diff options
Diffstat (limited to 'drivers/iio/adc/ad7298.c')
| -rw-r--r-- | drivers/iio/adc/ad7298.c | 408 |
1 files changed, 408 insertions, 0 deletions
diff --git a/drivers/iio/adc/ad7298.c b/drivers/iio/adc/ad7298.c new file mode 100644 index 000000000000..b34d754994d5 --- /dev/null +++ b/drivers/iio/adc/ad7298.c @@ -0,0 +1,408 @@ +/* + * AD7298 SPI ADC driver + * + * Copyright 2011 Analog Devices Inc. + * + * Licensed under the GPL-2. + */ + +#include <linux/device.h> +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/sysfs.h> +#include <linux/spi/spi.h> +#include <linux/regulator/consumer.h> +#include <linux/err.h> +#include <linux/delay.h> +#include <linux/module.h> +#include <linux/interrupt.h> + +#include <linux/iio/iio.h> +#include <linux/iio/sysfs.h> +#include <linux/iio/buffer.h> +#include <linux/iio/trigger_consumer.h> +#include <linux/iio/triggered_buffer.h> + +#include <linux/platform_data/ad7298.h> + +#define AD7298_WRITE (1 << 15) /* write to the control register */ +#define AD7298_REPEAT (1 << 14) /* repeated conversion enable */ +#define AD7298_CH(x) (1 << (13 - (x))) /* channel select */ +#define AD7298_TSENSE (1 << 5) /* temperature conversion enable */ +#define AD7298_EXTREF (1 << 2) /* external reference enable */ +#define AD7298_TAVG (1 << 1) /* temperature sensor averaging enable */ +#define AD7298_PDD (1 << 0) /* partial power down enable */ + +#define AD7298_MAX_CHAN 8 +#define AD7298_BITS 12 +#define AD7298_STORAGE_BITS 16 +#define AD7298_INTREF_mV 2500 + +#define AD7298_CH_TEMP 9 + +#define RES_MASK(bits) ((1 << (bits)) - 1) + +struct ad7298_state { + struct spi_device *spi; + struct regulator *reg; + unsigned ext_ref; + struct spi_transfer ring_xfer[10]; + struct spi_transfer scan_single_xfer[3]; + struct spi_message ring_msg; + struct spi_message scan_single_msg; + /* + * DMA (thus cache coherency maintenance) requires the + * transfer buffers to live in their own cache lines. + */ + __be16 rx_buf[12] ____cacheline_aligned; + __be16 tx_buf[2]; +}; + +#define AD7298_V_CHAN(index) \ + { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = index, \ + .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT | \ + IIO_CHAN_INFO_SCALE_SHARED_BIT, \ + .address = index, \ + .scan_index = index, \ + .scan_type = { \ + .sign = 'u', \ + .realbits = 12, \ + .storagebits = 16, \ + .endianness = IIO_BE, \ + }, \ + } + +static const struct iio_chan_spec ad7298_channels[] = { + { + .type = IIO_TEMP, + .indexed = 1, + .channel = 0, + .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT | + IIO_CHAN_INFO_SCALE_SEPARATE_BIT | + IIO_CHAN_INFO_OFFSET_SEPARATE_BIT, + .address = AD7298_CH_TEMP, + .scan_index = -1, + .scan_type = { + .sign = 's', + .realbits = 32, + .storagebits = 32, + }, + }, + AD7298_V_CHAN(0), + AD7298_V_CHAN(1), + AD7298_V_CHAN(2), + AD7298_V_CHAN(3), + AD7298_V_CHAN(4), + AD7298_V_CHAN(5), + AD7298_V_CHAN(6), + AD7298_V_CHAN(7), + IIO_CHAN_SOFT_TIMESTAMP(8), +}; + +/** + * ad7298_update_scan_mode() setup the spi transfer buffer for the new scan mask + **/ +static int ad7298_update_scan_mode(struct iio_dev *indio_dev, + const unsigned long *active_scan_mask) +{ + struct ad7298_state *st = iio_priv(indio_dev); + int i, m; + unsigned short command; + int scan_count; + + /* Now compute overall size */ + scan_count = bitmap_weight(active_scan_mask, indio_dev->masklength); + + command = AD7298_WRITE | st->ext_ref; + + for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1) + if (test_bit(i, active_scan_mask)) + command |= m; + + st->tx_buf[0] = cpu_to_be16(command); + + /* build spi ring message */ + st->ring_xfer[0].tx_buf = &st->tx_buf[0]; + st->ring_xfer[0].len = 2; + st->ring_xfer[0].cs_change = 1; + st->ring_xfer[1].tx_buf = &st->tx_buf[1]; + st->ring_xfer[1].len = 2; + st->ring_xfer[1].cs_change = 1; + + spi_message_init(&st->ring_msg); + spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg); + spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg); + + for (i = 0; i < scan_count; i++) { + st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i]; + st->ring_xfer[i + 2].len = 2; + st->ring_xfer[i + 2].cs_change = 1; + spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg); + } + /* make sure last transfer cs_change is not set */ + st->ring_xfer[i + 1].cs_change = 0; + + return 0; +} + +/** + * ad7298_trigger_handler() bh of trigger launched polling to ring buffer + * + * Currently there is no option in this driver to disable the saving of + * timestamps within the ring. + **/ +static irqreturn_t ad7298_trigger_handler(int irq, void *p) +{ + struct iio_poll_func *pf = p; + struct iio_dev *indio_dev = pf->indio_dev; + struct ad7298_state *st = iio_priv(indio_dev); + s64 time_ns = 0; + int b_sent; + + b_sent = spi_sync(st->spi, &st->ring_msg); + if (b_sent) + goto done; + + if (indio_dev->scan_timestamp) { + time_ns = iio_get_time_ns(); + memcpy((u8 *)st->rx_buf + indio_dev->scan_bytes - sizeof(s64), + &time_ns, sizeof(time_ns)); + } + + iio_push_to_buffers(indio_dev, (u8 *)st->rx_buf); + +done: + iio_trigger_notify_done(indio_dev->trig); + + return IRQ_HANDLED; +} + +static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch) +{ + int ret; + st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref | + (AD7298_CH(0) >> ch)); + + ret = spi_sync(st->spi, &st->scan_single_msg); + if (ret) + return ret; + + return be16_to_cpu(st->rx_buf[0]); +} + +static int ad7298_scan_temp(struct ad7298_state *st, int *val) +{ + int ret; + __be16 buf; + + buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE | + AD7298_TAVG | st->ext_ref); + + ret = spi_write(st->spi, (u8 *)&buf, 2); + if (ret) + return ret; + + buf = cpu_to_be16(0); + + ret = spi_write(st->spi, (u8 *)&buf, 2); + if (ret) + return ret; + + usleep_range(101, 1000); /* sleep > 100us */ + + ret = spi_read(st->spi, (u8 *)&buf, 2); + if (ret) + return ret; + + *val = sign_extend32(be16_to_cpu(buf), 11); + + return 0; +} + +static int ad7298_get_ref_voltage(struct ad7298_state *st) +{ + int vref; + + if (st->ext_ref) { + vref = regulator_get_voltage(st->reg); + if (vref < 0) + return vref; + + return vref / 1000; + } else { + return AD7298_INTREF_mV; + } +} + +static int ad7298_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, + int *val2, + long m) +{ + int ret; + struct ad7298_state *st = iio_priv(indio_dev); + + switch (m) { + case IIO_CHAN_INFO_RAW: + mutex_lock(&indio_dev->mlock); + if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) { + ret = -EBUSY; + } else { + if (chan->address == AD7298_CH_TEMP) + ret = ad7298_scan_temp(st, val); + else + ret = ad7298_scan_direct(st, chan->address); + } + mutex_unlock(&indio_dev->mlock); + + if (ret < 0) + return ret; + + if (chan->address != AD7298_CH_TEMP) + *val = ret & RES_MASK(AD7298_BITS); + + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + switch (chan->type) { + case IIO_VOLTAGE: + *val = ad7298_get_ref_voltage(st); + *val2 = chan->scan_type.realbits; + return IIO_VAL_FRACTIONAL_LOG2; + case IIO_TEMP: + *val = ad7298_get_ref_voltage(st); + *val2 = 10; + return IIO_VAL_FRACTIONAL; + default: + return -EINVAL; + } + case IIO_CHAN_INFO_OFFSET: + *val = 1093 - 2732500 / ad7298_get_ref_voltage(st); + return IIO_VAL_INT; + } + return -EINVAL; +} + +static const struct iio_info ad7298_info = { + .read_raw = &ad7298_read_raw, + .update_scan_mode = ad7298_update_scan_mode, + .driver_module = THIS_MODULE, +}; + +static int ad7298_probe(struct spi_device *spi) +{ + struct ad7298_platform_data *pdata = spi->dev.platform_data; + struct ad7298_state *st; + struct iio_dev *indio_dev = iio_device_alloc(sizeof(*st)); + int ret; + + if (indio_dev == NULL) + return -ENOMEM; + + st = iio_priv(indio_dev); + + if (pdata && pdata->ext_ref) + st->ext_ref = AD7298_EXTREF; + + if (st->ext_ref) { + st->reg = regulator_get(&spi->dev, "vref"); + if (IS_ERR(st->reg)) { + ret = PTR_ERR(st->reg); + goto error_free; + } + ret = regulator_enable(st->reg); + if (ret) + goto error_put_reg; + } + + spi_set_drvdata(spi, indio_dev); + + st->spi = spi; + + indio_dev->name = spi_get_device_id(spi)->name; + indio_dev->dev.parent = &spi->dev; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = ad7298_channels; + indio_dev->num_channels = ARRAY_SIZE(ad7298_channels); + indio_dev->info = &ad7298_info; + + /* Setup default message */ + + st->scan_single_xfer[0].tx_buf = &st->tx_buf[0]; + st->scan_single_xfer[0].len = 2; + st->scan_single_xfer[0].cs_change = 1; + st->scan_single_xfer[1].tx_buf = &st->tx_buf[1]; + st->scan_single_xfer[1].len = 2; + st->scan_single_xfer[1].cs_change = 1; + st->scan_single_xfer[2].rx_buf = &st->rx_buf[0]; + st->scan_single_xfer[2].len = 2; + + spi_message_init(&st->scan_single_msg); + spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg); + spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg); + spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg); + + ret = iio_triggered_buffer_setup(indio_dev, NULL, + &ad7298_trigger_handler, NULL); + if (ret) + goto error_disable_reg; + + ret = iio_device_register(indio_dev); + if (ret) + goto error_cleanup_ring; + + return 0; + +error_cleanup_ring: + iio_triggered_buffer_cleanup(indio_dev); +error_disable_reg: + if (st->ext_ref) + regulator_disable(st->reg); +error_put_reg: + if (st->ext_ref) + regulator_put(st->reg); +error_free: + iio_device_free(indio_dev); + + return ret; +} + +static int ad7298_remove(struct spi_device *spi) +{ + struct iio_dev *indio_dev = spi_get_drvdata(spi); + struct ad7298_state *st = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + iio_triggered_buffer_cleanup(indio_dev); + if (st->ext_ref) { + regulator_disable(st->reg); + regulator_put(st->reg); + } + iio_device_free(indio_dev); + + return 0; +} + +static const struct spi_device_id ad7298_id[] = { + {"ad7298", 0}, + {} +}; +MODULE_DEVICE_TABLE(spi, ad7298_id); + +static struct spi_driver ad7298_driver = { + .driver = { + .name = "ad7298", + .owner = THIS_MODULE, + }, + .probe = ad7298_probe, + .remove = ad7298_remove, + .id_table = ad7298_id, +}; +module_spi_driver(ad7298_driver); + +MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>"); +MODULE_DESCRIPTION("Analog Devices AD7298 ADC"); +MODULE_LICENSE("GPL v2"); |