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 struct device *sysfb_parent_dev(const struct screen_info *si); 43 44 static bool sysfb_unregister(void) 45 { 46 if (IS_ERR_OR_NULL(pd)) 47 return false; 48 49 platform_device_unregister(pd); 50 pd = NULL; 51 52 return true; 53 } 54 55 /** 56 * sysfb_disable() - disable the Generic System Framebuffers support 57 * @dev: the device to check if non-NULL 58 * 59 * This disables the registration of system framebuffer devices that match the 60 * generic drivers that make use of the system framebuffer set up by firmware. 61 * 62 * It also unregisters a device if this was already registered by sysfb_init(). 63 * 64 * Context: The function can sleep. A @disable_lock mutex is acquired to serialize 65 * against sysfb_init(), that registers a system framebuffer device. 66 */ 67 void sysfb_disable(struct device *dev) 68 { 69 struct screen_info *si = &screen_info; 70 struct device *parent; 71 72 mutex_lock(&disable_lock); 73 parent = sysfb_parent_dev(si); 74 if (!dev || !parent || dev == parent) { 75 sysfb_unregister(); 76 disabled = true; 77 } 78 mutex_unlock(&disable_lock); 79 } 80 EXPORT_SYMBOL_GPL(sysfb_disable); 81 82 /** 83 * sysfb_handles_screen_info() - reports if sysfb handles the global screen_info 84 * 85 * Callers can use sysfb_handles_screen_info() to determine whether the Generic 86 * System Framebuffers (sysfb) can handle the global screen_info data structure 87 * or not. Drivers might need this information to know if they have to setup the 88 * system framebuffer, or if they have to delegate this action to sysfb instead. 89 * 90 * Returns: 91 * True if sysfb handles the global screen_info data structure. 92 */ 93 bool sysfb_handles_screen_info(void) 94 { 95 const struct screen_info *si = &screen_info; 96 97 return !!screen_info_video_type(si); 98 } 99 EXPORT_SYMBOL_GPL(sysfb_handles_screen_info); 100 101 #if defined(CONFIG_PCI) 102 static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev) 103 { 104 /* 105 * TODO: Try to integrate this code into the PCI subsystem 106 */ 107 int ret; 108 u16 command; 109 110 ret = pci_read_config_word(pdev, PCI_COMMAND, &command); 111 if (ret != PCIBIOS_SUCCESSFUL) 112 return false; 113 if (!(command & PCI_COMMAND_MEMORY)) 114 return false; 115 return true; 116 } 117 #else 118 static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev) 119 { 120 return false; 121 } 122 #endif 123 124 static struct device *sysfb_parent_dev(const struct screen_info *si) 125 { 126 struct pci_dev *pdev; 127 128 pdev = screen_info_pci_dev(si); 129 if (IS_ERR(pdev)) { 130 return ERR_CAST(pdev); 131 } else if (pdev) { 132 if (!sysfb_pci_dev_is_enabled(pdev)) { 133 pci_dev_put(pdev); 134 return ERR_PTR(-ENODEV); 135 } 136 return &pdev->dev; 137 } 138 139 return NULL; 140 } 141 142 static __init int sysfb_init(void) 143 { 144 struct screen_info *si = &screen_info; 145 struct device *parent; 146 unsigned int type; 147 struct simplefb_platform_data mode; 148 const char *name; 149 bool compatible; 150 int ret = 0; 151 152 screen_info_apply_fixups(); 153 154 mutex_lock(&disable_lock); 155 if (disabled) 156 goto unlock_mutex; 157 158 sysfb_apply_efi_quirks(); 159 160 parent = sysfb_parent_dev(si); 161 if (IS_ERR(parent)) { 162 ret = PTR_ERR(parent); 163 goto unlock_mutex; 164 } 165 166 /* try to create a simple-framebuffer device */ 167 compatible = sysfb_parse_mode(si, &mode); 168 if (compatible) { 169 pd = sysfb_create_simplefb(si, &mode, parent); 170 if (!IS_ERR(pd)) 171 goto put_device; 172 } 173 174 type = screen_info_video_type(si); 175 176 /* if the FB is incompatible, create a legacy framebuffer device */ 177 switch (type) { 178 case VIDEO_TYPE_EGAC: 179 name = "ega-framebuffer"; 180 break; 181 case VIDEO_TYPE_VGAC: 182 name = "vga-framebuffer"; 183 break; 184 case VIDEO_TYPE_VLFB: 185 name = "vesa-framebuffer"; 186 break; 187 case VIDEO_TYPE_EFI: 188 name = "efi-framebuffer"; 189 break; 190 default: 191 name = "platform-framebuffer"; 192 break; 193 } 194 195 pd = platform_device_alloc(name, 0); 196 if (!pd) { 197 ret = -ENOMEM; 198 goto put_device; 199 } 200 201 pd->dev.parent = parent; 202 203 sysfb_set_efifb_fwnode(pd); 204 205 ret = platform_device_add_data(pd, si, sizeof(*si)); 206 if (ret) 207 goto err; 208 209 ret = platform_device_add(pd); 210 if (ret) 211 goto err; 212 213 goto put_device; 214 err: 215 platform_device_put(pd); 216 put_device: 217 put_device(parent); 218 unlock_mutex: 219 mutex_unlock(&disable_lock); 220 return ret; 221 } 222 223 /* must execute after PCI subsystem for EFI quirks */ 224 device_initcall(sysfb_init); 225