[PATCH 12/17] 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>
---
 drivers/mmc/host/renesas_sdhi.h      | 1 +
 drivers/mmc/host/renesas_sdhi_core.c | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/drivers/mmc/host/renesas_sdhi.h b/drivers/mmc/host/renesas_sdhi.h
index 6c024e7f69e1..10f634349da9 100644
--- a/drivers/mmc/host/renesas_sdhi.h
+++ b/drivers/mmc/host/renesas_sdhi.h
@@ -117,6 +117,7 @@ struct renesas_sdhi {
 	struct regulator_dev *rdev;
 
 	unsigned int divider;
+	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 ee1b1f70c9e3..974acdf110d3 100644
--- a/drivers/mmc/host/renesas_sdhi_core.c
+++ b/drivers/mmc/host/renesas_sdhi_core.c
@@ -1379,6 +1379,9 @@ int renesas_sdhi_suspend(struct device *dev)
 	};
 	int ret;
 
+	if (priv->rdev)
+		priv->cache_sd_status = sd_ctrl_read32(host, CTL_SD_STATUS);
+
 	ret = pm_runtime_force_suspend(dev);
 	if (ret)
 		return ret;
@@ -1410,6 +1413,9 @@ int renesas_sdhi_resume(struct device *dev)
 	if (ret)
 		reset_control_bulk_assert(ARRAY_SIZE(resets), resets);
 
+	if (priv->rdev)
+		sd_ctrl_write32(host, CTL_SD_STATUS, priv->cache_sd_status);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(renesas_sdhi_resume);
-- 
2.43.0