linux-kernel - [PATCH v2] serial: qcom-geni: Remove alias dependency from qcom serial driver

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Message-Id: <20250327070711.2585887-1-quic_vdadhani@quicinc.com>
Date: Thu, 27 Mar 2025 12:37:11 +0530
From: Viken Dadhaniya <quic_vdadhani@...cinc.com>
To: gregkh@...uxfoundation.org, jirislaby@...nel.org, johan+linaro@...nel.org,
        dianders@...omium.org, konradybcio@...nel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-serial@...r.kernel.org
Cc: quic_msavaliy@...cinc.com, quic_anupkulk@...cinc.com,
        Viken Dadhaniya <quic_vdadhani@...cinc.com>
Subject: [PATCH v2] serial: qcom-geni: Remove alias dependency from qcom serial driver

The absence of an alias in the device tree results in an invalid line
number, causing the driver probe to fail for GENI serial.

To prevent probe failures, dynamically assign line numbers if an alias is
not present in the device tree for non-console ports.

Signed-off-by: Viken Dadhaniya <quic_vdadhani@...cinc.com>
---

v1 -> v2:

- Used IDA APIs instead of IDR APIs.
- Updated commit log.

v1 Link: https://lore.kernel.org/lkml/2025030758-efficient-pledge-ba4c@gregkh/T/
---
---
 drivers/tty/serial/qcom_geni_serial.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index a80ce7aaf309..0293b6210aa6 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -98,6 +98,8 @@
 
 #define DMA_RX_BUF_SIZE		2048
 
+static DEFINE_IDA(port_ida);
+
 struct qcom_geni_device_data {
 	bool console;
 	enum geni_se_xfer_mode mode;
@@ -253,10 +255,24 @@ static struct qcom_geni_serial_port *get_port_from_line(int line, bool console)
 	struct qcom_geni_serial_port *port;
 	int nr_ports = console ? GENI_UART_CONS_PORTS : GENI_UART_PORTS;
 
-	if (line < 0 || line >= nr_ports)
-		return ERR_PTR(-ENXIO);
+	if (console) {
+		if (line < 0 || line >= nr_ports)
+			return ERR_PTR(-ENXIO);
+
+		port = &qcom_geni_console_port;
+	} else {
+		int max_alias_num = of_alias_get_highest_id("serial");
+
+		if (line < 0 || line >= nr_ports)
+			line = ida_alloc_range(&port_ida, max_alias_num + 1, nr_ports, GFP_KERNEL);
+		else
+			line = ida_alloc_range(&port_ida, line, nr_ports, GFP_KERNEL);
+
+		if (line < 0)
+			return ERR_PTR(-ENXIO);
 
-	port = console ? &qcom_geni_console_port : &qcom_geni_uart_ports[line];
+		port = &qcom_geni_uart_ports[line];
+	}
 	return port;
 }
 
@@ -1761,6 +1777,7 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 						port->wakeup_irq);
 		if (ret) {
 			device_init_wakeup(&pdev->dev, false);
+			ida_free(&port_ida, uport->line);
 			uart_remove_one_port(drv, uport);
 			return ret;
 		}
@@ -1772,10 +1789,12 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 static void qcom_geni_serial_remove(struct platform_device *pdev)
 {
 	struct qcom_geni_serial_port *port = platform_get_drvdata(pdev);
+	struct uart_port *uport = &port->uport;
 	struct uart_driver *drv = port->private_data.drv;
 
 	dev_pm_clear_wake_irq(&pdev->dev);
 	device_init_wakeup(&pdev->dev, false);
+	ida_free(&port_ida, uport->line);
 	uart_remove_one_port(drv, &port->uport);
 }
 
-- 
2.34.1