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 = dev_get_platdata(pdev->dev.parent); 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 (wm831x_pdata) 135 pdata = wm831x_pdata->backlight; 136 else 137 pdata = NULL; 138 139 if (!pdata) { 140 dev_err(&pdev->dev, "No platform data supplied\n"); 141 return -EINVAL; 142 } 143 144 /* Figure out the maximum current we can use */ 145 for (i = 0; i < WM831X_ISINK_MAX_ISEL; i++) { 146 if (wm831x_isinkv_values[i] > pdata->max_uA) 147 break; 148 } 149 150 if (i == 0) { 151 dev_err(&pdev->dev, "Invalid max_uA: %duA\n", pdata->max_uA); 152 return -EINVAL; 153 } 154 max_isel = i - 1; 155 156 if (pdata->max_uA != wm831x_isinkv_values[max_isel]) 157 dev_warn(&pdev->dev, 158 "Maximum current is %duA not %duA as requested\n", 159 wm831x_isinkv_values[max_isel], pdata->max_uA); 160 161 switch (pdata->isink) { 162 case 1: 163 isink_reg = WM831X_CURRENT_SINK_1; 164 dcdc_cfg = 0; 165 break; 166 case 2: 167 isink_reg = WM831X_CURRENT_SINK_2; 168 dcdc_cfg = WM831X_DC4_FBSRC; 169 break; 170 default: 171 dev_err(&pdev->dev, "Invalid ISINK %d\n", pdata->isink); 172 return -EINVAL; 173 } 174 175 /* Configure the ISINK to use for feedback */ 176 ret = wm831x_reg_unlock(wm831x); 177 if (ret < 0) 178 return ret; 179 180 ret = wm831x_set_bits(wm831x, WM831X_DC4_CONTROL, WM831X_DC4_FBSRC, 181 dcdc_cfg); 182 183 wm831x_reg_lock(wm831x); 184 if (ret < 0) 185 return ret; 186 187 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 188 if (data == NULL) 189 return -ENOMEM; 190 191 data->wm831x = wm831x; 192 data->current_brightness = 0; 193 data->isink_reg = isink_reg; 194 195 memset(&props, 0, sizeof(props)); 196 props.type = BACKLIGHT_RAW; 197 props.max_brightness = max_isel; 198 bl = devm_backlight_device_register(&pdev->dev, "wm831x", &pdev->dev, 199 data, &wm831x_backlight_ops, &props); 200 if (IS_ERR(bl)) { 201 dev_err(&pdev->dev, "failed to register backlight\n"); 202 return PTR_ERR(bl); 203 } 204 205 bl->props.brightness = max_isel; 206 207 platform_set_drvdata(pdev, bl); 208 209 /* Disable the DCDC if it was started so we can bootstrap */ 210 wm831x_set_bits(wm831x, WM831X_DCDC_ENABLE, WM831X_DC4_ENA, 0); 211 212 backlight_update_status(bl); 213 214 return 0; 215 } 216 217 static struct platform_driver wm831x_backlight_driver = { 218 .driver = { 219 .name = "wm831x-backlight", 220 .owner = THIS_MODULE, 221 }, 222 .probe = wm831x_backlight_probe, 223 }; 224 225 module_platform_driver(wm831x_backlight_driver); 226 227 MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs"); 228 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com"); 229 MODULE_LICENSE("GPL"); 230 MODULE_ALIAS("platform:wm831x-backlight"); 231