1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Generic System Framebuffers 4 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com> 5 */ 6 7 /* 8 * Simple-Framebuffer support 9 * Create a platform-device for any available boot framebuffer. The 10 * simple-framebuffer platform device is already available on DT systems, so 11 * this module parses the global "screen_info" object and creates a suitable 12 * platform device compatible with the "simple-framebuffer" DT object. If 13 * the framebuffer is incompatible, we instead create a legacy 14 * "vesa-framebuffer", "efi-framebuffer" or "platform-framebuffer" device and 15 * pass the screen_info as platform_data. This allows legacy drivers 16 * to pick these devices up without messing with simple-framebuffer drivers. 17 * The global "screen_info" is still valid at all times. 18 * 19 * If CONFIG_SYSFB_SIMPLEFB is not selected, never register "simple-framebuffer" 20 * platform devices, but only use legacy framebuffer devices for 21 * backwards compatibility. 22 * 23 * TODO: We set the dev_id field of all platform-devices to 0. This allows 24 * other OF/DT parsers to create such devices, too. However, they must 25 * start at offset 1 for this to work. 26 */ 27 28 #include <linux/err.h> 29 #include <linux/init.h> 30 #include <linux/kernel.h> 31 #include <linux/mm.h> 32 #include <linux/platform_data/simplefb.h> 33 #include <linux/platform_device.h> 34 #include <linux/screen_info.h> 35 #include <linux/sysfb.h> 36 37 static struct platform_device *pd; 38 static DEFINE_MUTEX(disable_lock); 39 static bool disabled; 40 41 static bool sysfb_unregister(void) 42 { 43 if (IS_ERR_OR_NULL(pd)) 44 return false; 45 46 platform_device_unregister(pd); 47 pd = NULL; 48 49 return true; 50 } 51 52 /** 53 * sysfb_disable() - disable the Generic System Framebuffers support 54 * 55 * This disables the registration of system framebuffer devices that match the 56 * generic drivers that make use of the system framebuffer set up by firmware. 57 * 58 * It also unregisters a device if this was already registered by sysfb_init(). 59 * 60 * Context: The function can sleep. A @disable_lock mutex is acquired to serialize 61 * against sysfb_init(), that registers a system framebuffer device. 62 */ 63 void sysfb_disable(void) 64 { 65 mutex_lock(&disable_lock); 66 sysfb_unregister(); 67 disabled = true; 68 mutex_unlock(&disable_lock); 69 } 70 EXPORT_SYMBOL_GPL(sysfb_disable); 71 72 static __init int sysfb_init(void) 73 { 74 struct screen_info *si = &screen_info; 75 struct simplefb_platform_data mode; 76 const char *name; 77 bool compatible; 78 int ret = 0; 79 80 mutex_lock(&disable_lock); 81 if (disabled) 82 goto unlock_mutex; 83 84 /* try to create a simple-framebuffer device */ 85 compatible = sysfb_parse_mode(si, &mode); 86 if (compatible) { 87 pd = sysfb_create_simplefb(si, &mode); 88 if (!IS_ERR(pd)) 89 goto unlock_mutex; 90 } 91 92 /* if the FB is incompatible, create a legacy framebuffer device */ 93 if (si->orig_video_isVGA == VIDEO_TYPE_EFI) 94 name = "efi-framebuffer"; 95 else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB) 96 name = "vesa-framebuffer"; 97 else if (si->orig_video_isVGA == VIDEO_TYPE_VGAC) 98 name = "vga-framebuffer"; 99 else if (si->orig_video_isVGA == VIDEO_TYPE_EGAC) 100 name = "ega-framebuffer"; 101 else 102 name = "platform-framebuffer"; 103 104 pd = platform_device_alloc(name, 0); 105 if (!pd) { 106 ret = -ENOMEM; 107 goto unlock_mutex; 108 } 109 110 sysfb_apply_efi_quirks(pd); 111 112 ret = platform_device_add_data(pd, si, sizeof(*si)); 113 if (ret) 114 goto err; 115 116 ret = platform_device_add(pd); 117 if (ret) 118 goto err; 119 120 goto unlock_mutex; 121 err: 122 platform_device_put(pd); 123 unlock_mutex: 124 mutex_unlock(&disable_lock); 125 return ret; 126 } 127 128 /* must execute after PCI subsystem for EFI quirks */ 129 device_initcall(sysfb_init); 130