tty: serial: imx: Allow UART to be a source for wakeup

Allow UART to be a source for wakeup from low power mode.

Tested on a MX27PDK by doing:

echo enabled > /sys/devices/platform/imx21-uart.0/tty/ttymxc0/power/wakeup

echo mem > /sys/power/state

and then pressing a key in the console will wakeup the sytem.

Suggested-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Tested-by: Richard Zhao <richard.zhao@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 962cafa175f7..ed6e1448e7eb 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -566,6 +566,9 @@ static irqreturn_t imx_int(int irq, void *dev_id)
         if (sts & USR1_RTSD)
                 imx_rtsint(irq, dev_id);
 
+        if (sts & USR1_AWAKE)
+                writel(USR1_AWAKE, sport->port.membase + USR1);
+
         return IRQ_HANDLED;
 }
 
@@ -1269,6 +1272,12 @@ static struct uart_driver imx_reg = {
 static int serial_imx_suspend(struct platform_device *dev, pm_message_t state)
 {
         struct imx_port *sport = platform_get_drvdata(dev);
+        unsigned int val;
+
+        /* enable wakeup from i.MX UART */
+        val = readl(sport->port.membase + UCR3);
+        val |= UCR3_AWAKEN;
+        writel(val, sport->port.membase + UCR3);
 
         if (sport)
                 uart_suspend_port(&imx_reg, &sport->port);
@@ -1279,6 +1288,12 @@ static int serial_imx_suspend(struct platform_device *dev, pm_message_t state)
 static int serial_imx_resume(struct platform_device *dev)
 {
         struct imx_port *sport = platform_get_drvdata(dev);
+        unsigned int val;
+
+        /* disable wakeup from i.MX UART */
+        val = readl(sport->port.membase + UCR3);
+        val &= ~UCR3_AWAKEN;
+        writel(val, sport->port.membase + UCR3);
 
         if (sport)
                 uart_resume_port(&imx_reg, &sport->port);