[PATCH v3 1/2] mmc: sdhci: fix abort due to missing runtime PM

[Stefan Agner]

When using i.MX ESDHC driver, while entering suspend while the device
is in runtime PM, the sdhci_(suspend|resume)_host function are called
with disabled clocks. Since this functions access the SDHC host
registers, this leads to an external abort on Vybrid SoC:

[   37.772967] Unhandled fault: imprecise external abort (0x1c06) at 0x76f5f000
[   37.780304] Internal error: : 1c06 [#1] ARM
[   37.784670] Modules linked in:
[   37.787908] CPU: 0 PID: 428 Comm: sh Not tainted 3.18.0-rc5-00119-geefd097-dirty #1540
[   37.796142] task: 8e246c00 ti: 8ca6c000 task.ti: 8ca6c000
[   37.801785] PC is at esdhc_writel_le+0x40/0xec
[   37.806431] LR is at sdhci_set_card_detection+0xe0/0xe4
[   37.811877] pc : [<803f0584>]    lr : [<803eaaa0>]    psr: 400f0013
[   37.811877] sp : 8ca6dd28  ip : 00000001  fp : 8ca6dd3c
[   37.823766] r10: 807a233c  r9 : 00000000  r8 : 8e8b7210
[   37.829194] r7 : 802d8a08  r6 : 8082e928  r5 : 00000000  r4 : 00000002
[   37.835974] r3 : 8ea34e90  r2 : 00000038  r1 : 00000000  r0 : 8ea32ac0
...

Clocks need to be enabled to access the registers. Fix the issue by
add runtime PM enabled pltfm implementation of suspend/resume which
take care of clocks by using the runtime PM API properly.

Signed-off-by: Stefan Agner <stefan at agner.ch>
---
Changes since v2:
- Implement a generic pltfm suspend/resume function instead of a local
  function in sdhci-esdhc-imx.c
- Convert sdhci-pxav3 to use the runtime PM enabled pltfm suspend/resume
  function too

 drivers/mmc/host/sdhci-esdhc-imx.c |  2 +-
 drivers/mmc/host/sdhci-pltfm.c     | 36 ++++++++++++++++++++++++++++++++++++
 drivers/mmc/host/sdhci-pltfm.h     |  2 ++
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index 82f512d..7b7b3a3 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -1132,7 +1132,7 @@ static int sdhci_esdhc_runtime_resume(struct device *dev)
 #endif
 
 static const struct dev_pm_ops sdhci_esdhc_pmops = {
-	SET_SYSTEM_SLEEP_PM_OPS(sdhci_pltfm_suspend, sdhci_pltfm_resume)
+	SET_SYSTEM_SLEEP_PM_OPS(sdhci_pltfm_rpm_suspend, sdhci_pltfm_rpm_resume)
 	SET_RUNTIME_PM_OPS(sdhci_esdhc_runtime_suspend,
 				sdhci_esdhc_runtime_resume, NULL)
 };
diff --git a/drivers/mmc/host/sdhci-pltfm.c b/drivers/mmc/host/sdhci-pltfm.c
index a207f5a..38c03cd 100644
--- a/drivers/mmc/host/sdhci-pltfm.c
+++ b/drivers/mmc/host/sdhci-pltfm.c
@@ -31,6 +31,7 @@
 #include <linux/err.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/pm_runtime.h>
 #ifdef CONFIG_PPC
 #include <asm/machdep.h>
 #endif
@@ -256,6 +257,41 @@ const struct dev_pm_ops sdhci_pltfm_pmops = {
 	.resume		= sdhci_pltfm_resume,
 };
 EXPORT_SYMBOL_GPL(sdhci_pltfm_pmops);
+
+int sdhci_pltfm_rpm_suspend(struct device *dev)
+{
+	int ret;
+	struct sdhci_host *host = dev_get_drvdata(dev);
+
+	pm_runtime_get_sync(dev);
+	ret = sdhci_suspend_host(host);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
+	if (ret)
+		return ret;
+
+	return pm_runtime_force_suspend(dev);
+}
+EXPORT_SYMBOL_GPL(sdhci_pltfm_rpm_suspend);
+
+int sdhci_pltfm_rpm_resume(struct device *dev)
+{
+	int ret;
+	struct sdhci_host *host = dev_get_drvdata(dev);
+
+	ret = pm_runtime_force_resume(dev);
+
+	if (ret)
+		return ret;
+
+	pm_runtime_get_sync(dev);
+	ret = sdhci_resume_host(host);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sdhci_pltfm_rpm_resume);
 #endif	/* CONFIG_PM */
 
 static int __init sdhci_pltfm_drv_init(void)
diff --git a/drivers/mmc/host/sdhci-pltfm.h b/drivers/mmc/host/sdhci-pltfm.h
index 04bc248..ac5f6ea 100644
--- a/drivers/mmc/host/sdhci-pltfm.h
+++ b/drivers/mmc/host/sdhci-pltfm.h
@@ -114,6 +114,8 @@ static inline void *sdhci_pltfm_priv(struct sdhci_pltfm_host *host)
 extern int sdhci_pltfm_suspend(struct device *dev);
 extern int sdhci_pltfm_resume(struct device *dev);
 extern const struct dev_pm_ops sdhci_pltfm_pmops;
+extern int sdhci_pltfm_rpm_suspend(struct device *dev);
+extern int sdhci_pltfm_rpm_resume(struct device *dev);
 #define SDHCI_PLTFM_PMOPS (&sdhci_pltfm_pmops)
 #else
 #define SDHCI_PLTFM_PMOPS NULL
-- 
2.4.1