[PATCH v4 10/10] scsi: ufs: ufs-qcom: Add support for UFS device version detection

[Can Guo <quic_cang@quicinc.com>]

From: "Bao D. Nguyen" <quic_nguyenb@quicinc.com>

A spare register in UFS host controller is used to indicate the UFS device
version. The spare register is populated by bootloader for now, but in
future it will be populated by HW automatically during link startup with
its best efforts in any boot stages prior to Linux.

During host driver init, read the spare register, if it is not populated
with a UFS device version, go ahead with the dual init mechanism. If a UFS
device version is in there, use the UFS device version together with host
controller's HW version to decide the proper PHY gear which should be used
to configure the UFS PHY without going through the second init.

Signed-off-by: Bao D. Nguyen <quic_nguyenb@quicinc.com>
Signed-off-by: Can Guo <quic_cang@quicinc.com>
---
 drivers/ufs/host/ufs-qcom.c | 23 ++++++++++++++++++-----
 drivers/ufs/host/ufs-qcom.h |  2 ++
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
index 7bbccf4..70bedd9 100644
--- a/drivers/ufs/host/ufs-qcom.c
+++ b/drivers/ufs/host/ufs-qcom.c
@@ -1070,15 +1070,28 @@ static void ufs_qcom_advertise_quirks(struct ufs_hba *hba)
 static void ufs_qcom_set_phy_gear(struct ufs_qcom_host *host)
 {
 	struct ufs_host_params *host_params = &host->host_params;
+	u32 val, dev_major = 0;
 
 	host->phy_gear = host_params->hs_tx_gear;
 
-	/*
-	 * Power up the PHY using the minimum supported gear (UFS_HS_G2).
-	 * Switching to max gear will be performed during reinit if supported.
-	 */
-	if (host->hw_ver.major < 0x5)
+	if (host->hw_ver.major < 0x5) {
+		/*
+		 * Power up the PHY using the minimum supported gear (UFS_HS_G2).
+		 * Switching to max gear will be performed during reinit if supported.
+		 */
 		host->phy_gear = UFS_HS_G2;
+	} else {
+		val = ufshcd_readl(host->hba, REG_UFS_DEBUG_SPARE_CFG);
+		dev_major = FIELD_GET(GENMASK(7, 4), val);
+
+		/* UFS device version populated, no need to do init twice */
+		if (dev_major != 0)
+			host->hba->quirks &= ~UFSHCD_QUIRK_REINIT_AFTER_MAX_GEAR_SWITCH;
+
+		/* For UFS 3.1 and older, apply HS-G4 PHY gear to save power */
+		if (dev_major < 0x4 && dev_major > 0)
+			host->phy_gear = UFS_HS_G4;
+	}
 }
 
 static void ufs_qcom_set_host_params(struct ufs_hba *hba)
diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
index 11419eb..d12fc5a 100644
--- a/drivers/ufs/host/ufs-qcom.h
+++ b/drivers/ufs/host/ufs-qcom.h
@@ -54,6 +54,8 @@ enum {
 	UFS_AH8_CFG				= 0xFC,
 
 	REG_UFS_CFG3				= 0x271C,
+
+	REG_UFS_DEBUG_SPARE_CFG			= 0x284C,
 };
 
 /* QCOM UFS host controller vendor specific debug registers */
-- 
2.7.4