[PATCH v3 06/10] serial: stm32: add support for no_console_suspend

[Erwan Le Ray]

In order to display console messages in low power mode, console pins
must be kept active after suspend call.

Signed-off-by: Bich Hemon <bich.he...@st.com>
Signed-off-by: Erwan Le Ray <erwan.le...@st.com>

Conflicts:
        drivers/tty/serial/stm32-usart.c

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index b0fb420..00e4d7a 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -25,6 +25,7 @@
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/pinctrl/consumer.h>
+#include <linux/pinctrl/devinfo.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/pm_wakeirq.h>
@@ -847,6 +848,7 @@ static int stm32_init_port(struct stm32_port *stm32port,
 {
        struct uart_port *port = &stm32port->port;
        struct resource *res;
+       struct pinctrl *uart_pinctrl;
        int ret;
 
        port->iotype    = UPIO_MEM;
@@ -880,6 +882,24 @@ static int stm32_init_port(struct stm32_port *stm32port,
 
        stm32port->fifoen = stm32port->info->cfg.has_fifo;
 
+       uart_pinctrl = devm_pinctrl_get(&pdev->dev);
+       if (IS_ERR(uart_pinctrl)) {
+               ret = PTR_ERR(uart_pinctrl);
+               if (ret != -ENODEV) {
+                       dev_err(&pdev->dev, "Can't get pinctrl, error %d\n",
+                               ret);
+                       return ret;
+               }
+               stm32port->console_pins = ERR_PTR(-ENODEV);
+       } else {
+               stm32port->console_pins = pinctrl_lookup_state
+                       (uart_pinctrl, "no_console_suspend");
+       }
+
+       if (IS_ERR(stm32port->console_pins) && PTR_ERR(stm32port->console_pins)
+           != -ENODEV)
+               return PTR_ERR(stm32port->console_pins);
+
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        port->membase = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(port->membase))
@@ -1304,6 +1324,7 @@ static void __maybe_unused 
stm32_serial_enable_wakeup(struct uart_port *port,
 static int __maybe_unused stm32_serial_suspend(struct device *dev)
 {
        struct uart_port *port = dev_get_drvdata(dev);
+       struct stm32_port *stm32_port = to_stm32_port(port);
 
        uart_suspend_port(&stm32_usart_driver, port);
 
@@ -1312,7 +1333,19 @@ static int __maybe_unused stm32_serial_suspend(struct 
device *dev)
        else
                stm32_serial_enable_wakeup(port, false);
 
-       pinctrl_pm_select_sleep_state(dev);
+       if (uart_console(port) && !console_suspend_enabled) {
+               if (IS_ERR(stm32_port->console_pins)) {
+                       dev_err(dev, "no_console_suspend pinctrl not found\n");
+                       return PTR_ERR(stm32_port->console_pins);
+               }
+
+               pinctrl_select_state(dev->pins->p, stm32_port->console_pins);
+       } else {
+               if (device_may_wakeup(dev))
+                       pinctrl_pm_select_idle_state(dev);
+               else
+                       pinctrl_pm_select_sleep_state(dev);
+       }
 
        return 0;
 }
diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h
index 30d2433..050fe04 100644
--- a/drivers/tty/serial/stm32-usart.h
+++ b/drivers/tty/serial/stm32-usart.h
@@ -255,6 +255,7 @@ struct stm32_port {
        bool fifoen;
        int wakeirq;
        int rdr_mask;           /* receive data register mask */
+       struct pinctrl_state *console_pins;
 };
 
 static struct stm32_port stm32_ports[STM32_MAX_PORTS];
-- 
1.9.1