projects/linux·blob 9e947d96 · refs

187 lines · 4.8 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * framebuffer-coreboot.c
4 *
5 * Memory based framebuffer accessed through coreboot table.
6 *
7 * Copyright 2012-2013 David Herrmann <[email protected]>
8 * Copyright 2017 Google Inc.
9 * Copyright 2017 Samuel Holland <[email protected]>
10 */
11
12#include <linux/device.h>
13#include <linux/kernel.h>
14#include <linux/mm.h>
15#include <linux/device-id/coreboot.h>
16#include <linux/module.h>
17#include <linux/pci.h>
18#include <linux/platform_data/simplefb.h>
19#include <linux/platform_device.h>
20#include <linux/sysfb.h>
21
22#include "coreboot_table.h"
23
24#if defined(CONFIG_PCI)
25static bool framebuffer_pci_dev_is_enabled(struct pci_dev *pdev)
26{
27 /*
28 * TODO: Try to integrate this code into the PCI subsystem
29 */
30 int ret;
31 u16 command;
32
33 ret = pci_read_config_word(pdev, PCI_COMMAND, &command);
34 if (ret != PCIBIOS_SUCCESSFUL)
35 return false;
36 if (!(command & PCI_COMMAND_MEMORY))
37 return false;
38 return true;
39}
40
41static struct pci_dev *framebuffer_parent_pci_dev(struct resource *res)
42{
43 struct pci_dev *pdev = NULL;
44 const struct resource *r = NULL;
45
46 while (!r && (pdev = pci_get_base_class(PCI_BASE_CLASS_DISPLAY, pdev)))
47 r = pci_find_resource(pdev, res);
48
49 if (!r || !pdev)
50 return NULL; /* not found; not an error */
51
52 if (!framebuffer_pci_dev_is_enabled(pdev)) {
53 pci_dev_put(pdev);
54 return ERR_PTR(-ENODEV);
55 }
56
57 return pdev;
58}
59#else
60static struct pci_dev *framebuffer_parent_pci_dev(struct resource *res)
61{
62 return NULL;
63}
64#endif
65
66static struct device *framebuffer_parent_dev(struct resource *res)
67{
68 struct pci_dev *pdev;
69
70 pdev = framebuffer_parent_pci_dev(res);
71 if (IS_ERR(pdev))
72 return ERR_CAST(pdev);
73 else if (pdev)
74 return &pdev->dev;
75
76 return NULL;
77}
78
79static int framebuffer_probe(struct coreboot_device *dev)
80{
81 struct lb_framebuffer *fb = &dev->framebuffer;
82 struct device *parent;
83 struct platform_device *pdev;
84 struct resource res;
85 int ret;
86#if !IS_ENABLED(CONFIG_DRM_COREBOOTDRM)
87 struct simplefb_platform_data pdata = {
88 .width = fb->x_resolution,
89 .height = fb->y_resolution,
90 .stride = fb->bytes_per_line,
91 .format = NULL,
92 };
93 int i;
94 static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
95#endif
96
97 /*
98 * On coreboot systems, the advertised LB_TAG_FRAMEBUFFER entry
99 * in the coreboot table should only be used if the payload did
100 * not pass a framebuffer information to the Linux kernel.
101 *
102 * If the global screen_info data has been filled, the Generic
103 * System Framebuffers (sysfb) will already register a platform
104 * device and pass that screen_info as platform_data to a driver
105 * that can scan-out using the system provided framebuffer.
106 */
107 if (sysfb_handles_screen_info())
108 return -ENODEV;
109
110 if (!fb->physical_address)
111 return -ENODEV;
112
113 res = DEFINE_RES_MEM(fb->physical_address,
114 PAGE_ALIGN(fb->y_resolution * fb->bytes_per_line));
115 if (res.end <= res.start)
116 return -EINVAL;
117
118 parent = framebuffer_parent_dev(&res);
119 if (IS_ERR(parent))
120 return PTR_ERR(parent);
121
122#if IS_ENABLED(CONFIG_DRM_COREBOOTDRM)
123 pdev = platform_device_register_resndata(parent, "coreboot-framebuffer", 0,
124 &res, 1, fb, fb->size);
125 if (IS_ERR(pdev)) {
126 pr_warn("coreboot: could not register framebuffer\n");
127 ret = PTR_ERR(pdev);
128 goto out_put_device_parent;
129 }
130#else
131 /*
132 * FIXME: Coreboot systems should use a driver that binds to
133 * coreboot-framebuffer devices. Remove support for
134 * simple-framebuffer at some point.
135 */
136 for (i = 0; i < ARRAY_SIZE(formats); ++i) {
137 if (fb->bits_per_pixel == formats[i].bits_per_pixel &&
138 fb->red_mask_pos == formats[i].red.offset &&
139 fb->red_mask_size == formats[i].red.length &&
140 fb->green_mask_pos == formats[i].green.offset &&
141 fb->green_mask_size == formats[i].green.length &&
142 fb->blue_mask_pos == formats[i].blue.offset &&
143 fb->blue_mask_size == formats[i].blue.length)
144 pdata.format = formats[i].name;
145 }
146 if (!pdata.format) {
147 ret = -ENODEV;
148 goto out_put_device_parent;
149 }
150
151 pdev = platform_device_register_resndata(parent,
152 "simple-framebuffer", 0,
153 &res, 1, &pdata,
154 sizeof(pdata));
155 if (IS_ERR(pdev)) {
156 ret = PTR_ERR(pdev);
157 pr_warn("coreboot: could not register framebuffer\n");
158 goto out_put_device_parent;
159 }
160#endif
161
162 ret = 0;
163
164out_put_device_parent:
165 if (parent)
166 put_device(parent);
167 return ret;
168}
169
170static const struct coreboot_device_id framebuffer_ids[] = {
171 { .tag = CB_TAG_FRAMEBUFFER },
172 { /* sentinel */ }
173};
174MODULE_DEVICE_TABLE(coreboot, framebuffer_ids);
175
176static struct coreboot_driver framebuffer_driver = {
177 .probe = framebuffer_probe,
178 .drv = {
179 .name = "framebuffer",
180 },
181 .id_table = framebuffer_ids,
182};
183module_coreboot_driver(framebuffer_driver);
184
185MODULE_AUTHOR("Samuel Holland <[email protected]>");
186MODULE_DESCRIPTION("Memory based framebuffer accessed through coreboot table");
187MODULE_LICENSE("GPL");