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 
27 static 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 
54 static 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 		 */
97 out:
98 	jornada_ssp_end();
99 
100 	return ret;
101 }
102 
103 static 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 
109 static 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 
143 static struct platform_driver jornada_bl_driver = {
144 	.probe		= jornada_bl_probe,
145 	.driver	= {
146 		.name	= "jornada_bl",
147 	},
148 };
149 
150 module_platform_driver(jornada_bl_driver);
151 
152 MODULE_AUTHOR("Kristoffer Ericson <kristoffer.ericson>");
153 MODULE_DESCRIPTION("HP Jornada 710/720/728 Backlight driver");
154 MODULE_LICENSE("GPL");
155