scsi: ufs: ufs-mediatek: Support host power control

Add interfaces for controlling the host power to optimize the power
consumption in MediaTek UFS platforms.

Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Stanley Chu <[e-mail]>
Reviewed-by: Bart Van Assche <[e-mail]>
Signed-off-by: Po-Wen Kao <[e-mail]>
Signed-off-by: Stanley Chu <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/ufs/host/ufs-mediatek.c

···
 	if (ufshcd_is_link_off(hba))
 		ufs_mtk_device_reset_ctrl(0, res);
 
+	ufs_mtk_host_pwr_ctrl(HOST_PWR_HCI, false, res);
+
 	return 0;
 fail:
 	/*
···
 static int ufs_mtk_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 {
 	int err;
+	struct arm_smccc_res res;
 
 	if (hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL)
 		ufs_mtk_dev_vreg_set_lpm(hba, false);
+
+	ufs_mtk_host_pwr_ctrl(HOST_PWR_HCI, true, res);
 
 	err = ufs_mtk_mphy_power_on(hba, true);
 	if (err)

drivers/ufs/host/ufs-mediatek.h

···
 #define UFS_MTK_SIP_DEVICE_RESET          BIT(1)
 #define UFS_MTK_SIP_CRYPTO_CTRL           BIT(2)
 #define UFS_MTK_SIP_REF_CLK_NOTIFICATION  BIT(3)
+#define UFS_MTK_SIP_HOST_PWR_CTRL         BIT(5)
 #define UFS_MTK_SIP_GET_VCC_NUM           BIT(6)
 #define UFS_MTK_SIP_DEVICE_PWR_CTRL       BIT(7)
 
···
 };
 
 /*
+ * Host Power Control options
+ */
+enum {
+	HOST_PWR_HCI = 0,
+	HOST_PWR_MPHY
+};
+
+/*
  * SMC call wrapper function
  */
 struct ufs_mtk_smc_arg {
···
 
 #define ufs_mtk_device_reset_ctrl(high, res) \
 	ufs_mtk_smc(UFS_MTK_SIP_DEVICE_RESET, &(res), high)
+
+#define ufs_mtk_host_pwr_ctrl(opt, on, res) \
+	ufs_mtk_smc(UFS_MTK_SIP_HOST_PWR_CTRL, &(res), opt, on)
 
 #define ufs_mtk_get_vcc_num(res) \
 	ufs_mtk_smc(UFS_MTK_SIP_GET_VCC_NUM, &(res))