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 int brightness = bl->props.brightness; 95 96 if (bl->props.power != FB_BLANK_UNBLANK) 97 brightness = 0; 98 99 if (bl->props.fb_blank != FB_BLANK_UNBLANK) 100 brightness = 0; 101 102 if (bl->props.state & BL_CORE_SUSPENDED) 103 brightness = 0; 104 105 return wm831x_backlight_set(bl, brightness); 106 } 107 108 static int wm831x_backlight_get_brightness(struct backlight_device *bl) 109 { 110 struct wm831x_backlight_data *data = bl_get_data(bl); 111 112 return data->current_brightness; 113 } 114 115 static const struct backlight_ops wm831x_backlight_ops = { 116 .options = BL_CORE_SUSPENDRESUME, 117 .update_status = wm831x_backlight_update_status, 118 .get_brightness = wm831x_backlight_get_brightness, 119 }; 120 121 static int wm831x_backlight_probe(struct platform_device *pdev) 122 { 123 struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent); 124 struct wm831x_pdata *wm831x_pdata = dev_get_platdata(pdev->dev.parent); 125 struct wm831x_backlight_pdata *pdata; 126 struct wm831x_backlight_data *data; 127 struct backlight_device *bl; 128 struct backlight_properties props; 129 int ret, i, max_isel, isink_reg, dcdc_cfg; 130 131 /* We need platform data */ 132 if (wm831x_pdata) 133 pdata = wm831x_pdata->backlight; 134 else 135 pdata = NULL; 136 137 if (!pdata) { 138 dev_err(&pdev->dev, "No platform data supplied\n"); 139 return -EINVAL; 140 } 141 142 /* Figure out the maximum current we can use */ 143 for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) { 144 if (wm831x_isinkv_values[i] > pdata->max_uA) 145 break; 146 } 147 148 if (i == 0) { 149 dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA); 150 return -EINVAL; 151 } 152 max_isel = i - 1; 153 154 if (pdata->max_uA != wm831x_isinkv_values[max_isel]) 155 dev_warn(&pdev->dev, 156 "Maximum current is %duA not %duA as requested\n", 157 wm831x_isinkv_values[max_isel], pdata->max_uA); 158 159 switch (pdata->isink) { 160 case 1: 161 isink_reg = WM831X_CURRENT_SINK_1; 162 dcdc_cfg = 0; 163 break; 164 case 2: 165 isink_reg = WM831X_CURRENT_SINK_2; 166 dcdc_cfg = WM831X_DC4_FBSRC; 167 break; 168 default: 169 dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink); 170 return -EINVAL; 171 } 172 173 /* Configure the ISINK to use for feedback */ 174 ret = wm831x_reg_unlock(wm831x); 175 if (ret < 0) 176 return ret; 177 178 ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC, 179 dcdc_cfg); 180 181 wm831x_reg_lock(wm831x); 182 if (ret < 0) 183 return ret; 184 185 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 186 if (data == NULL) 187 return -ENOMEM; 188 189 data->wm831x = wm831x; 190 data->current_brightness = 0; 191 data->isink_reg = isink_reg; 192 193 memset(&props, 0, sizeof(props)); 194 props.type = BACKLIGHT_RAW; 195 props.max_brightness = max_isel; 196 bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev, 197 data, &wm831x_backlight_ops, &props); 198 if (IS_ERR(bl)) { 199 dev_err(&pdev->dev, "failed to register backlight\n"); 200 return PTR_ERR(bl); 201 } 202 203 bl->props.brightness = max_isel; 204 205 platform_set_drvdata(pdev, bl); 206 207 /* Disable the DCDC if it was started so we can bootstrap */ 208 wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0); 209 210 backlight_update_status(bl); 211 212 return 0; 213 } 214 215 static struct platform_driver wm831x_backlight_driver = { 216 .driver = { 217 .name = "wm831x-backlight", 218 }, 219 .probe = wm831x_backlight_probe, 220 }; 221 222 module_platform_driver(wm831x_backlight_driver); 223 224 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs"); 225 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com"); 226 MODULE_LICENSE("GPL"); 227 MODULE_ALIAS("platform:wm831x-backlight"); 228