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/pci.h> 33 #include <linux/platform_data/simplefb.h> 34 #include <linux/platform_device.h> 35 #include <linux/screen_info.h> 36 #include <linux/sysfb.h> 37 38 static struct platform_device *pd; 39 static DEFINE_MUTEX(disable_lock); 40 static bool disabled; 41 42 static bool sysfb_unregister(void) 43 { 44 if (IS_ERR_OR_NULL(pd)) 45 return false; 46 47 platform_device_unregister(pd); 48 pd = NULL; 49 50 return true; 51 } 52 53 /** 54 * sysfb_disable() - disable the Generic System Framebuffers support 55 * 56 * This disables the registration of system framebuffer devices that match the 57 * generic drivers that make use of the system framebuffer set up by firmware. 58 * 59 * It also unregisters a device if this was already registered by sysfb_init(). 60 * 61 * Context: The function can sleep. A @disable_lock mutex is acquired to serialize 62 * against sysfb_init(), that registers a system framebuffer device. 63 */ 64 void sysfb_disable(void) 65 { 66 mutex_lock(&disable_lock); 67 sysfb_unregister(); 68 disabled = true; 69 mutex_unlock(&disable_lock); 70 } 71 EXPORT_SYMBOL_GPL(sysfb_disable); 72 73 #if defined(CONFIG_PCI) 74 static __init bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev) 75 { 76 /* 77 * TODO: Try to integrate this code into the PCI subsystem 78 */ 79 int ret; 80 u16 command; 81 82 ret = pci_read_config_word(pdev, PCI_COMMAND, &command); 83 if (ret != PCIBIOS_SUCCESSFUL) 84 return false; 85 if (!(command & PCI_COMMAND_MEMORY)) 86 return false; 87 return true; 88 } 89 #else 90 static __init bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev) 91 { 92 return false; 93 } 94 #endif 95 96 static __init struct device *sysfb_parent_dev(const struct screen_info *si) 97 { 98 struct pci_dev *pdev; 99 100 pdev = screen_info_pci_dev(si); 101 if (IS_ERR(pdev)) { 102 return ERR_CAST(pdev); 103 } else if (pdev) { 104 if (!sysfb_pci_dev_is_enabled(pdev)) 105 return ERR_PTR(-ENODEV); 106 return &pdev->dev; 107 } 108 109 return NULL; 110 } 111 112 static __init int sysfb_init(void) 113 { 114 struct screen_info *si = &screen_info; 115 struct device *parent; 116 struct simplefb_platform_data mode; 117 const char *name; 118 bool compatible; 119 int ret = 0; 120 121 screen_info_apply_fixups(); 122 123 mutex_lock(&disable_lock); 124 if (disabled) 125 goto unlock_mutex; 126 127 sysfb_apply_efi_quirks(); 128 129 parent = sysfb_parent_dev(si); 130 if (IS_ERR(parent)) 131 goto unlock_mutex; 132 133 /* try to create a simple-framebuffer device */ 134 compatible = sysfb_parse_mode(si, &mode); 135 if (compatible) { 136 pd = sysfb_create_simplefb(si, &mode, parent); 137 if (!IS_ERR(pd)) 138 goto unlock_mutex; 139 } 140 141 /* if the FB is incompatible, create a legacy framebuffer device */ 142 if (si->orig_video_isVGA == VIDEO_TYPE_EFI) 143 name = "efi-framebuffer"; 144 else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB) 145 name = "vesa-framebuffer"; 146 else if (si->orig_video_isVGA == VIDEO_TYPE_VGAC) 147 name = "vga-framebuffer"; 148 else if (si->orig_video_isVGA == VIDEO_TYPE_EGAC) 149 name = "ega-framebuffer"; 150 else 151 name = "platform-framebuffer"; 152 153 pd = platform_device_alloc(name, 0); 154 if (!pd) { 155 ret = -ENOMEM; 156 goto unlock_mutex; 157 } 158 159 pd->dev.parent = parent; 160 161 sysfb_set_efifb_fwnode(pd); 162 163 ret = platform_device_add_data(pd, si, sizeof(*si)); 164 if (ret) 165 goto err; 166 167 ret = platform_device_add(pd); 168 if (ret) 169 goto err; 170 171 goto unlock_mutex; 172 err: 173 platform_device_put(pd); 174 unlock_mutex: 175 mutex_unlock(&disable_lock); 176 return ret; 177 } 178 179 /* must execute after PCI subsystem for EFI quirks */ 180 device_initcall(sysfb_init); 181