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/module.h> 15 #include <linux/fb.h> 16 #include <linux/backlight.h> 17 #include <linux/slab.h> 18 19 #include <linux/mfd/wm831x/core.h> 20 #include <linux/mfd/wm831x/pdata.h> 21 #include <linux/mfd/wm831x/regulator.h> 22 23 struct wm831x_backlight_data { 24 struct wm831x *wm831x; 25 int isink_reg; 26 int current_brightness; 27 }; 28 29 static int wm831x_backlight_set(struct backlight_device *bl, int brightness) 30 { 31 struct wm831x_backlight_data *data = bl_get_data(bl); 32 struct wm831x *wm831x = data->wm831x; 33 int power_up = !data->current_brightness && brightness; 34 int power_down = data->current_brightness && !brightness; 35 int ret; 36 37 if (power_up) { 38 /* Enable the ISINK */ 39 ret = wm831x_set_bits(wm831x, data->isink_reg, 40 WM831X_CS1_ENA, WM831X_CS1_ENA); 41 if (ret < 0) 42 goto err; 43 44 /* Enable the DC-DC */ 45 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, 46 WM831X_DC4_ENA, WM831X_DC4_ENA); 47 if (ret < 0) 48 goto err; 49 } 50 51 if (power_down) { 52 /* DCDC first */ 53 ret = wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, 54 WM831X_DC4_ENA, 0); 55 if (ret < 0) 56 goto err; 57 58 /* ISINK */ 59 ret = wm831x_set_bits(wm831x, data->isink_reg, 60 WM831X_CS1_DRIVE | WM831X_CS1_ENA, 0); 61 if (ret < 0) 62 goto err; 63 } 64 65 /* Set the new brightness */ 66 ret = wm831x_set_bits(wm831x, data->isink_reg, 67 WM831X_CS1_ISEL_MASK, brightness); 68 if (ret < 0) 69 goto err; 70 71 if (power_up) { 72 /* Drive current through the ISINK */ 73 ret = wm831x_set_bits(wm831x, data->isink_reg, 74 WM831X_CS1_DRIVE, WM831X_CS1_DRIVE); 75 if (ret < 0) 76 return ret; 77 } 78 79 data->current_brightness = brightness; 80 81 return 0; 82 83 err: 84 /* If we were in the middle of a power transition always shut down 85 * for safety. 86 */ 87 if (power_up || power_down) { 88 wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0); 89 wm831x_set_bits(wm831x, data->isink_reg, WM831X_CS1_ENA, 0); 90 } 91 92 return ret; 93 } 94 95 static int wm831x_backlight_update_status(struct backlight_device *bl) 96 { 97 int brightness = bl->props.brightness; 98 99 if (bl->props.power != FB_BLANK_UNBLANK) 100 brightness = 0; 101 102 if (bl->props.fb_blank != FB_BLANK_UNBLANK) 103 brightness = 0; 104 105 if (bl->props.state & BL_CORE_SUSPENDED) 106 brightness = 0; 107 108 return wm831x_backlight_set(bl, brightness); 109 } 110 111 static int wm831x_backlight_get_brightness(struct backlight_device *bl) 112 { 113 struct wm831x_backlight_data *data = bl_get_data(bl); 114 return data->current_brightness; 115 } 116 117 static const struct backlight_ops wm831x_backlight_ops = { 118 .options = BL_CORE_SUSPENDRESUME, 119 .update_status = wm831x_backlight_update_status, 120 .get_brightness = wm831x_backlight_get_brightness, 121 }; 122 123 static int wm831x_backlight_probe(struct platform_device *pdev) 124 { 125 struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent); 126 struct wm831x_pdata *wm831x_pdata; 127 struct wm831x_backlight_pdata *pdata; 128 struct wm831x_backlight_data *data; 129 struct backlight_device *bl; 130 struct backlight_properties props; 131 int ret, i, max_isel, isink_reg, dcdc_cfg; 132 133 /* We need platform data */ 134 if (pdev->dev.parent->platform_data) { 135 wm831x_pdata = pdev->dev.parent->platform_data; 136 pdata = wm831x_pdata->backlight; 137 } else { 138 pdata = NULL; 139 } 140 141 if (!pdata) { 142 dev_err(&pdev->dev, "No platform data supplied\n"); 143 return -EINVAL; 144 } 145 146 /* Figure out the maximum current we can use */ 147 for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) { 148 if (wm831x_isinkv_values[i] > pdata->max_uA) 149 break; 150 } 151 152 if (i == 0) { 153 dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA); 154 return -EINVAL; 155 } 156 max_isel = i - 1; 157 158 if (pdata->max_uA != wm831x_isinkv_values[max_isel]) 159 dev_warn(&pdev->dev, 160 "Maximum current is %duA not %duA as requested\n", 161 wm831x_isinkv_values[max_isel], pdata->max_uA); 162 163 switch (pdata->isink) { 164 case 1: 165 isink_reg = WM831X_CURRENT_SINK_1; 166 dcdc_cfg = 0; 167 break; 168 case 2: 169 isink_reg = WM831X_CURRENT_SINK_2; 170 dcdc_cfg = WM831X_DC4_FBSRC; 171 break; 172 default: 173 dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink); 174 return -EINVAL; 175 } 176 177 /* Configure the ISINK to use for feedback */ 178 ret = wm831x_reg_unlock(wm831x); 179 if (ret < 0) 180 return ret; 181 182 ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC, 183 dcdc_cfg); 184 185 wm831x_reg_lock(wm831x); 186 if (ret < 0) 187 return ret; 188 189 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 190 if (data == NULL) 191 return -ENOMEM; 192 193 data->wm831x = wm831x; 194 data->current_brightness = 0; 195 data->isink_reg = isink_reg; 196 197 props.type = BACKLIGHT_RAW; 198 props.max_brightness = max_isel; 199 bl = backlight_device_register("wm831x", &pdev->dev, data, 200 &wm831x_backlight_ops, &props); 201 if (IS_ERR(bl)) { 202 dev_err(&pdev->dev, "failed to register backlight\n"); 203 return PTR_ERR(bl); 204 } 205 206 bl->props.brightness = max_isel; 207 208 platform_set_drvdata(pdev, bl); 209 210 /* Disable the DCDC if it was started so we can bootstrap */ 211 wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0); 212 213 backlight_update_status(bl); 214 215 return 0; 216 } 217 218 static int wm831x_backlight_remove(struct platform_device *pdev) 219 { 220 struct backlight_device *bl = platform_get_drvdata(pdev); 221 222 backlight_device_unregister(bl); 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 module_platform_driver(wm831x_backlight_driver); 236 237 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs"); 238 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com"); 239 MODULE_LICENSE("GPL"); 240 MODULE_ALIAS("platform:wm831x-backlight"); 241