rt4831-backlight.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2
  3#include <dt-bindings/leds/rt4831-backlight.h>
  4#include <linux/backlight.h>
  5#include <linux/bitops.h>
  6#include <linux/kernel.h>
  7#include <linux/mod_devicetable.h>
  8#include <linux/module.h>
  9#include <linux/platform_device.h>
 10#include <linux/property.h>
 11#include <linux/regmap.h>
 12
 13#define RT4831_REG_BLCFG	0x02
 14#define RT4831_REG_BLDIML	0x04
 15#define RT4831_REG_ENABLE	0x08
 16#define RT4831_REG_BLOPT2	0x11
 17
 18#define RT4831_BLMAX_BRIGHTNESS	2048
 19
 20#define RT4831_BLOVP_MASK	GENMASK(7, 5)
 21#define RT4831_BLOVP_SHIFT	5
 22#define RT4831_BLPWMEN_MASK	BIT(0)
 23#define RT4831_BLEN_MASK	BIT(4)
 24#define RT4831_BLCH_MASK	GENMASK(3, 0)
 25#define RT4831_BLDIML_MASK	GENMASK(2, 0)
 26#define RT4831_BLDIMH_MASK	GENMASK(10, 3)
 27#define RT4831_BLDIMH_SHIFT	3
 28#define RT4831_BLOCP_MASK	GENMASK(1, 0)
 29
 30#define RT4831_BLOCP_MINUA	900000
 31#define RT4831_BLOCP_MAXUA	1800000
 32#define RT4831_BLOCP_STEPUA	300000
 33
 34struct rt4831_priv {
 35	struct device *dev;
 36	struct regmap *regmap;
 37	struct backlight_device *bl;
 38};
 39
 40static int rt4831_bl_update_status(struct backlight_device *bl_dev)
 41{
 42	struct rt4831_priv *priv = bl_get_data(bl_dev);
 43	int brightness = backlight_get_brightness(bl_dev);
 44	unsigned int enable = brightness ? RT4831_BLEN_MASK : 0;
 45	u8 v[2];
 46	int ret;
 47
 48	if (brightness) {
 49		v[0] = (brightness - 1) & RT4831_BLDIML_MASK;
 50		v[1] = ((brightness - 1) & RT4831_BLDIMH_MASK) >> RT4831_BLDIMH_SHIFT;
 51
 52		ret = regmap_raw_write(priv->regmap, RT4831_REG_BLDIML, v, sizeof(v));
 53		if (ret)
 54			return ret;
 55	}
 56
 57	return regmap_update_bits(priv->regmap, RT4831_REG_ENABLE, RT4831_BLEN_MASK, enable);
 58
 59}
 60
 61static int rt4831_bl_get_brightness(struct backlight_device *bl_dev)
 62{
 63	struct rt4831_priv *priv = bl_get_data(bl_dev);
 64	unsigned int val;
 65	u8 v[2];
 66	int ret;
 67
 68	ret = regmap_read(priv->regmap, RT4831_REG_ENABLE, &val);
 69	if (ret)
 70		return ret;
 71
 72	if (!(val & RT4831_BLEN_MASK))
 73		return 0;
 74
 75	ret = regmap_raw_read(priv->regmap, RT4831_REG_BLDIML, v, sizeof(v));
 76	if (ret)
 77		return ret;
 78
 79	ret = (v[1] << RT4831_BLDIMH_SHIFT) + (v[0] & RT4831_BLDIML_MASK) + 1;
 80
 81	return ret;
 82}
 83
 84static const struct backlight_ops rt4831_bl_ops = {
 85	.options = BL_CORE_SUSPENDRESUME,
 86	.update_status = rt4831_bl_update_status,
 87	.get_brightness = rt4831_bl_get_brightness,
 88};
 89
 90static int rt4831_parse_backlight_properties(struct rt4831_priv *priv,
 91					     struct backlight_properties *bl_props)
 92{
 93	struct device *dev = priv->dev;
 94	u8 propval;
 95	u32 brightness, ocp_uA;
 96	unsigned int val = 0;
 97	int ret;
 98
 99	/* common properties */
100	ret = device_property_read_u32(dev, "max-brightness", &brightness);
101	if (ret)
102		brightness = RT4831_BLMAX_BRIGHTNESS;
103
104	bl_props->max_brightness = min_t(u32, brightness, RT4831_BLMAX_BRIGHTNESS);
105
106	ret = device_property_read_u32(dev, "default-brightness", &brightness);
107	if (ret)
108		brightness = bl_props->max_brightness;
109
110	bl_props->brightness = min_t(u32, brightness, bl_props->max_brightness);
111
112	/* vendor properties */
113	if (device_property_read_bool(dev, "richtek,pwm-enable"))
114		val = RT4831_BLPWMEN_MASK;
115
116	ret = regmap_update_bits(priv->regmap, RT4831_REG_BLCFG, RT4831_BLPWMEN_MASK, val);
117	if (ret)
118		return ret;
119
120	ret = device_property_read_u8(dev, "richtek,bled-ovp-sel", &propval);
121	if (ret)
122		propval = RT4831_BLOVPLVL_21V;
123
124	propval = min_t(u8, propval, RT4831_BLOVPLVL_29V);
125	ret = regmap_update_bits(priv->regmap, RT4831_REG_BLCFG, RT4831_BLOVP_MASK,
126				 propval << RT4831_BLOVP_SHIFT);
127	if (ret)
128		return ret;
129
130	/*
131	 * This OCP level is used to protect and limit the inductor current.
132	 * If inductor peak current reach the level, low-side MOSFET will be
133	 * turned off. Meanwhile, the output channel current may be limited.
134	 * To match the configured channel current, the inductor chosen must
135	 * be higher than the OCP level.
136	 *
137	 * Not like the OVP level, the default 21V can be used in the most
138	 * application. But if the chosen OCP level is smaller than needed,
139	 * it will also affect the backlight channel output current to be
140	 * smaller than the register setting.
141	 */
142	ret = device_property_read_u32(dev, "richtek,bled-ocp-microamp",
143				       &ocp_uA);
144	if (!ret) {
145		ocp_uA = clamp_val(ocp_uA, RT4831_BLOCP_MINUA,
146				   RT4831_BLOCP_MAXUA);
147		val = DIV_ROUND_UP(ocp_uA - RT4831_BLOCP_MINUA,
148				   RT4831_BLOCP_STEPUA);
149		ret = regmap_update_bits(priv->regmap, RT4831_REG_BLOPT2,
150					 RT4831_BLOCP_MASK, val);
151		if (ret)
152			return ret;
153	}
154
155	ret = device_property_read_u8(dev, "richtek,channel-use", &propval);
156	if (ret) {
157		dev_err(dev, "richtek,channel-use DT property missing\n");
158		return ret;
159	}
160
161	if (!(propval & RT4831_BLCH_MASK)) {
162		dev_err(dev, "No channel specified\n");
163		return -EINVAL;
164	}
165
166	return regmap_update_bits(priv->regmap, RT4831_REG_ENABLE, RT4831_BLCH_MASK, propval);
167}
168
169static int rt4831_bl_probe(struct platform_device *pdev)
170{
171	struct rt4831_priv *priv;
172	struct backlight_properties bl_props = { .type = BACKLIGHT_RAW,
173						 .scale = BACKLIGHT_SCALE_LINEAR };
174	int ret;
175
176	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
177	if (!priv)
178		return -ENOMEM;
179
180	priv->dev = &pdev->dev;
181
182	priv->regmap = dev_get_regmap(pdev->dev.parent, NULL);
183	if (!priv->regmap) {
184		dev_err(&pdev->dev, "Failed to init regmap\n");
185		return -ENODEV;
186	}
187
188	ret = rt4831_parse_backlight_properties(priv, &bl_props);
189	if (ret) {
190		dev_err(&pdev->dev, "Failed to parse backlight properties\n");
191		return ret;
192	}
193
194	priv->bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev, priv,
195						  &rt4831_bl_ops, &bl_props);
196	if (IS_ERR(priv->bl)) {
197		dev_err(&pdev->dev, "Failed to register backlight\n");
198		return PTR_ERR(priv->bl);
199	}
200
201	backlight_update_status(priv->bl);
202	platform_set_drvdata(pdev, priv);
203
204	return 0;
205}
206
207static void rt4831_bl_remove(struct platform_device *pdev)
208{
209	struct rt4831_priv *priv = platform_get_drvdata(pdev);
210	struct backlight_device *bl_dev = priv->bl;
211
212	bl_dev->props.brightness = 0;
213	backlight_update_status(priv->bl);
214}
215
216static const struct of_device_id __maybe_unused rt4831_bl_of_match[] = {
217	{ .compatible = "richtek,rt4831-backlight", },
218	{}
219};
220MODULE_DEVICE_TABLE(of, rt4831_bl_of_match);
221
222static struct platform_driver rt4831_bl_driver = {
223	.driver = {
224		.name = "rt4831-backlight",
225		.of_match_table = rt4831_bl_of_match,
226	},
227	.probe = rt4831_bl_probe,
228	.remove = rt4831_bl_remove,
229};
230module_platform_driver(rt4831_bl_driver);
231
232MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
233MODULE_DESCRIPTION("Richtek RT4831 Backlight Driver");
234MODULE_LICENSE("GPL v2");