Re: [RFC 1/3] serdev: Add ACPI support

[Marcel Holtmann <marcel@holtmann.org>]

Hi Fred,

> Signed-off-by: Frédéric Danis <frederic.danis.oss@gmail.com>
> ---
> drivers/tty/serdev/core.c | 99 ++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 94 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
> index ae1aaa0..923dd4ad 100644
> --- a/drivers/tty/serdev/core.c
> +++ b/drivers/tty/serdev/core.c
> @@ -14,6 +14,7 @@
>  * GNU General Public License for more details.
>  */
> 
> +#include <linux/acpi.h>
> #include <linux/errno.h>
> #include <linux/idr.h>
> #include <linux/kernel.h>
> @@ -49,13 +50,22 @@ static const struct device_type serdev_ctrl_type = {
> 
> static int serdev_device_match(struct device *dev, struct device_driver *drv)
> {
> -	/* TODO: ACPI and platform matching */
> +	/* TODO: platform matching */
> +	if (acpi_driver_match_device(dev, drv))
> +		return 1;
> +
> 	return of_driver_match_device(dev, drv);
> }
> 
> static int serdev_uevent(struct device *dev, struct kobj_uevent_env *env)
> {
> -	/* TODO: ACPI and platform modalias */
> +	int rc;
> +
> +	/* TODO: platform modalias */
> +	rc = acpi_device_uevent_modalias(dev, env);
> +	if (rc != -ENODEV)
> +		return rc;
> +
> 	return of_device_uevent_modalias(dev, env);
> }
> 
> @@ -260,6 +270,12 @@ static int serdev_drv_remove(struct device *dev)
> static ssize_t modalias_show(struct device *dev,
> 			     struct device_attribute *attr, char *buf)
> {
> +	int len;
> +
> +	len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
> +	if (len != -ENODEV)
> +		return len;
> +
> 	return of_device_modalias(dev, buf, PAGE_SIZE);
> }
> DEVICE_ATTR_RO(modalias);
> @@ -385,6 +401,74 @@ static int of_serdev_register_devices(struct serdev_controller *ctrl)
> 	return 0;
> }
> 
> +#ifdef CONFIG_ACPI
> +static acpi_status acpi_serdev_register_device(struct serdev_controller *ctrl,
> +					    struct acpi_device *adev)
> +{
> +	struct serdev_device *serdev = NULL;
> +	int err;
> +
> +	if (acpi_bus_get_status(adev) || !adev->status.present ||
> +	    acpi_device_enumerated(adev))
> +		return AE_OK;
> +
> +	serdev = serdev_device_alloc(ctrl);
> +	if (!serdev) {
> +		dev_err(&ctrl->dev, "failed to allocate Serial device for %s\n",
> +			dev_name(&adev->dev));
> +		return AE_NO_MEMORY;
> +	}
> +
> +	ACPI_COMPANION_SET(&serdev->dev, adev);
> +	acpi_device_set_enumerated(adev);
> +
> +	err = serdev_device_add(serdev);
> +	if (err) {
> +		dev_err(&serdev->dev,
> +			"failure adding ACPI device. status %d\n", err);
> +		serdev_device_put(serdev);
> +	}
> +
> +	return AE_OK;
> +}
> +
> +static acpi_status acpi_serdev_add_device(acpi_handle handle, u32 level,
> +				       void *data, void **return_value)
> +{
> +	struct serdev_controller *ctrl = data;
> +	struct acpi_device *adev;
> +
> +	if (acpi_bus_get_device(handle, &adev))
> +		return AE_OK;
> +
> +	return acpi_serdev_register_device(ctrl, adev);
> +}
> +
> +static int acpi_serdev_register_devices(struct serdev_controller *ctrl)
> +{
> +	acpi_status status;
> +	acpi_handle handle;
> +
> +	handle = ACPI_HANDLE(ctrl->dev.parent);
> +	if (!handle)
> +		return -ENODEV;
> +
> +	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
> +				     acpi_serdev_add_device, NULL, ctrl, NULL);
> +	if (ACPI_FAILURE(status)) {
> +		dev_warn(&ctrl->dev, "failed to enumerate Serial slaves\n");
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}

how are we ensuring that we only take UART devices into account here?

> +#else
> +static inline int acpi_serdev_register_devices(struct serdev_controller *ctlr)
> +{
> +	return -ENODEV;
> +}
> +#endif /* CONFIG_ACPI */
> +
> /**
>  * serdev_controller_add() - Add an serdev controller
>  * @ctrl:	controller to be registered.
> @@ -394,7 +478,7 @@ static int of_serdev_register_devices(struct serdev_controller *ctrl)
>  */
> int serdev_controller_add(struct serdev_controller *ctrl)
> {
> -	int ret;
> +	int ret_of, ret_acpi, ret;
> 
> 	/* Can't register until after driver model init */
> 	if (WARN_ON(!is_registered))
> @@ -404,9 +488,14 @@ int serdev_controller_add(struct serdev_controller *ctrl)
> 	if (ret)
> 		return ret;
> 
> -	ret = of_serdev_register_devices(ctrl);
> -	if (ret)
> +	ret_of = of_serdev_register_devices(ctrl);
> +	ret_acpi = acpi_serdev_register_devices(ctrl);
> +	if (ret_of && ret_acpi) {
> +		dev_dbg(&ctrl->dev, "serdev%d no devices registered: of:%d acpi:%d\n",
> +			ctrl->nr, ret_of, ret_acpi);
> +		ret = -ENODEV;
> 		goto out_dev_del;
> +	}
> 
> 	dev_dbg(&ctrl->dev, "serdev%d registered: dev:%p\n",
> 		ctrl->nr, &ctrl->dev);

Shouldn’t we just consider to always register the controller? Even if there are no devices attached to it.

Regards

Marcel