[PATCH 0/2] support 8250-mtk uart in-band wake up

[PATCH 0/2] support 8250-mtk uart in-band wake up

[Claire Chang]

enable irq wake on an edge sensitive interrupt of Rx pin before suspend to
support uart in-band wake up

Claire Chang (2):
  dt-bindings: serial: add documentation for Rx in-band wakeup support
  uart: mediatek: support Rx in-band wakeup

 .../devicetree/bindings/serial/mtk-uart.txt   | 13 ++++++--
 drivers/tty/serial/8250/8250_mtk.c            | 33 +++++++++++++++++++
 2 files changed, 44 insertions(+), 2 deletions(-)

-- 
2.21.0.1020.gf2820cf01a-goog

[PATCH 1/2] dt-bindings: serial: add documentation for Rx in-band wakeup support

[Claire Chang]

Signed-off-by: Claire Chang <tientzu-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
---
 .../devicetree/bindings/serial/mtk-uart.txt         | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/serial/mtk-uart.txt b/Documentation/devicetree/bindings/serial/mtk-uart.txt
index c6b5262eb352..11966de2a4b3 100644
--- a/Documentation/devicetree/bindings/serial/mtk-uart.txt
+++ b/Documentation/devicetree/bindings/serial/mtk-uart.txt
@@ -23,7 +23,12 @@ Required properties:
 
 - reg: The base address of the UART register bank.
 
-- interrupts: A single interrupt specifier.
+- interrupts or interrupts-extended:
+  index 0: an interrupt specifier for the UART controller itself
+  index 1: optional, an interrupt specifier with edge sensitivity on Rx pin to
+           support Rx in-band wake up. If one would like to use this feature,
+           one must create an addtional pinctrl to reconfigure Rx pin to normal
+           GPIO before suspend.
 
 - clocks : Must contain an entry for each entry in clock-names.
   See ../clocks/clock-bindings.txt for details.
@@ -39,7 +44,11 @@ Example:
 	uart0: serial@11006000 {
 		compatible = "mediatek,mt6589-uart", "mediatek,mt6577-uart";
 		reg = <0x11006000 0x400>;
-		interrupts = <GIC_SPI 51 IRQ_TYPE_LEVEL_LOW>;
+		interrupts-extended = <&sysirq GIC_SPI 51 IRQ_TYPE_LEVEL_LOW>,
+				      <&gpio 121 IRQ_TYPE_EDGE_FALLING>;
 		clocks = <&uart_clk>, <&bus_clk>;
 		clock-names = "baud", "bus";
+		pinctrl-names = "default", "sleep";
+		pinctrl-0 = <&uart_pin>;
+		pinctrl-1 = <&uart_pin_sleep>;
 	};
-- 
2.21.0.1020.gf2820cf01a-goog

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

[Claire Chang]

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-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
---
 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;
+		}
+	}
+	pinctrl_pm_select_default_state(dev);
 
 	serial8250_resume_port(data->line);
 
-- 
2.21.0.1020.gf2820cf01a-goog

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

[Nicolas Boichat]

On Tue, May 21, 2019 at 4:47 PM Claire Chang <tientzu-F7+t8E8rja9g9hUCZPvPmw@public.gmane.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-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> ---
>  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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> Linux-mediatek-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
> http://lists.infradead.org/mailman/listinfo/linux-mediatek

Re: [PATCH 1/2] dt-bindings: serial: add documentation for Rx in-band wakeup support

[Greg KH]

On Tue, May 21, 2019 at 04:47:00PM +0800, Claire Chang wrote:
> Signed-off-by: Claire Chang <tientzu-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> ---

I can not take patches without any changelog text at all.  Part of
writing a good patch is actually describing why you are making a change.

thanks,

greg k-h