diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/iio/adc/ltc2497.c | 294 |
1 files changed, 294 insertions, 0 deletions
diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c new file mode 100644 index 000000000..f1f7cdf66 --- /dev/null +++ b/drivers/iio/adc/ltc2497.c @@ -0,0 +1,294 @@ +/* + * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC + * + * Copyright (C) 2017 Analog Devices Inc. + * + * Licensed under the GPL-2. + * + * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf + */ + +#include <linux/delay.h> +#include <linux/i2c.h> +#include <linux/iio/iio.h> +#include <linux/iio/driver.h> +#include <linux/iio/sysfs.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/regulator/consumer.h> + +#define LTC2497_ENABLE 0xA0 +#define LTC2497_SGL BIT(4) +#define LTC2497_DIFF 0 +#define LTC2497_SIGN BIT(3) +#define LTC2497_CONFIG_DEFAULT LTC2497_ENABLE +#define LTC2497_CONVERSION_TIME_MS 150ULL + +struct ltc2497_st { + struct i2c_client *client; + struct regulator *ref; + ktime_t time_prev; + u8 addr_prev; + /* + * DMA (thus cache coherency maintenance) requires the + * transfer buffers to live in their own cache lines. + */ + __be32 buf ____cacheline_aligned; +}; + +static int ltc2497_wait_conv(struct ltc2497_st *st) +{ + s64 time_elapsed; + + time_elapsed = ktime_ms_delta(ktime_get(), st->time_prev); + + if (time_elapsed < LTC2497_CONVERSION_TIME_MS) { + /* delay if conversion time not passed + * since last read or write + */ + if (msleep_interruptible( + LTC2497_CONVERSION_TIME_MS - time_elapsed)) + return -ERESTARTSYS; + + return 0; + } + + if (time_elapsed - LTC2497_CONVERSION_TIME_MS <= 0) { + /* We're in automatic mode - + * so the last reading is stil not outdated + */ + return 0; + } + + return 1; +} + +static int ltc2497_read(struct ltc2497_st *st, u8 address, int *val) +{ + struct i2c_client *client = st->client; + int ret; + + ret = ltc2497_wait_conv(st); + if (ret < 0) + return ret; + + if (ret || st->addr_prev != address) { + ret = i2c_smbus_write_byte(st->client, + LTC2497_ENABLE | address); + if (ret < 0) + return ret; + st->addr_prev = address; + if (msleep_interruptible(LTC2497_CONVERSION_TIME_MS)) + return -ERESTARTSYS; + } + ret = i2c_master_recv(client, (char *)&st->buf, 3); + if (ret < 0) { + dev_err(&client->dev, "i2c_master_recv failed\n"); + return ret; + } + st->time_prev = ktime_get(); + + /* convert and shift the result, + * and finally convert from offset binary to signed integer + */ + *val = (be32_to_cpu(st->buf) >> 14) - (1 << 17); + + return ret; +} + +static int ltc2497_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct ltc2497_st *st = iio_priv(indio_dev); + int ret; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + mutex_lock(&indio_dev->mlock); + ret = ltc2497_read(st, chan->address, val); + mutex_unlock(&indio_dev->mlock); + if (ret < 0) + return ret; + + return IIO_VAL_INT; + + case IIO_CHAN_INFO_SCALE: + ret = regulator_get_voltage(st->ref); + if (ret < 0) + return ret; + + *val = ret / 1000; + *val2 = 17; + + return IIO_VAL_FRACTIONAL_LOG2; + + default: + return -EINVAL; + } +} + +#define LTC2497_CHAN(_chan, _addr, _ds_name) { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = (_chan), \ + .address = (_addr | (_chan / 2) | ((_chan & 1) ? LTC2497_SIGN : 0)), \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ + .datasheet_name = (_ds_name), \ +} + +#define LTC2497_CHAN_DIFF(_chan, _addr) { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 1 : 0), \ + .channel2 = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 0 : 1),\ + .address = (_addr | _chan), \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ + .differential = 1, \ +} + +static const struct iio_chan_spec ltc2497_channel[] = { + LTC2497_CHAN(0, LTC2497_SGL, "CH0"), + LTC2497_CHAN(1, LTC2497_SGL, "CH1"), + LTC2497_CHAN(2, LTC2497_SGL, "CH2"), + LTC2497_CHAN(3, LTC2497_SGL, "CH3"), + LTC2497_CHAN(4, LTC2497_SGL, "CH4"), + LTC2497_CHAN(5, LTC2497_SGL, "CH5"), + LTC2497_CHAN(6, LTC2497_SGL, "CH6"), + LTC2497_CHAN(7, LTC2497_SGL, "CH7"), + LTC2497_CHAN(8, LTC2497_SGL, "CH8"), + LTC2497_CHAN(9, LTC2497_SGL, "CH9"), + LTC2497_CHAN(10, LTC2497_SGL, "CH10"), + LTC2497_CHAN(11, LTC2497_SGL, "CH11"), + LTC2497_CHAN(12, LTC2497_SGL, "CH12"), + LTC2497_CHAN(13, LTC2497_SGL, "CH13"), + LTC2497_CHAN(14, LTC2497_SGL, "CH14"), + LTC2497_CHAN(15, LTC2497_SGL, "CH15"), + LTC2497_CHAN_DIFF(0, LTC2497_DIFF), + LTC2497_CHAN_DIFF(1, LTC2497_DIFF), + LTC2497_CHAN_DIFF(2, LTC2497_DIFF), + LTC2497_CHAN_DIFF(3, LTC2497_DIFF), + LTC2497_CHAN_DIFF(4, LTC2497_DIFF), + LTC2497_CHAN_DIFF(5, LTC2497_DIFF), + LTC2497_CHAN_DIFF(6, LTC2497_DIFF), + LTC2497_CHAN_DIFF(7, LTC2497_DIFF), + LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN), + LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN), + LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN), + LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN), + LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN), + LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN), + LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN), + LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN), +}; + +static const struct iio_info ltc2497_info = { + .read_raw = ltc2497_read_raw, +}; + +static int ltc2497_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct iio_dev *indio_dev; + struct ltc2497_st *st; + struct iio_map *plat_data; + int ret; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | + I2C_FUNC_SMBUS_WRITE_BYTE)) + return -EOPNOTSUPP; + + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st)); + if (!indio_dev) + return -ENOMEM; + + st = iio_priv(indio_dev); + i2c_set_clientdata(client, indio_dev); + st->client = client; + + indio_dev->dev.parent = &client->dev; + indio_dev->name = id->name; + indio_dev->info = <c2497_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = ltc2497_channel; + indio_dev->num_channels = ARRAY_SIZE(ltc2497_channel); + + st->ref = devm_regulator_get(&client->dev, "vref"); + if (IS_ERR(st->ref)) + return PTR_ERR(st->ref); + + ret = regulator_enable(st->ref); + if (ret < 0) + return ret; + + if (client->dev.platform_data) { + plat_data = ((struct iio_map *)client->dev.platform_data); + ret = iio_map_array_register(indio_dev, plat_data); + if (ret) { + dev_err(&indio_dev->dev, "iio map err: %d\n", ret); + goto err_regulator_disable; + } + } + + ret = i2c_smbus_write_byte(st->client, LTC2497_CONFIG_DEFAULT); + if (ret < 0) + goto err_array_unregister; + + st->addr_prev = LTC2497_CONFIG_DEFAULT; + st->time_prev = ktime_get(); + + ret = iio_device_register(indio_dev); + if (ret < 0) + goto err_array_unregister; + + return 0; + +err_array_unregister: + iio_map_array_unregister(indio_dev); + +err_regulator_disable: + regulator_disable(st->ref); + + return ret; +} + +static int ltc2497_remove(struct i2c_client *client) +{ + struct iio_dev *indio_dev = i2c_get_clientdata(client); + struct ltc2497_st *st = iio_priv(indio_dev); + + iio_map_array_unregister(indio_dev); + iio_device_unregister(indio_dev); + regulator_disable(st->ref); + + return 0; +} + +static const struct i2c_device_id ltc2497_id[] = { + { "ltc2497", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, ltc2497_id); + +static const struct of_device_id ltc2497_of_match[] = { + { .compatible = "lltc,ltc2497", }, + {}, +}; +MODULE_DEVICE_TABLE(of, ltc2497_of_match); + +static struct i2c_driver ltc2497_driver = { + .driver = { + .name = "ltc2497", + .of_match_table = of_match_ptr(ltc2497_of_match), + }, + .probe = ltc2497_probe, + .remove = ltc2497_remove, + .id_table = ltc2497_id, +}; +module_i2c_driver(ltc2497_driver); + +MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>"); +MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver"); +MODULE_LICENSE("GPL v2"); |