1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Backlight Driver for Intel-based Apples |
4 | * |
5 | * Copyright (c) Red Hat <mjg@redhat.com> |
6 | * Based on code from Pommed: |
7 | * Copyright (C) 2006 Nicolas Boichat <nicolas @boichat.ch> |
8 | * Copyright (C) 2006 Felipe Alfaro Solana <felipe_alfaro @linuxmail.org> |
9 | * Copyright (C) 2007 Julien BLACHE <jb@jblache.org> |
10 | * |
11 | * This driver triggers SMIs which cause the firmware to change the |
12 | * backlight brightness. This is icky in many ways, but it's impractical to |
13 | * get at the firmware code in order to figure out what it's actually doing. |
14 | */ |
15 | |
16 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
17 | |
18 | #include <linux/module.h> |
19 | #include <linux/kernel.h> |
20 | #include <linux/init.h> |
21 | #include <linux/backlight.h> |
22 | #include <linux/err.h> |
23 | #include <linux/io.h> |
24 | #include <linux/pci.h> |
25 | #include <linux/acpi.h> |
26 | #include <linux/atomic.h> |
27 | #include <acpi/video.h> |
28 | |
29 | static struct backlight_device *apple_backlight_device; |
30 | |
31 | struct hw_data { |
32 | /* I/O resource to allocate. */ |
33 | unsigned long iostart; |
34 | unsigned long iolen; |
35 | /* Backlight operations structure. */ |
36 | const struct backlight_ops backlight_ops; |
37 | void (*set_brightness)(int); |
38 | }; |
39 | |
40 | static const struct hw_data *hw_data; |
41 | |
42 | /* Module parameters. */ |
43 | static int debug; |
44 | module_param_named(debug, debug, int, 0644); |
45 | MODULE_PARM_DESC(debug, "Set to one to enable debugging messages." ); |
46 | |
47 | /* |
48 | * Implementation for machines with Intel chipset. |
49 | */ |
50 | static void intel_chipset_set_brightness(int intensity) |
51 | { |
52 | outb(value: 0x04 | (intensity << 4), port: 0xb3); |
53 | outb(value: 0xbf, port: 0xb2); |
54 | } |
55 | |
56 | static int intel_chipset_send_intensity(struct backlight_device *bd) |
57 | { |
58 | int intensity = bd->props.brightness; |
59 | |
60 | if (debug) |
61 | pr_debug("setting brightness to %d\n" , intensity); |
62 | |
63 | intel_chipset_set_brightness(intensity); |
64 | return 0; |
65 | } |
66 | |
67 | static int intel_chipset_get_intensity(struct backlight_device *bd) |
68 | { |
69 | int intensity; |
70 | |
71 | outb(value: 0x03, port: 0xb3); |
72 | outb(value: 0xbf, port: 0xb2); |
73 | intensity = inb(port: 0xb3) >> 4; |
74 | |
75 | if (debug) |
76 | pr_debug("read brightness of %d\n" , intensity); |
77 | |
78 | return intensity; |
79 | } |
80 | |
81 | static const struct hw_data intel_chipset_data = { |
82 | .iostart = 0xb2, |
83 | .iolen = 2, |
84 | .backlight_ops = { |
85 | .options = BL_CORE_SUSPENDRESUME, |
86 | .get_brightness = intel_chipset_get_intensity, |
87 | .update_status = intel_chipset_send_intensity, |
88 | }, |
89 | .set_brightness = intel_chipset_set_brightness, |
90 | }; |
91 | |
92 | /* |
93 | * Implementation for machines with Nvidia chipset. |
94 | */ |
95 | static void nvidia_chipset_set_brightness(int intensity) |
96 | { |
97 | outb(value: 0x04 | (intensity << 4), port: 0x52f); |
98 | outb(value: 0xbf, port: 0x52e); |
99 | } |
100 | |
101 | static int nvidia_chipset_send_intensity(struct backlight_device *bd) |
102 | { |
103 | int intensity = bd->props.brightness; |
104 | |
105 | if (debug) |
106 | pr_debug("setting brightness to %d\n" , intensity); |
107 | |
108 | nvidia_chipset_set_brightness(intensity); |
109 | return 0; |
110 | } |
111 | |
112 | static int nvidia_chipset_get_intensity(struct backlight_device *bd) |
113 | { |
114 | int intensity; |
115 | |
116 | outb(value: 0x03, port: 0x52f); |
117 | outb(value: 0xbf, port: 0x52e); |
118 | intensity = inb(port: 0x52f) >> 4; |
119 | |
120 | if (debug) |
121 | pr_debug("read brightness of %d\n" , intensity); |
122 | |
123 | return intensity; |
124 | } |
125 | |
126 | static const struct hw_data nvidia_chipset_data = { |
127 | .iostart = 0x52e, |
128 | .iolen = 2, |
129 | .backlight_ops = { |
130 | .options = BL_CORE_SUSPENDRESUME, |
131 | .get_brightness = nvidia_chipset_get_intensity, |
132 | .update_status = nvidia_chipset_send_intensity |
133 | }, |
134 | .set_brightness = nvidia_chipset_set_brightness, |
135 | }; |
136 | |
137 | static int apple_bl_add(struct acpi_device *dev) |
138 | { |
139 | struct backlight_properties props; |
140 | struct pci_dev *host; |
141 | int intensity; |
142 | |
143 | host = pci_get_domain_bus_and_slot(domain: 0, bus: 0, devfn: 0); |
144 | |
145 | if (!host) { |
146 | pr_err("unable to find PCI host\n" ); |
147 | return -ENODEV; |
148 | } |
149 | |
150 | if (host->vendor == PCI_VENDOR_ID_INTEL) |
151 | hw_data = &intel_chipset_data; |
152 | else if (host->vendor == PCI_VENDOR_ID_NVIDIA) |
153 | hw_data = &nvidia_chipset_data; |
154 | |
155 | pci_dev_put(dev: host); |
156 | |
157 | if (!hw_data) { |
158 | pr_err("unknown hardware\n" ); |
159 | return -ENODEV; |
160 | } |
161 | |
162 | /* Check that the hardware responds - this may not work under EFI */ |
163 | |
164 | intensity = hw_data->backlight_ops.get_brightness(NULL); |
165 | |
166 | if (!intensity) { |
167 | hw_data->set_brightness(1); |
168 | if (!hw_data->backlight_ops.get_brightness(NULL)) |
169 | return -ENODEV; |
170 | |
171 | hw_data->set_brightness(0); |
172 | } |
173 | |
174 | if (!request_region(hw_data->iostart, hw_data->iolen, |
175 | "Apple backlight" )) |
176 | return -ENXIO; |
177 | |
178 | memset(&props, 0, sizeof(struct backlight_properties)); |
179 | props.type = BACKLIGHT_PLATFORM; |
180 | props.max_brightness = 15; |
181 | apple_backlight_device = backlight_device_register(name: "apple_backlight" , |
182 | NULL, NULL, ops: &hw_data->backlight_ops, props: &props); |
183 | |
184 | if (IS_ERR(ptr: apple_backlight_device)) { |
185 | release_region(hw_data->iostart, hw_data->iolen); |
186 | return PTR_ERR(ptr: apple_backlight_device); |
187 | } |
188 | |
189 | apple_backlight_device->props.brightness = |
190 | hw_data->backlight_ops.get_brightness(apple_backlight_device); |
191 | backlight_update_status(bd: apple_backlight_device); |
192 | |
193 | return 0; |
194 | } |
195 | |
196 | static void apple_bl_remove(struct acpi_device *dev) |
197 | { |
198 | backlight_device_unregister(bd: apple_backlight_device); |
199 | |
200 | release_region(hw_data->iostart, hw_data->iolen); |
201 | hw_data = NULL; |
202 | } |
203 | |
204 | static const struct acpi_device_id apple_bl_ids[] = { |
205 | {"APP0002" , 0}, |
206 | {"" , 0}, |
207 | }; |
208 | |
209 | static struct acpi_driver apple_bl_driver = { |
210 | .name = "Apple backlight" , |
211 | .ids = apple_bl_ids, |
212 | .ops = { |
213 | .add = apple_bl_add, |
214 | .remove = apple_bl_remove, |
215 | }, |
216 | }; |
217 | |
218 | static int __init apple_bl_init(void) |
219 | { |
220 | /* |
221 | * Use ACPI video detection code to see if this driver should register |
222 | * or if another driver, e.g. the apple-gmux driver should be used. |
223 | */ |
224 | if (acpi_video_get_backlight_type() != acpi_backlight_vendor) |
225 | return -ENODEV; |
226 | |
227 | return acpi_bus_register_driver(driver: &apple_bl_driver); |
228 | } |
229 | |
230 | static void __exit apple_bl_exit(void) |
231 | { |
232 | acpi_bus_unregister_driver(driver: &apple_bl_driver); |
233 | } |
234 | |
235 | module_init(apple_bl_init); |
236 | module_exit(apple_bl_exit); |
237 | |
238 | MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>" ); |
239 | MODULE_DESCRIPTION("Apple Backlight Driver" ); |
240 | MODULE_LICENSE("GPL" ); |
241 | MODULE_DEVICE_TABLE(acpi, apple_bl_ids); |
242 | MODULE_ALIAS("mbp_nvidia_bl" ); |
243 | |