[PATCH v2 1/2] serdev: Split and export serdev_acpi_get_uart_resource()

[PATCH v2 1/2] serdev: Split and export serdev_acpi_get_uart_resource()

[Andy Shevchenko]

The same as for I²C Serial Bus resource split and export
serdev_acpi_get_uart_resource(). We have already a few users
one of which is converted here.

Rationale of this is to consolidate parsing UART Serial Bus
resource in one place as it's done, e.g., for I²C Serial Bus.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
---
v2: added Rb tag (Hans)
 drivers/tty/serdev/core.c | 36 +++++++++++++++++++++++++++++-------
 include/linux/serdev.h    | 14 ++++++++++++++
 2 files changed, 43 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
index 92498961fd92..436e3d1ba92c 100644
--- a/drivers/tty/serdev/core.c
+++ b/drivers/tty/serdev/core.c
@@ -562,23 +562,45 @@ struct acpi_serdev_lookup {
 	int index;
 };
 
+/**
+ * serdev_acpi_get_uart_resource - Gets UARTSerialBus resource if type matches
+ * @ares:	ACPI resource
+ * @uart:	Pointer to UARTSerialBus resource will be returned here
+ *
+ * Checks if the given ACPI resource is of type UARTSerialBus.
+ * In this case, returns a pointer to it to the caller.
+ *
+ * Returns true if resource type is of UARTSerialBus, otherwise false.
+ */
+bool serdev_acpi_get_uart_resource(struct acpi_resource *ares,
+				   struct acpi_resource_uart_serialbus **uart)
+{
+	struct acpi_resource_uart_serialbus *sb;
+
+	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+		return false;
+
+	sb = &ares->data.uart_serial_bus;
+	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_UART)
+		return false;
+
+	*uart = sb;
+	return true;
+}
+EXPORT_SYMBOL_GPL(serdev_acpi_get_uart_resource);
+
 static int acpi_serdev_parse_resource(struct acpi_resource *ares, void *data)
 {
 	struct acpi_serdev_lookup *lookup = data;
 	struct acpi_resource_uart_serialbus *sb;
 	acpi_status status;
 
-	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
-		return 1;
-
-	if (ares->data.common_serial_bus.type != ACPI_RESOURCE_SERIAL_TYPE_UART)
+	if (!serdev_acpi_get_uart_resource(ares, &sb))
 		return 1;
 
 	if (lookup->index != -1 && lookup->n++ != lookup->index)
 		return 1;
 
-	sb = &ares->data.uart_serial_bus;
-
 	status = acpi_get_handle(lookup->device_handle,
 				 sb->resource_source.string_ptr,
 				 &lookup->controller_handle);
@@ -586,7 +608,7 @@ static int acpi_serdev_parse_resource(struct acpi_resource *ares, void *data)
 		return 1;
 
 	/*
-	 * NOTE: Ideally, we would also want to retreive other properties here,
+	 * NOTE: Ideally, we would also want to retrieve other properties here,
 	 * once setting them before opening the device is supported by serdev.
 	 */
 
diff --git a/include/linux/serdev.h b/include/linux/serdev.h
index 9f14f9c12ec4..3368c261ab62 100644
--- a/include/linux/serdev.h
+++ b/include/linux/serdev.h
@@ -327,4 +327,18 @@ static inline int serdev_tty_port_unregister(struct tty_port *port)
 }
 #endif /* CONFIG_SERIAL_DEV_CTRL_TTYPORT */
 
+struct acpi_resource;
+struct acpi_resource_uart_serialbus;
+
+#ifdef CONFIG_ACPI
+bool serdev_acpi_get_uart_resource(struct acpi_resource *ares,
+				   struct acpi_resource_uart_serialbus **uart);
+#else
+static inline bool serdev_acpi_get_uart_resource(struct acpi_resource *ares,
+						 struct acpi_resource_uart_serialbus **uart)
+{
+	return false;
+}
+#endif /* CONFIG_ACPI */
+
 #endif /*_LINUX_SERDEV_H */
-- 
2.30.2

[PATCH v2 2/2] platform/surface: aggregator: Use serdev_acpi_get_uart_resource() helper

[Andy Shevchenko]

serdev provides a generic helper to get UART Serial Bus resources.
Use it instead of an open coded variant.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com>
---
v2: added Rb tag (Maximilian)
 drivers/platform/surface/aggregator/core.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/platform/surface/aggregator/core.c b/drivers/platform/surface/aggregator/core.c
index 279d9df19c01..c61bbeeec2df 100644
--- a/drivers/platform/surface/aggregator/core.c
+++ b/drivers/platform/surface/aggregator/core.c
@@ -301,20 +301,13 @@ static acpi_status ssam_serdev_setup_via_acpi_crs(struct acpi_resource *rsc,
 						  void *ctx)
 {
 	struct serdev_device *serdev = ctx;
-	struct acpi_resource_common_serialbus *serial;
 	struct acpi_resource_uart_serialbus *uart;
 	bool flow_control;
 	int status = 0;
 
-	if (rsc->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+	if (!serdev_acpi_get_uart_resource(rsc, &uart))
 		return AE_OK;
 
-	serial = &rsc->data.common_serial_bus;
-	if (serial->type != ACPI_RESOURCE_SERIAL_TYPE_UART)
-		return AE_OK;
-
-	uart = &rsc->data.uart_serial_bus;
-
 	/* Set up serdev device. */
 	serdev_device_set_baudrate(serdev, uart->default_baud_rate);
 
-- 
2.30.2

Re: [PATCH v2 1/2] serdev: Split and export serdev_acpi_get_uart_resource()

[Jiri Slaby]

On 04. 08. 21, 16:29, Andy Shevchenko wrote:
> The same as for I²C Serial Bus resource split and export
> serdev_acpi_get_uart_resource(). We have already a few users
> one of which is converted here.
> 
> Rationale of this is to consolidate parsing UART Serial Bus
> resource in one place as it's done, e.g., for I²C Serial Bus.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>
> ---
> v2: added Rb tag (Hans)
>   drivers/tty/serdev/core.c | 36 +++++++++++++++++++++++++++++-------
>   include/linux/serdev.h    | 14 ++++++++++++++
>   2 files changed, 43 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
> index 92498961fd92..436e3d1ba92c 100644
> --- a/drivers/tty/serdev/core.c
> +++ b/drivers/tty/serdev/core.c
> @@ -562,23 +562,45 @@ struct acpi_serdev_lookup {
>   	int index;
>   };
>   
> +/**
> + * serdev_acpi_get_uart_resource - Gets UARTSerialBus resource if type matches
> + * @ares:	ACPI resource
> + * @uart:	Pointer to UARTSerialBus resource will be returned here
> + *
> + * Checks if the given ACPI resource is of type UARTSerialBus.
> + * In this case, returns a pointer to it to the caller.
> + *
> + * Returns true if resource type is of UARTSerialBus, otherwise false.

Better to write:
  * Return: True if resource type is of UARTSerialBus, otherwise false.
which is recognized by sphinx.

> + */
> +bool serdev_acpi_get_uart_resource(struct acpi_resource *ares,
> +				   struct acpi_resource_uart_serialbus **uart)
> +{
> +	struct acpi_resource_uart_serialbus *sb;
> +
> +	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
> +		return false;
> +
> +	sb = &ares->data.uart_serial_bus;
> +	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_UART)
> +		return false;
> +
> +	*uart = sb;
> +	return true;

Why don't you return NULL, or sb, thus eliminating the parameter?

> +}
> +EXPORT_SYMBOL_GPL(serdev_acpi_get_uart_resource);

thanks,
-- 
js
suse labs

Re: [PATCH v2 1/2] serdev: Split and export serdev_acpi_get_uart_resource()

[Andy Shevchenko]

On Thu, Aug 5, 2021 at 10:36 AM Jiri Slaby <jirislaby@kernel.org> wrote:
> On 04. 08. 21, 16:29, Andy Shevchenko wrote:

...

> > +/**
> > + * serdev_acpi_get_uart_resource - Gets UARTSerialBus resource if type matches
> > + * @ares:    ACPI resource
> > + * @uart:    Pointer to UARTSerialBus resource will be returned here
> > + *
> > + * Checks if the given ACPI resource is of type UARTSerialBus.
> > + * In this case, returns a pointer to it to the caller.
> > + *
> > + * Returns true if resource type is of UARTSerialBus, otherwise false.
>
> Better to write:
>   * Return: True if resource type is of UARTSerialBus, otherwise false.
> which is recognized by sphinx.

Will fix it in v3.

> > + */

...

> Why don't you return NULL, or sb, thus eliminating the parameter?

1. That's how other similar APIs are done.
2. It will save a line of code in the callers. Usual pattern
  if (...get_res(..., &sb))
   return ERR_or_so;

With your proposal

  sb = get_res(...);
  if (!sb)
    return ERR_or_so;

> > +}

-- 
With Best Regards,
Andy Shevchenko