1/*
2 * Backlight code for via-pmu
3 *
4 * Copyright (C) 1998 Paul Mackerras and Fabio Riccardi.
5 * Copyright (C) 2001-2002 Benjamin Herrenschmidt
6 * Copyright (C) 2006      Michael Hanselmann <linux-kernel@hansmi.ch>
7 *
8 */
9
10#include <asm/ptrace.h>
11#include <linux/adb.h>
12#include <linux/pmu.h>
13#include <asm/backlight.h>
14#include <asm/prom.h>
15
16#define MAX_PMU_LEVEL 0xFF
17
18static struct backlight_ops pmu_backlight_data;
19static DEFINE_SPINLOCK(pmu_backlight_lock);
20static int sleeping;
21static u8 bl_curve[FB_BACKLIGHT_LEVELS];
22
23static void pmu_backlight_init_curve(u8 off, u8 min, u8 max)
24{
25	unsigned int i, flat, count, range = (max - min);
26
27	bl_curve[0] = off;
28
29	for (flat = 1; flat < (FB_BACKLIGHT_LEVELS / 16); ++flat)
30		bl_curve[flat] = min;
31
32	count = FB_BACKLIGHT_LEVELS * 15 / 16;
33	for (i = 0; i < count; ++i)
34		bl_curve[flat + i] = min + (range * (i + 1) / count);
35}
36
37static int pmu_backlight_curve_lookup(int value)
38{
39	int level = (FB_BACKLIGHT_LEVELS - 1);
40	int i, max = 0;
41
42	/* Look for biggest value */
43	for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
44		max = max((int)bl_curve[i], max);
45
46	/* Look for nearest value */
47	for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
48		int diff = abs(bl_curve[i] - value);
49		if (diff < max) {
50			max = diff;
51			level = i;
52		}
53	}
54	return level;
55}
56
57static int pmu_backlight_get_level_brightness(int level)
58{
59	int pmulevel;
60
61	/* Get and convert the value */
62	pmulevel = bl_curve[level] * FB_BACKLIGHT_MAX / MAX_PMU_LEVEL;
63	if (pmulevel < 0)
64		pmulevel = 0;
65	else if (pmulevel > MAX_PMU_LEVEL)
66		pmulevel = MAX_PMU_LEVEL;
67
68	return pmulevel;
69}
70
71static int pmu_backlight_update_status(struct backlight_device *bd)
72{
73	struct adb_request req;
74	unsigned long flags;
75	int level = bd->props.brightness;
76
77	spin_lock_irqsave(&pmu_backlight_lock, flags);
78
79	/* Don't update brightness when sleeping */
80	if (sleeping)
81		goto out;
82
83	if (bd->props.power != FB_BLANK_UNBLANK ||
84	    bd->props.fb_blank != FB_BLANK_UNBLANK)
85		level = 0;
86
87	if (level > 0) {
88		int pmulevel = pmu_backlight_get_level_brightness(level);
89
90		pmu_request(&req, NULL, 2, PMU_BACKLIGHT_BRIGHT, pmulevel);
91		pmu_wait_complete(&req);
92
93		pmu_request(&req, NULL, 2, PMU_POWER_CTRL,
94			PMU_POW_BACKLIGHT | PMU_POW_ON);
95		pmu_wait_complete(&req);
96	} else {
97		pmu_request(&req, NULL, 2, PMU_POWER_CTRL,
98			PMU_POW_BACKLIGHT | PMU_POW_OFF);
99		pmu_wait_complete(&req);
100	}
101
102out:
103	spin_unlock_irqrestore(&pmu_backlight_lock, flags);
104
105	return 0;
106}
107
108static int pmu_backlight_get_brightness(struct backlight_device *bd)
109{
110	return bd->props.brightness;
111}
112
113static struct backlight_ops pmu_backlight_data = {
114	.get_brightness	= pmu_backlight_get_brightness,
115	.update_status	= pmu_backlight_update_status,
116
117};
118
119#ifdef CONFIG_PM
120void pmu_backlight_set_sleep(int sleep)
121{
122	unsigned long flags;
123
124	spin_lock_irqsave(&pmu_backlight_lock, flags);
125	sleeping = sleep;
126	spin_unlock_irqrestore(&pmu_backlight_lock, flags);
127}
128#endif /* CONFIG_PM */
129
130void __init pmu_backlight_init()
131{
132	struct backlight_device *bd;
133	char name[10];
134	int level, autosave;
135
136	/* Special case for the old PowerBook since I can't test on it */
137	autosave =
138		machine_is_compatible("AAPL,3400/2400") ||
139		machine_is_compatible("AAPL,3500");
140
141	if (!autosave &&
142	    !pmac_has_backlight_type("pmu") &&
143	    !machine_is_compatible("AAPL,PowerBook1998") &&
144	    !machine_is_compatible("PowerBook1,1"))
145		return;
146
147	snprintf(name, sizeof(name), "pmubl");
148
149	bd = backlight_device_register(name, NULL, NULL, &pmu_backlight_data);
150	if (IS_ERR(bd)) {
151		printk("pmubl: Backlight registration failed\n");
152		goto error;
153	}
154	bd->props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
155	pmu_backlight_init_curve(0x7F, 0x46, 0x0E);
156
157	level = bd->props.max_brightness;
158
159	if (autosave) {
160		/* read autosaved value if available */
161		struct adb_request req;
162		pmu_request(&req, NULL, 2, 0xd9, 0);
163		pmu_wait_complete(&req);
164
165		level = pmu_backlight_curve_lookup(
166				(req.reply[0] >> 4) *
167				bd->props.max_brightness / 15);
168	}
169
170	bd->props.brightness = level;
171	bd->props.power = FB_BLANK_UNBLANK;
172	backlight_update_status(bd);
173
174	printk("pmubl: Backlight initialized (%s)\n", name);
175
176	return;
177
178error:
179	return;
180}
181