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 71 mutex_lock(&disable_lock); 72 if (!dev || dev == sysfb_parent_dev(si)) { 73 sysfb_unregister(); 74 disabled = true; 75 } 76 mutex_unlock(&disable_lock); 77 } 78 EXPORT_SYMBOL_GPL(sysfb_disable); 79 80 #if defined(CONFIG_PCI) 81 static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev) 82 { 83 /* 84 * TODO: Try to integrate this code into the PCI subsystem 85 */ 86 int ret; 87 u16 command; 88 89 ret = pci_read_config_word(pdev, PCI_COMMAND, &command); 90 if (ret != PCIBIOS_SUCCESSFUL) 91 return false; 92 if (!(command & PCI_COMMAND_MEMORY)) 93 return false; 94 return true; 95 } 96 #else 97 static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev) 98 { 99 return false; 100 } 101 #endif 102 103 static struct device *sysfb_parent_dev(const struct screen_info *si) 104 { 105 struct pci_dev *pdev; 106 107 pdev = screen_info_pci_dev(si); 108 if (IS_ERR(pdev)) { 109 return ERR_CAST(pdev); 110 } else if (pdev) { 111 if (!sysfb_pci_dev_is_enabled(pdev)) { 112 pci_dev_put(pdev); 113 return ERR_PTR(-ENODEV); 114 } 115 return &pdev->dev; 116 } 117 118 return NULL; 119 } 120 121 static __init int sysfb_init(void) 122 { 123 struct screen_info *si = &screen_info; 124 struct device *parent; 125 struct simplefb_platform_data mode; 126 const char *name; 127 bool compatible; 128 int ret = 0; 129 130 screen_info_apply_fixups(); 131 132 mutex_lock(&disable_lock); 133 if (disabled) 134 goto unlock_mutex; 135 136 sysfb_apply_efi_quirks(); 137 138 parent = sysfb_parent_dev(si); 139 if (IS_ERR(parent)) { 140 ret = PTR_ERR(parent); 141 goto unlock_mutex; 142 } 143 144 /* try to create a simple-framebuffer device */ 145 compatible = sysfb_parse_mode(si, &mode); 146 if (compatible) { 147 pd = sysfb_create_simplefb(si, &mode, parent); 148 if (!IS_ERR(pd)) 149 goto put_device; 150 } 151 152 /* if the FB is incompatible, create a legacy framebuffer device */ 153 if (si->orig_video_isVGA == VIDEO_TYPE_EFI) 154 name = "efi-framebuffer"; 155 else if (si->orig_video_isVGA == VIDEO_TYPE_VLFB) 156 name = "vesa-framebuffer"; 157 else if (si->orig_video_isVGA == VIDEO_TYPE_VGAC) 158 name = "vga-framebuffer"; 159 else if (si->orig_video_isVGA == VIDEO_TYPE_EGAC) 160 name = "ega-framebuffer"; 161 else 162 name = "platform-framebuffer"; 163 164 pd = platform_device_alloc(name, 0); 165 if (!pd) { 166 ret = -ENOMEM; 167 goto put_device; 168 } 169 170 pd->dev.parent = parent; 171 172 sysfb_set_efifb_fwnode(pd); 173 174 ret = platform_device_add_data(pd, si, sizeof(*si)); 175 if (ret) 176 goto err; 177 178 ret = platform_device_add(pd); 179 if (ret) 180 goto err; 181 182 goto put_device; 183 err: 184 platform_device_put(pd); 185 put_device: 186 put_device(parent); 187 unlock_mutex: 188 mutex_unlock(&disable_lock); 189 return ret; 190 } 191 192 /* must execute after PCI subsystem for EFI quirks */ 193 device_initcall(sysfb_init); 194