scsi: ufs: exynos: Allow UFS Gear 4

UFS Gear 4 offers faster speeds, and better power usage so lets enable
it.

Currently ufshcd_init_host_params() sets UFS_HS_G3 as a default, so even
if the device supports G4 we end up negotiating down to G3.

For SoCs like gs101 which have a UFS major controller version of 3 or
above advertise Gear 4. This then allows a Gear 4 link on Pixel 6.

For earlier controller versions keep the current default behaviour of
reporting G3.

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Link: https://lore.kernel.org/r/20241031150033.3440894-4-peter.griffin@linaro.org
Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: petegriffin

drivers/ufs/host/ufs-exynos.c

@@ -766,6 +766,21 @@ static void exynos_ufs_config_sync_pattern_mask(struct exynos_ufs *ufs,
 	exynos_ufs_disable_ov_tm(hba);
 }
 
+#define UFS_HW_VER_MAJOR_MASK   GENMASK(15, 8)
+
+static u32 exynos_ufs_get_hs_gear(struct ufs_hba *hba)
+{
+	u8 major;
+
+	major = FIELD_GET(UFS_HW_VER_MAJOR_MASK, hba->ufs_version);
+
+	if (major >= 3)
+		return UFS_HS_G4;
+
+	/* Default is HS-G3 */
+	return UFS_HS_G3;
+}
+
 static int exynos_ufs_pre_pwr_mode(struct ufs_hba *hba,
 				struct ufs_pa_layer_attr *dev_max_params,
 				struct ufs_pa_layer_attr *dev_req_params)
@@ -783,6 +798,10 @@ static int exynos_ufs_pre_pwr_mode(struct ufs_hba *hba,
 
 	ufshcd_init_host_params(&host_params);
 
+	/* This driver only support symmetric gear setting e.g. hs_tx_gear == hs_rx_gear */
+	host_params.hs_tx_gear = exynos_ufs_get_hs_gear(hba);
+	host_params.hs_rx_gear = exynos_ufs_get_hs_gear(hba);
+
 	ret = ufshcd_negotiate_pwr_params(&host_params, dev_max_params, dev_req_params);
 	if (ret) {
 		pr_err("%s: failed to determine capabilities\n", __func__);