[PATCH 3/3] mmc: msm_sdhci: Add DLL control hook to disable DLL below 100 MHz

[Loic Poulain]

From: Sumit Garg <sumit.garg at oss.qualcomm.com>

Introduce an SDHCI ops hook (config_dll) for MSM SDHCI and implement a
minimal DLL control routine that ensures the core DLL is disabled when
the bus clock is at or below 100 MHz. This approach mirrors the Linux
MSM SDHCI driver.

Signed-off-by: Sumit Garg <sumit.garg at oss.qualcomm.com>
Signed-off-by: Loic Poulain <loic.poulain at oss.qualcomm.com>
---
 drivers/mmc/msm_sdhci.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/mmc/msm_sdhci.c b/drivers/mmc/msm_sdhci.c
index ec003991928..38dc36a2194 100644
--- a/drivers/mmc/msm_sdhci.c
+++ b/drivers/mmc/msm_sdhci.c
@@ -36,6 +36,11 @@
 
 #define CORE_VENDOR_SPEC_POR_VAL 0xa9c
 
+#define CORE_DLL_PDN		BIT(29)
+#define CORE_DLL_RST		BIT(30)
+
+#define MHZ(X) ((X) * 1000000UL)
+
 struct msm_sdhc_plat {
 	struct mmc_config cfg;
 	struct mmc mmc;
@@ -51,6 +56,7 @@ struct msm_sdhc {
 struct msm_sdhc_variant_info {
 	bool mci_removed;
 
+	u32 core_dll_config;
 	u32 core_vendor_spec;
 	u32 core_vendor_spec_capabilities0;
 };
@@ -149,6 +155,34 @@ static int msm_sdc_mci_init(struct msm_sdhc *prv)
 	return 0;
 }
 
+static int msm_sdhci_config_dll(struct sdhci_host *host, u32 clock, bool enable)
+{
+	struct udevice *dev = mmc_to_dev(host->mmc);
+	const struct msm_sdhc_variant_info *var_info = (void *)dev_get_driver_data(dev);
+	u32 config;
+
+	if (enable && clock < MHZ(100)) {
+		/*
+		 * DLL is not required for clock <= 100MHz
+		 * Thus, make sure DLL is disabled when not required
+		 */
+		config = readl(host->ioaddr + var_info->core_dll_config);
+		config |= CORE_DLL_RST;
+		writel(config, host->ioaddr + var_info->core_dll_config);
+
+		config = readl(host->ioaddr + var_info->core_dll_config);
+		config |= CORE_DLL_PDN;
+		writel(config, host->ioaddr + var_info->core_dll_config);
+	}
+
+	return 0;
+}
+
+struct sdhci_ops msm_sdhci_ops = {
+	.config_dll = &msm_sdhci_config_dll,
+	.set_control_reg = &sdhci_set_control_reg,
+};
+
 static int msm_sdc_probe(struct udevice *dev)
 {
 	struct mmc_uclass_priv *upriv = dev_get_uclass_priv(dev);
@@ -223,6 +257,7 @@ static int msm_sdc_probe(struct udevice *dev)
 
 	host->mmc = &plat->mmc;
 	host->mmc->dev = dev;
+	host->ops = &msm_sdhci_ops;
 	ret = sdhci_setup_cfg(&plat->cfg, host, 0, 0);
 	if (ret)
 		return ret;
@@ -288,6 +323,7 @@ static int msm_sdc_bind(struct udevice *dev)
 static const struct msm_sdhc_variant_info msm_sdhc_mci_var = {
 	.mci_removed = false,
 
+	.core_dll_config = 0x100,
 	.core_vendor_spec = 0x10c,
 	.core_vendor_spec_capabilities0 = 0x11c,
 };
@@ -295,6 +331,7 @@ static const struct msm_sdhc_variant_info msm_sdhc_mci_var = {
 static const struct msm_sdhc_variant_info msm_sdhc_v5_var = {
 	.mci_removed = true,
 
+	.core_dll_config = 0x200,
 	.core_vendor_spec = 0x20c,
 	.core_vendor_spec_capabilities0 = 0x21c,
 };
-- 
2.34.1