On Wed, Apr 06, 2022 at 11:39:16PM +0200, Javier Martinez Canillas wrote:
> These can be used by subsystems to unregister a platform device registered
> by sysfb and also to disable future platform device registration in sysfb.
>
> Suggested-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
> ---
>
> drivers/firmware/sysfb.c | 47 +++++++++++++++++++++++++++++++++++-----
> include/linux/sysfb.h | 19 ++++++++++++++++
> 2 files changed, 60 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c
> index b032f40a92de..08ae78c083f1 100644
> --- a/drivers/firmware/sysfb.c
> +++ b/drivers/firmware/sysfb.c
> @@ -34,21 +34,52 @@
> #include <linux/screen_info.h>
> #include <linux/sysfb.h>
>
> +static struct platform_device *pd;
> +static DEFINE_MUTEX(load_lock);
> +static bool disabled;
> +
> +void sysfb_disable(void)
> +{
> + mutex_lock(&load_lock);
> + disabled = true;
> + mutex_unlock(&load_lock);
> +}
> +EXPORT_SYMBOL_GPL(sysfb_disable);
> +
> +bool sysfb_try_unregister(struct device *dev)
> +{
> + bool ret = true;
> +
> + mutex_lock(&load_lock);
> + if (!pd || pd != to_platform_device(dev))
> + return false;
> +
> + platform_device_unregister(to_platform_device(dev));
> + pd = NULL;
> + mutex_unlock(&load_lock);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(sysfb_try_unregister);
Kerneldoc for these plus adding that to
Documentation/firmware/other_interfaces.rst would be really neat.
With that added Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> +
> static __init int sysfb_init(void)
> {
> struct screen_info *si = &screen_info;
> struct simplefb_platform_data mode;
> - struct platform_device *pd;
> const char *name;
> bool compatible;
> - int ret;
> + int ret = 0;
> +
> + mutex_lock(&load_lock);
> + if (disabled)
> + goto unlock_mutex;
>
> /* try to create a simple-framebuffer device */
> compatible = sysfb_parse_mode(si, &mode);
> if (compatible) {
> pd = sysfb_create_simplefb(si, &mode);
> if (!IS_ERR(pd))
> - return 0;
> + goto unlock_mutex;
> }
>
> /* if the FB is incompatible, create a legacy framebuffer device */
> @@ -60,8 +91,10 @@ static __init int sysfb_init(void)
> name = "platform-framebuffer";
>
> pd = platform_device_alloc(name, 0);
> - if (!pd)
> - return -ENOMEM;
> + if (!pd) {
> + ret = -ENOMEM;
> + goto unlock_mutex;
> + }
>
> sysfb_apply_efi_quirks(pd);
>
> @@ -73,9 +106,11 @@ static __init int sysfb_init(void)
> if (ret)
> goto err;
>
> - return 0;
> + goto unlock_mutex;
> err:
> platform_device_put(pd);
> +unlock_mutex:
> + mutex_unlock(&load_lock);
> return ret;
> }
>
> diff --git a/include/linux/sysfb.h b/include/linux/sysfb.h
> index 708152e9037b..e8c0313fac8f 100644
> --- a/include/linux/sysfb.h
> +++ b/include/linux/sysfb.h
> @@ -55,6 +55,25 @@ struct efifb_dmi_info {
> int flags;
> };
>
> +#ifdef CONFIG_SYSFB
> +
> +void sysfb_disable(void);
> +bool sysfb_try_unregister(struct device *dev);
> +
> +#else /* CONFIG_SYSFB */
> +
> +static inline void sysfb_disable(void)
> +{
> +
> +}
> +
> +static inline bool sysfb_try_unregister(struct device *dev)
> +{
> + return false;
> +}
> +
> +#endif /* CONFIG_SYSFB */
> +
> #ifdef CONFIG_EFI
>
> extern struct efifb_dmi_info efifb_dmi_list[];
> --
> 2.35.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
