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 */
intel_chipset_set_brightness(int intensity)50 static void intel_chipset_set_brightness(int intensity)
51 {
52 outb(0x04 | (intensity << 4), 0xb3);
53 outb(0xbf, 0xb2);
54 }
55
intel_chipset_send_intensity(struct backlight_device * bd)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
intel_chipset_get_intensity(struct backlight_device * bd)67 static int intel_chipset_get_intensity(struct backlight_device *bd)
68 {
69 int intensity;
70
71 outb(0x03, 0xb3);
72 outb(0xbf, 0xb2);
73 intensity = inb(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 */
nvidia_chipset_set_brightness(int intensity)95 static void nvidia_chipset_set_brightness(int intensity)
96 {
97 outb(0x04 | (intensity << 4), 0x52f);
98 outb(0xbf, 0x52e);
99 }
100
nvidia_chipset_send_intensity(struct backlight_device * bd)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
nvidia_chipset_get_intensity(struct backlight_device * bd)112 static int nvidia_chipset_get_intensity(struct backlight_device *bd)
113 {
114 int intensity;
115
116 outb(0x03, 0x52f);
117 outb(0xbf, 0x52e);
118 intensity = inb(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
apple_bl_add(struct acpi_device * dev)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(0, 0, 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(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("apple_backlight",
182 NULL, NULL, &hw_data->backlight_ops, &props);
183
184 if (IS_ERR(apple_backlight_device)) {
185 release_region(hw_data->iostart, hw_data->iolen);
186 return PTR_ERR(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(apple_backlight_device);
192
193 return 0;
194 }
195
apple_bl_remove(struct acpi_device * dev)196 static void apple_bl_remove(struct acpi_device *dev)
197 {
198 backlight_device_unregister(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
apple_bl_init(void)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(&apple_bl_driver);
228 }
229
apple_bl_exit(void)230 static void __exit apple_bl_exit(void)
231 {
232 acpi_bus_unregister_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