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 <linux/apple_bl.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(0x04 | (intensity << 4), 0xb3);
53 	outb(0xbf, 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(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  */
95 static void nvidia_chipset_set_brightness(int intensity)
96 {
97 	outb(0x04 | (intensity << 4), 0x52f);
98 	outb(0xbf, 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(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 
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 
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 
218 static atomic_t apple_bl_registered = ATOMIC_INIT(0);
219 
220 int apple_bl_register(void)
221 {
222 	if (atomic_xchg(&apple_bl_registered, 1) == 0)
223 		return acpi_bus_register_driver(&apple_bl_driver);
224 
225 	return 0;
226 }
227 EXPORT_SYMBOL_GPL(apple_bl_register);
228 
229 void apple_bl_unregister(void)
230 {
231 	if (atomic_xchg(&apple_bl_registered, 0) == 1)
232 		acpi_bus_unregister_driver(&apple_bl_driver);
233 }
234 EXPORT_SYMBOL_GPL(apple_bl_unregister);
235 
236 static int __init apple_bl_init(void)
237 {
238 	return apple_bl_register();
239 }
240 
241 static void __exit apple_bl_exit(void)
242 {
243 	apple_bl_unregister();
244 }
245 
246 module_init(apple_bl_init);
247 module_exit(apple_bl_exit);
248 
249 MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
250 MODULE_DESCRIPTION("Apple Backlight Driver");
251 MODULE_LICENSE("GPL");
252 MODULE_DEVICE_TABLE(acpi, apple_bl_ids);
253 MODULE_ALIAS("mbp_nvidia_bl");
254