apple_bl.c

  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
 29static struct backlight_device *apple_backlight_device;
 30
 31struct 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
 40static const struct hw_data *hw_data;
 41
 42/* Module parameters. */
 43static int debug;
 44module_param_named(debug, debug, int, 0644);
 45MODULE_PARM_DESC(debug, "Set to one to enable debugging messages.");
 46
 47/*
 48 * Implementation for machines with Intel chipset.
 49 */
 50static void intel_chipset_set_brightness(int intensity)
 51{
 52	outb(0x04 | (intensity << 4), 0xb3);
 53	outb(0xbf, 0xb2);
 54}
 55
 56static 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
 67static 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
 81static 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 */
 95static void nvidia_chipset_set_brightness(int intensity)
 96{
 97	outb(0x04 | (intensity << 4), 0x52f);
 98	outb(0xbf, 0x52e);
 99}
100
101static 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
112static 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
126static 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
137static 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
196static 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
204static const struct acpi_device_id apple_bl_ids[] = {
205	{"APP0002", 0},
206	{"", 0},
207};
208
209static 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
218static 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
230static void __exit apple_bl_exit(void)
231{
232	acpi_bus_unregister_driver(&apple_bl_driver);
233}
234
235module_init(apple_bl_init);
236module_exit(apple_bl_exit);
237
238MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
239MODULE_DESCRIPTION("Apple Backlight Driver");
240MODULE_LICENSE("GPL");
241MODULE_DEVICE_TABLE(acpi, apple_bl_ids);
242MODULE_ALIAS("mbp_nvidia_bl");