[PATCH 2/2] mmc: sdhci-brcmstb: Add ability to increase max clock rate for 72116b0

[Kamal Dasu]

From: Al Cooper <alcooperx at gmail.com>

The 72116B0 has improved SDIO controllers that allow the max clock
rate to be increased from a max of 100MHz to a max of 150MHz. The
driver will need to get the clock and increase it's default rate
and override the caps register, that still indicates a max of 100MHz.
The new clock will be named "sdio_freq" in the DT node's "clock-names"
list. The driver will use a DT property, "clock-frequency", to
enable this functionality and will get the actual rate in MHz
from the property to allow various speeds to be requested.

Signed-off-by: Al Cooper <alcooperx at gmail.com>
Signed-off-by: Kamal Dasu <kdasu.kdev at gmail.com>
---
 drivers/mmc/host/sdhci-brcmstb.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/mmc/host/sdhci-brcmstb.c b/drivers/mmc/host/sdhci-brcmstb.c
index 8eb57de48e0c..a1ffdd3f1640 100644
--- a/drivers/mmc/host/sdhci-brcmstb.c
+++ b/drivers/mmc/host/sdhci-brcmstb.c
@@ -250,6 +250,9 @@ static int sdhci_brcmstb_probe(struct platform_device *pdev)
 	struct sdhci_pltfm_host *pltfm_host;
 	const struct of_device_id *match;
 	struct sdhci_brcmstb_priv *priv;
+	struct clk *master_clk;
+	u32 base_clock_hz = 0;
+	u32 actual_clock_mhz;
 	struct sdhci_host *host;
 	struct resource *iomem;
 	struct clk *clk;
@@ -330,6 +333,33 @@ static int sdhci_brcmstb_probe(struct platform_device *pdev)
 	if (match_priv->flags & BRCMSTB_MATCH_FLAGS_BROKEN_TIMEOUT)
 		host->quirks |= SDHCI_QUIRK_BROKEN_TIMEOUT_VAL;
 
+	/* Change the base clock frequency if the DT property exists */
+	if (device_property_read_u32(&pdev->dev, "max-frequency",
+				     &base_clock_hz) != 0)
+		goto add_host;
+
+	master_clk = devm_clk_get(&pdev->dev, "sdio_freq");
+	if (IS_ERR(master_clk)) {
+		dev_warn(&pdev->dev, "Clock for \"sdio_freq\" not found\n");
+		goto add_host;
+	} else {
+		res = clk_prepare_enable(master_clk);
+		if (res)
+			goto err;
+	}
+
+	/* set improved clock rate */
+	clk_set_rate(master_clk, base_clock_hz);
+	actual_clock_mhz = clk_get_rate(master_clk) / 1000000;
+
+	host->caps &= ~SDHCI_CLOCK_V3_BASE_MASK;
+	host->caps |= (actual_clock_mhz << SDHCI_CLOCK_BASE_SHIFT);
+	/* Disable presets because they are now incorrect */
+	host->quirks2 |= SDHCI_QUIRK2_PRESET_VALUE_BROKEN;
+	dev_dbg(&pdev->dev, "Base Clock Frequency changed to %dMHz\n",
+		actual_clock_mhz);
+
+add_host:
 	res = sdhci_brcmstb_add_host(host, priv);
 	if (res)
 		goto err;
-- 
2.17.1