soc: mediatek: pm-domains: Add support always on flag

There is a t-phy shared by PCIe and USB3 on mt8195, if the t-phy is
used by PCIe, when power off its mtcmos, need software reset it
(workaround way, usually hardware do it, but has an issue on mt8195),
but it has side effect to USB2 phy(works with USB3 phy to support
USB3.2 Gen1), so add support GENPD_FLAG_ALWAYS_ON flag, and make its
power always on.
Another reason is that USB3.2 Gen1/2 need keep power always on when
support runtime-pm due to hardware limitation until now.
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220617095841.23031-1-chunfeng.yun@mediatek.com
[mb: smaller nit fixes on commit message]
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

drivers/soc/mediatek/mt8195-pm-domains.h

@@ -67,7 +67,7 @@ static const struct scpsys_domain_data scpsys_domain_data_mt8195[] = {
 		.ctl_offs = 0x334,
 		.pwr_sta_offs = 0x174,
 		.pwr_sta2nd_offs = 0x178,
-		.caps = MTK_SCPD_ACTIVE_WAKEUP,
+		.caps = MTK_SCPD_ACTIVE_WAKEUP | MTK_SCPD_ALWAYS_ON,
 	},
 	[MT8195_POWER_DOMAIN_CSI_RX_TOP] = {
 		.name = "csi_rx_top",

drivers/soc/mediatek/mtk-pm-domains.c

@@ -428,6 +428,9 @@ generic_pm_domain *scpsys_add_one_domain(struct scpsys *scpsys, struct device_no
 			dev_err(scpsys->dev, "%pOF: failed to power on domain: %d\n", node, ret);
 			goto err_put_subsys_clocks;
 		}
+
+		if (MTK_SCPD_CAPS(pd, MTK_SCPD_ALWAYS_ON))
+			pd->genpd.flags |= GENPD_FLAG_ALWAYS_ON;
 	}
 
 	if (scpsys->domains[id]) {

drivers/soc/mediatek/mtk-pm-domains.h

@@ -8,6 +8,8 @@
 #define MTK_SCPD_SRAM_ISO		BIT(2)
 #define MTK_SCPD_KEEP_DEFAULT_OFF	BIT(3)
 #define MTK_SCPD_DOMAIN_SUPPLY		BIT(4)
+/* can't set MTK_SCPD_KEEP_DEFAULT_OFF at the same time */
+#define MTK_SCPD_ALWAYS_ON		BIT(5)
 #define MTK_SCPD_CAPS(_scpd, _x)	((_scpd)->data->caps & (_x))
 
 #define SPM_VDE_PWR_CON			0x0210