[PATCH v3 1/3] extcon: usbc-tusb320: Add support for mode setting and reset

[Yassine Oudjana]

Reset the chip and set its mode to default (maintain mode set by PORT pin)
during probe to make sure it comes up in the default state.

Changes since v2:
 - Read state before setting default mode, then update it again after resetting.
 - Remove mode tracing from irq handler
 - Add a delay after reset to handle tSOFT_RESET

Signed-off-by: Yassine Oudjana <y.oudjana@xxxxxxxxxxxxxx>
---
 drivers/extcon/extcon-usbc-tusb320.c | 92 ++++++++++++++++++++++++++--
 1 file changed, 88 insertions(+), 4 deletions(-)

diff --git a/drivers/extcon/extcon-usbc-tusb320.c b/drivers/extcon/extcon-usbc-tusb320.c
index 805af73b4152..867fb2bf2bdc 100644
--- a/drivers/extcon/extcon-usbc-tusb320.c
+++ b/drivers/extcon/extcon-usbc-tusb320.c
@@ -19,15 +19,32 @@
 #define TUSB320_REG9_ATTACHED_STATE_MASK	0x3
 #define TUSB320_REG9_CABLE_DIRECTION		BIT(5)
 #define TUSB320_REG9_INTERRUPT_STATUS		BIT(4)
-#define TUSB320_ATTACHED_STATE_NONE		0x0
-#define TUSB320_ATTACHED_STATE_DFP		0x1
-#define TUSB320_ATTACHED_STATE_UFP		0x2
-#define TUSB320_ATTACHED_STATE_ACC		0x3
+
+#define TUSB320_REGA				0xa
+#define TUSB320_REGA_I2C_SOFT_RESET		BIT(3)
+#define TUSB320_REGA_MODE_SELECT_SHIFT		4
+#define TUSB320_REGA_MODE_SELECT_MASK		0x3
+
+enum tusb320_attached_state {
+	TUSB320_ATTACHED_STATE_NONE,
+	TUSB320_ATTACHED_STATE_DFP,
+	TUSB320_ATTACHED_STATE_UFP,
+	TUSB320_ATTACHED_STATE_ACC,
+};
+
+enum tusb320_mode {
+	TUSB320_MODE_PORT,
+	TUSB320_MODE_UFP,
+	TUSB320_MODE_DFP,
+	TUSB320_MODE_DRP,
+};
 
 struct tusb320_priv {
 	struct device *dev;
 	struct regmap *regmap;
 	struct extcon_dev *edev;
+
+	enum tusb320_attached_state state;
 };
 
 static const char * const tusb_attached_states[] = {
@@ -37,6 +54,13 @@ static const char * const tusb_attached_states[] = {
 	[TUSB320_ATTACHED_STATE_ACC]  = "accessory",
 };
 
+static const char * const tusb_modes[] = {
+	[TUSB320_MODE_PORT] = "maintain mode set by PORT pin",
+	[TUSB320_MODE_UFP]  = "upstream facing port",
+	[TUSB320_MODE_DFP]  = "downstream facing port",
+	[TUSB320_MODE_DRP]  = "dual role port",
+};
+
 static const unsigned int tusb320_extcon_cable[] = {
 	EXTCON_USB,
 	EXTCON_USB_HOST,
@@ -62,6 +86,53 @@ static int tusb320_check_signature(struct tusb320_priv *priv)
 	return 0;
 }
 
+static int tusb320_set_mode(struct tusb320_priv *priv, enum tusb320_mode mode)
+{
+	int ret;
+
+	/* Mode cannot be changed while cable is attached */
+	if (priv->state != TUSB320_ATTACHED_STATE_NONE)
+		return -EBUSY;
+
+	/* Write mode */
+	ret = regmap_write_bits(priv->regmap, TUSB320_REGA,
+		TUSB320_REGA_MODE_SELECT_MASK << TUSB320_REGA_MODE_SELECT_SHIFT,
+		mode << TUSB320_REGA_MODE_SELECT_SHIFT);
+	if (ret) {
+		dev_err(priv->dev, "failed to write mode: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int tusb320_reset(struct tusb320_priv *priv)
+{
+	int ret;
+
+	/* Set mode to default (follow PORT pin) */
+	ret = tusb320_set_mode(priv, TUSB320_MODE_PORT);
+	if (ret && ret != -EBUSY) {
+		dev_err(priv->dev,
+			"failed to set mode to PORT: %d\n", ret);
+		return ret;
+	}
+
+	/* Perform soft reset */
+	ret = regmap_write_bits(priv->regmap, TUSB320_REGA,
+			TUSB320_REGA_I2C_SOFT_RESET, 1);
+	if (ret) {
+		dev_err(priv->dev,
+			"failed to write soft reset bit: %d\n", ret);
+		return ret;
+	}
+
+	/* Wait for chip to go through reset */
+	msleep(95);
+
+	return 0;
+}
+
 static irqreturn_t tusb320_irq_handler(int irq, void *dev_id)
 {
 	struct tusb320_priv *priv = dev_id;
@@ -96,6 +167,8 @@ static irqreturn_t tusb320_irq_handler(int irq, void *dev_id)
 	extcon_sync(priv->edev, EXTCON_USB);
 	extcon_sync(priv->edev, EXTCON_USB_HOST);
 
+	priv->state = state;
+
 	regmap_write(priv->regmap, TUSB320_REG9, reg);
 
 	return IRQ_HANDLED;
@@ -145,6 +218,17 @@ static int tusb320_extcon_probe(struct i2c_client *client,
 	/* update initial state */
 	tusb320_irq_handler(client->irq, priv);
 
+	/* Reset chip to its default state */
+	ret = tusb320_reset(priv);
+	if (ret)
+		dev_warn(priv->dev, "failed to reset chip: %d\n", ret);
+	else
+		/*
+		 * State and polarity might change after a reset, so update
+		 * them again and make sure the interrupt status bit is cleared.
+		 */
+		tusb320_irq_handler(client->irq, priv);
+
 	ret = devm_request_threaded_irq(priv->dev, client->irq, NULL,
 					tusb320_irq_handler,
 					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
-- 
2.32.0