[PATCH] mmc: sdhci-of-arasan: Add support for dynamic configuration

[Sai Krishna Potthuri]

Add dynamic configuration support for Xilinx ZynqMP which takes care of
configuring the SD secure space configuration registers using EEMI APIs,
performing SD reset assert and deassert.
High level sequence:
- Check for the PM dynamic configuration support, if no error proceed with
SD dynamic configurations(next steps) otherwise skip the dynamic
configuration.
- Put the SD Controller in reset.
- Configure SD Fixed configurations.
- Configure the SD Slot Type.
- Configure the BASE_CLOCK.
- Configure the 8-bit support.
- Bring the SD Controller out of reset.
- Wait for 1msec delay.

Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@xxxxxxx>
---
 drivers/mmc/host/sdhci-of-arasan.c | 69 ++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)

diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
index 3997cad1f793..f051f3802aff 100644
--- a/drivers/mmc/host/sdhci-of-arasan.c
+++ b/drivers/mmc/host/sdhci-of-arasan.c
@@ -21,6 +21,7 @@
 #include <linux/of_device.h>
 #include <linux/phy/phy.h>
 #include <linux/regmap.h>
+#include <linux/reset.h>
 #include <linux/of.h>
 #include <linux/firmware/xlnx-zynqmp.h>
 
@@ -1521,6 +1522,65 @@ static int sdhci_arasan_register_sdclk(struct sdhci_arasan_data *sdhci_arasan,
 	return 0;
 }
 
+static int sdhci_zynqmp_set_dynamic_config(struct device *dev,
+					   struct sdhci_arasan_data *sdhci_arasan)
+{
+	struct sdhci_host *host = sdhci_arasan->host;
+	struct clk_hw *hw = &sdhci_arasan->clk_data.sdcardclk_hw;
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	const char *clk_name = clk_hw_get_name(hw);
+	u32 mhz, node_id = !strcmp(clk_name, "clk_out_sd0") ? NODE_SD_0 : NODE_SD_1;
+	struct reset_control *rstc;
+	int ret;
+
+	/* Obtain SDHC reset control */
+	rstc = devm_reset_control_get_optional_exclusive(dev, NULL);
+	if (IS_ERR(rstc)) {
+		dev_err(dev, "Cannot get SDHC reset.\n");
+		return PTR_ERR(rstc);
+	}
+
+	ret = reset_control_assert(rstc);
+	if (ret)
+		return ret;
+
+	ret = zynqmp_pm_set_sd_config(node_id, SD_CONFIG_FIXED, 0);
+	if (ret)
+		return ret;
+
+	ret = zynqmp_pm_set_sd_config(node_id, SD_CONFIG_EMMC_SEL,
+				      !!(host->mmc->caps & MMC_CAP_NONREMOVABLE));
+	if (ret)
+		return ret;
+
+	mhz = DIV_ROUND_CLOSEST_ULL(clk_get_rate(pltfm_host->clk), 1000000);
+	if (mhz > 100 && mhz <= 200)
+		mhz = 200;
+	else if (mhz > 50 && mhz <= 100)
+		mhz = 100;
+	else if (mhz > 25 && mhz <= 50)
+		mhz = 50;
+	else
+		mhz = 25;
+
+	ret = zynqmp_pm_set_sd_config(node_id, SD_CONFIG_BASECLK, mhz);
+	if (ret)
+		return ret;
+
+	ret = zynqmp_pm_set_sd_config(node_id, SD_CONFIG_8BIT,
+				      !!(host->mmc->caps & MMC_CAP_8_BIT_DATA));
+	if (ret)
+		return ret;
+
+	ret = reset_control_deassert(rstc);
+	if (ret)
+		return ret;
+
+	usleep_range(1000, 1500);
+
+	return 0;
+}
+
 static int sdhci_arasan_add_host(struct sdhci_arasan_data *sdhci_arasan)
 {
 	struct sdhci_host *host = sdhci_arasan->host;
@@ -1685,6 +1745,15 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
 		goto unreg_clk;
 	}
 
+	if (of_device_is_compatible(np, "xlnx,zynqmp-8.9a")) {
+		ret = zynqmp_pm_is_function_supported(PM_IOCTL, IOCTL_SET_SD_CONFIG);
+		if (!ret) {
+			ret = sdhci_zynqmp_set_dynamic_config(dev, sdhci_arasan);
+			if (ret)
+				goto unreg_clk;
+		}
+	}
+
 	sdhci_arasan->phy = ERR_PTR(-ENODEV);
 	if (of_device_is_compatible(np, "arasan,sdhci-5.1")) {
 		sdhci_arasan->phy = devm_phy_get(dev, "phy_arasan");
-- 
2.17.1