tty: serial: qcom_geni_serial: Wakeup over UART RX

Add system wakeup capability over UART RX line for wakeup capable UART.
When system is suspended, RX line act as an interrupt to wakeup system
for any communication requests from peer.

Signed-off-by: Akash Asthana <akashast@codeaurora.org>
Link: https://lore.kernel.org/r/1570700803-17566-1-git-send-email-akashast@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/qcom_geni_serial.c

@@ -14,6 +14,7 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/pm_wakeirq.h>
 #include <linux/qcom-geni-se.h>
 #include <linux/serial.h>
 #include <linux/serial_core.h>
@@ -116,6 +117,7 @@ struct qcom_geni_serial_port {
 	bool brk;
 
 	unsigned int tx_remaining;
+	int wakeup_irq;
 };
 
 static const struct uart_ops qcom_geni_console_pops;
@@ -755,6 +757,15 @@ out_write_wakeup:
 		uart_write_wakeup(uport);
 }
 
+static irqreturn_t qcom_geni_serial_wakeup_isr(int isr, void *dev)
+{
+	struct uart_port *uport = dev;
+
+	pm_wakeup_event(uport->dev, 2000);
+
+	return IRQ_HANDLED;
+}
+
 static irqreturn_t qcom_geni_serial_isr(int isr, void *dev)
 {
 	u32 m_irq_en;
@@ -1306,6 +1317,29 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	if (!console) {
+		port->wakeup_irq = platform_get_irq(pdev, 1);
+		if (port->wakeup_irq < 0) {
+			dev_err(&pdev->dev, "Failed to get wakeup IRQ %d\n",
+					port->wakeup_irq);
+		} else {
+			irq_set_status_flags(port->wakeup_irq, IRQ_NOAUTOEN);
+			ret = devm_request_irq(uport->dev, port->wakeup_irq,
+				qcom_geni_serial_wakeup_isr,
+				IRQF_TRIGGER_FALLING, "uart_wakeup", uport);
+			if (ret) {
+				dev_err(uport->dev, "Failed to register wakeup IRQ ret %d\n",
+						ret);
+				return ret;
+			}
+
+			device_init_wakeup(&pdev->dev, true);
+			ret = dev_pm_set_wake_irq(&pdev->dev, port->wakeup_irq);
+			if (unlikely(ret))
+				dev_err(uport->dev, "%s:Failed to set IRQ wake:%d\n",
+						__func__, ret);
+		}
+	}
 	uport->private_data = drv;
 	platform_set_drvdata(pdev, port);
 	port->handle_rx = console ? handle_rx_console : handle_rx_uart;
@@ -1328,7 +1362,12 @@ static int __maybe_unused qcom_geni_serial_sys_suspend(struct device *dev)
 	struct qcom_geni_serial_port *port = dev_get_drvdata(dev);
 	struct uart_port *uport = &port->uport;
 
-	return uart_suspend_port(uport->private_data, uport);
+	uart_suspend_port(uport->private_data, uport);
+
+	if (port->wakeup_irq > 0)
+		enable_irq(port->wakeup_irq);
+
+	return 0;
 }
 
 static int __maybe_unused qcom_geni_serial_sys_resume(struct device *dev)
@@ -1336,6 +1375,9 @@ static int __maybe_unused qcom_geni_serial_sys_resume(struct device *dev)
 	struct qcom_geni_serial_port *port = dev_get_drvdata(dev);
 	struct uart_port *uport = &port->uport;
 
+	if (port->wakeup_irq > 0)
+		disable_irq(port->wakeup_irq);
+
 	return uart_resume_port(uport->private_data, uport);
 }