1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Backlight driver for Maxim MAX8925 4 * 5 * Copyright (C) 2009 Marvell International Ltd. 6 * Haojian Zhuang <haojian.zhuang@marvell.com> 7 */ 8 9 #include <linux/init.h> 10 #include <linux/kernel.h> 11 #include <linux/platform_device.h> 12 #include <linux/fb.h> 13 #include <linux/i2c.h> 14 #include <linux/backlight.h> 15 #include <linux/mfd/max8925.h> 16 #include <linux/slab.h> 17 #include <linux/module.h> 18 19 #define MAX_BRIGHTNESS (0xff) 20 #define MIN_BRIGHTNESS (0) 21 22 #define LWX_FREQ(x) (((x - 601) / 100) & 0x7) 23 24 struct max8925_backlight_data { 25 struct max8925_chip *chip; 26 27 int current_brightness; 28 int reg_mode_cntl; 29 int reg_cntl; 30 }; 31 32 static int max8925_backlight_set(struct backlight_device *bl, int brightness) 33 { 34 struct max8925_backlight_data *data = bl_get_data(bl); 35 struct max8925_chip *chip = data->chip; 36 unsigned char value; 37 int ret; 38 39 if (brightness > MAX_BRIGHTNESS) 40 value = MAX_BRIGHTNESS; 41 else 42 value = brightness; 43 44 ret = max8925_reg_write(chip->i2c, data->reg_cntl, value); 45 if (ret < 0) 46 goto out; 47 48 if (!data->current_brightness && brightness) 49 /* enable WLED output */ 50 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1); 51 else if (!brightness) 52 /* disable WLED output */ 53 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0); 54 if (ret < 0) 55 goto out; 56 dev_dbg(chip->dev, "set brightness %d\n", value); 57 data->current_brightness = value; 58 return 0; 59 out: 60 dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n", 61 value, ret); 62 return ret; 63 } 64 65 static int max8925_backlight_update_status(struct backlight_device *bl) 66 { 67 return max8925_backlight_set(bl, backlight_get_brightness(bl)); 68 } 69 70 static int max8925_backlight_get_brightness(struct backlight_device *bl) 71 { 72 struct max8925_backlight_data *data = bl_get_data(bl); 73 struct max8925_chip *chip = data->chip; 74 int ret; 75 76 ret = max8925_reg_read(chip->i2c, data->reg_cntl); 77 if (ret < 0) 78 return -EINVAL; 79 data->current_brightness = ret; 80 dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness); 81 return ret; 82 } 83 84 static const struct backlight_ops max8925_backlight_ops = { 85 .options = BL_CORE_SUSPENDRESUME, 86 .update_status = max8925_backlight_update_status, 87 .get_brightness = max8925_backlight_get_brightness, 88 }; 89 90 static void max8925_backlight_dt_init(struct platform_device *pdev) 91 { 92 struct device_node *nproot = pdev->dev.parent->of_node, *np; 93 struct max8925_backlight_pdata *pdata; 94 u32 val; 95 96 if (!nproot || !IS_ENABLED(CONFIG_OF)) 97 return; 98 99 pdata = devm_kzalloc(&pdev->dev, 100 sizeof(struct max8925_backlight_pdata), 101 GFP_KERNEL); 102 if (!pdata) 103 return; 104 105 np = of_get_child_by_name(nproot, "backlight"); 106 if (!np) { 107 dev_err(&pdev->dev, "failed to find backlight node\n"); 108 return; 109 } 110 111 if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val)) 112 pdata->dual_string = val; 113 114 of_node_put(np); 115 116 pdev->dev.platform_data = pdata; 117 } 118 119 static int max8925_backlight_probe(struct platform_device *pdev) 120 { 121 struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent); 122 struct max8925_backlight_pdata *pdata; 123 struct max8925_backlight_data *data; 124 struct backlight_device *bl; 125 struct backlight_properties props; 126 struct resource *res; 127 unsigned char value; 128 int ret = 0; 129 130 data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data), 131 GFP_KERNEL); 132 if (data == NULL) 133 return -ENOMEM; 134 135 res = platform_get_resource(pdev, IORESOURCE_REG, 0); 136 if (!res) { 137 dev_err(&pdev->dev, "No REG resource for mode control!\n"); 138 return -ENXIO; 139 } 140 data->reg_mode_cntl = res->start; 141 res = platform_get_resource(pdev, IORESOURCE_REG, 1); 142 if (!res) { 143 dev_err(&pdev->dev, "No REG resource for control!\n"); 144 return -ENXIO; 145 } 146 data->reg_cntl = res->start; 147 148 data->chip = chip; 149 data->current_brightness = 0; 150 151 memset(&props, 0, sizeof(struct backlight_properties)); 152 props.type = BACKLIGHT_RAW; 153 props.max_brightness = MAX_BRIGHTNESS; 154 bl = devm_backlight_device_register(&pdev->dev, "max8925-backlight", 155 &pdev->dev, data, 156 &max8925_backlight_ops, &props); 157 if (IS_ERR(bl)) { 158 dev_err(&pdev->dev, "failed to register backlight\n"); 159 return PTR_ERR(bl); 160 } 161 bl->props.brightness = MAX_BRIGHTNESS; 162 163 platform_set_drvdata(pdev, bl); 164 165 value = 0; 166 if (!pdev->dev.platform_data) 167 max8925_backlight_dt_init(pdev); 168 169 pdata = pdev->dev.platform_data; 170 if (pdata) { 171 if (pdata->lxw_scl) 172 value |= (1 << 7); 173 if (pdata->lxw_freq) 174 value |= (LWX_FREQ(pdata->lxw_freq) << 4); 175 if (pdata->dual_string) 176 value |= (1 << 1); 177 } 178 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value); 179 if (ret < 0) 180 return ret; 181 backlight_update_status(bl); 182 return 0; 183 } 184 185 static struct platform_driver max8925_backlight_driver = { 186 .driver = { 187 .name = "max8925-backlight", 188 }, 189 .probe = max8925_backlight_probe, 190 }; 191 192 module_platform_driver(max8925_backlight_driver); 193 194 MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925"); 195 MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>"); 196 MODULE_LICENSE("GPL"); 197 MODULE_ALIAS("platform:max8925-backlight"); 198