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 #if defined(CONFIG_PCI) 83 static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev) 84 { 85 /* 86 * TODO: Try to integrate this code into the PCI subsystem 87 */ 88 int ret; 89 u16 command; 90 91 ret = pci_read_config_word(pdev, PCI_COMMAND, &command); 92 if (ret != PCIBIOS_SUCCESSFUL) 93 return false; 94 if (!(command & PCI_COMMAND_MEMORY)) 95 return false; 96 return true; 97 } 98 #else 99 static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev) 100 { 101 return false; 102 } 103 #endif 104 105 static struct device *sysfb_parent_dev(const struct screen_info *si) 106 { 107 struct pci_dev *pdev; 108 109 pdev = screen_info_pci_dev(si); 110 if (IS_ERR(pdev)) { 111 return ERR_CAST(pdev); 112 } else if (pdev) { 113 if (!sysfb_pci_dev_is_enabled(pdev)) { 114 pci_dev_put(pdev); 115 return ERR_PTR(-ENODEV); 116 } 117 return &pdev->dev; 118 } 119 120 return NULL; 121 } 122 123 static __init int sysfb_init(void) 124 { 125 struct screen_info *si = &screen_info; 126 struct device *parent; 127 struct simplefb_platform_data mode; 128 const char *name; 129 bool compatible; 130 int ret = 0; 131 132 screen_info_apply_fixups(); 133 134 mutex_lock(&disable_lock); 135 if (disabled) 136 goto unlock_mutex; 137 138 sysfb_apply_efi_quirks(); 139 140 parent = sysfb_parent_dev(si); 141 if (IS_ERR(parent)) { 142 ret = PTR_ERR(parent); 143 goto unlock_mutex; 144 } 145 146 /* try to create a simple-framebuffer device */ 147 compatible = sysfb_parse_mode(si, &mode); 148 if (compatible) { 149 pd = sysfb_create_simplefb(si, &mode, parent); 150 if (!IS_ERR(pd)) 151 goto put_device; 152 } 153 154 /* if the FB is incompatible, create a legacy framebuffer device */ 155 if (si->orig_video_isVGA == VIDEO_TYPE_EFI) 156 name = "efi-framebuffer"; 157 else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB) 158 name = "vesa-framebuffer"; 159 else if (si->orig_video_isVGA == VIDEO_TYPE_VGAC) 160 name = "vga-framebuffer"; 161 else if (si->orig_video_isVGA == VIDEO_TYPE_EGAC) 162 name = "ega-framebuffer"; 163 else 164 name = "platform-framebuffer"; 165 166 pd = platform_device_alloc(name, 0); 167 if (!pd) { 168 ret = -ENOMEM; 169 goto put_device; 170 } 171 172 pd->dev.parent = parent; 173 174 sysfb_set_efifb_fwnode(pd); 175 176 ret = platform_device_add_data(pd, si, sizeof(*si)); 177 if (ret) 178 goto err; 179 180 ret = platform_device_add(pd); 181 if (ret) 182 goto err; 183 184 goto put_device; 185 err: 186 platform_device_put(pd); 187 put_device: 188 put_device(parent); 189 unlock_mutex: 190 mutex_unlock(&disable_lock); 191 return ret; 192 } 193 194 /* must execute after PCI subsystem for EFI quirks */ 195 device_initcall(sysfb_init); 196