1 /*
2  * t5403.c - Support for EPCOS T5403 pressure/temperature sensor
3  *
4  * Copyright (c) 2014 Peter Meerwald <pmeerw@pmeerw.net>
5  *
6  * This file is subject to the terms and conditions of version 2 of
7  * the GNU General Public License.  See the file COPYING in the main
8  * directory of this archive for more details.
9  *
10  * (7-bit I2C slave address 0x77)
11  *
12  * TODO: end-of-conversion irq
13  */
14 
15 #include <linux/module.h>
16 #include <linux/i2c.h>
17 #include <linux/iio/iio.h>
18 #include <linux/iio/sysfs.h>
19 #include <linux/delay.h>
20 
21 #define T5403_DATA 0xf5 /* data, LSB first, 16 bit */
22 #define T5403_CALIB_DATA 0x8e /* 10 calibration coeff., LSB first, 16 bit */
23 #define T5403_SLAVE_ADDR 0x88 /* I2C slave address, 0x77 */
24 #define T5403_COMMAND 0xf1
25 
26 /* command bits */
27 #define T5403_MODE_SHIFT 3 /* conversion time: 2, 8, 16, 66 ms */
28 #define T5403_PT BIT(1) /* 0 .. pressure, 1 .. temperature measurement */
29 #define T5403_SCO BIT(0) /* start conversion */
30 
31 #define T5403_MODE_LOW 0
32 #define T5403_MODE_STANDARD 1
33 #define T5403_MODE_HIGH 2
34 #define T5403_MODE_ULTRA_HIGH 3
35 
36 #define T5403_I2C_MASK (~BIT(7))
37 #define T5403_I2C_ADDR 0x77
38 
39 static const int t5403_pressure_conv_ms[] = {2, 8, 16, 66};
40 
41 struct t5403_data {
42 	struct i2c_client *client;
43 	struct mutex lock;
44 	int mode;
45 	__le16 c[10];
46 };
47 
48 #define T5403_C_U16(i) le16_to_cpu(data->c[(i) - 1])
49 #define T5403_C(i) sign_extend32(T5403_C_U16(i), 15)
50 
t5403_read(struct t5403_data * data,bool pressure)51 static int t5403_read(struct t5403_data *data, bool pressure)
52 {
53 	int wait_time = 3;  /* wakeup time in ms */
54 
55 	int ret = i2c_smbus_write_byte_data(data->client, T5403_COMMAND,
56 		(pressure ? (data->mode << T5403_MODE_SHIFT) : T5403_PT) |
57 		T5403_SCO);
58 	if (ret < 0)
59 		return ret;
60 
61 	wait_time += pressure ? t5403_pressure_conv_ms[data->mode] : 2;
62 
63 	msleep(wait_time);
64 
65 	return i2c_smbus_read_word_data(data->client, T5403_DATA);
66 }
67 
t5403_comp_pressure(struct t5403_data * data,int * val,int * val2)68 static int t5403_comp_pressure(struct t5403_data *data, int *val, int *val2)
69 {
70 	int ret;
71 	s16 t_r;
72 	u16 p_r;
73 	s32 S, O, X;
74 
75 	mutex_lock(&data->lock);
76 
77 	ret = t5403_read(data, false);
78 	if (ret < 0)
79 		goto done;
80 	t_r = ret;
81 
82 	ret = t5403_read(data, true);
83 	if (ret < 0)
84 		goto done;
85 	p_r = ret;
86 
87 	/* see EPCOS application note */
88 	S = T5403_C_U16(3) + (s32) T5403_C_U16(4) * t_r / 0x20000 +
89 		T5403_C(5) * t_r / 0x8000 * t_r / 0x80000 +
90 		T5403_C(9) * t_r / 0x8000 * t_r / 0x8000 * t_r / 0x10000;
91 
92 	O = T5403_C(6) * 0x4000 + T5403_C(7) * t_r / 8 +
93 		T5403_C(8) * t_r / 0x8000 * t_r / 16 +
94 		T5403_C(9) * t_r / 0x8000 * t_r / 0x10000 * t_r;
95 
96 	X = (S * p_r + O) / 0x4000;
97 
98 	X += ((X - 75000) * (X - 75000) / 0x10000 - 9537) *
99 	    T5403_C(10) / 0x10000;
100 
101 	*val = X / 1000;
102 	*val2 = (X % 1000) * 1000;
103 
104 done:
105 	mutex_unlock(&data->lock);
106 	return ret;
107 }
108 
t5403_comp_temp(struct t5403_data * data,int * val)109 static int t5403_comp_temp(struct t5403_data *data, int *val)
110 {
111 	int ret;
112 	s16 t_r;
113 
114 	mutex_lock(&data->lock);
115 	ret = t5403_read(data, false);
116 	if (ret < 0)
117 		goto done;
118 	t_r = ret;
119 
120 	/* see EPCOS application note */
121 	*val = ((s32) T5403_C_U16(1) * t_r / 0x100 +
122 		(s32) T5403_C_U16(2) * 0x40) * 1000 / 0x10000;
123 
124 done:
125 	mutex_unlock(&data->lock);
126 	return ret;
127 }
128 
t5403_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)129 static int t5403_read_raw(struct iio_dev *indio_dev,
130 			  struct iio_chan_spec const *chan,
131 			  int *val, int *val2, long mask)
132 {
133 	struct t5403_data *data = iio_priv(indio_dev);
134 	int ret;
135 
136 	switch (mask) {
137 	case IIO_CHAN_INFO_PROCESSED:
138 		switch (chan->type) {
139 		case IIO_PRESSURE:
140 			ret = t5403_comp_pressure(data, val, val2);
141 			if (ret < 0)
142 				return ret;
143 			return IIO_VAL_INT_PLUS_MICRO;
144 		case IIO_TEMP:
145 			ret = t5403_comp_temp(data, val);
146 			if (ret < 0)
147 				return ret;
148 			return IIO_VAL_INT;
149 		default:
150 			return -EINVAL;
151 	    }
152 	case IIO_CHAN_INFO_INT_TIME:
153 		*val = 0;
154 		*val2 = t5403_pressure_conv_ms[data->mode] * 1000;
155 		return IIO_VAL_INT_PLUS_MICRO;
156 	default:
157 		return -EINVAL;
158 	}
159 }
160 
t5403_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)161 static int t5403_write_raw(struct iio_dev *indio_dev,
162 			   struct iio_chan_spec const *chan,
163 			   int val, int val2, long mask)
164 {
165 	struct t5403_data *data = iio_priv(indio_dev);
166 	int i;
167 
168 	switch (mask) {
169 	case IIO_CHAN_INFO_INT_TIME:
170 		if (val != 0)
171 			return -EINVAL;
172 		for (i = 0; i < ARRAY_SIZE(t5403_pressure_conv_ms); i++)
173 			if (val2 == t5403_pressure_conv_ms[i] * 1000) {
174 				mutex_lock(&data->lock);
175 				data->mode = i;
176 				mutex_unlock(&data->lock);
177 				return 0;
178 			}
179 		return -EINVAL;
180 	default:
181 		return -EINVAL;
182 	}
183 }
184 
185 static const struct iio_chan_spec t5403_channels[] = {
186 	{
187 		.type = IIO_PRESSURE,
188 		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
189 		    BIT(IIO_CHAN_INFO_INT_TIME),
190 	},
191 	{
192 		.type = IIO_TEMP,
193 		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
194 	},
195 };
196 
197 static IIO_CONST_ATTR_INT_TIME_AVAIL("0.002 0.008 0.016 0.066");
198 
199 static struct attribute *t5403_attributes[] = {
200 	&iio_const_attr_integration_time_available.dev_attr.attr,
201 	NULL
202 };
203 
204 static const struct attribute_group t5403_attribute_group = {
205 	.attrs = t5403_attributes,
206 };
207 
208 static const struct iio_info t5403_info = {
209 	.read_raw = &t5403_read_raw,
210 	.write_raw = &t5403_write_raw,
211 	.attrs = &t5403_attribute_group,
212 };
213 
t5403_probe(struct i2c_client * client,const struct i2c_device_id * id)214 static int t5403_probe(struct i2c_client *client,
215 			 const struct i2c_device_id *id)
216 {
217 	struct t5403_data *data;
218 	struct iio_dev *indio_dev;
219 	int ret;
220 
221 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA |
222 	    I2C_FUNC_SMBUS_I2C_BLOCK))
223 		return -EOPNOTSUPP;
224 
225 	ret = i2c_smbus_read_byte_data(client, T5403_SLAVE_ADDR);
226 	if (ret < 0)
227 		return ret;
228 	if ((ret & T5403_I2C_MASK) != T5403_I2C_ADDR)
229 		return -ENODEV;
230 
231 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
232 	if (!indio_dev)
233 		return -ENOMEM;
234 
235 	data = iio_priv(indio_dev);
236 	data->client = client;
237 	mutex_init(&data->lock);
238 
239 	i2c_set_clientdata(client, indio_dev);
240 	indio_dev->info = &t5403_info;
241 	indio_dev->name = id->name;
242 	indio_dev->dev.parent = &client->dev;
243 	indio_dev->modes = INDIO_DIRECT_MODE;
244 	indio_dev->channels = t5403_channels;
245 	indio_dev->num_channels = ARRAY_SIZE(t5403_channels);
246 
247 	data->mode = T5403_MODE_STANDARD;
248 
249 	ret = i2c_smbus_read_i2c_block_data(data->client, T5403_CALIB_DATA,
250 	    sizeof(data->c), (u8 *) data->c);
251 	if (ret < 0)
252 		return ret;
253 
254 	return devm_iio_device_register(&client->dev, indio_dev);
255 }
256 
257 static const struct i2c_device_id t5403_id[] = {
258 	{ "t5403", 0 },
259 	{ }
260 };
261 MODULE_DEVICE_TABLE(i2c, t5403_id);
262 
263 static struct i2c_driver t5403_driver = {
264 	.driver = {
265 		.name	= "t5403",
266 	},
267 	.probe = t5403_probe,
268 	.id_table = t5403_id,
269 };
270 module_i2c_driver(t5403_driver);
271 
272 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
273 MODULE_DESCRIPTION("EPCOS T5403 pressure/temperature sensor driver");
274 MODULE_LICENSE("GPL");
275