linux-kernel - [PATCH v2] usb: typec: tcpci: support edge irq

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Message-Id: <20240905065328.7116-1-parth105105@gmail.com>
Date: Thu,  5 Sep 2024 08:53:28 +0200
From: Parth Pancholi <parth105105@...il.com>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Emanuele Ghidoli <emanuele.ghidoli@...adex.com>,
	linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Parth Pancholi <parth.pancholi@...adex.com>
Subject: [PATCH v2] usb: typec: tcpci: support edge irq

From: Emanuele Ghidoli <emanuele.ghidoli@...adex.com>

TCPCI USB PHY - PTN5110 could be used with SOCs that only support
the edge-triggered GPIO interrupts such as TI's K3 device AM69.
Move the interrupt configuration to the firmware which would
allow to accommodate edge triggered interrupts for such SOCs.
In order to support the edge interrupts, register irq line in advance
and keep track of occurrence during port registering.

When the edge interrupts are used, it is observed that some of the
interrupts are missed when tcpci_irq() is serving the current
interrupt. Therefore, check the status register at the end of
tcpci_irq() and re-run the function if the status is not clear
i.e. pending interrupt.

Signed-off-by: Emanuele Ghidoli <emanuele.ghidoli@...adex.com>
Signed-off-by: Parth Pancholi <parth.pancholi@...adex.com>
---
v2: Re-enable irq irrespective of tcpci_register_port() return status which was disabled before this call
---
 drivers/usb/typec/tcpm/tcpci.c | 30 ++++++++++++++++++++----------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
index a2651a2a7f2e..ed32583829be 100644
--- a/drivers/usb/typec/tcpm/tcpci.c
+++ b/drivers/usb/typec/tcpm/tcpci.c
@@ -707,10 +707,13 @@ irqreturn_t tcpci_irq(struct tcpci *tcpci)
 {
 	u16 status;
 	int ret;
+	int irq_ret;
 	unsigned int raw;
 
 	tcpci_read16(tcpci, TCPC_ALERT, &status);
+	irq_ret = status & tcpci->alert_mask;
 
+process_status:
 	/*
 	 * Clear alert status for everything except RX_STATUS, which shouldn't
 	 * be cleared until we have successfully retrieved message.
@@ -783,7 +786,12 @@ irqreturn_t tcpci_irq(struct tcpci *tcpci)
 	else if (status & TCPC_ALERT_TX_FAILED)
 		tcpm_pd_transmit_complete(tcpci->port, TCPC_TX_FAILED);
 
-	return IRQ_RETVAL(status & tcpci->alert_mask);
+	tcpci_read16(tcpci, TCPC_ALERT, &status);
+
+	if (status & tcpci->alert_mask)
+		goto process_status;
+
+	return IRQ_RETVAL(irq_ret);
 }
 EXPORT_SYMBOL_GPL(tcpci_irq);
 
@@ -915,20 +923,22 @@ static int tcpci_probe(struct i2c_client *client)
 
 	chip->data.set_orientation = err;
 
-	chip->tcpci = tcpci_register_port(&client->dev, &chip->data);
-	if (IS_ERR(chip->tcpci))
-		return PTR_ERR(chip->tcpci);
-
 	err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
 					_tcpci_irq,
-					IRQF_SHARED | IRQF_ONESHOT | IRQF_TRIGGER_LOW,
+					IRQF_SHARED | IRQF_ONESHOT,
 					dev_name(&client->dev), chip);
-	if (err < 0) {
-		tcpci_unregister_port(chip->tcpci);
+	if (err < 0)
 		return err;
-	}
 
-	return 0;
+	/*
+	 * Disable irq while registering port. If irq is configured as an edge
+	 * irq this allow to keep track and process the irq as soon as it is enabled.
+	 */
+	disable_irq(client->irq);
+	chip->tcpci = tcpci_register_port(&client->dev, &chip->data);
+	enable_irq(client->irq);
+
+	return PTR_ERR_OR_ZERO(chip->tcpci);
 }
 
 static void tcpci_remove(struct i2c_client *client)
-- 
2.34.1