1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Backlight driver for Wolfson Microelectronics WM831x PMICs 4 * 5 * Copyright 2009 Wolfson Microelectonics plc 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/init.h> 10 #include <linux/platform_device.h> 11 #include <linux/module.h> 12 #include <linux/fb.h> 13 #include <linux/backlight.h> 14 #include <linux/slab.h> 15 16 #include <linux/mfd/wm831x/core.h> 17 #include <linux/mfd/wm831x/pdata.h> 18 #include <linux/mfd/wm831x/regulator.h> 19 20 struct wm831x_backlight_data { 21 struct wm831x *wm831x; 22 int isink_reg; 23 int current_brightness; 24 }; 25 26 static int wm831x_backlight_set(struct backlight_device *bl, int brightness) 27 { 28 struct wm831x_backlight_data *data = bl_get_data(bl); 29 struct wm831x *wm831x = data->wm831x; 30 int power_up = !data->current_brightness && brightness; 31 int power_down = data->current_brightness && !brightness; 32 int ret; 33 34 if (power_up) { 35 /* Enable the ISINK */ 36 ret = wm831x_set_bits(wm831x, data->isink_reg, 37 WM831X_CS1_ENA, WM831X_CS1_ENA); 38 if (ret < 0) 39 goto err; 40 41 /* Enable the DC-DC */ 42 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, 43 WM831X_DC4_ENA, WM831X_DC4_ENA); 44 if (ret < 0) 45 goto err; 46 } 47 48 if (power_down) { 49 /* DCDC first */ 50 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, 51 WM831X_DC4_ENA, 0); 52 if (ret < 0) 53 goto err; 54 55 /* ISINK */ 56 ret = wm831x_set_bits(wm831x, data->isink_reg, 57 WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0); 58 if (ret < 0) 59 goto err; 60 } 61 62 /* Set the new brightness */ 63 ret = wm831x_set_bits(wm831x, data->isink_reg, 64 WM831X_CS1_ISEL_MASK, brightness); 65 if (ret < 0) 66 goto err; 67 68 if (power_up) { 69 /* Drive current through the ISINK */ 70 ret = wm831x_set_bits(wm831x, data->isink_reg, 71 WM831X_CS1_DRIVE, WM831X_CS1_DRIVE); 72 if (ret < 0) 73 return ret; 74 } 75 76 data->current_brightness = brightness; 77 78 return 0; 79 80 err: 81 /* If we were in the middle of a power transition always shut down 82 * for safety. 83 */ 84 if (power_up || power_down) { 85 wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0); 86 wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0); 87 } 88 89 return ret; 90 } 91 92 static int wm831x_backlight_update_status(struct backlight_device *bl) 93 { 94 return wm831x_backlight_set(bl, backlight_get_brightness(bl)); 95 } 96 97 static int wm831x_backlight_get_brightness(struct backlight_device *bl) 98 { 99 struct wm831x_backlight_data *data = bl_get_data(bl); 100 101 return data->current_brightness; 102 } 103 104 static const struct backlight_ops wm831x_backlight_ops = { 105 .options = BL_CORE_SUSPENDRESUME, 106 .update_status = wm831x_backlight_update_status, 107 .get_brightness = wm831x_backlight_get_brightness, 108 }; 109 110 static int wm831x_backlight_probe(struct platform_device *pdev) 111 { 112 struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent); 113 struct wm831x_pdata *wm831x_pdata = dev_get_platdata(pdev->dev.parent); 114 struct wm831x_backlight_pdata *pdata; 115 struct wm831x_backlight_data *data; 116 struct backlight_device *bl; 117 struct backlight_properties props; 118 int ret, i, max_isel, isink_reg, dcdc_cfg; 119 120 /* We need platform data */ 121 if (wm831x_pdata) 122 pdata = wm831x_pdata->backlight; 123 else 124 pdata = NULL; 125 126 if (!pdata) { 127 dev_err(&pdev->dev, "No platform data supplied\n"); 128 return -EINVAL; 129 } 130 131 /* Figure out the maximum current we can use */ 132 for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) { 133 if (wm831x_isinkv_values[i] > pdata->max_uA) 134 break; 135 } 136 137 if (i == 0) { 138 dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA); 139 return -EINVAL; 140 } 141 max_isel = i - 1; 142 143 if (pdata->max_uA != wm831x_isinkv_values[max_isel]) 144 dev_warn(&pdev->dev, 145 "Maximum current is %duA not %duA as requested\n", 146 wm831x_isinkv_values[max_isel], pdata->max_uA); 147 148 switch (pdata->isink) { 149 case 1: 150 isink_reg = WM831X_CURRENT_SINK_1; 151 dcdc_cfg = 0; 152 break; 153 case 2: 154 isink_reg = WM831X_CURRENT_SINK_2; 155 dcdc_cfg = WM831X_DC4_FBSRC; 156 break; 157 default: 158 dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink); 159 return -EINVAL; 160 } 161 162 /* Configure the ISINK to use for feedback */ 163 ret = wm831x_reg_unlock(wm831x); 164 if (ret < 0) 165 return ret; 166 167 ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC, 168 dcdc_cfg); 169 170 wm831x_reg_lock(wm831x); 171 if (ret < 0) 172 return ret; 173 174 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 175 if (data == NULL) 176 return -ENOMEM; 177 178 data->wm831x = wm831x; 179 data->current_brightness = 0; 180 data->isink_reg = isink_reg; 181 182 memset(&props, 0, sizeof(props)); 183 props.type = BACKLIGHT_RAW; 184 props.max_brightness = max_isel; 185 bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev, 186 data, &wm831x_backlight_ops, &props); 187 if (IS_ERR(bl)) { 188 dev_err(&pdev->dev, "failed to register backlight\n"); 189 return PTR_ERR(bl); 190 } 191 192 bl->props.brightness = max_isel; 193 194 platform_set_drvdata(pdev, bl); 195 196 /* Disable the DCDC if it was started so we can bootstrap */ 197 wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0); 198 199 backlight_update_status(bl); 200 201 return 0; 202 } 203 204 static struct platform_driver wm831x_backlight_driver = { 205 .driver = { 206 .name = "wm831x-backlight", 207 }, 208 .probe = wm831x_backlight_probe, 209 }; 210 211 module_platform_driver(wm831x_backlight_driver); 212 213 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs"); 214 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com"); 215 MODULE_LICENSE("GPL"); 216 MODULE_ALIAS("platform:wm831x-backlight"); 217