On Tue, May 21, 2019 at 4:47 PM Claire Chang <tientzu@xxxxxxxxxxxx> 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@xxxxxxxxxxxx>
> ---
> drivers/tty/serial/8250/8250_mtk.c | 33 ++++++++++++++++++++++++++++++
> 1 file changed, 33 insertions(+)
>
> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
> index 417c7c810df9..61892abf707d 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 +576,44 @@ 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);
> + struct uart_8250_port *up = serial8250_get_port(data->line);
> + 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;
> + int err;
> +
> + if (irq >= 0) {
> + err = disable_irq_wake(irq);
> + if (err) {
> + dev_err(dev,
> + "failed to disable irq wake on IRQ %d: %d\n",
> + irq, err);
> + return err;
I'd drop this return err in the resume path, still better to restore
the pinctrl and resume the port, even if we can't disable the irq_wake
(which, really, shouldn't happen if we could enable it earlier...).
Also, many other callers of disable_irq_wake just ignore the return
value, so maybe it's ok to do the same, but I'll let other people
comment.
> + }
> + }
> + pinctrl_pm_select_default_state(dev);
>
> serial8250_resume_port(data->line);
>
> --
> 2.21.0.1020.gf2820cf01a-goog
>
>
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