1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles
4  * (C) 2007 EADS Astrium
5  *
6  * This driver is based on the lm75 and other lm_sensors/hwmon drivers
7  *
8  * Written by Steve Hardy <shardy@redhat.com>
9  *
10  * ADS7830 support, by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
11  *
12  * For further information, see the Documentation/hwmon/ads7828.rst file.
13  */
14 
15 #include <linux/err.h>
16 #include <linux/hwmon.h>
17 #include <linux/hwmon-sysfs.h>
18 #include <linux/i2c.h>
19 #include <linux/init.h>
20 #include <linux/module.h>
21 #include <linux/of_device.h>
22 #include <linux/platform_data/ads7828.h>
23 #include <linux/regmap.h>
24 #include <linux/slab.h>
25 #include <linux/regulator/consumer.h>
26 
27 /* The ADS7828 registers */
28 #define ADS7828_CMD_SD_SE	0x80	/* Single ended inputs */
29 #define ADS7828_CMD_PD1		0x04	/* Internal vref OFF && A/D ON */
30 #define ADS7828_CMD_PD3		0x0C	/* Internal vref ON && A/D ON */
31 #define ADS7828_INT_VREF_MV	2500	/* Internal vref is 2.5V, 2500mV */
32 #define ADS7828_EXT_VREF_MV_MIN	50	/* External vref min value 0.05V */
33 #define ADS7828_EXT_VREF_MV_MAX	5250	/* External vref max value 5.25V */
34 
35 /* List of supported devices */
36 enum ads7828_chips { ads7828, ads7830 };
37 
38 /* Client specific data */
39 struct ads7828_data {
40 	struct regmap *regmap;
41 	u8 cmd_byte;			/* Command byte without channel bits */
42 	unsigned int lsb_resol;		/* Resolution of the ADC sample LSB */
43 };
44 
45 /* Command byte C2,C1,C0 - see datasheet */
ads7828_cmd_byte(u8 cmd,int ch)46 static inline u8 ads7828_cmd_byte(u8 cmd, int ch)
47 {
48 	return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
49 }
50 
51 /* sysfs callback function */
ads7828_in_show(struct device * dev,struct device_attribute * da,char * buf)52 static ssize_t ads7828_in_show(struct device *dev,
53 			       struct device_attribute *da, char *buf)
54 {
55 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
56 	struct ads7828_data *data = dev_get_drvdata(dev);
57 	u8 cmd = ads7828_cmd_byte(data->cmd_byte, attr->index);
58 	unsigned int regval;
59 	int err;
60 
61 	err = regmap_read(data->regmap, cmd, &regval);
62 	if (err < 0)
63 		return err;
64 
65 	return sprintf(buf, "%d\n",
66 		       DIV_ROUND_CLOSEST(regval * data->lsb_resol, 1000));
67 }
68 
69 static SENSOR_DEVICE_ATTR_RO(in0_input, ads7828_in, 0);
70 static SENSOR_DEVICE_ATTR_RO(in1_input, ads7828_in, 1);
71 static SENSOR_DEVICE_ATTR_RO(in2_input, ads7828_in, 2);
72 static SENSOR_DEVICE_ATTR_RO(in3_input, ads7828_in, 3);
73 static SENSOR_DEVICE_ATTR_RO(in4_input, ads7828_in, 4);
74 static SENSOR_DEVICE_ATTR_RO(in5_input, ads7828_in, 5);
75 static SENSOR_DEVICE_ATTR_RO(in6_input, ads7828_in, 6);
76 static SENSOR_DEVICE_ATTR_RO(in7_input, ads7828_in, 7);
77 
78 static struct attribute *ads7828_attrs[] = {
79 	&sensor_dev_attr_in0_input.dev_attr.attr,
80 	&sensor_dev_attr_in1_input.dev_attr.attr,
81 	&sensor_dev_attr_in2_input.dev_attr.attr,
82 	&sensor_dev_attr_in3_input.dev_attr.attr,
83 	&sensor_dev_attr_in4_input.dev_attr.attr,
84 	&sensor_dev_attr_in5_input.dev_attr.attr,
85 	&sensor_dev_attr_in6_input.dev_attr.attr,
86 	&sensor_dev_attr_in7_input.dev_attr.attr,
87 	NULL
88 };
89 
90 ATTRIBUTE_GROUPS(ads7828);
91 
92 static const struct regmap_config ads2828_regmap_config = {
93 	.reg_bits = 8,
94 	.val_bits = 16,
95 };
96 
97 static const struct regmap_config ads2830_regmap_config = {
98 	.reg_bits = 8,
99 	.val_bits = 8,
100 };
101 
ads7828_probe(struct i2c_client * client,const struct i2c_device_id * id)102 static int ads7828_probe(struct i2c_client *client,
103 			 const struct i2c_device_id *id)
104 {
105 	struct device *dev = &client->dev;
106 	struct ads7828_platform_data *pdata = dev_get_platdata(dev);
107 	struct ads7828_data *data;
108 	struct device *hwmon_dev;
109 	unsigned int vref_mv = ADS7828_INT_VREF_MV;
110 	unsigned int vref_uv;
111 	bool diff_input = false;
112 	bool ext_vref = false;
113 	unsigned int regval;
114 	enum ads7828_chips chip;
115 	struct regulator *reg;
116 
117 	data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL);
118 	if (!data)
119 		return -ENOMEM;
120 
121 	if (pdata) {
122 		diff_input = pdata->diff_input;
123 		ext_vref = pdata->ext_vref;
124 		if (ext_vref && pdata->vref_mv)
125 			vref_mv = pdata->vref_mv;
126 	} else if (dev->of_node) {
127 		diff_input = of_property_read_bool(dev->of_node,
128 						   "ti,differential-input");
129 		reg = devm_regulator_get_optional(dev, "vref");
130 		if (!IS_ERR(reg)) {
131 			vref_uv = regulator_get_voltage(reg);
132 			vref_mv = DIV_ROUND_CLOSEST(vref_uv, 1000);
133 			if (vref_mv < ADS7828_EXT_VREF_MV_MIN ||
134 			    vref_mv > ADS7828_EXT_VREF_MV_MAX)
135 				return -EINVAL;
136 			ext_vref = true;
137 		}
138 	}
139 
140 	if (client->dev.of_node)
141 		chip = (enum ads7828_chips)
142 			of_device_get_match_data(&client->dev);
143 	else
144 		chip = id->driver_data;
145 
146 	/* Bound Vref with min/max values */
147 	vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN,
148 			    ADS7828_EXT_VREF_MV_MAX);
149 
150 	/* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
151 	if (chip == ads7828) {
152 		data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 4096);
153 		data->regmap = devm_regmap_init_i2c(client,
154 						    &ads2828_regmap_config);
155 	} else {
156 		data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 256);
157 		data->regmap = devm_regmap_init_i2c(client,
158 						    &ads2830_regmap_config);
159 	}
160 
161 	if (IS_ERR(data->regmap))
162 		return PTR_ERR(data->regmap);
163 
164 	data->cmd_byte = ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
165 	if (!diff_input)
166 		data->cmd_byte |= ADS7828_CMD_SD_SE;
167 
168 	/*
169 	 * Datasheet specifies internal reference voltage is disabled by
170 	 * default. The internal reference voltage needs to be enabled and
171 	 * voltage needs to settle before getting valid ADC data. So perform a
172 	 * dummy read to enable the internal reference voltage.
173 	 */
174 	if (!ext_vref)
175 		regmap_read(data->regmap, data->cmd_byte, &regval);
176 
177 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
178 							   data,
179 							   ads7828_groups);
180 	return PTR_ERR_OR_ZERO(hwmon_dev);
181 }
182 
183 static const struct i2c_device_id ads7828_device_ids[] = {
184 	{ "ads7828", ads7828 },
185 	{ "ads7830", ads7830 },
186 	{ }
187 };
188 MODULE_DEVICE_TABLE(i2c, ads7828_device_ids);
189 
190 static const struct of_device_id __maybe_unused ads7828_of_match[] = {
191 	{
192 		.compatible = "ti,ads7828",
193 		.data = (void *)ads7828
194 	},
195 	{
196 		.compatible = "ti,ads7830",
197 		.data = (void *)ads7830
198 	},
199 	{ },
200 };
201 MODULE_DEVICE_TABLE(of, ads7828_of_match);
202 
203 static struct i2c_driver ads7828_driver = {
204 	.driver = {
205 		.name = "ads7828",
206 		.of_match_table = of_match_ptr(ads7828_of_match),
207 	},
208 
209 	.id_table = ads7828_device_ids,
210 	.probe = ads7828_probe,
211 };
212 
213 module_i2c_driver(ads7828_driver);
214 
215 MODULE_LICENSE("GPL");
216 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
217 MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");
218