155 lines
4.1 KiB
C
155 lines
4.1 KiB
C
/*
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* Backlight driver for Pandora handheld.
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* Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight.
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* Based on pwm_bl.c
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*
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* Copyright 2009,2012 Gražvydas Ignotas <notasas@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/delay.h>
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#include <linux/fb.h>
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#include <linux/backlight.h>
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#include <linux/mfd/twl.h>
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#include <linux/err.h>
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#define TWL_PWM0_ON 0x00
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#define TWL_PWM0_OFF 0x01
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#define TWL_INTBR_GPBR1 0x0c
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#define TWL_INTBR_PMBR1 0x0d
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#define TWL_PMBR1_PWM0_MUXMASK 0x0c
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#define TWL_PMBR1_PWM0 0x04
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#define PWM0_CLK_ENABLE BIT(0)
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#define PWM0_ENABLE BIT(2)
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/* range accepted by hardware */
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#define MIN_VALUE 9
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#define MAX_VALUE 63
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#define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
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#define PANDORABL_WAS_OFF BL_CORE_DRIVER1
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static int pandora_backlight_update_status(struct backlight_device *bl)
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{
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int brightness = bl->props.brightness;
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u8 r;
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if (bl->props.power != FB_BLANK_UNBLANK)
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brightness = 0;
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if (bl->props.state & BL_CORE_FBBLANK)
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brightness = 0;
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if (bl->props.state & BL_CORE_SUSPENDED)
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brightness = 0;
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if ((unsigned int)brightness > MAX_USER_VALUE)
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brightness = MAX_USER_VALUE;
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if (brightness == 0) {
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if (bl->props.state & PANDORABL_WAS_OFF)
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goto done;
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/* first disable PWM0 output, then clock */
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twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
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r &= ~PWM0_ENABLE;
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twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
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r &= ~PWM0_CLK_ENABLE;
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twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
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goto done;
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}
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if (bl->props.state & PANDORABL_WAS_OFF) {
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/*
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* set PWM duty cycle to max. TPS61161 seems to use this
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* to calibrate it's PWM sensitivity when it starts.
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*/
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twl_i2c_write_u8(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
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/* first enable clock, then PWM0 out */
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twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
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r &= ~PWM0_ENABLE;
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r |= PWM0_CLK_ENABLE;
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twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
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r |= PWM0_ENABLE;
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twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
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/*
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* TI made it very easy to enable digital control, so easy that
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* it often triggers unintentionally and disabes PWM control,
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* so wait until 1 wire mode detection window ends.
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*/
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usleep_range(2000, 10000);
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}
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twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF);
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done:
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if (brightness != 0)
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bl->props.state &= ~PANDORABL_WAS_OFF;
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else
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bl->props.state |= PANDORABL_WAS_OFF;
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return 0;
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}
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static const struct backlight_ops pandora_backlight_ops = {
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.options = BL_CORE_SUSPENDRESUME,
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.update_status = pandora_backlight_update_status,
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};
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static int pandora_backlight_probe(struct platform_device *pdev)
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{
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struct backlight_properties props;
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struct backlight_device *bl;
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u8 r;
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memset(&props, 0, sizeof(props));
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props.max_brightness = MAX_USER_VALUE;
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props.type = BACKLIGHT_RAW;
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bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
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NULL, &pandora_backlight_ops, &props);
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if (IS_ERR(bl)) {
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dev_err(&pdev->dev, "failed to register backlight\n");
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return PTR_ERR(bl);
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}
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platform_set_drvdata(pdev, bl);
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/* 64 cycle period, ON position 0 */
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twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
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bl->props.state |= PANDORABL_WAS_OFF;
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bl->props.brightness = MAX_USER_VALUE;
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backlight_update_status(bl);
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/* enable PWM function in pin mux */
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twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
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r &= ~TWL_PMBR1_PWM0_MUXMASK;
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r |= TWL_PMBR1_PWM0;
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twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
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return 0;
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}
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static struct platform_driver pandora_backlight_driver = {
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.driver = {
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.name = "pandora-backlight",
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},
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.probe = pandora_backlight_probe,
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};
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module_platform_driver(pandora_backlight_driver);
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MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
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MODULE_DESCRIPTION("Pandora Backlight Driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:pandora-backlight");
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