xref: /openbmc/linux/drivers/iio/dac/ltc2632.c (revision 6aa7de05)
1 /*
2  * LTC2632 Digital to analog convertors spi driver
3  *
4  * Copyright 2017 Maxime Roussin-B�langer
5  *
6  * Licensed under the GPL-2.
7  */
8 
9 #include <linux/device.h>
10 #include <linux/spi/spi.h>
11 #include <linux/module.h>
12 #include <linux/iio/iio.h>
13 
14 #define LTC2632_DAC_CHANNELS                    2
15 
16 #define LTC2632_ADDR_DAC0                       0x0
17 #define LTC2632_ADDR_DAC1                       0x1
18 
19 #define LTC2632_CMD_WRITE_INPUT_N               0x0
20 #define LTC2632_CMD_UPDATE_DAC_N                0x1
21 #define LTC2632_CMD_WRITE_INPUT_N_UPDATE_ALL    0x2
22 #define LTC2632_CMD_WRITE_INPUT_N_UPDATE_N      0x3
23 #define LTC2632_CMD_POWERDOWN_DAC_N             0x4
24 #define LTC2632_CMD_POWERDOWN_CHIP              0x5
25 #define LTC2632_CMD_INTERNAL_REFER              0x6
26 #define LTC2632_CMD_EXTERNAL_REFER              0x7
27 
28 /**
29  * struct ltc2632_chip_info - chip specific information
30  * @channels:		channel spec for the DAC
31  * @vref_mv:		reference voltage
32  */
33 struct ltc2632_chip_info {
34 	const struct iio_chan_spec *channels;
35 	const int vref_mv;
36 };
37 
38 /**
39  * struct ltc2632_state - driver instance specific data
40  * @spi_dev:			pointer to the spi_device struct
41  * @powerdown_cache_mask	used to show current channel powerdown state
42  */
43 struct ltc2632_state {
44 	struct spi_device *spi_dev;
45 	unsigned int powerdown_cache_mask;
46 };
47 
48 enum ltc2632_supported_device_ids {
49 	ID_LTC2632L12,
50 	ID_LTC2632L10,
51 	ID_LTC2632L8,
52 	ID_LTC2632H12,
53 	ID_LTC2632H10,
54 	ID_LTC2632H8,
55 };
56 
57 static int ltc2632_spi_write(struct spi_device *spi,
58 			     u8 cmd, u8 addr, u16 val, u8 shift)
59 {
60 	u32 data;
61 	u8 msg[3];
62 
63 	/*
64 	 * The input shift register is 24 bits wide.
65 	 * The next four are the command bits, C3 to C0,
66 	 * followed by the 4-bit DAC address, A3 to A0, and then the
67 	 * 12-, 10-, 8-bit data-word. The data-word comprises the 12-,
68 	 * 10-, 8-bit input code followed by 4, 6, or 8 don't care bits.
69 	 */
70 	data = (cmd << 20) | (addr << 16) | (val << shift);
71 	msg[0] = data >> 16;
72 	msg[1] = data >> 8;
73 	msg[2] = data;
74 
75 	return spi_write(spi, msg, sizeof(msg));
76 }
77 
78 static int ltc2632_read_raw(struct iio_dev *indio_dev,
79 			    struct iio_chan_spec const *chan,
80 			    int *val,
81 			    int *val2,
82 			    long m)
83 {
84 	struct ltc2632_chip_info *chip_info;
85 
86 	const struct ltc2632_state *st = iio_priv(indio_dev);
87 	const struct spi_device_id *spi_dev_id = spi_get_device_id(st->spi_dev);
88 
89 	chip_info = (struct ltc2632_chip_info *)spi_dev_id->driver_data;
90 
91 	switch (m) {
92 	case IIO_CHAN_INFO_SCALE:
93 		*val = chip_info->vref_mv;
94 		*val2 = chan->scan_type.realbits;
95 		return IIO_VAL_FRACTIONAL_LOG2;
96 	}
97 	return -EINVAL;
98 }
99 
100 static int ltc2632_write_raw(struct iio_dev *indio_dev,
101 			     struct iio_chan_spec const *chan,
102 			     int val,
103 			     int val2,
104 			     long mask)
105 {
106 	struct ltc2632_state *st = iio_priv(indio_dev);
107 
108 	switch (mask) {
109 	case IIO_CHAN_INFO_RAW:
110 		if (val >= (1 << chan->scan_type.realbits) || val < 0)
111 			return -EINVAL;
112 
113 		return ltc2632_spi_write(st->spi_dev,
114 					 LTC2632_CMD_WRITE_INPUT_N_UPDATE_N,
115 					 chan->address, val,
116 					 chan->scan_type.shift);
117 	default:
118 		return -EINVAL;
119 	}
120 }
121 
122 static ssize_t ltc2632_read_dac_powerdown(struct iio_dev *indio_dev,
123 					  uintptr_t private,
124 					  const struct iio_chan_spec *chan,
125 					  char *buf)
126 {
127 	struct ltc2632_state *st = iio_priv(indio_dev);
128 
129 	return sprintf(buf, "%d\n",
130 		       !!(st->powerdown_cache_mask & (1 << chan->channel)));
131 }
132 
133 static ssize_t ltc2632_write_dac_powerdown(struct iio_dev *indio_dev,
134 					   uintptr_t private,
135 					   const struct iio_chan_spec *chan,
136 					   const char *buf,
137 					   size_t len)
138 {
139 	bool pwr_down;
140 	int ret;
141 	struct ltc2632_state *st = iio_priv(indio_dev);
142 
143 	ret = strtobool(buf, &pwr_down);
144 	if (ret)
145 		return ret;
146 
147 	if (pwr_down)
148 		st->powerdown_cache_mask |= (1 << chan->channel);
149 	else
150 		st->powerdown_cache_mask &= ~(1 << chan->channel);
151 
152 	ret = ltc2632_spi_write(st->spi_dev,
153 				LTC2632_CMD_POWERDOWN_DAC_N,
154 				chan->channel, 0, 0);
155 
156 	return ret ? ret : len;
157 }
158 
159 static const struct iio_info ltc2632_info = {
160 	.write_raw	= ltc2632_write_raw,
161 	.read_raw	= ltc2632_read_raw,
162 	.driver_module	= THIS_MODULE,
163 };
164 
165 static const struct iio_chan_spec_ext_info ltc2632_ext_info[] = {
166 	{
167 		.name = "powerdown",
168 		.read = ltc2632_read_dac_powerdown,
169 		.write = ltc2632_write_dac_powerdown,
170 		.shared = IIO_SEPARATE,
171 	},
172 	{ },
173 };
174 
175 #define LTC2632_CHANNEL(_chan, _bits) { \
176 		.type = IIO_VOLTAGE, \
177 		.indexed = 1, \
178 		.output = 1, \
179 		.channel = (_chan), \
180 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
181 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
182 		.address = (_chan), \
183 		.scan_type = { \
184 			.realbits	= (_bits), \
185 			.shift		= 16 - (_bits), \
186 		}, \
187 		.ext_info = ltc2632_ext_info, \
188 }
189 
190 #define DECLARE_LTC2632_CHANNELS(_name, _bits) \
191 	const struct iio_chan_spec _name ## _channels[] = { \
192 		LTC2632_CHANNEL(0, _bits), \
193 		LTC2632_CHANNEL(1, _bits), \
194 	}
195 
196 static DECLARE_LTC2632_CHANNELS(ltc2632l12, 12);
197 static DECLARE_LTC2632_CHANNELS(ltc2632l10, 10);
198 static DECLARE_LTC2632_CHANNELS(ltc2632l8, 8);
199 
200 static DECLARE_LTC2632_CHANNELS(ltc2632h12, 12);
201 static DECLARE_LTC2632_CHANNELS(ltc2632h10, 10);
202 static DECLARE_LTC2632_CHANNELS(ltc2632h8, 8);
203 
204 static const struct ltc2632_chip_info ltc2632_chip_info_tbl[] = {
205 	[ID_LTC2632L12] = {
206 		.channels	= ltc2632l12_channels,
207 		.vref_mv	= 2500,
208 	},
209 	[ID_LTC2632L10] = {
210 		.channels	= ltc2632l10_channels,
211 		.vref_mv	= 2500,
212 	},
213 	[ID_LTC2632L8] =  {
214 		.channels	= ltc2632l8_channels,
215 		.vref_mv	= 2500,
216 	},
217 	[ID_LTC2632H12] = {
218 		.channels	= ltc2632h12_channels,
219 		.vref_mv	= 4096,
220 	},
221 	[ID_LTC2632H10] = {
222 		.channels	= ltc2632h10_channels,
223 		.vref_mv	= 4096,
224 	},
225 	[ID_LTC2632H8] =  {
226 		.channels	= ltc2632h8_channels,
227 		.vref_mv	= 4096,
228 	},
229 };
230 
231 static int ltc2632_probe(struct spi_device *spi)
232 {
233 	struct ltc2632_state *st;
234 	struct iio_dev *indio_dev;
235 	struct ltc2632_chip_info *chip_info;
236 	int ret;
237 
238 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
239 	if (!indio_dev)
240 		return -ENOMEM;
241 
242 	st = iio_priv(indio_dev);
243 
244 	spi_set_drvdata(spi, indio_dev);
245 	st->spi_dev = spi;
246 
247 	chip_info = (struct ltc2632_chip_info *)
248 			spi_get_device_id(spi)->driver_data;
249 
250 	indio_dev->dev.parent = &spi->dev;
251 	indio_dev->name = dev_of_node(&spi->dev) ? dev_of_node(&spi->dev)->name
252 						 : spi_get_device_id(spi)->name;
253 	indio_dev->info = &ltc2632_info;
254 	indio_dev->modes = INDIO_DIRECT_MODE;
255 	indio_dev->channels = chip_info->channels;
256 	indio_dev->num_channels = LTC2632_DAC_CHANNELS;
257 
258 	ret = ltc2632_spi_write(spi, LTC2632_CMD_INTERNAL_REFER, 0, 0, 0);
259 	if (ret) {
260 		dev_err(&spi->dev,
261 			"Set internal reference command failed, %d\n", ret);
262 		return ret;
263 	}
264 
265 	return devm_iio_device_register(&spi->dev, indio_dev);
266 }
267 
268 static const struct spi_device_id ltc2632_id[] = {
269 	{ "ltc2632-l12", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L12] },
270 	{ "ltc2632-l10", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L10] },
271 	{ "ltc2632-l8", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632L8] },
272 	{ "ltc2632-h12", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H12] },
273 	{ "ltc2632-h10", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H10] },
274 	{ "ltc2632-h8", (kernel_ulong_t)&ltc2632_chip_info_tbl[ID_LTC2632H8] },
275 	{}
276 };
277 MODULE_DEVICE_TABLE(spi, ltc2632_id);
278 
279 static struct spi_driver ltc2632_driver = {
280 	.driver		= {
281 		.name	= "ltc2632",
282 	},
283 	.probe		= ltc2632_probe,
284 	.id_table	= ltc2632_id,
285 };
286 module_spi_driver(ltc2632_driver);
287 
288 static const struct of_device_id ltc2632_of_match[] = {
289 	{
290 		.compatible = "lltc,ltc2632-l12",
291 		.data = &ltc2632_chip_info_tbl[ID_LTC2632L12]
292 	}, {
293 		.compatible = "lltc,ltc2632-l10",
294 		.data = &ltc2632_chip_info_tbl[ID_LTC2632L10]
295 	}, {
296 		.compatible = "lltc,ltc2632-l8",
297 		.data = &ltc2632_chip_info_tbl[ID_LTC2632L8]
298 	}, {
299 		.compatible = "lltc,ltc2632-h12",
300 		.data = &ltc2632_chip_info_tbl[ID_LTC2632H12]
301 	}, {
302 		.compatible = "lltc,ltc2632-h10",
303 		.data = &ltc2632_chip_info_tbl[ID_LTC2632H10]
304 	}, {
305 		.compatible = "lltc,ltc2632-h8",
306 		.data = &ltc2632_chip_info_tbl[ID_LTC2632H8]
307 	},
308 	{}
309 };
310 MODULE_DEVICE_TABLE(of, ltc2632_of_match);
311 
312 MODULE_AUTHOR("Maxime Roussin-Belanger <maxime.roussinbelanger@gmail.com>");
313 MODULE_DESCRIPTION("LTC2632 DAC SPI driver");
314 MODULE_LICENSE("GPL v2");
315