[PATCH v3 2/2] uart: mediatek: support Rx in-band wakeup

Nicolas Boichat drinkcat at chromium.org
Sun Jun 2 20:31:25 PDT 2019


On Mon, May 27, 2019 at 4:32 PM Claire Chang <tientzu at chromium.org> wrote:
>
> In order to support Rx in-band wakeup, we need to enable irq wake on an
> edge sensitive interrupt of Rx pin before suspend and disable it when
> resuming.
>
> This interrupt is used only as wake source to resume the system when
> suspended. Note that the sent character will be lost as the controller is
> actually suspended.
>
> We use this to support wakeup on bluetooth. Bluetooth will repeatedly send
> 0xFD to wakeup host. Once host detects Rx falling, an interrupt is
> triggered, and the system leaves sleep state. Then, the bluetooth driver
> will send 0xFC to bluetooth and bluetooth can start to send normal HCI
> packets.
>
> Signed-off-by: Claire Chang <tientzu at chromium.org>

Reviewed-by: Nicolas Boichat <drinkcat at chromium.org>

> ---
>  drivers/tty/serial/8250/8250_mtk.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>
> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
> index 417c7c810df9..5b94b853387d 100644
> --- a/drivers/tty/serial/8250/8250_mtk.c
> +++ b/drivers/tty/serial/8250/8250_mtk.c
> @@ -10,6 +10,7 @@
>  #include <linux/module.h>
>  #include <linux/of_irq.h>
>  #include <linux/of_platform.h>
> +#include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/serial_8250.h>
> @@ -70,6 +71,7 @@ struct mtk8250_data {
>  #ifdef CONFIG_SERIAL_8250_DMA
>         enum dma_rx_status      rx_status;
>  #endif
> +       int                     rx_wakeup_irq;
>  };
>
>  /* flow control mode */
> @@ -551,6 +553,8 @@ static int mtk8250_probe(struct platform_device *pdev)
>         pm_runtime_set_active(&pdev->dev);
>         pm_runtime_enable(&pdev->dev);
>
> +       data->rx_wakeup_irq = platform_get_irq(pdev, 1);
> +
>         return 0;
>  }
>
> @@ -572,15 +576,35 @@ static int mtk8250_remove(struct platform_device *pdev)
>  static int __maybe_unused mtk8250_suspend(struct device *dev)
>  {
>         struct mtk8250_data *data = dev_get_drvdata(dev);
> +       int irq = data->rx_wakeup_irq;
> +       int err;
>
>         serial8250_suspend_port(data->line);
>
> +       pinctrl_pm_select_sleep_state(dev);
> +       if (irq >= 0) {
> +               err = enable_irq_wake(irq);
> +               if (err) {
> +                       dev_err(dev,
> +                               "failed to enable irq wake on IRQ %d: %d\n",
> +                               irq, err);
> +                       pinctrl_pm_select_default_state(dev);
> +                       serial8250_resume_port(data->line);
> +                       return err;
> +               }
> +       }
> +
>         return 0;
>  }
>
>  static int __maybe_unused mtk8250_resume(struct device *dev)
>  {
>         struct mtk8250_data *data = dev_get_drvdata(dev);
> +       int irq = data->rx_wakeup_irq;
> +
> +       if (irq >= 0)
> +               disable_irq_wake(irq);
> +       pinctrl_pm_select_default_state(dev);
>
>         serial8250_resume_port(data->line);
>
> --
> 2.22.0.rc1.257.g3120a18244-goog
>



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