1/* 2 * Copyright (C) 2012 Bachmann electronic GmbH 3 * Christian Gmeiner <christian.gmeiner@gmail.com> 4 * 5 * Backlight driver for ot200 visualisation device from 6 * Bachmann electronic GmbH. 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License version 2 as published by 10 * the Free Software Foundation. 11 */ 12 13#include <linux/module.h> 14#include <linux/fb.h> 15#include <linux/backlight.h> 16#include <linux/gpio.h> 17#include <linux/cs5535.h> 18 19static struct cs5535_mfgpt_timer *pwm_timer; 20 21/* this array defines the mapping of brightness in % to pwm frequency */ 22static const u8 dim_table[101] = {0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 23 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 24 4, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9, 25 10, 10, 11, 11, 12, 12, 13, 14, 15, 15, 16, 26 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 27 30, 31, 33, 35, 37, 39, 41, 43, 45, 47, 50, 28 53, 55, 58, 61, 65, 68, 72, 75, 79, 84, 88, 29 93, 97, 103, 108, 114, 120, 126, 133, 140, 30 147, 155, 163}; 31 32struct ot200_backlight_data { 33 int current_brightness; 34}; 35 36#define GPIO_DIMM 27 37#define SCALE 1 38#define CMP1MODE 0x2 /* compare on GE; output high on compare 39 * greater than or equal */ 40#define PWM_SETUP (SCALE | CMP1MODE << 6 | MFGPT_SETUP_CNTEN) 41#define MAX_COMP2 163 42 43static int ot200_backlight_update_status(struct backlight_device *bl) 44{ 45 struct ot200_backlight_data *data = bl_get_data(bl); 46 int brightness = bl->props.brightness; 47 48 if (bl->props.state & BL_CORE_FBBLANK) 49 brightness = 0; 50 51 /* enable or disable PWM timer */ 52 if (brightness == 0) 53 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, 0); 54 else if (data->current_brightness == 0) { 55 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0); 56 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, 57 MFGPT_SETUP_CNTEN); 58 } 59 60 /* apply new brightness value */ 61 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1, 62 MAX_COMP2 - dim_table[brightness]); 63 data->current_brightness = brightness; 64 65 return 0; 66} 67 68static int ot200_backlight_get_brightness(struct backlight_device *bl) 69{ 70 struct ot200_backlight_data *data = bl_get_data(bl); 71 return data->current_brightness; 72} 73 74static const struct backlight_ops ot200_backlight_ops = { 75 .update_status = ot200_backlight_update_status, 76 .get_brightness = ot200_backlight_get_brightness, 77}; 78 79static int ot200_backlight_probe(struct platform_device *pdev) 80{ 81 struct backlight_device *bl; 82 struct ot200_backlight_data *data; 83 struct backlight_properties props; 84 int retval = 0; 85 86 /* request gpio */ 87 if (gpio_request(GPIO_DIMM, "ot200 backlight dimmer") < 0) { 88 dev_err(&pdev->dev, "failed to request GPIO %d\n", GPIO_DIMM); 89 return -ENODEV; 90 } 91 92 /* request timer */ 93 pwm_timer = cs5535_mfgpt_alloc_timer(7, MFGPT_DOMAIN_ANY); 94 if (!pwm_timer) { 95 dev_err(&pdev->dev, "MFGPT 7 not available\n"); 96 retval = -ENODEV; 97 goto error_mfgpt_alloc; 98 } 99 100 data = kzalloc(sizeof(*data), GFP_KERNEL); 101 if (!data) { 102 retval = -ENOMEM; 103 goto error_kzalloc; 104 } 105 106 /* setup gpio */ 107 cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_ENABLE); 108 cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_AUX1); 109 110 /* setup timer */ 111 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1, 0); 112 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP2, MAX_COMP2); 113 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, PWM_SETUP); 114 115 data->current_brightness = 100; 116 props.max_brightness = 100; 117 props.brightness = 100; 118 props.type = BACKLIGHT_RAW; 119 120 bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, data, 121 &ot200_backlight_ops, &props); 122 if (IS_ERR(bl)) { 123 dev_err(&pdev->dev, "failed to register backlight\n"); 124 retval = PTR_ERR(bl); 125 goto error_backlight_device_register; 126 } 127 128 platform_set_drvdata(pdev, bl); 129 130 return 0; 131 132error_backlight_device_register: 133 kfree(data); 134error_kzalloc: 135 cs5535_mfgpt_free_timer(pwm_timer); 136error_mfgpt_alloc: 137 gpio_free(GPIO_DIMM); 138 return retval; 139} 140 141static int ot200_backlight_remove(struct platform_device *pdev) 142{ 143 struct backlight_device *bl = platform_get_drvdata(pdev); 144 struct ot200_backlight_data *data = bl_get_data(bl); 145 146 backlight_device_unregister(bl); 147 148 /* on module unload set brightness to 100% */ 149 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0); 150 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN); 151 cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1, 152 MAX_COMP2 - dim_table[100]); 153 154 cs5535_mfgpt_free_timer(pwm_timer); 155 gpio_free(GPIO_DIMM); 156 157 kfree(data); 158 return 0; 159} 160 161static struct platform_driver ot200_backlight_driver = { 162 .driver = { 163 .name = "ot200-backlight", 164 .owner = THIS_MODULE, 165 }, 166 .probe = ot200_backlight_probe, 167 .remove = ot200_backlight_remove, 168}; 169 170module_platform_driver(ot200_backlight_driver); 171 172MODULE_DESCRIPTION("backlight driver for ot200 visualisation device"); 173MODULE_AUTHOR("Christian Gmeiner <christian.gmeiner@gmail.com>"); 174MODULE_LICENSE("GPL"); 175MODULE_ALIAS("platform:ot200-backlight"); 176