[PATCH v20 06/12] mmc: renesas_sdhi: Add TMIO_MMC_INTERNAL_DIVIDER flag

From: Biju Das <[email protected]>

The RZ/G3L SoC integrates a fixed internal /2 clock divider that is
active across all bus timing modes except for HS400.

Introduce a new feature flag, TMIO_MMC_INTERNAL_DIVIDER (bit 14),
inside the TMIO platform headers to mark hardware profiles carrying
this integrated divider scheme.

Modify renesas_sdhi_clk_update() to inspect this flag when setting
and reporting clock rates. When the flag is set, the function
bypasses the standard base division logic via a modified clkh_shift
adjustment, then factors the physical /2 division step directly into
the final calculated frequency value, provided the current bus
timing is not MMC_TIMING_MMC_HS400.

As no existing platforms configure this newly introduced bitmask
flag, this patch delivers the underlying operational infrastructure
with zero functional impact on existing supported chip variants.

Signed-off-by: Biju Das <[email protected]>
---
v19->v20:
 * No change.
v18->v19:
 * Updated commit description.
 * Dropped divider variable from struct renesas_sdhi.
 * Updated renesas_sdhi_clk_update() to return rate for HS400mode
   and nonHS400mode(uses 1/2 internal divider).
v18:
 * New patch using flag.
---
 drivers/mmc/host/renesas_sdhi_core.c | 13 +++++++++++--
 include/linux/platform_data/tmio.h   |  3 +++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
index 569009ff4c52..d3f6d459fdc7 100644
--- a/drivers/mmc/host/renesas_sdhi_core.c
+++ b/drivers/mmc/host/renesas_sdhi_core.c
@@ -184,10 +184,19 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host,
 
 	clk_set_rate(ref_clk, best_freq);
 
-	if (priv->clkh)
+	if (priv->clkh) {
+		if (host->pdata->flags & TMIO_MMC_INTERNAL_DIVIDER)
+			clkh_shift = 1;
+
 		clk_set_rate(priv->clk, best_freq >> clkh_shift);
+	}
+
+	freq = clk_get_rate(priv->clk);
+	if ((host->pdata->flags & TMIO_MMC_INTERNAL_DIVIDER) &&
+	    host->mmc->ios.timing != MMC_TIMING_MMC_HS400)
+		freq /= 2;
 
-	return clk_get_rate(priv->clk);
+	return freq;
 }
 
 static void renesas_sdhi_set_clock(struct tmio_mmc_host *host,
diff --git a/include/linux/platform_data/tmio.h b/include/linux/platform_data/tmio.h
index 868a21842fa5..6c512e96e192 100644
--- a/include/linux/platform_data/tmio.h
+++ b/include/linux/platform_data/tmio.h
@@ -53,6 +53,9 @@
 /* Some controllers have tuning delay */
 #define TMIO_MMC_TUNING_DELAY		BIT(13)
 
+/* Some controllers have internal divider */
+#define TMIO_MMC_INTERNAL_DIVIDER	BIT(14)
+
 struct tmio_mmc_data {
 	void				*chan_priv_tx;
 	void				*chan_priv_rx;
-- 
2.43.0