1/*
2 *
3 * Backlight driver for HP Jornada 700 series (710/720/728)
4 * Copyright (C) 2006-2009 Kristoffer Ericson <kristoffer.ericson@gmail.com>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License version
8 * 2 or any later version as published by the Free Software Foundation.
9 *
10 */
11
12#include <linux/backlight.h>
13#include <linux/device.h>
14#include <linux/fb.h>
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/platform_device.h>
18
19#include <mach/jornada720.h>
20#include <mach/hardware.h>
21
22#include <video/s1d13xxxfb.h>
23
24#define BL_MAX_BRIGHT	255
25#define BL_DEF_BRIGHT	25
26
27static int jornada_bl_get_brightness(struct backlight_device *bd)
28{
29	int ret;
30
31	/* check if backlight is on */
32	if (!(PPSR & PPC_LDD1))
33		return 0;
34
35	jornada_ssp_start();
36
37	/* cmd should return txdummy */
38	ret = jornada_ssp_byte(GETBRIGHTNESS);
39
40	if (jornada_ssp_byte(GETBRIGHTNESS) != TXDUMMY) {
41		dev_err(&bd->dev, "get brightness timeout\n");
42		jornada_ssp_end();
43		return -ETIMEDOUT;
44	}
45
46	/* exchange txdummy for value */
47	ret = jornada_ssp_byte(TXDUMMY);
48
49	jornada_ssp_end();
50
51	return BL_MAX_BRIGHT - ret;
52}
53
54static int jornada_bl_update_status(struct backlight_device *bd)
55{
56	int ret = 0;
57
58	jornada_ssp_start();
59
60	/* If backlight is off then really turn it off */
61	if ((bd->props.power != FB_BLANK_UNBLANK) || (bd->props.fb_blank != FB_BLANK_UNBLANK)) {
62		ret = jornada_ssp_byte(BRIGHTNESSOFF);
63		if (ret != TXDUMMY) {
64			dev_info(&bd->dev, "brightness off timeout\n");
65			/* turn off backlight */
66			PPSR &= ~PPC_LDD1;
67			PPDR |= PPC_LDD1;
68			ret = -ETIMEDOUT;
69		}
70	} else  /* turn on backlight */
71		PPSR |= PPC_LDD1;
72
73		/* send command to our mcu */
74		if (jornada_ssp_byte(SETBRIGHTNESS) != TXDUMMY) {
75			dev_info(&bd->dev, "failed to set brightness\n");
76			ret = -ETIMEDOUT;
77			goto out;
78		}
79
80		/*
81		 * at this point we expect that the mcu has accepted
82		 * our command and is waiting for our new value
83		 * please note that maximum brightness is 255,
84		 * but due to physical layout it is equal to 0, so we simply
85		 * invert the value (MAX VALUE - NEW VALUE).
86		 */
87		if (jornada_ssp_byte(BL_MAX_BRIGHT - bd->props.brightness)
88			!= TXDUMMY) {
89			dev_err(&bd->dev, "set brightness failed\n");
90			ret = -ETIMEDOUT;
91		}
92
93		/*
94		 * If infact we get an TXDUMMY as output we are happy and dont
95		 * make any further comments about it
96		 */
97out:
98	jornada_ssp_end();
99
100	return ret;
101}
102
103static const struct backlight_ops jornada_bl_ops = {
104	.get_brightness = jornada_bl_get_brightness,
105	.update_status = jornada_bl_update_status,
106	.options = BL_CORE_SUSPENDRESUME,
107};
108
109static int jornada_bl_probe(struct platform_device *pdev)
110{
111	struct backlight_properties props;
112	int ret;
113	struct backlight_device *bd;
114
115	memset(&props, 0, sizeof(struct backlight_properties));
116	props.type = BACKLIGHT_RAW;
117	props.max_brightness = BL_MAX_BRIGHT;
118
119	bd = devm_backlight_device_register(&pdev->dev, S1D_DEVICENAME,
120					&pdev->dev, NULL, &jornada_bl_ops,
121					&props);
122	if (IS_ERR(bd)) {
123		ret = PTR_ERR(bd);
124		dev_err(&pdev->dev, "failed to register device, err=%x\n", ret);
125		return ret;
126	}
127
128	bd->props.power = FB_BLANK_UNBLANK;
129	bd->props.brightness = BL_DEF_BRIGHT;
130	/*
131	 * note. make sure max brightness is set otherwise
132	 * you will get seemingly non-related errors when
133	 * trying to change brightness
134	 */
135	jornada_bl_update_status(bd);
136
137	platform_set_drvdata(pdev, bd);
138	dev_info(&pdev->dev, "HP Jornada 700 series backlight driver\n");
139
140	return 0;
141}
142
143static struct platform_driver jornada_bl_driver = {
144	.probe		= jornada_bl_probe,
145	.driver	= {
146		.name	= "jornada_bl",
147	},
148};
149
150module_platform_driver(jornada_bl_driver);
151
152MODULE_AUTHOR("Kristoffer Ericson <kristoffer.ericson>");
153MODULE_DESCRIPTION("HP Jornada 710/720/728 Backlight driver");
154MODULE_LICENSE("GPL");
155