[PATCH v4 2/4] mmc: dw_mmc: Add exynos resume_noirq 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.  This has been seen to happen on exynos5420
silicon despite the fact that we haven't enabled any wakeup events due
to a silicon errata.  It is safe to do on all exynos variants.

Signed-off-by: Doug Anderson <dianders at chromium.org>
---
Changes in v4:
- Take Seungwon's suggestion and don't add any dw_mmc-pltfm code.

Changes in v3:
- Add freeze/thaw and poweroff/restore noirq entries.

Changes in v2:
- Use suspend_noirq as per James Hogan.

 drivers/mmc/host/dw_mmc-exynos.c | 51 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 49 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c
index 866edef..0c1f192 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 EXYNOS4210_FIXED_CIU_CLK_DIV	2
 #define EXYNOS4412_FIXED_CIU_CLK_DIV	4
@@ -100,6 +101,30 @@ static int dw_mci_exynos_setup_clock(struct dw_mci *host)
 	return 0;
 }
 
+/**
+ * dw_mci_exynos_resume_noirq - Exynos-specific resume code
+ *
+ * On exynos5420 there is a silicon errata that will sometimes 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.
+ *
+ * We run this code on all exynos variants because it doesn't hurt and the bug
+ * may be more widespread than just exynos5420.
+ */
+
+static int dw_mci_exynos_resume_noirq(struct device *dev)
+{
+	struct dw_mci *host = dev_get_drvdata(dev);
+	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)
 {
 	/*
@@ -187,17 +212,39 @@ static int dw_mci_exynos_probe(struct platform_device *pdev)
 	return dw_mci_pltfm_register(pdev, drv_data);
 }
 
+static struct dev_pm_ops dw_mci_exynos_pmops;
+
 static struct platform_driver dw_mci_exynos_pltfm_driver = {
 	.probe		= dw_mci_exynos_probe,
 	.remove		= __exit_p(dw_mci_pltfm_remove),
 	.driver		= {
 		.name		= "dwmmc_exynos",
 		.of_match_table	= dw_mci_exynos_match,
-		.pm		= &dw_mci_pltfm_pmops,
+		.pm		= &dw_mci_exynos_pmops,
 	},
 };
 
-module_platform_driver(dw_mci_exynos_pltfm_driver);
+static int __init dw_mci_exynos_init(void)
+{
+	/* Add a "noirq" resume to platform pmops */
+	memcpy(&dw_mci_exynos_pmops, &dw_mci_pltfm_pmops,
+	       sizeof(dw_mci_exynos_pmops));
+	WARN_ON(dw_mci_exynos_pmops.resume_noirq ||
+		dw_mci_exynos_pmops.thaw_noirq ||
+		dw_mci_exynos_pmops.restore_noirq);
+	dw_mci_exynos_pmops.resume_noirq = dw_mci_exynos_resume_noirq;
+	dw_mci_exynos_pmops.thaw_noirq = dw_mci_exynos_resume_noirq;
+	dw_mci_exynos_pmops.restore_noirq = dw_mci_exynos_resume_noirq;
+
+	return platform_driver_register(&dw_mci_exynos_pltfm_driver);
+}
+module_init(dw_mci_exynos_init);
+
+static void __exit dw_mci_exynos_exit(void)
+{
+	platform_driver_unregister(&dw_mci_exynos_pltfm_driver);
+}
+module_exit(dw_mci_exynos_exit);
 
 MODULE_DESCRIPTION("Samsung Specific DW-MSHC Driver Extension");
 MODULE_AUTHOR("Thomas Abraham <thomas.ab at samsung.com");
-- 
1.8.3