Unverified Commit bc824922 authored by Javier Martinez Canillas's avatar Javier Martinez Canillas
Browse files

firmware: sysfb: Add sysfb_disable() helper function 



This 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: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: default avatarJavier Martinez Canillas <javierm@redhat.com>
Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220607182338.344270-3-javierm@redhat.com
parent 0949ee75

Documentation/driver-api/firmware/other_interfaces.rst

+6 −0
Original line number Diff line number Diff line
@@ -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

drivers/firmware/sysfb.c

+48 −6
Original line number Diff line number Diff line
@@ -34,21 +34,59 @@ 
#include <linux/screen_info.h>

#include <linux/sysfb.h>



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().

 *

 * Context: The function can sleep. A @disable_lock mutex is acquired to serialize

 *          against sysfb_init(), that registers a system framebuffer device.

 */

void sysfb_disable(void)

{

	mutex_lock(&disable_lock);

	sysfb_unregister();

	disabled = true;

	mutex_unlock(&disable_lock);

}

EXPORT_SYMBOL_GPL(sysfb_disable);



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 +98,10 @@ 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 +113,11 @@ 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;

}

include/linux/sysfb.h

+12 −0
Original line number Diff line number Diff line
@@ -55,6 +55,18 @@ struct efifb_dmi_info { 
	int flags;

};



#ifdef CONFIG_SYSFB



void sysfb_disable(void);



#else /* CONFIG_SYSFB */



static inline void sysfb_disable(void)

{

}



#endif /* CONFIG_SYSFB */



#ifdef CONFIG_EFI



extern struct efifb_dmi_info efifb_dmi_list[];