1 /* 2 * Backlight driver for Maxim MAX8925 3 * 4 * Copyright (C) 2009 Marvell International Ltd. 5 * Haojian Zhuang <haojian.zhuang@marvell.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 12 #include <linux/init.h> 13 #include <linux/kernel.h> 14 #include <linux/platform_device.h> 15 #include <linux/fb.h> 16 #include <linux/i2c.h> 17 #include <linux/backlight.h> 18 #include <linux/mfd/max8925.h> 19 #include <linux/slab.h> 20 #include <linux/module.h> 21 22 #define MAX_BRIGHTNESS (0xff) 23 #define MIN_BRIGHTNESS (0) 24 25 #define LWX_FREQ(x) (((x - 601) / 100) & 0x7) 26 27 struct max8925_backlight_data { 28 struct max8925_chip *chip; 29 30 int current_brightness; 31 int reg_mode_cntl; 32 int reg_cntl; 33 }; 34 35 static int max8925_backlight_set(struct backlight_device *bl, int brightness) 36 { 37 struct max8925_backlight_data *data = bl_get_data(bl); 38 struct max8925_chip *chip = data->chip; 39 unsigned char value; 40 int ret; 41 42 if (brightness > MAX_BRIGHTNESS) 43 value = MAX_BRIGHTNESS; 44 else 45 value = brightness; 46 47 ret = max8925_reg_write(chip->i2c, data->reg_cntl, value); 48 if (ret < 0) 49 goto out; 50 51 if (!data->current_brightness && brightness) 52 /* enable WLED output */ 53 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1); 54 else if (!brightness) 55 /* disable WLED output */ 56 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0); 57 if (ret < 0) 58 goto out; 59 dev_dbg(chip->dev, "set brightness %d\n", value); 60 data->current_brightness = value; 61 return 0; 62 out: 63 dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n", 64 value, ret); 65 return ret; 66 } 67 68 static int max8925_backlight_update_status(struct backlight_device *bl) 69 { 70 int brightness = bl->props.brightness; 71 72 if (bl->props.power != FB_BLANK_UNBLANK) 73 brightness = 0; 74 75 if (bl->props.fb_blank != FB_BLANK_UNBLANK) 76 brightness = 0; 77 78 if (bl->props.state & BL_CORE_SUSPENDED) 79 brightness = 0; 80 81 return max8925_backlight_set(bl, brightness); 82 } 83 84 static int max8925_backlight_get_brightness(struct backlight_device *bl) 85 { 86 struct max8925_backlight_data *data = bl_get_data(bl); 87 struct max8925_chip *chip = data->chip; 88 int ret; 89 90 ret = max8925_reg_read(chip->i2c, data->reg_cntl); 91 if (ret < 0) 92 return -EINVAL; 93 data->current_brightness = ret; 94 dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness); 95 return ret; 96 } 97 98 static const struct backlight_ops max8925_backlight_ops = { 99 .options = BL_CORE_SUSPENDRESUME, 100 .update_status = max8925_backlight_update_status, 101 .get_brightness = max8925_backlight_get_brightness, 102 }; 103 104 static void max8925_backlight_dt_init(struct platform_device *pdev) 105 { 106 struct device_node *nproot = pdev->dev.parent->of_node, *np; 107 struct max8925_backlight_pdata *pdata; 108 u32 val; 109 110 if (!nproot || !IS_ENABLED(CONFIG_OF)) 111 return; 112 113 pdata = devm_kzalloc(&pdev->dev, 114 sizeof(struct max8925_backlight_pdata), 115 GFP_KERNEL); 116 if (!pdata) 117 return; 118 119 np = of_get_child_by_name(nproot, "backlight"); 120 if (!np) { 121 dev_err(&pdev->dev, "failed to find backlight node\n"); 122 return; 123 } 124 125 if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val)) 126 pdata->dual_string = val; 127 128 of_node_put(np); 129 130 pdev->dev.platform_data = pdata; 131 } 132 133 static int max8925_backlight_probe(struct platform_device *pdev) 134 { 135 struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent); 136 struct max8925_backlight_pdata *pdata; 137 struct max8925_backlight_data *data; 138 struct backlight_device *bl; 139 struct backlight_properties props; 140 struct resource *res; 141 unsigned char value; 142 int ret = 0; 143 144 data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data), 145 GFP_KERNEL); 146 if (data == NULL) 147 return -ENOMEM; 148 149 res = platform_get_resource(pdev, IORESOURCE_REG, 0); 150 if (!res) { 151 dev_err(&pdev->dev, "No REG resource for mode control!\n"); 152 return -ENXIO; 153 } 154 data->reg_mode_cntl = res->start; 155 res = platform_get_resource(pdev, IORESOURCE_REG, 1); 156 if (!res) { 157 dev_err(&pdev->dev, "No REG resource for control!\n"); 158 return -ENXIO; 159 } 160 data->reg_cntl = res->start; 161 162 data->chip = chip; 163 data->current_brightness = 0; 164 165 memset(&props, 0, sizeof(struct backlight_properties)); 166 props.type = BACKLIGHT_RAW; 167 props.max_brightness = MAX_BRIGHTNESS; 168 bl = devm_backlight_device_register(&pdev->dev, "max8925-backlight", 169 &pdev->dev, data, 170 &max8925_backlight_ops, &props); 171 if (IS_ERR(bl)) { 172 dev_err(&pdev->dev, "failed to register backlight\n"); 173 return PTR_ERR(bl); 174 } 175 bl->props.brightness = MAX_BRIGHTNESS; 176 177 platform_set_drvdata(pdev, bl); 178 179 value = 0; 180 if (!pdev->dev.platform_data) 181 max8925_backlight_dt_init(pdev); 182 183 pdata = pdev->dev.platform_data; 184 if (pdata) { 185 if (pdata->lxw_scl) 186 value |= (1 << 7); 187 if (pdata->lxw_freq) 188 value |= (LWX_FREQ(pdata->lxw_freq) << 4); 189 if (pdata->dual_string) 190 value |= (1 << 1); 191 } 192 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value); 193 if (ret < 0) 194 return ret; 195 backlight_update_status(bl); 196 return 0; 197 } 198 199 static struct platform_driver max8925_backlight_driver = { 200 .driver = { 201 .name = "max8925-backlight", 202 }, 203 .probe = max8925_backlight_probe, 204 }; 205 206 module_platform_driver(max8925_backlight_driver); 207 208 MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925"); 209 MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>"); 210 MODULE_LICENSE("GPL"); 211 MODULE_ALIAS("platform:max8925-backlight"); 212