Am 11.05.22 um 13:24 schrieb Javier Martinez Canillas: > 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 > Signed-off-by: Javier Martinez Canillas > Reviewed-by: Daniel Vetter > --- > > (no changes since v4) > > Changes in v4: > - Make sysfb_disable() to also attempt to unregister a device. > > Changes in v2: > - Add kernel-doc comments and include in other_interfaces.rst (Daniel Vetter). > > .../driver-api/firmware/other_interfaces.rst | 6 ++ > drivers/firmware/sysfb.c | 87 +++++++++++++++++-- > include/linux/sysfb.h | 19 ++++ > 3 files changed, 106 insertions(+), 6 deletions(-) > > diff --git a/Documentation/driver-api/firmware/other_interfaces.rst b/Documentation/driver-api/firmware/other_interfaces.rst > index b81794e0cfbb..06ac89adaafb 100644 > --- a/Documentation/driver-api/firmware/other_interfaces.rst > +++ b/Documentation/driver-api/firmware/other_interfaces.rst > @@ -13,6 +13,12 @@ EDD Interfaces > .. kernel-doc:: drivers/firmware/edd.c > :internal: > > +Generic System Framebuffers Interface > +------------------------------------- > + > +.. kernel-doc:: drivers/firmware/sysfb.c > + :export: > + > Intel Stratix10 SoC Service Layer > --------------------------------- > Some features of the Intel Stratix10 SoC require a level of privilege > diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c > index b032f40a92de..6768968949e6 100644 > --- a/drivers/firmware/sysfb.c > +++ b/drivers/firmware/sysfb.c > @@ -34,21 +34,92 @@ > #include > #include > > +static struct platform_device *pd; > +static DEFINE_MUTEX(disable_lock); > +static bool disabled; > + > +static bool sysfb_unregister(void) > +{ > + if (IS_ERR_OR_NULL(pd)) > + return false; > + > + platform_device_unregister(pd); > + pd = NULL; > + > + return true; > +} > + > +/** > + * sysfb_disable() - disable the Generic System Framebuffers support > + * > + * This disables the registration of system framebuffer devices that match the > + * generic drivers that make use of the system framebuffer set up by firmware. > + * > + * It also unregisters a device if this was already registered by sysfb_init(). Why? I still cannot wrap my mind around, why we need to store *pd at all and use sysfb_try_unregister() for unregistering. > + * > + * Context: The function can sleep. A @disable_lock mutex is acquired to serialize > + * against sysfb_init(), that registers a system framebuffer device and > + * sysfb_try_unregister(), that tries to unregister a framebuffer device. > + */ > +void sysfb_disable(void) > +{ > + mutex_lock(&disable_lock); > + sysfb_unregister(); > + disabled = true; > + mutex_unlock(&disable_lock); > +} > +EXPORT_SYMBOL_GPL(sysfb_disable); > + > +/** > + * sysfb_try_unregister() - attempt to unregister a system framebuffer device > + * @dev: device to unregister > + * > + * This tries to unregister a system framebuffer device if this was registered > + * by the Generic System Framebuffers. The device will only be unregistered if > + * it was registered by sysfb_init(), otherwise it will not be unregistered. > + * > + * Context: The function can sleep. a @load_lock mutex is acquired to serialize > + * against sysfb_init(), that registers a simple framebuffer device and > + * sysfb_disable(), that disables the Generic System Framebuffers support. > + * > + * Return: > + * * true - the device was unregistered successfully > + * * false - the device was not unregistered > + */ > +bool sysfb_try_unregister(struct device *dev) As it stands, I strongly object the use of this function as still don't really get the purpose. It looks like a glorified wrapper around platform_device_unregister(). Do we need disable_lock to serialize with something else? Best regards Thomas > +{ > + bool ret = false; > + > + mutex_lock(&disable_lock); > + if (IS_ERR_OR_NULL(pd) || pd != to_platform_device(dev)) > + goto unlock_mutex; > + > + ret = sysfb_unregister(); > + > +unlock_mutex: > + mutex_unlock(&disable_lock); > + return ret; > +} > +EXPORT_SYMBOL_GPL(sysfb_try_unregister); > + > 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(&disable_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 +131,10 @@ 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 +146,11 @@ static __init int sysfb_init(void) > if (ret) > goto err; > > - return 0; > + goto unlock_mutex; > err: > platform_device_put(pd); > +unlock_mutex: > + mutex_unlock(&disable_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[]; -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev