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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Generic System Framebuffers
* Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
*/
/*
* Simple-Framebuffer support
* Create a platform-device for any available boot framebuffer. The
* simple-framebuffer platform device is already available on DT systems, so
* this module parses the global "screen_info" object and creates a suitable
* platform device compatible with the "simple-framebuffer" DT object. If
* the framebuffer is incompatible, we instead create a legacy
* "vesa-framebuffer", "efi-framebuffer" or "platform-framebuffer" device and
* pass the screen_info as platform_data. This allows legacy drivers
* to pick these devices up without messing with simple-framebuffer drivers.
* The global "screen_info" is still valid at all times.
*
* If CONFIG_SYSFB_SIMPLEFB is not selected, never register "simple-framebuffer"
* platform devices, but only use legacy framebuffer devices for
* backwards compatibility.
*
* TODO: We set the dev_id field of all platform-devices to 0. This allows
* other OF/DT parsers to create such devices, too. However, they must
* start at offset 1 for this to work.
*/
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/pci.h>
#include <linux/platform_data/simplefb.h>
#include <linux/platform_device.h>
#include <linux/screen_info.h>
#include <linux/sysfb.h>
static struct platform_device *pd;
static DEFINE_MUTEX(disable_lock);
static bool disabled;
static struct device *sysfb_parent_dev(const struct screen_info *si);
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
* @dev: the device to check if non-NULL
*
* 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(struct device *dev)
{
struct screen_info *si = &screen_info;
struct device *parent;
mutex_lock(&disable_lock);
parent = sysfb_parent_dev(si);
if (!dev || !parent || dev == parent) {
sysfb_unregister();
disabled = true;
}
mutex_unlock(&disable_lock);
}
EXPORT_SYMBOL_GPL(sysfb_disable);
#if defined(CONFIG_PCI)
static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
{
/*
* TODO: Try to integrate this code into the PCI subsystem
*/
int ret;
u16 command;
ret = pci_read_config_word(pdev, PCI_COMMAND, &command);
if (ret != PCIBIOS_SUCCESSFUL)
return false;
if (!(command & PCI_COMMAND_MEMORY))
return false;
return true;
}
#else
static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
{
return false;
}
#endif
static struct device *sysfb_parent_dev(const struct screen_info *si)
{
struct pci_dev *pdev;
pdev = screen_info_pci_dev(si);
if (IS_ERR(pdev)) {
return ERR_CAST(pdev);
} else if (pdev) {
if (!sysfb_pci_dev_is_enabled(pdev)) {
pci_dev_put(pdev);
return ERR_PTR(-ENODEV);
}
return &pdev->dev;
}
return NULL;
}
static __init int sysfb_init(void)
{
struct screen_info *si = &screen_info;
struct device *parent;
struct simplefb_platform_data mode;
const char *name;
bool compatible;
int ret = 0;
screen_info_apply_fixups();
mutex_lock(&disable_lock);
if (disabled)
goto unlock_mutex;
sysfb_apply_efi_quirks();
parent = sysfb_parent_dev(si);
if (IS_ERR(parent)) {
ret = PTR_ERR(parent);
goto unlock_mutex;
}
/* try to create a simple-framebuffer device */
compatible = sysfb_parse_mode(si, &mode);
if (compatible) {
pd = sysfb_create_simplefb(si, &mode, parent);
if (!IS_ERR(pd))
goto put_device;
}
/* if the FB is incompatible, create a legacy framebuffer device */
if (si->orig_video_isVGA == VIDEO_TYPE_EFI)
name = "efi-framebuffer";
else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
name = "vesa-framebuffer";
else if (si->orig_video_isVGA == VIDEO_TYPE_VGAC)
name = "vga-framebuffer";
else if (si->orig_video_isVGA == VIDEO_TYPE_EGAC)
name = "ega-framebuffer";
else
name = "platform-framebuffer";
pd = platform_device_alloc(name, 0);
if (!pd) {
ret = -ENOMEM;
goto put_device;
}
pd->dev.parent = parent;
sysfb_set_efifb_fwnode(pd);
ret = platform_device_add_data(pd, si, sizeof(*si));
if (ret)
goto err;
ret = platform_device_add(pd);
if (ret)
goto err;
goto put_device;
err:
platform_device_put(pd);
put_device:
put_device(parent);
unlock_mutex:
mutex_unlock(&disable_lock);
return ret;
}
/* must execute after PCI subsystem for EFI quirks */
device_initcall(sysfb_init);
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