scsi: ufs-qcom: Control ufs-ref-clk-supply from host node

UFS device requires a reference clock for
operating in HS (High-speed) gears. This device
reference clock is provided by the dedicated SoC pad
on QCOM platforms. This rail needs to be powered by
1.2v power pads.
Currently, that supply is being controlled
in the ufs phy driver. Phy driver doesn't have any
knowledge of the system-pm state. Hence, it can't
selectively toggle this supply.

Hence, move the control of this supply to ufs driver.
The host driver has the knowledge of system-pm state &
is better equipped to toggle this supply.

Change-Id: Ia19c6e7d9ffb856a01d31ab56ea97a7bb1affae6
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>

Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt

@@ -141,6 +141,9 @@ enabled and functional in the driver:
 - qcom,pm-qos-default-cpu:		PM QoS voting is based on the cpu associated with each IO request by the block layer.
 					This defined the default cpu used for PM QoS voting in case a specific cpu value is not available.
 
+- qcom,vddp-ref-clk-supply	 : reference clock to ufs device. Controlled by the host driver.
+- qcom,vddp-ref-clk-max-microamp : specifies max. load that can be drawn for
+				   ref-clk supply.
 Example:
 	ufshc@0xfc598000 {
 		...

drivers/scsi/ufs/ufs-qcom.c

@@ -35,6 +35,9 @@
 #include "ufs-qcom-debugfs.h"
 #include <linux/clk/msm-clk.h>
 
+#define MAX_PROP_SIZE		   32
+#define VDDP_REF_CLK_MIN_UV        1200000
+#define VDDP_REF_CLK_MAX_UV        1200000
 /* TODO: further tuning for this parameter may be required */
 #define UFS_QCOM_PM_QOS_UNVOTE_TIMEOUT_US	(10000) /* microseconds */
 
@@ -709,40 +712,105 @@ static int ufs_qcom_link_startup_notify(struct ufs_hba *hba,
 	return err;
 }
 
+
+static int ufs_qcom_config_vreg(struct device *dev,
+		struct ufs_vreg *vreg, bool on)
+{
+	int ret = 0;
+	struct regulator *reg;
+	int min_uV, uA_load;
+
+	if (!vreg) {
+		WARN_ON(1);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	reg = vreg->reg;
+	if (regulator_count_voltages(reg) > 0) {
+		min_uV = on ? vreg->min_uV : 0;
+		ret = regulator_set_voltage(reg, min_uV, vreg->max_uV);
+		if (ret) {
+			dev_err(dev, "%s: %s set voltage failed, err=%d\n",
+					__func__, vreg->name, ret);
+			goto out;
+		}
+
+		uA_load = on ? vreg->max_uA : 0;
+		ret = regulator_set_load(vreg->reg, uA_load);
+		if (ret)
+			goto out;
+	}
+out:
+	return ret;
+}
+
+static int ufs_qcom_enable_vreg(struct device *dev, struct ufs_vreg *vreg)
+{
+	int ret = 0;
+
+	if (vreg->enabled)
+		return ret;
+
+	ret = ufs_qcom_config_vreg(dev, vreg, true);
+	if (ret)
+		goto out;
+
+	ret = regulator_enable(vreg->reg);
+	if (ret)
+		goto out;
+
+	vreg->enabled = true;
+out:
+	return ret;
+}
+
+static int ufs_qcom_disable_vreg(struct device *dev, struct ufs_vreg *vreg)
+{
+	int ret = 0;
+
+	if (!vreg->enabled)
+		return ret;
+
+	ret = regulator_disable(vreg->reg);
+	if (ret)
+		goto out;
+
+	ret = ufs_qcom_config_vreg(dev, vreg, false);
+	if (ret)
+		goto out;
+
+	vreg->enabled = false;
+out:
+	return ret;
+}
+
 static int ufs_qcom_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
 	struct phy *phy = host->generic_phy;
 	int ret = 0;
 
-	if (ufs_qcom_is_link_off(hba)) {
-		/*
-		 * Disable the tx/rx lane symbol clocks before PHY is
-		 * powered down as the PLL source should be disabled
-		 * after downstream clocks are disabled.
-		 */
-		ufs_qcom_disable_lane_clks(host);
-		phy_power_off(phy);
-		ret = ufs_qcom_ice_suspend(host);
-		if (ret)
-			dev_err(hba->dev, "%s: failed ufs_qcom_ice_suspend %d\n",
-					__func__, ret);
-
-		/* Assert PHY soft reset */
-		ufs_qcom_assert_reset(hba);
-		goto out;
-	}
-
 	/*
-	 * If UniPro link is not active, PHY ref_clk, main PHY analog power
-	 * rail and low noise analog power rail for PLL can be switched off.
+	 * If UniPro link is not active or OFF, PHY ref_clk, main PHY analog
+	 * power rail and low noise analog power rail for PLL can be
+	 * switched off.
 	 */
 	if (!ufs_qcom_is_link_active(hba)) {
 		ufs_qcom_disable_lane_clks(host);
 		phy_power_off(phy);
-		ufs_qcom_ice_suspend(host);
-	}
 
+		if (host->vddp_ref_clk && ufs_qcom_is_link_off(hba))
+			ret = ufs_qcom_disable_vreg(hba->dev,
+					host->vddp_ref_clk);
+		ufs_qcom_ice_suspend(host);
+
+		if (ufs_qcom_is_link_off(hba)) {
+			/* Assert PHY soft reset */
+			ufs_qcom_assert_reset(hba);
+			goto out;
+		}
+	}
 	/* Unvote PM QoS */
 	ufs_qcom_pm_qos_suspend(host);
 
@@ -763,6 +831,11 @@ static int ufs_qcom_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 		goto out;
 	}
 
+	if (host->vddp_ref_clk && (hba->rpm_lvl > UFS_PM_LVL_3 ||
+				   hba->spm_lvl > UFS_PM_LVL_3))
+		ufs_qcom_enable_vreg(hba->dev,
+				      host->vddp_ref_clk);
+
 	err = ufs_qcom_enable_lane_clks(host);
 	if (err)
 		goto out;
@@ -1951,6 +2024,57 @@ static void ufs_qcom_parse_lpm(struct ufs_qcom_host *host)
 		pr_info("%s: will disable all LPM modes\n", __func__);
 }
 
+static int ufs_qcom_parse_reg_info(struct ufs_qcom_host *host, char *name,
+				   struct ufs_vreg **out_vreg)
+{
+	int ret = 0;
+	char prop_name[MAX_PROP_SIZE];
+	struct ufs_vreg *vreg = NULL;
+	struct device *dev = host->hba->dev;
+	struct device_node *np = dev->of_node;
+
+	if (!np) {
+		dev_err(dev, "%s: non DT initialization\n", __func__);
+		goto out;
+	}
+
+	snprintf(prop_name, MAX_PROP_SIZE, "%s-supply", name);
+	if (!of_parse_phandle(np, prop_name, 0)) {
+		dev_info(dev, "%s: Unable to find %s regulator, assuming enabled\n",
+			 __func__, prop_name);
+		ret = -ENODEV;
+		goto out;
+	}
+
+	vreg = devm_kzalloc(dev, sizeof(*vreg), GFP_KERNEL);
+	if (!vreg)
+		return -ENOMEM;
+
+	vreg->name = name;
+
+	snprintf(prop_name, MAX_PROP_SIZE, "%s-max-microamp", name);
+	ret = of_property_read_u32(np, prop_name, &vreg->max_uA);
+	if (ret) {
+		dev_err(dev, "%s: unable to find %s err %d\n",
+			__func__, prop_name, ret);
+		goto out;
+	}
+
+	vreg->reg = devm_regulator_get(dev, vreg->name);
+	if (IS_ERR(vreg->reg)) {
+		ret = PTR_ERR(vreg->reg);
+		dev_err(dev, "%s: %s get failed, err=%d\n",
+			__func__, vreg->name, ret);
+	}
+	vreg->min_uV = VDDP_REF_CLK_MIN_UV;
+	vreg->max_uV = VDDP_REF_CLK_MAX_UV;
+
+out:
+	if (!ret)
+		*out_vreg = vreg;
+	return ret;
+}
+
 /**
  * ufs_qcom_init - bind phy with controller
  * @hba: host controller instance
@@ -2068,14 +2192,24 @@ static int ufs_qcom_init(struct ufs_hba *hba)
 	ufs_qcom_phy_save_controller_version(host->generic_phy,
 		host->hw_ver.major, host->hw_ver.minor, host->hw_ver.step);
 
+	err = ufs_qcom_parse_reg_info(host, "qcom,vddp-ref-clk",
+				      &host->vddp_ref_clk);
 	phy_init(host->generic_phy);
 	err = phy_power_on(host->generic_phy);
 	if (err)
 		goto out_unregister_bus;
+	if (host->vddp_ref_clk) {
+		err = ufs_qcom_enable_vreg(dev, host->vddp_ref_clk);
+		if (err) {
+			dev_err(dev, "%s: failed enabling ref clk supply: %d\n",
+				__func__, err);
+			goto out_disable_phy;
+		}
+	}
 
 	err = ufs_qcom_init_lane_clks(host);
 	if (err)
-		goto out_disable_phy;
+		goto out_disable_vddp;
 
 	ufs_qcom_parse_lpm(host);
 	if (host->disable_lpm)
@@ -2100,6 +2234,9 @@ static int ufs_qcom_init(struct ufs_hba *hba)
 
 	goto out;
 
+out_disable_vddp:
+	if (host->vddp_ref_clk)
+		ufs_qcom_disable_vreg(dev, host->vddp_ref_clk);
 out_disable_phy:
 	phy_power_off(host->generic_phy);
 out_unregister_bus:

drivers/scsi/ufs/ufs-qcom.h

@@ -373,6 +373,7 @@ struct ufs_qcom_host {
 	spinlock_t ice_work_lock;
 	struct work_struct ice_cfg_work;
 	struct request *req_pending;
+	struct ufs_vreg *vddp_ref_clk;
 };
 
 static inline u32