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_find_node_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 pdev->dev.platform_data = pdata; 129 } 130 131 static int max8925_backlight_probe(struct platform_device *pdev) 132 { 133 struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent); 134 struct max8925_backlight_pdata *pdata; 135 struct max8925_backlight_data *data; 136 struct backlight_device *bl; 137 struct backlight_properties props; 138 struct resource *res; 139 unsigned char value; 140 int ret = 0; 141 142 data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data), 143 GFP_KERNEL); 144 if (data == NULL) 145 return -ENOMEM; 146 147 res = platform_get_resource(pdev, IORESOURCE_REG, 0); 148 if (!res) { 149 dev_err(&pdev->dev, "No REG resource for mode control!\n"); 150 return -ENXIO; 151 } 152 data->reg_mode_cntl = res->start; 153 res = platform_get_resource(pdev, IORESOURCE_REG, 1); 154 if (!res) { 155 dev_err(&pdev->dev, "No REG resource for control!\n"); 156 return -ENXIO; 157 } 158 data->reg_cntl = res->start; 159 160 data->chip = chip; 161 data->current_brightness = 0; 162 163 memset(&props, 0, sizeof(struct backlight_properties)); 164 props.type = BACKLIGHT_RAW; 165 props.max_brightness = MAX_BRIGHTNESS; 166 bl = backlight_device_register("max8925-backlight", &pdev->dev, data, 167 &max8925_backlight_ops, &props); 168 if (IS_ERR(bl)) { 169 dev_err(&pdev->dev, "failed to register backlight\n"); 170 return PTR_ERR(bl); 171 } 172 bl->props.brightness = MAX_BRIGHTNESS; 173 174 platform_set_drvdata(pdev, bl); 175 176 value = 0; 177 if (!pdev->dev.platform_data) 178 max8925_backlight_dt_init(pdev); 179 180 pdata = pdev->dev.platform_data; 181 if (pdata) { 182 if (pdata->lxw_scl) 183 value |= (1 << 7); 184 if (pdata->lxw_freq) 185 value |= (LWX_FREQ(pdata->lxw_freq) << 4); 186 if (pdata->dual_string) 187 value |= (1 << 1); 188 } 189 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value); 190 if (ret < 0) 191 goto out_brt; 192 backlight_update_status(bl); 193 return 0; 194 out_brt: 195 backlight_device_unregister(bl); 196 return ret; 197 } 198 199 static int max8925_backlight_remove(struct platform_device *pdev) 200 { 201 struct backlight_device *bl = platform_get_drvdata(pdev); 202 203 backlight_device_unregister(bl); 204 return 0; 205 } 206 207 static struct platform_driver max8925_backlight_driver = { 208 .driver = { 209 .name = "max8925-backlight", 210 .owner = THIS_MODULE, 211 }, 212 .probe = max8925_backlight_probe, 213 .remove = max8925_backlight_remove, 214 }; 215 216 module_platform_driver(max8925_backlight_driver); 217 218 MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925"); 219 MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>"); 220 MODULE_LICENSE("GPL"); 221 MODULE_ALIAS("platform:max8925-backlight"); 222