[PATCH v21 10/12] mmc: renesas_sdhi: Save and restore IOVS across suspend/resume

[Biju]

From: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>

The SD_STATUS register, specifically the IOVS (I/O Voltage Switch) bit, is
not automatically restored after a suspend/resume cycle, causing the
regulator to report an incorrect voltage on resume.

Fix this by caching the CTL_SD_STATUS register value in the renesas_sdhi
private struct at suspend time and writing it back during resume. The
save/restore is only performed when a regulator device (rdev) is present,
as the IOVS bit is only relevant in that context.

Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
---
v20->v21:
 * No change.
v19->v20:
 * Updated resume() with scoped PM runtime call.
v18->v19:
 * Updated suspend/resume with scoped runtime calls in suspend.
v17->v18:
 * No change.
v1->v17:
 * No change.
---
 drivers/mmc/host/renesas_sdhi.h      |  2 ++
 drivers/mmc/host/renesas_sdhi_core.c | 26 +++++++++++++++++++++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/renesas_sdhi.h b/drivers/mmc/host/renesas_sdhi.h
index a085a4cb2e38..e2c26917b884 100644
--- a/drivers/mmc/host/renesas_sdhi.h
+++ b/drivers/mmc/host/renesas_sdhi.h
@@ -105,6 +105,8 @@ struct renesas_sdhi {
 	struct reset_control *rstc_axim;
 	struct tmio_mmc_host *host;
 	struct regulator_dev *rdev;
+
+	u32 cache_sd_status;
 };
 
 #define host_to_priv(host) \
diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
index e3ffe790cb21..d5d8afde9bfc 100644
--- a/drivers/mmc/host/renesas_sdhi_core.c
+++ b/drivers/mmc/host/renesas_sdhi_core.c
@@ -1406,6 +1406,15 @@ int renesas_sdhi_suspend(struct device *dev)
 	};
 	int ret;
 
+	if (priv->rdev) {
+		PM_RUNTIME_ACQUIRE_IF_ENABLED(dev, pm);
+		ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+		if (ret < 0)
+			return ret;
+
+		priv->cache_sd_status = sd_ctrl_read32(host, CTL_SD_STATUS);
+	}
+
 	ret = pm_runtime_force_suspend(dev);
 	if (ret)
 		return ret;
@@ -1435,8 +1444,23 @@ int renesas_sdhi_resume(struct device *dev)
 
 	ret = pm_runtime_force_resume(dev);
 	if (ret)
-		reset_control_bulk_assert(ARRAY_SIZE(resets), resets);
+		goto err_assert;
+
+	if (priv->rdev) {
+		PM_RUNTIME_ACQUIRE_IF_ENABLED(dev, pm);
+		ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+		if (ret < 0)
+			goto err_pm;
+
+		sd_ctrl_write32(host, CTL_SD_STATUS, priv->cache_sd_status);
+	}
+
+	return 0;
 
+err_pm:
+	pm_runtime_force_suspend(dev);
+err_assert:
+	reset_control_bulk_assert(ARRAY_SIZE(resets), resets);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(renesas_sdhi_resume);
-- 
2.43.0