[PATCH v23 07/14] mmc: renesas_sdhi: Add TMIO_MMC_INTERNAL_DIVIDER flag

From: Biju Das <[email protected]>

RZ/G3L has a fixed internal /2 clock divider active in all bus
timing modes except HS400, where the divider is bypassed. Add a
TMIO_MMC_INTERNAL_DIVIDER flag to mark controllers with this
divider.

Add renesas_sdhi_clk_get_rate() to fold the /2 division into the
reported clock rate when the flag is set, and use it in
renesas_sdhi_clk_update() in place of clk_get_rate(). HS400 is not
yet supported in software for this SoC. Adjust clkh_shift for the
internal divider case.

No existing platform sets this flag, so this is infrastructure only,
with no functional change for current SoCs.

Signed-off-by: Biju Das <[email protected]>
---
v22->v23:
 * Updated commit description.
v21->v22:
 * Updated commit description.
 * Added renesas_sdhi_is_internal_divider_enabled() and
   renesas_sdhi_clk_get_rate() to simplify the clock rate logic.
v20->v21:
 * No change.
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 | 31 +++++++++++++++++++++++++---
 include/linux/platform_data/tmio.h   |  3 +++
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
index a0922bc9d4a5..655f0920c015 100644
--- a/drivers/mmc/host/renesas_sdhi_core.c
+++ b/drivers/mmc/host/renesas_sdhi_core.c
@@ -125,6 +125,27 @@ static int renesas_sdhi_clk_enable(struct tmio_mmc_host *host)
 	return 0;
 }
 
+static bool renesas_sdhi_is_internal_divider_enabled(struct tmio_mmc_host *host)
+{
+	bool enable = false;
+
+	if (host->pdata->flags & TMIO_MMC_INTERNAL_DIVIDER)
+		enable = true;
+
+	return enable;
+}
+
+static unsigned int renesas_sdhi_clk_get_rate(struct tmio_mmc_host *host,
+					      struct clk *clk)
+{
+	unsigned int freq = clk_get_rate(clk);
+
+	if (renesas_sdhi_is_internal_divider_enabled(host))
+		freq /= 2;
+
+	return freq;
+}
+
 static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host,
 					    unsigned int wanted_clock)
 {
@@ -141,7 +162,7 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host,
 	 * clock during tuning, so we don't change the external clock setup.
 	 */
 	if (!(host->pdata->flags & TMIO_MMC_MIN_RCAR2) || mmc_doing_tune(host->mmc))
-		return clk_get_rate(priv->clk);
+		return renesas_sdhi_clk_get_rate(host, priv->clk);
 
 	if (priv->clkh) {
 		/* HS400 with 4TAP needs different clock settings */
@@ -184,10 +205,14 @@ 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);
+	}
 
-	return clk_get_rate(priv->clk);
+	return renesas_sdhi_clk_get_rate(host, priv->clk);
 }
 
 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 abf4134a8bd8..8d435f7690a5 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