217 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Backlight driver for Wolfson Microelectronics WM831x PMICs4 *5 * Copyright 2009 Wolfson Microelectonics plc6 */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 20struct wm831x_backlight_data {21 struct wm831x *wm831x;22 int isink_reg;23 int current_brightness;24};25 26static 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 80err:81 /* If we were in the middle of a power transition always shut down82 * 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 92static int wm831x_backlight_update_status(struct backlight_device *bl)93{94 return wm831x_backlight_set(bl, backlight_get_brightness(bl));95}96 97static 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 104static 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 110static 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 else124 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 204static struct platform_driver wm831x_backlight_driver = {205 .driver = {206 .name = "wm831x-backlight",207 },208 .probe = wm831x_backlight_probe,209};210 211module_platform_driver(wm831x_backlight_driver);212 213MODULE_DESCRIPTION("Backlight Driver for WM831x PMICs");214MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com");215MODULE_LICENSE("GPL");216MODULE_ALIAS("platform:wm831x-backlight");217