2 * Backlight driver for Pandora handheld.
3 * Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight.
6 * Copyright 2009,2012 Gražvydas Ignotas <notasas@gmail.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
13 #include <linux/module.h>
14 #include <linux/kernel.h>
15 #include <linux/platform_device.h>
16 #include <linux/delay.h>
18 #include <linux/backlight.h>
19 #include <linux/mfd/twl.h>
20 #include <linux/err.h>
22 #define TWL_PWM0_ON 0x00
23 #define TWL_PWM0_OFF 0x01
25 #define TWL_INTBR_GPBR1 0x0c
26 #define TWL_INTBR_PMBR1 0x0d
28 #define TWL_PMBR1_PWM0_MUXMASK 0x0c
29 #define TWL_PMBR1_PWM0 0x04
30 #define PWM0_CLK_ENABLE BIT(0)
31 #define PWM0_ENABLE BIT(2)
33 /* range accepted by hardware */
36 #define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
38 struct pandora_private {
40 #define PANDORABL_WAS_OFF 1
43 static int pandora_backlight_update_status(struct backlight_device *bl)
45 int brightness = bl->props.brightness;
46 struct pandora_private *priv = bl_get_data(bl);
49 if (bl->props.power != FB_BLANK_UNBLANK)
51 if (bl->props.state & BL_CORE_FBBLANK)
53 if (bl->props.state & BL_CORE_SUSPENDED)
56 if ((unsigned int)brightness > MAX_USER_VALUE)
57 brightness = MAX_USER_VALUE;
59 if (brightness == 0) {
60 if (priv->old_state == PANDORABL_WAS_OFF)
63 /* first disable PWM0 output, then clock */
64 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
66 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
67 r &= ~PWM0_CLK_ENABLE;
68 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
73 if (priv->old_state == PANDORABL_WAS_OFF) {
75 * set PWM duty cycle to max. TPS61161 seems to use this
76 * to calibrate it's PWM sensitivity when it starts.
78 twl_i2c_write_u8(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
80 /* first enable clock, then PWM0 out */
81 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
84 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
86 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
89 * TI made it very easy to enable digital control, so easy that
90 * it often triggers unintentionally and disabes PWM control,
91 * so wait until 1 wire mode detection window ends.
93 usleep_range(2000, 10000);
96 twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF);
102 priv->old_state = PANDORABL_WAS_OFF;
107 static const struct backlight_ops pandora_backlight_ops = {
108 .options = BL_CORE_SUSPENDRESUME,
109 .update_status = pandora_backlight_update_status,
112 static int pandora_backlight_probe(struct platform_device *pdev)
114 struct backlight_properties props;
115 struct backlight_device *bl;
116 struct pandora_private *priv;
119 priv = devm_kmalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
121 dev_err(&pdev->dev, "failed to allocate driver private data\n");
125 memset(&props, 0, sizeof(props));
126 props.max_brightness = MAX_USER_VALUE;
127 props.type = BACKLIGHT_RAW;
128 bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
129 priv, &pandora_backlight_ops, &props);
131 dev_err(&pdev->dev, "failed to register backlight\n");
135 platform_set_drvdata(pdev, bl);
137 /* 64 cycle period, ON position 0 */
138 twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
140 priv->old_state = PANDORABL_WAS_OFF;
141 bl->props.brightness = MAX_USER_VALUE;
142 backlight_update_status(bl);
144 /* enable PWM function in pin mux */
145 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
146 r &= ~TWL_PMBR1_PWM0_MUXMASK;
148 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
153 static struct platform_driver pandora_backlight_driver = {
155 .name = "pandora-backlight",
157 .probe = pandora_backlight_probe,
160 module_platform_driver(pandora_backlight_driver);
162 MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
163 MODULE_DESCRIPTION("Pandora Backlight Driver");
164 MODULE_LICENSE("GPL");
165 MODULE_ALIAS("platform:pandora-backlight");