void dw_mci_exynos_prepare_command(struct dw_mci *host, u32 *cmdr)
 {
 	/*
@@ -165,6 +187,7 @@ static const struct dw_mci_drv_data exynos_drv_data = {
 	.caps			= exynos_dwmmc_caps,
 	.init			= dw_mci_exynos_priv_init,
 	.setup_clock		= dw_mci_exynos_setup_clock,
+	.resume			= dw_mci_exynos_resume,
 	.prepare_command	= dw_mci_exynos_prepare_command,
 	.set_ios		= dw_mci_exynos_set_ios,
 	.parse_dt		= dw_mci_exynos_parse_dt,
-- 
1.8.3