[U-Boot] [PATCH v4 2/3] mmc: dw_mmc: Support bypass mode with the get_mmc_clk() method

[Simon Glass]

Some SoCs want to adjust the input clock to the DWMMC block as a way of
controlling the MMC bus clock. Update the get_mmc_clk() method to support
this.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

Changes in v4:
- Update commit message to indicate this patch is for the dw_mmc driver

 drivers/mmc/dw_mmc.c        |  2 +-
 drivers/mmc/exynos_dw_mmc.c |  2 +-
 include/dwmmc.h             | 16 +++++++++++++++-
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c
index 8f28d7e..a034c3f 100644
--- a/drivers/mmc/dw_mmc.c
+++ b/drivers/mmc/dw_mmc.c
@@ -248,7 +248,7 @@ static int dwmci_setup_bus(struct dwmci_host *host, u32 freq)
 	 * host->bus_hz should be set by user.
 	 */
 	if (host->get_mmc_clk)
-		sclk = host->get_mmc_clk(host);
+		sclk = host->get_mmc_clk(host, freq);
 	else if (host->bus_hz)
 		sclk = host->bus_hz;
 	else {
diff --git a/drivers/mmc/exynos_dw_mmc.c b/drivers/mmc/exynos_dw_mmc.c
index e083745..3f702ba 100644
--- a/drivers/mmc/exynos_dw_mmc.c
+++ b/drivers/mmc/exynos_dw_mmc.c
@@ -39,7 +39,7 @@ static void exynos_dwmci_clksel(struct dwmci_host *host)
 	dwmci_writel(host, DWMCI_CLKSEL, priv->sdr_timing);
 }
 
-unsigned int exynos_dwmci_get_clk(struct dwmci_host *host)
+unsigned int exynos_dwmci_get_clk(struct dwmci_host *host, uint freq)
 {
 	unsigned long sclk;
 	int8_t clk_div;
diff --git a/include/dwmmc.h b/include/dwmmc.h
index 7a7555a..25cf42c 100644
--- a/include/dwmmc.h
+++ b/include/dwmmc.h
@@ -163,7 +163,21 @@ struct dwmci_host {
 
 	void (*clksel)(struct dwmci_host *host);
 	void (*board_init)(struct dwmci_host *host);
-	unsigned int (*get_mmc_clk)(struct dwmci_host *host);
+
+	/**
+	 * Get / set a particular MMC clock frequency
+	 *
+	 * This is used to request the current clock frequency of the clock
+	 * that drives the DWMMC peripheral. The caller will then use this
+	 * information to work out the divider it needs to achieve the
+	 * required MMC bus clock frequency. If you want to handle the
+	 * clock external to DWMMC, use @freq to select the frequency and
+	 * return that value too. Then DWMMC will put itself in bypass mode.
+	 *
+	 * @host:	DWMMC host
+	 * @freq:	Frequency the host is trying to achieve
+	 */
+	unsigned int (*get_mmc_clk)(struct dwmci_host *host, uint freq);
 
 	struct mmc_config cfg;
 };
-- 
2.5.0.rc2.392.g76e840b