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