linux-kernel - [PATCH 1/2] usb: typec: tps6598x: add reset gpio support

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Message-Id: <20230912-topic-tps6598x_reset-v1-1-78dc0bf61790@wolfvision.net>
Date:   Fri, 15 Sep 2023 08:50:52 +0200
From:   Javier Carrasco <javier.carrasco@...fvision.net>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org,
        Javier Carrasco <javier.carrasco@...fvision.net>
Subject: [PATCH 1/2] usb: typec: tps6598x: add reset gpio support

The TPS6598x PD controller provides an active-high hardware reset input
that reinitializes all device settings. If it is not grounded by
design, the driver must be able to de-assert it in order to initialize
the device.

The PD controller is not ready for registration right after the reset
de-assertion and a delay must be introduced in that case. According to
TI, the delay can reach up to 1000 ms [1], which is in line with the
experimental results obtained with a TPS65987D.

Add a GPIO descriptor for the reset signal and basic reset management
for initialization and suspend/resume.

[1] https://e2e.ti.com/support/power-management-group/power-management/
f/power-management-forum/1269856/tps65987d-tps65987d-reset-de-assert-
to-normal-operation/4809389#4809389

Signed-off-by: Javier Carrasco <javier.carrasco@...fvision.net>
---
 drivers/usb/typec/tipd/core.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/typec/tipd/core.c b/drivers/usb/typec/tipd/core.c
index 37b56ce75f39..550f5913e985 100644
--- a/drivers/usb/typec/tipd/core.c
+++ b/drivers/usb/typec/tipd/core.c
@@ -8,6 +8,7 @@
 
 #include <linux/i2c.h>
 #include <linux/acpi.h>
+#include <linux/gpio/consumer.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/power_supply.h>
@@ -43,6 +44,9 @@
 /* TPS_REG_SYSTEM_CONF bits */
 #define TPS_SYSCONF_PORTINFO(c)		((c) & 7)
 
+/* reset de-assertion to ready for operation */
+#define SETUP_MS			1000
+
 enum {
 	TPS_PORTINFO_SINK,
 	TPS_PORTINFO_SINK_ACCESSORY,
@@ -86,6 +90,7 @@ struct tps6598x {
 	struct mutex lock; /* device lock */
 	u8 i2c_protocol:1;
 
+	struct gpio_desc *reset;
 	struct typec_port *port;
 	struct typec_partner *partner;
 	struct usb_pd_identity partner_identity;
@@ -717,6 +722,13 @@ static int tps6598x_probe(struct i2c_client *client)
 	mutex_init(&tps->lock);
 	tps->dev = &client->dev;
 
+	tps->reset = devm_gpiod_get_optional(tps->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(tps->reset))
+		return dev_err_probe(tps->dev, PTR_ERR(tps->reset),
+				     "failed to get reset GPIO\n");
+	if (tps->reset)
+		msleep(SETUP_MS);
+
 	tps->regmap = devm_regmap_init_i2c(client, &tps6598x_regmap_config);
 	if (IS_ERR(tps->regmap))
 		return PTR_ERR(tps->regmap);
@@ -892,6 +904,9 @@ static void tps6598x_remove(struct i2c_client *client)
 	tps6598x_disconnect(tps, 0);
 	typec_unregister_port(tps->port);
 	usb_role_switch_put(tps->role_sw);
+
+	if (tps->reset)
+		gpiod_set_value_cansleep(tps->reset, 1);
 }
 
 static int __maybe_unused tps6598x_suspend(struct device *dev)
@@ -902,7 +917,8 @@ static int __maybe_unused tps6598x_suspend(struct device *dev)
 	if (tps->wakeup) {
 		disable_irq(client->irq);
 		enable_irq_wake(client->irq);
-	}
+	} else if (tps->reset)
+		gpiod_set_value_cansleep(tps->reset, 1);
 
 	if (!client->irq)
 		cancel_delayed_work_sync(&tps->wq_poll);
@@ -918,6 +934,9 @@ static int __maybe_unused tps6598x_resume(struct device *dev)
 	if (tps->wakeup) {
 		disable_irq_wake(client->irq);
 		enable_irq(client->irq);
+	} else if (tps->reset) {
+		gpiod_set_value_cansleep(tps->reset, 0);
+		msleep(SETUP_MS);
 	}
 
 	if (!client->irq)

-- 
2.39.2