[PATCH v3 5/6] usb: typec: tipd: Switch CD321X power state to S0

[Sven Peter <sven@svenpeter.dev>]

The Apple CD321x comes up in a low-power state after boot. Usually, the
bootloader will already power it up to S0 but let's do it here as well
in case that didn't happen.

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Suggested-by: Stan Skowronek <stan@corellium.com>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
---
no changes since v2

changes since v1:
  - dropped the supports_spss flag and only call this for the Apple chip
  - added Alyssa's r-b

 drivers/usb/typec/tipd/core.c     | 37 +++++++++++++++++++++++++++++++
 drivers/usb/typec/tipd/tps6598x.h |  6 +++++
 2 files changed, 43 insertions(+)

diff --git a/drivers/usb/typec/tipd/core.c b/drivers/usb/typec/tipd/core.c
index cc4a154eabcb..c74fc9ae1686 100644
--- a/drivers/usb/typec/tipd/core.c
+++ b/drivers/usb/typec/tipd/core.c
@@ -30,6 +30,7 @@
 #define TPS_REG_INT_MASK2		0x17
 #define TPS_REG_INT_CLEAR1		0x18
 #define TPS_REG_INT_CLEAR2		0x19
+#define TPS_REG_SYSTEM_POWER_STATE	0x20
 #define TPS_REG_STATUS			0x1a
 #define TPS_REG_SYSTEM_CONF		0x28
 #define TPS_REG_CTRL_CONF		0x29
@@ -152,6 +153,11 @@ static int tps6598x_block_write(struct tps6598x *tps, u8 reg,
 	return regmap_raw_write(tps->regmap, reg, data, len + 1);
 }
 
+static inline int tps6598x_read8(struct tps6598x *tps, u8 reg, u8 *val)
+{
+	return tps6598x_block_read(tps, reg, val, sizeof(u8));
+}
+
 static inline int tps6598x_read16(struct tps6598x *tps, u8 reg, u16 *val)
 {
 	return tps6598x_block_read(tps, reg, val, sizeof(u16));
@@ -635,6 +641,32 @@ static int tps6598x_psy_get_prop(struct power_supply *psy,
 	return ret;
 }
 
+static int cd321x_switch_power_state(struct tps6598x *tps, u8 target_state)
+{
+	u8 state;
+	int ret;
+
+	ret = tps6598x_read8(tps, TPS_REG_SYSTEM_POWER_STATE, &state);
+	if (ret)
+		return ret;
+
+	if (state == target_state)
+		return 0;
+
+	ret = tps6598x_exec_cmd(tps, "SPSS", sizeof(u8), &target_state, 0, NULL);
+	if (ret)
+		return ret;
+
+	ret = tps6598x_read8(tps, TPS_REG_SYSTEM_POWER_STATE, &state);
+	if (ret)
+		return ret;
+
+	if (state != target_state)
+		return -EINVAL;
+
+	return 0;
+}
+
 static int devm_tps6598_psy_register(struct tps6598x *tps)
 {
 	struct power_supply_config psy_cfg = {};
@@ -707,6 +739,11 @@ static int tps6598x_probe(struct i2c_client *client)
 		return ret;
 
 	if (np && of_device_is_compatible(np, "apple,cd321x")) {
+		/* Switch CD321X chips to the correct system power state */
+		ret = cd321x_switch_power_state(tps, TPS_SYSTEM_POWER_STATE_S0);
+		if (ret)
+			return ret;
+
 		/* CD321X chips have all interrupts masked initially */
 		ret = tps6598x_write64(tps, TPS_REG_INT_MASK1,
 					APPLE_CD_REG_INT_POWER_STATUS_UPDATE |
diff --git a/drivers/usb/typec/tipd/tps6598x.h b/drivers/usb/typec/tipd/tps6598x.h
index e13b16419843..3dae84c524fb 100644
--- a/drivers/usb/typec/tipd/tps6598x.h
+++ b/drivers/usb/typec/tipd/tps6598x.h
@@ -135,6 +135,12 @@
 #define APPLE_CD_REG_INT_STATUS_UPDATE			BIT(8)
 #define APPLE_CD_REG_INT_PLUG_EVENT			BIT(1)
 
+/* TPS_REG_SYSTEM_POWER_STATE states */
+#define TPS_SYSTEM_POWER_STATE_S0	0x00
+#define TPS_SYSTEM_POWER_STATE_S3	0x03
+#define TPS_SYSTEM_POWER_STATE_S4	0x04
+#define TPS_SYSTEM_POWER_STATE_S5	0x05
+
 /* TPS_REG_POWER_STATUS bits */
 #define TPS_POWER_STATUS_CONNECTION(x)  TPS_FIELD_GET(BIT(0), (x))
 #define TPS_POWER_STATUS_SOURCESINK(x)	TPS_FIELD_GET(BIT(1), (x))
-- 
2.25.1