1 /* 2 * Backlight driver for Wolfson Microelectronics WM831x PMICs 3 * 4 * Copyright 2009 Wolfson Microelectonics plc 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 11 #include <linux/kernel.h> 12 #include <linux/init.h> 13 #include <linux/platform_device.h> 14 #include <linux/fb.h> 15 #include <linux/backlight.h> 16 17 #include <linux/mfd/wm831x/core.h> 18 #include <linux/mfd/wm831x/pdata.h> 19 #include <linux/mfd/wm831x/regulator.h> 20 21 struct wm831x_backlight_data { 22 struct wm831x *wm831x; 23 int isink_reg; 24 int current_brightness; 25 }; 26 27 static int wm831x_backlight_set(struct backlight_device *bl, int brightness) 28 { 29 struct wm831x_backlight_data *data = bl_get_data(bl); 30 struct wm831x *wm831x = data->wm831x; 31 int power_up = !data->current_brightness && brightness; 32 int power_down = data->current_brightness && !brightness; 33 int ret; 34 35 if (power_up) { 36 /* Enable the ISINK */ 37 ret = wm831x_set_bits(wm831x, data->isink_reg, 38 WM831X_CS1_ENA, WM831X_CS1_ENA); 39 if (ret < 0) 40 goto err; 41 42 /* Enable the DC-DC */ 43 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, 44 WM831X_DC4_ENA, WM831X_DC4_ENA); 45 if (ret < 0) 46 goto err; 47 } 48 49 if (power_down) { 50 /* DCDC first */ 51 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, 52 WM831X_DC4_ENA, 0); 53 if (ret < 0) 54 goto err; 55 56 /* ISINK */ 57 ret = wm831x_set_bits(wm831x, data->isink_reg, 58 WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0); 59 if (ret < 0) 60 goto err; 61 } 62 63 /* Set the new brightness */ 64 ret = wm831x_set_bits(wm831x, data->isink_reg, 65 WM831X_CS1_ISEL_MASK, brightness); 66 if (ret < 0) 67 goto err; 68 69 if (power_up) { 70 /* Drive current through the ISINK */ 71 ret = wm831x_set_bits(wm831x, data->isink_reg, 72 WM831X_CS1_DRIVE, WM831X_CS1_DRIVE); 73 if (ret < 0) 74 return ret; 75 } 76 77 data->current_brightness = brightness; 78 79 return 0; 80 81 err: 82 /* If we were in the middle of a power transition always shut down 83 * for safety. 84 */ 85 if (power_up || power_down) { 86 wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0); 87 wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0); 88 } 89 90 return ret; 91 } 92 93 static int wm831x_backlight_update_status(struct backlight_device *bl) 94 { 95 int brightness = bl->props.brightness; 96 97 if (bl->props.power != FB_BLANK_UNBLANK) 98 brightness = 0; 99 100 if (bl->props.fb_blank != FB_BLANK_UNBLANK) 101 brightness = 0; 102 103 if (bl->props.state & BL_CORE_SUSPENDED) 104 brightness = 0; 105 106 return wm831x_backlight_set(bl, brightness); 107 } 108 109 static int wm831x_backlight_get_brightness(struct backlight_device *bl) 110 { 111 struct wm831x_backlight_data *data = bl_get_data(bl); 112 return data->current_brightness; 113 } 114 115 static 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; 125 struct wm831x_backlight_pdata *pdata; 126 struct wm831x_backlight_data *data; 127 struct backlight_device *bl; 128 int ret, i, max_isel, isink_reg, dcdc_cfg; 129 130 /* We need platform data */ 131 if (pdev->dev.parent->platform_data) { 132 wm831x_pdata = pdev->dev.parent->platform_data; 133 pdata = wm831x_pdata->backlight; 134 } else { 135 pdata = NULL; 136 } 137 138 if (!pdata) { 139 dev_err(&pdev->dev, "No platform data supplied\n"); 140 return -EINVAL; 141 } 142 143 /* Figure out the maximum current we can use */ 144 for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) { 145 if (wm831x_isinkv_values[i] > pdata->max_uA) 146 break; 147 } 148 149 if (i == 0) { 150 dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA); 151 return -EINVAL; 152 } 153 max_isel = i - 1; 154 155 if (pdata->max_uA != wm831x_isinkv_values[max_isel]) 156 dev_warn(&pdev->dev, 157 "Maximum current is %duA not %duA as requested\n", 158 wm831x_isinkv_values[max_isel], pdata->max_uA); 159 160 switch (pdata->isink) { 161 case 1: 162 isink_reg = WM831X_CURRENT_SINK_1; 163 dcdc_cfg = 0; 164 break; 165 case 2: 166 isink_reg = WM831X_CURRENT_SINK_2; 167 dcdc_cfg = WM831X_DC4_FBSRC; 168 break; 169 default: 170 dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink); 171 return -EINVAL; 172 } 173 174 /* Configure the ISINK to use for feedback */ 175 ret = wm831x_reg_unlock(wm831x); 176 if (ret < 0) 177 return ret; 178 179 ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC, 180 dcdc_cfg); 181 182 wm831x_reg_lock(wm831x); 183 if (ret < 0) 184 return ret; 185 186 data = kzalloc(sizeof(*data), GFP_KERNEL); 187 if (data == NULL) 188 return -ENOMEM; 189 190 data->wm831x = wm831x; 191 data->current_brightness = 0; 192 data->isink_reg = isink_reg; 193 194 bl = backlight_device_register("wm831x", &pdev->dev, 195 data, &wm831x_backlight_ops); 196 if (IS_ERR(bl)) { 197 dev_err(&pdev->dev, "failed to register backlight\n"); 198 kfree(data); 199 return PTR_ERR(bl); 200 } 201 202 bl->props.max_brightness = max_isel; 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); 209 210 211 backlight_update_status(bl); 212 213 return 0; 214 } 215 216 static int wm831x_backlight_remove(struct platform_device *pdev) 217 { 218 struct backlight_device *bl = platform_get_drvdata(pdev); 219 struct wm831x_backlight_data *data = bl_get_data(bl); 220 221 backlight_device_unregister(bl); 222 kfree(data); 223 return 0; 224 } 225 226 static struct platform_driver wm831x_backlight_driver = { 227 .driver = { 228 .name = "wm831x-backlight", 229 .owner = THIS_MODULE, 230 }, 231 .probe = wm831x_backlight_probe, 232 .remove = wm831x_backlight_remove, 233 }; 234 235 static int __init wm831x_backlight_init(void) 236 { 237 return platform_driver_register(&wm831x_backlight_driver); 238 } 239 module_init(wm831x_backlight_init); 240 241 static void __exit wm831x_backlight_exit(void) 242 { 243 platform_driver_unregister(&wm831x_backlight_driver); 244 } 245 module_exit(wm831x_backlight_exit); 246 247 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs"); 248 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com"); 249 MODULE_LICENSE("GPL"); 250 MODULE_ALIAS("platform:wm831x-backlight"); 251