pmdomain: mediatek: Handle SoCs with inverted SRAM power-down bits

Some SoCs, and even some subsystems in the same SoC, may have the
logic for SRAM power-down inverted, as in, setting the bit means
"power down" and unsetting means "power up": this is because some
hardware subsystems use this as a power-lock indication and some
use this as a power down one (for example, usually, the modem ss
has it inverted!).

In preparation for adding support for power domains with inverted
SRAM_PDN bits, add a new MTK_SCPD_SRAM_PDN_INVERTED flag and check
for it in scpsys_sram_enable() and scpsys_sram_disable().

Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20250805074746.29457-6-angelogioacchino.delregno@collabora.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Author: AngeloGioacchino Del Regno

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

@@ -79,16 +79,23 @@ static bool scpsys_domain_is_on(struct scpsys_domain *pd)
 
 static int scpsys_sram_enable(struct scpsys_domain *pd)
 {
-	u32 pdn_ack = pd->data->sram_pdn_ack_bits;
+	u32 expected_ack, pdn_ack = pd->data->sram_pdn_ack_bits;
 	struct scpsys *scpsys = pd->scpsys;
 	unsigned int tmp;
 	int ret;
 
-	regmap_clear_bits(scpsys->base, pd->data->ctl_offs, pd->data->sram_pdn_bits);
+	if (MTK_SCPD_CAPS(pd, MTK_SCPD_SRAM_PDN_INVERTED)) {
+		regmap_set_bits(scpsys->base, pd->data->ctl_offs, pd->data->sram_pdn_bits);
+		expected_ack = pdn_ack;
+	} else {
+		regmap_clear_bits(scpsys->base, pd->data->ctl_offs, pd->data->sram_pdn_bits);
+		expected_ack = 0;
+	}
 
 	/* Either wait until SRAM_PDN_ACK all 1 or 0 */
 	ret = regmap_read_poll_timeout(scpsys->base, pd->data->ctl_offs, tmp,
-				       (tmp & pdn_ack) == 0, MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
+				       (tmp & pdn_ack) == expected_ack,
+				       MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
 	if (ret < 0)
 		return ret;
 
@@ -103,7 +110,7 @@ static int scpsys_sram_enable(struct scpsys_domain *pd)
 
 static int scpsys_sram_disable(struct scpsys_domain *pd)
 {
-	u32 pdn_ack = pd->data->sram_pdn_ack_bits;
+	u32 expected_ack, pdn_ack = pd->data->sram_pdn_ack_bits;
 	struct scpsys *scpsys = pd->scpsys;
 	unsigned int tmp;
 
@@ -113,12 +120,18 @@ static int scpsys_sram_disable(struct scpsys_domain *pd)
 		regmap_clear_bits(scpsys->base, pd->data->ctl_offs, PWR_SRAM_ISOINT_B_BIT);
 	}
 
-	regmap_set_bits(scpsys->base, pd->data->ctl_offs, pd->data->sram_pdn_bits);
+	if (MTK_SCPD_CAPS(pd, MTK_SCPD_SRAM_PDN_INVERTED)) {
+		regmap_clear_bits(scpsys->base, pd->data->ctl_offs, pd->data->sram_pdn_bits);
+		expected_ack = 0;
+	} else {
+		regmap_set_bits(scpsys->base, pd->data->ctl_offs, pd->data->sram_pdn_bits);
+		expected_ack = pdn_ack;
+	}
 
 	/* Either wait until SRAM_PDN_ACK all 1 or 0 */
 	return regmap_read_poll_timeout(scpsys->base, pd->data->ctl_offs, tmp,
-					(tmp & pdn_ack) == pdn_ack, MTK_POLL_DELAY_US,
-					MTK_POLL_TIMEOUT);
+					(tmp & pdn_ack) == expected_ack,
+					MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
 }
 
 static struct regmap *scpsys_bus_protect_get_regmap(struct scpsys_domain *pd,

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

@@ -13,6 +13,7 @@
 #define MTK_SCPD_EXT_BUCK_ISO		BIT(6)
 #define MTK_SCPD_HAS_INFRA_NAO		BIT(7)
 #define MTK_SCPD_STRICT_BUS_PROTECTION	BIT(8)
+#define MTK_SCPD_SRAM_PDN_INVERTED	BIT(9)
 #define MTK_SCPD_CAPS(_scpd, _x)	((_scpd)->data->caps & (_x))
 
 #define SPM_VDE_PWR_CON			0x0210