pandora_bl.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Backlight driver for Pandora handheld.
  4 * Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight.
  5 * Based on pwm_bl.c
  6 *
  7 * Copyright 2009,2012 Gražvydas Ignotas <notasas@gmail.com>
  8 */
  9
 10#include <linux/module.h>
 11#include <linux/kernel.h>
 12#include <linux/platform_device.h>
 13#include <linux/delay.h>
 14#include <linux/backlight.h>
 15#include <linux/mfd/twl.h>
 16#include <linux/err.h>
 17
 18#define TWL_PWM0_ON		0x00
 19#define TWL_PWM0_OFF		0x01
 20
 21#define TWL_INTBR_GPBR1		0x0c
 22#define TWL_INTBR_PMBR1		0x0d
 23
 24#define TWL_PMBR1_PWM0_MUXMASK	0x0c
 25#define TWL_PMBR1_PWM0		0x04
 26#define PWM0_CLK_ENABLE		BIT(0)
 27#define PWM0_ENABLE		BIT(2)
 28
 29/* range accepted by hardware */
 30#define MIN_VALUE 9
 31#define MAX_VALUE 63
 32#define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
 33
 34struct pandora_private {
 35	unsigned old_state;
 36#define PANDORABL_WAS_OFF 1
 37};
 38
 39static int pandora_backlight_update_status(struct backlight_device *bl)
 40{
 41	int brightness = bl->props.brightness;
 42	struct pandora_private *priv = bl_get_data(bl);
 43	u8 r;
 44
 45	if (bl->props.power != BACKLIGHT_POWER_ON)
 46		brightness = 0;
 47	if (bl->props.state & BL_CORE_FBBLANK)
 48		brightness = 0;
 49	if (bl->props.state & BL_CORE_SUSPENDED)
 50		brightness = 0;
 51
 52	if ((unsigned int)brightness > MAX_USER_VALUE)
 53		brightness = MAX_USER_VALUE;
 54
 55	if (brightness == 0) {
 56		if (priv->old_state == PANDORABL_WAS_OFF)
 57			goto done;
 58
 59		/* first disable PWM0 output, then clock */
 60		twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
 61		r &= ~PWM0_ENABLE;
 62		twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
 63		r &= ~PWM0_CLK_ENABLE;
 64		twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
 65
 66		goto done;
 67	}
 68
 69	if (priv->old_state == PANDORABL_WAS_OFF) {
 70		/*
 71		 * set PWM duty cycle to max. TPS61161 seems to use this
 72		 * to calibrate it's PWM sensitivity when it starts.
 73		 */
 74		twl_i2c_write_u8(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
 75
 76		/* first enable clock, then PWM0 out */
 77		twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
 78		r &= ~PWM0_ENABLE;
 79		r |= PWM0_CLK_ENABLE;
 80		twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
 81		r |= PWM0_ENABLE;
 82		twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
 83
 84		/*
 85		 * TI made it very easy to enable digital control, so easy that
 86		 * it often triggers unintentionally and disabes PWM control,
 87		 * so wait until 1 wire mode detection window ends.
 88		 */
 89		usleep_range(2000, 10000);
 90	}
 91
 92	twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF);
 93
 94done:
 95	if (brightness != 0)
 96		priv->old_state = 0;
 97	else
 98		priv->old_state = PANDORABL_WAS_OFF;
 99
100	return 0;
101}
102
103static const struct backlight_ops pandora_backlight_ops = {
104	.options	= BL_CORE_SUSPENDRESUME,
105	.update_status	= pandora_backlight_update_status,
106};
107
108static int pandora_backlight_probe(struct platform_device *pdev)
109{
110	struct backlight_properties props;
111	struct backlight_device *bl;
112	struct pandora_private *priv;
113	u8 r;
114
115	priv = devm_kmalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
116	if (!priv)
117		return -ENOMEM;
118
119	memset(&props, 0, sizeof(props));
120	props.max_brightness = MAX_USER_VALUE;
121	props.type = BACKLIGHT_RAW;
122	bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
123					priv, &pandora_backlight_ops, &props);
124	if (IS_ERR(bl)) {
125		dev_err(&pdev->dev, "failed to register backlight\n");
126		return PTR_ERR(bl);
127	}
128
129	platform_set_drvdata(pdev, bl);
130
131	/* 64 cycle period, ON position 0 */
132	twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
133
134	priv->old_state = PANDORABL_WAS_OFF;
135	bl->props.brightness = MAX_USER_VALUE;
136	backlight_update_status(bl);
137
138	/* enable PWM function in pin mux */
139	twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
140	r &= ~TWL_PMBR1_PWM0_MUXMASK;
141	r |= TWL_PMBR1_PWM0;
142	twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
143
144	return 0;
145}
146
147static struct platform_driver pandora_backlight_driver = {
148	.driver		= {
149		.name	= "pandora-backlight",
150	},
151	.probe		= pandora_backlight_probe,
152};
153
154module_platform_driver(pandora_backlight_driver);
155
156MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
157MODULE_DESCRIPTION("Pandora Backlight Driver");
158MODULE_LICENSE("GPL");
159MODULE_ALIAS("platform:pandora-backlight");