ufs: qcom: add dts property to disable LPM modes

Since msmcobalt RUMI uses QRBTC-V2 UFS PHY, there are a few limitations
that must be applied in order to be able to initialize UFS:
1. UFS should remain in PWM-G1 1-Lane and never change its gear, as other
gears are not stable
2. hibern8 enter/exit should be bypassed
3. we should avoid any power change (as in runtime suspend/resume)

Add "qcom,disable-lpm" property to facilitate disabling of these.

Change-Id: I3f1801da1e2bf1ce8ce98f5ab08211683106ae8c
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
Signed-off-by: Gilad Broner <gbroner@codeaurora.org>

Documentation/devicetree/bindings/ufs/ufs-qcom.txt

@@ -28,6 +28,8 @@ Optional properties:
 - vddp-ref-clk-supply   : phandle to UFS device ref_clk pad power supply
 - vddp-ref-clk-max-microamp : specifies max. load that can be drawn from this supply
 - vddp-ref-clk-always-on : specifies if this supply needs to be kept always on
+- qcom,disable-lpm : disable various LPM mechanisms in UFS for platform compatibility
+  (limit link to PWM Gear-1, 1-lane slow mode; disable hibernate, and avoid suspend/resume)
 
 Example:
 

drivers/phy/phy-qcom-ufs.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2015, Linux Foundation. All rights reserved.
+ * Copyright (c) 2013-2016, Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -612,6 +612,14 @@ int ufs_qcom_phy_calibrate_phy(struct phy *generic_phy, bool is_rate_B)
 }
 EXPORT_SYMBOL_GPL(ufs_qcom_phy_calibrate_phy);
 
+const char *ufs_qcom_phy_name(struct phy *phy)
+{
+	struct ufs_qcom_phy *ufs_qcom_phy = get_ufs_qcom_phy(phy);
+
+	return ufs_qcom_phy->name;
+}
+EXPORT_SYMBOL(ufs_qcom_phy_name);
+
 int ufs_qcom_phy_remove(struct phy *generic_phy,
 			struct ufs_qcom_phy *ufs_qcom_phy)
 {

drivers/scsi/ufs/ufs-qcom.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2015, Linux Foundation. All rights reserved.
+ * Copyright (c) 2013-2016, Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -1122,6 +1122,18 @@ static int ufs_qcom_pwr_change_notify(struct ufs_hba *hba,
 				ufs_qcom_cap.hs_rx_gear = UFS_HS_G2;
 		}
 
+		/*
+		 * Platforms using QRBTCv2 phy must limit link to PWM Gear-1
+		 * and SLOW mode to successfully bring up the link.
+		 */
+		if (!strcmp(ufs_qcom_phy_name(phy), "ufs_phy_qrbtc_v2")) {
+			ufs_qcom_cap.tx_lanes = 1;
+			ufs_qcom_cap.rx_lanes = 1;
+			ufs_qcom_cap.pwm_rx_gear = UFS_PWM_G1;
+			ufs_qcom_cap.pwm_tx_gear = UFS_PWM_G1;
+			ufs_qcom_cap.desired_working_mode = SLOW;
+		}
+
 		ret = ufs_qcom_get_pwr_dev_param(&ufs_qcom_cap,
 						 dev_max_params,
 						 dev_req_params);
@@ -1253,12 +1265,16 @@ static void ufs_qcom_set_caps(struct ufs_hba *hba)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
 
-	hba->caps |= UFSHCD_CAP_CLK_GATING | UFSHCD_CAP_HIBERN8_WITH_CLK_GATING;
-	hba->caps |= UFSHCD_CAP_CLK_SCALING;
+	if (!host->disable_lpm) {
+		hba->caps |= UFSHCD_CAP_CLK_GATING;
+		hba->caps |= UFSHCD_CAP_HIBERN8_WITH_CLK_GATING;
+		hba->caps |= UFSHCD_CAP_CLK_SCALING;
+	}
 	hba->caps |= UFSHCD_CAP_AUTO_BKOPS_SUSPEND;
 
 	if (host->hw_ver.major >= 0x2) {
-		hba->caps |= UFSHCD_CAP_POWER_COLLAPSE_DURING_HIBERN8;
+		if (!host->disable_lpm)
+			hba->caps |= UFSHCD_CAP_POWER_COLLAPSE_DURING_HIBERN8;
 		host->caps = UFS_QCOM_CAP_QUNIPRO |
 			     UFS_QCOM_CAP_RETAIN_SEC_CFG_AFTER_PWR_COLLAPSE;
 	}
@@ -1735,6 +1751,18 @@ static int __init get_android_boot_dev(char *str)
 __setup("androidboot.bootdevice=", get_android_boot_dev);
 #endif
 
+/*
+ * ufs_qcom_parse_lpm - read from DTS whether LPM modes should be disabled.
+ */
+static void ufs_qcom_parse_lpm(struct ufs_qcom_host *host)
+{
+	struct device_node *node = host->hba->dev->of_node;
+
+	host->disable_lpm = of_property_read_bool(node, "qcom,disable-lpm");
+	if (host->disable_lpm)
+		pr_info("%s: will disable all LPM modes\n", __func__);
+}
+
 /**
  * ufs_qcom_init - bind phy with controller
  * @hba: host controller instance
@@ -1866,6 +1894,9 @@ static int ufs_qcom_init(struct ufs_hba *hba)
 	if (err)
 		goto out_disable_phy;
 
+	ufs_qcom_parse_lpm(host);
+	if (host->disable_lpm)
+		pm_runtime_forbid(host->hba->dev);
 	ufs_qcom_set_caps(hba);
 	ufs_qcom_advertise_quirks(hba);
 

drivers/scsi/ufs/ufs-qcom.h

@@ -1,4 +1,4 @@
-/* Copyright (c) 2013-2015, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2013-2016, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -323,6 +323,7 @@ struct ufs_qcom_host {
 	/* PM Quality-of-Service (QoS) data */
 	struct ufs_qcom_pm_qos pm_qos;
 
+	bool disable_lpm;
 	bool is_lane_clks_enabled;
 	bool sec_cfg_updated;
 	struct ufs_qcom_ice_data ice;

include/linux/phy/phy-qcom-ufs.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2015, Linux Foundation. All rights reserved.
+ * Copyright (c) 2013-2016, Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -56,5 +56,6 @@ int ufs_qcom_phy_calibrate_phy(struct phy *phy, bool is_rate_B);
 int ufs_qcom_phy_is_pcs_ready(struct phy *phy);
 void ufs_qcom_phy_save_controller_version(struct phy *phy,
 			u8 major, u16 minor, u16 step);
+const char *ufs_qcom_phy_name(struct phy *phy);
 
 #endif /* PHY_QCOM_UFS_H_ */