1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Texas Instruments LMP92064 SPI ADC driver
4 *
5 * Copyright (c) 2022 Leonard Göhrs <kernel@pengutronix.de>, Pengutronix
6 *
7 * Based on linux/drivers/iio/adc/ti-tsc2046.c
8 * Copyright (c) 2021 Oleksij Rempel <kernel@pengutronix.de>, Pengutronix
9 */
10
11 #include <linux/delay.h>
12 #include <linux/gpio/consumer.h>
13 #include <linux/module.h>
14 #include <linux/regmap.h>
15 #include <linux/regulator/consumer.h>
16 #include <linux/spi/spi.h>
17
18 #include <linux/iio/iio.h>
19 #include <linux/iio/buffer.h>
20 #include <linux/iio/driver.h>
21 #include <linux/iio/triggered_buffer.h>
22 #include <linux/iio/trigger_consumer.h>
23
24 #define TI_LMP92064_REG_CONFIG_A 0x0000
25 #define TI_LMP92064_REG_CONFIG_B 0x0001
26 #define TI_LMP92064_REG_CHIP_REV 0x0006
27
28 #define TI_LMP92064_REG_MFR_ID1 0x000C
29 #define TI_LMP92064_REG_MFR_ID2 0x000D
30
31 #define TI_LMP92064_REG_REG_UPDATE 0x000F
32 #define TI_LMP92064_REG_CONFIG_REG 0x0100
33 #define TI_LMP92064_REG_STATUS 0x0103
34
35 #define TI_LMP92064_REG_DATA_VOUT_LSB 0x0200
36 #define TI_LMP92064_REG_DATA_VOUT_MSB 0x0201
37 #define TI_LMP92064_REG_DATA_COUT_LSB 0x0202
38 #define TI_LMP92064_REG_DATA_COUT_MSB 0x0203
39
40 #define TI_LMP92064_VAL_CONFIG_A 0x99
41 #define TI_LMP92064_VAL_CONFIG_B 0x00
42 #define TI_LMP92064_VAL_STATUS_OK 0x01
43
44 /*
45 * Channel number definitions for the two channels of the device
46 * - IN Current (INC)
47 * - IN Voltage (INV)
48 */
49 #define TI_LMP92064_CHAN_INC 0
50 #define TI_LMP92064_CHAN_INV 1
51
52 static const struct regmap_range lmp92064_readable_reg_ranges[] = {
53 regmap_reg_range(TI_LMP92064_REG_CONFIG_A, TI_LMP92064_REG_CHIP_REV),
54 regmap_reg_range(TI_LMP92064_REG_MFR_ID1, TI_LMP92064_REG_MFR_ID2),
55 regmap_reg_range(TI_LMP92064_REG_REG_UPDATE, TI_LMP92064_REG_REG_UPDATE),
56 regmap_reg_range(TI_LMP92064_REG_CONFIG_REG, TI_LMP92064_REG_CONFIG_REG),
57 regmap_reg_range(TI_LMP92064_REG_STATUS, TI_LMP92064_REG_STATUS),
58 regmap_reg_range(TI_LMP92064_REG_DATA_VOUT_LSB, TI_LMP92064_REG_DATA_COUT_MSB),
59 };
60
61 static const struct regmap_access_table lmp92064_readable_regs = {
62 .yes_ranges = lmp92064_readable_reg_ranges,
63 .n_yes_ranges = ARRAY_SIZE(lmp92064_readable_reg_ranges),
64 };
65
66 static const struct regmap_range lmp92064_writable_reg_ranges[] = {
67 regmap_reg_range(TI_LMP92064_REG_CONFIG_A, TI_LMP92064_REG_CONFIG_B),
68 regmap_reg_range(TI_LMP92064_REG_REG_UPDATE, TI_LMP92064_REG_REG_UPDATE),
69 regmap_reg_range(TI_LMP92064_REG_CONFIG_REG, TI_LMP92064_REG_CONFIG_REG),
70 };
71
72 static const struct regmap_access_table lmp92064_writable_regs = {
73 .yes_ranges = lmp92064_writable_reg_ranges,
74 .n_yes_ranges = ARRAY_SIZE(lmp92064_writable_reg_ranges),
75 };
76
77 static const struct regmap_config lmp92064_spi_regmap_config = {
78 .reg_bits = 16,
79 .val_bits = 8,
80 .max_register = TI_LMP92064_REG_DATA_COUT_MSB,
81 .rd_table = &lmp92064_readable_regs,
82 .wr_table = &lmp92064_writable_regs,
83 };
84
85 struct lmp92064_adc_priv {
86 int shunt_resistor_uohm;
87 struct spi_device *spi;
88 struct regmap *regmap;
89 };
90
91 static const struct iio_chan_spec lmp92064_adc_channels[] = {
92 {
93 .type = IIO_CURRENT,
94 .address = TI_LMP92064_CHAN_INC,
95 .info_mask_separate =
96 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
97 .scan_index = TI_LMP92064_CHAN_INC,
98 .scan_type = {
99 .sign = 'u',
100 .realbits = 12,
101 .storagebits = 16,
102 },
103 .datasheet_name = "INC",
104 },
105 {
106 .type = IIO_VOLTAGE,
107 .address = TI_LMP92064_CHAN_INV,
108 .info_mask_separate =
109 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
110 .scan_index = TI_LMP92064_CHAN_INV,
111 .scan_type = {
112 .sign = 'u',
113 .realbits = 12,
114 .storagebits = 16,
115 },
116 .datasheet_name = "INV",
117 },
118 IIO_CHAN_SOFT_TIMESTAMP(2),
119 };
120
121 static const unsigned long lmp92064_scan_masks[] = {
122 BIT(TI_LMP92064_CHAN_INC) | BIT(TI_LMP92064_CHAN_INV),
123 0
124 };
125
lmp92064_read_meas(struct lmp92064_adc_priv * priv,u16 * res)126 static int lmp92064_read_meas(struct lmp92064_adc_priv *priv, u16 *res)
127 {
128 __be16 raw[2];
129 int ret;
130
131 /*
132 * The ADC only latches in new samples if all DATA registers are read
133 * in descending sequential order.
134 * The ADC auto-decrements the register index with each clocked byte.
135 * Read both channels in single SPI transfer by selecting the highest
136 * register using the command below and clocking out all four data
137 * bytes.
138 */
139
140 ret = regmap_bulk_read(priv->regmap, TI_LMP92064_REG_DATA_COUT_MSB,
141 &raw, sizeof(raw));
142
143 if (ret) {
144 dev_err(&priv->spi->dev, "regmap_bulk_read failed: %pe\n",
145 ERR_PTR(ret));
146 return ret;
147 }
148
149 res[0] = be16_to_cpu(raw[0]);
150 res[1] = be16_to_cpu(raw[1]);
151
152 return 0;
153 }
154
lmp92064_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)155 static int lmp92064_read_raw(struct iio_dev *indio_dev,
156 struct iio_chan_spec const *chan, int *val,
157 int *val2, long mask)
158 {
159 struct lmp92064_adc_priv *priv = iio_priv(indio_dev);
160 u16 raw[2];
161 int ret;
162
163 switch (mask) {
164 case IIO_CHAN_INFO_RAW:
165 ret = lmp92064_read_meas(priv, raw);
166 if (ret < 0)
167 return ret;
168
169 *val = (chan->address == TI_LMP92064_CHAN_INC) ? raw[0] : raw[1];
170
171 return IIO_VAL_INT;
172 case IIO_CHAN_INFO_SCALE:
173 if (chan->address == TI_LMP92064_CHAN_INC) {
174 /*
175 * processed (mA) = raw * current_lsb (mA)
176 * current_lsb (mA) = shunt_voltage_lsb (nV) / shunt_resistor (uOhm)
177 * shunt_voltage_lsb (nV) = 81920000 / 4096 = 20000
178 */
179 *val = 20000;
180 *val2 = priv->shunt_resistor_uohm;
181 } else {
182 /*
183 * processed (mV) = raw * voltage_lsb (mV)
184 * voltage_lsb (mV) = 2048 / 4096
185 */
186 *val = 2048;
187 *val2 = 4096;
188 }
189 return IIO_VAL_FRACTIONAL;
190 default:
191 return -EINVAL;
192 }
193 }
194
lmp92064_trigger_handler(int irq,void * p)195 static irqreturn_t lmp92064_trigger_handler(int irq, void *p)
196 {
197 struct iio_poll_func *pf = p;
198 struct iio_dev *indio_dev = pf->indio_dev;
199 struct lmp92064_adc_priv *priv = iio_priv(indio_dev);
200 struct {
201 u16 values[2];
202 int64_t timestamp __aligned(8);
203 } data;
204 int ret;
205
206 memset(&data, 0, sizeof(data));
207
208 ret = lmp92064_read_meas(priv, data.values);
209 if (ret)
210 goto err;
211
212 iio_push_to_buffers_with_timestamp(indio_dev, &data,
213 iio_get_time_ns(indio_dev));
214
215 err:
216 iio_trigger_notify_done(indio_dev->trig);
217
218 return IRQ_HANDLED;
219 }
220
lmp92064_reset(struct lmp92064_adc_priv * priv,struct gpio_desc * gpio_reset)221 static int lmp92064_reset(struct lmp92064_adc_priv *priv,
222 struct gpio_desc *gpio_reset)
223 {
224 unsigned int status;
225 int ret, i;
226
227 if (gpio_reset) {
228 /*
229 * Perform a hard reset if gpio_reset is available.
230 * The datasheet specifies a very low 3.5ns reset pulse duration and does not
231 * specify how long to wait after a reset to access the device.
232 * Use more conservative pulse lengths to allow analog RC filtering of the
233 * reset line at the board level (as recommended in the datasheet).
234 */
235 gpiod_set_value_cansleep(gpio_reset, 1);
236 usleep_range(1, 10);
237 gpiod_set_value_cansleep(gpio_reset, 0);
238 usleep_range(500, 750);
239 } else {
240 /*
241 * Perform a soft-reset if not.
242 * Also write default values to the config registers that are not
243 * affected by soft reset.
244 */
245 ret = regmap_write(priv->regmap, TI_LMP92064_REG_CONFIG_A,
246 TI_LMP92064_VAL_CONFIG_A);
247 if (ret < 0)
248 return ret;
249
250 ret = regmap_write(priv->regmap, TI_LMP92064_REG_CONFIG_B,
251 TI_LMP92064_VAL_CONFIG_B);
252 if (ret < 0)
253 return ret;
254 }
255
256 /*
257 * Wait for the device to signal readiness to prevent reading bogus data
258 * and make sure device is actually connected.
259 * The datasheet does not specify how long this takes but usually it is
260 * not more than 3-4 iterations of this loop.
261 */
262 for (i = 0; i < 10; i++) {
263 ret = regmap_read(priv->regmap, TI_LMP92064_REG_STATUS, &status);
264 if (ret < 0)
265 return ret;
266
267 if (status == TI_LMP92064_VAL_STATUS_OK)
268 return 0;
269
270 usleep_range(1000, 2000);
271 }
272
273 /*
274 * No (correct) response received.
275 * Device is mostly likely not connected to the bus.
276 */
277 return -ENXIO;
278 }
279
280 static const struct iio_info lmp92064_adc_info = {
281 .read_raw = lmp92064_read_raw,
282 };
283
lmp92064_adc_probe(struct spi_device * spi)284 static int lmp92064_adc_probe(struct spi_device *spi)
285 {
286 struct device *dev = &spi->dev;
287 struct lmp92064_adc_priv *priv;
288 struct gpio_desc *gpio_reset;
289 struct iio_dev *indio_dev;
290 u32 shunt_resistor_uohm;
291 struct regmap *regmap;
292 int ret;
293
294 ret = spi_setup(spi);
295 if (ret < 0)
296 return dev_err_probe(dev, ret, "Error in SPI setup\n");
297
298 regmap = devm_regmap_init_spi(spi, &lmp92064_spi_regmap_config);
299 if (IS_ERR(regmap))
300 return dev_err_probe(dev, PTR_ERR(regmap),
301 "Failed to set up SPI regmap\n");
302
303 indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
304 if (!indio_dev)
305 return -ENOMEM;
306
307 priv = iio_priv(indio_dev);
308
309 priv->spi = spi;
310 priv->regmap = regmap;
311
312 ret = device_property_read_u32(dev, "shunt-resistor-micro-ohms",
313 &shunt_resistor_uohm);
314 if (ret < 0)
315 return dev_err_probe(dev, ret,
316 "Failed to get shunt-resistor value\n");
317
318 /*
319 * The shunt resistance is passed to userspace as the denominator of an iio
320 * fraction. Make sure it is in range for that.
321 */
322 if (shunt_resistor_uohm == 0 || shunt_resistor_uohm > INT_MAX) {
323 dev_err(dev, "Shunt resistance is out of range\n");
324 return -EINVAL;
325 }
326
327 priv->shunt_resistor_uohm = shunt_resistor_uohm;
328
329 ret = devm_regulator_get_enable(dev, "vdd");
330 if (ret)
331 return ret;
332
333 ret = devm_regulator_get_enable(dev, "vdig");
334 if (ret)
335 return ret;
336
337 gpio_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
338 if (IS_ERR(gpio_reset))
339 return dev_err_probe(dev, PTR_ERR(gpio_reset),
340 "Failed to get GPIO reset pin\n");
341
342 ret = lmp92064_reset(priv, gpio_reset);
343 if (ret < 0)
344 return dev_err_probe(dev, ret, "Failed to reset device\n");
345
346 indio_dev->name = "lmp92064";
347 indio_dev->modes = INDIO_DIRECT_MODE;
348 indio_dev->channels = lmp92064_adc_channels;
349 indio_dev->num_channels = ARRAY_SIZE(lmp92064_adc_channels);
350 indio_dev->info = &lmp92064_adc_info;
351 indio_dev->available_scan_masks = lmp92064_scan_masks;
352
353 ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
354 lmp92064_trigger_handler, NULL);
355 if (ret)
356 return dev_err_probe(dev, ret, "Failed to setup buffered read\n");
357
358 return devm_iio_device_register(dev, indio_dev);
359 }
360
361 static const struct spi_device_id lmp92064_id_table[] = {
362 { "lmp92064" },
363 {}
364 };
365 MODULE_DEVICE_TABLE(spi, lmp92064_id_table);
366
367 static const struct of_device_id lmp92064_of_table[] = {
368 { .compatible = "ti,lmp92064" },
369 {}
370 };
371 MODULE_DEVICE_TABLE(of, lmp92064_of_table);
372
373 static struct spi_driver lmp92064_adc_driver = {
374 .driver = {
375 .name = "lmp92064",
376 .of_match_table = lmp92064_of_table,
377 },
378 .probe = lmp92064_adc_probe,
379 .id_table = lmp92064_id_table,
380 };
381 module_spi_driver(lmp92064_adc_driver);
382
383 MODULE_AUTHOR("Leonard Göhrs <kernel@pengutronix.de>");
384 MODULE_DESCRIPTION("TI LMP92064 ADC");
385 MODULE_LICENSE("GPL");
386