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linux/drivers/iio/adc/ti-ads7950.c
David Lechner 8134b613b0 iio: adc: ti-ads7950: allow simultaneous use of buffer and direct mode 
This modifies the TI ADS7950 A/DC driver to allow the simultaneous use
of both the triggered buffer and reading channels directly (via in-
kernel API or sysfs).

The use case for this is on LEGO MINDSTORMS EV3. Two of the voltage
channels are used in-kernel by a power supply driver, which reads the
values using iio_read_channel_processed(). These channels are only read
at a slow rate (<= 1Hz).  However, we want to be able to read 12 other
channels at the same time using the triggered buffer at a high rate (>=
100Hz).

Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2018-07-23 19:18:12 +01:00

521 lines
14 KiB
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// SPDX-License-Identifier: GPL-2.0
/*
* Texas Instruments ADS7950 SPI ADC driver
*
* Copyright 2016 David Lechner <david@lechnology.com>
*
* Based on iio/ad7923.c:
* Copyright 2011 Analog Devices Inc
* Copyright 2012 CS Systemes d'Information
*
* And also on hwmon/ads79xx.c
* Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com/
* Nishanth Menon
*/
#include <linux/acpi.h>
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/iio/buffer.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
/*
* In case of ACPI, we use the 5000 mV as default for the reference pin.
* Device tree users encode that via the vref-supply regulator.
*/
#define TI_ADS7950_VA_MV_ACPI_DEFAULT 5000
#define TI_ADS7950_CR_MANUAL BIT(12)
#define TI_ADS7950_CR_WRITE BIT(11)
#define TI_ADS7950_CR_CHAN(ch) ((ch) << 7)
#define TI_ADS7950_CR_RANGE_5V BIT(6)
#define TI_ADS7950_MAX_CHAN 16
#define TI_ADS7950_TIMESTAMP_SIZE (sizeof(int64_t) / sizeof(__be16))
/* val = value, dec = left shift, bits = number of bits of the mask */
#define TI_ADS7950_EXTRACT(val, dec, bits) \
(((val) >> (dec)) & ((1 << (bits)) - 1))
struct ti_ads7950_state {
struct spi_device *spi;
struct spi_transfer ring_xfer[TI_ADS7950_MAX_CHAN + 2];
struct spi_transfer scan_single_xfer[3];
struct spi_message ring_msg;
struct spi_message scan_single_msg;
struct regulator *reg;
unsigned int vref_mv;
unsigned int settings;
/*
* DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines.
*/
__be16 rx_buf[TI_ADS7950_MAX_CHAN + TI_ADS7950_TIMESTAMP_SIZE]
____cacheline_aligned;
__be16 tx_buf[TI_ADS7950_MAX_CHAN];
__be16 single_tx;
__be16 single_rx;
};
struct ti_ads7950_chip_info {
const struct iio_chan_spec *channels;
unsigned int num_channels;
};
enum ti_ads7950_id {
TI_ADS7950,
TI_ADS7951,
TI_ADS7952,
TI_ADS7953,
TI_ADS7954,
TI_ADS7955,
TI_ADS7956,
TI_ADS7957,
TI_ADS7958,
TI_ADS7959,
TI_ADS7960,
TI_ADS7961,
};
#define TI_ADS7950_V_CHAN(index, bits) \
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = index, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
.address = index, \
.datasheet_name = "CH##index", \
.scan_index = index, \
.scan_type = { \
.sign = 'u', \
.realbits = bits, \
.storagebits = 16, \
.shift = 12 - (bits), \
.endianness = IIO_BE, \
}, \
}
#define DECLARE_TI_ADS7950_4_CHANNELS(name, bits) \
const struct iio_chan_spec name ## _channels[] = { \
TI_ADS7950_V_CHAN(0, bits), \
TI_ADS7950_V_CHAN(1, bits), \
TI_ADS7950_V_CHAN(2, bits), \
TI_ADS7950_V_CHAN(3, bits), \
IIO_CHAN_SOFT_TIMESTAMP(4), \
}
#define DECLARE_TI_ADS7950_8_CHANNELS(name, bits) \
const struct iio_chan_spec name ## _channels[] = { \
TI_ADS7950_V_CHAN(0, bits), \
TI_ADS7950_V_CHAN(1, bits), \
TI_ADS7950_V_CHAN(2, bits), \
TI_ADS7950_V_CHAN(3, bits), \
TI_ADS7950_V_CHAN(4, bits), \
TI_ADS7950_V_CHAN(5, bits), \
TI_ADS7950_V_CHAN(6, bits), \
TI_ADS7950_V_CHAN(7, bits), \
IIO_CHAN_SOFT_TIMESTAMP(8), \
}
#define DECLARE_TI_ADS7950_12_CHANNELS(name, bits) \
const struct iio_chan_spec name ## _channels[] = { \
TI_ADS7950_V_CHAN(0, bits), \
TI_ADS7950_V_CHAN(1, bits), \
TI_ADS7950_V_CHAN(2, bits), \
TI_ADS7950_V_CHAN(3, bits), \
TI_ADS7950_V_CHAN(4, bits), \
TI_ADS7950_V_CHAN(5, bits), \
TI_ADS7950_V_CHAN(6, bits), \
TI_ADS7950_V_CHAN(7, bits), \
TI_ADS7950_V_CHAN(8, bits), \
TI_ADS7950_V_CHAN(9, bits), \
TI_ADS7950_V_CHAN(10, bits), \
TI_ADS7950_V_CHAN(11, bits), \
IIO_CHAN_SOFT_TIMESTAMP(12), \
}
#define DECLARE_TI_ADS7950_16_CHANNELS(name, bits) \
const struct iio_chan_spec name ## _channels[] = { \
TI_ADS7950_V_CHAN(0, bits), \
TI_ADS7950_V_CHAN(1, bits), \
TI_ADS7950_V_CHAN(2, bits), \
TI_ADS7950_V_CHAN(3, bits), \
TI_ADS7950_V_CHAN(4, bits), \
TI_ADS7950_V_CHAN(5, bits), \
TI_ADS7950_V_CHAN(6, bits), \
TI_ADS7950_V_CHAN(7, bits), \
TI_ADS7950_V_CHAN(8, bits), \
TI_ADS7950_V_CHAN(9, bits), \
TI_ADS7950_V_CHAN(10, bits), \
TI_ADS7950_V_CHAN(11, bits), \
TI_ADS7950_V_CHAN(12, bits), \
TI_ADS7950_V_CHAN(13, bits), \
TI_ADS7950_V_CHAN(14, bits), \
TI_ADS7950_V_CHAN(15, bits), \
IIO_CHAN_SOFT_TIMESTAMP(16), \
}
static DECLARE_TI_ADS7950_4_CHANNELS(ti_ads7950, 12);
static DECLARE_TI_ADS7950_8_CHANNELS(ti_ads7951, 12);
static DECLARE_TI_ADS7950_12_CHANNELS(ti_ads7952, 12);
static DECLARE_TI_ADS7950_16_CHANNELS(ti_ads7953, 12);
static DECLARE_TI_ADS7950_4_CHANNELS(ti_ads7954, 10);
static DECLARE_TI_ADS7950_8_CHANNELS(ti_ads7955, 10);
static DECLARE_TI_ADS7950_12_CHANNELS(ti_ads7956, 10);
static DECLARE_TI_ADS7950_16_CHANNELS(ti_ads7957, 10);
static DECLARE_TI_ADS7950_4_CHANNELS(ti_ads7958, 8);
static DECLARE_TI_ADS7950_8_CHANNELS(ti_ads7959, 8);
static DECLARE_TI_ADS7950_12_CHANNELS(ti_ads7960, 8);
static DECLARE_TI_ADS7950_16_CHANNELS(ti_ads7961, 8);
static const struct ti_ads7950_chip_info ti_ads7950_chip_info[] = {
[TI_ADS7950] = {
.channels = ti_ads7950_channels,
.num_channels = ARRAY_SIZE(ti_ads7950_channels),
},
[TI_ADS7951] = {
.channels = ti_ads7951_channels,
.num_channels = ARRAY_SIZE(ti_ads7951_channels),
},
[TI_ADS7952] = {
.channels = ti_ads7952_channels,
.num_channels = ARRAY_SIZE(ti_ads7952_channels),
},
[TI_ADS7953] = {
.channels = ti_ads7953_channels,
.num_channels = ARRAY_SIZE(ti_ads7953_channels),
},
[TI_ADS7954] = {
.channels = ti_ads7954_channels,
.num_channels = ARRAY_SIZE(ti_ads7954_channels),
},
[TI_ADS7955] = {
.channels = ti_ads7955_channels,
.num_channels = ARRAY_SIZE(ti_ads7955_channels),
},
[TI_ADS7956] = {
.channels = ti_ads7956_channels,
.num_channels = ARRAY_SIZE(ti_ads7956_channels),
},
[TI_ADS7957] = {
.channels = ti_ads7957_channels,
.num_channels = ARRAY_SIZE(ti_ads7957_channels),
},
[TI_ADS7958] = {
.channels = ti_ads7958_channels,
.num_channels = ARRAY_SIZE(ti_ads7958_channels),
},
[TI_ADS7959] = {
.channels = ti_ads7959_channels,
.num_channels = ARRAY_SIZE(ti_ads7959_channels),
},
[TI_ADS7960] = {
.channels = ti_ads7960_channels,
.num_channels = ARRAY_SIZE(ti_ads7960_channels),
},
[TI_ADS7961] = {
.channels = ti_ads7961_channels,
.num_channels = ARRAY_SIZE(ti_ads7961_channels),
},
};
/*
* ti_ads7950_update_scan_mode() setup the spi transfer buffer for the new
* scan mask
*/
static int ti_ads7950_update_scan_mode(struct iio_dev *indio_dev,
const unsigned long *active_scan_mask)
{
struct ti_ads7950_state *st = iio_priv(indio_dev);
int i, cmd, len;
len = 0;
for_each_set_bit(i, active_scan_mask, indio_dev->num_channels) {
cmd = TI_ADS7950_CR_WRITE | TI_ADS7950_CR_CHAN(i) | st->settings;
st->tx_buf[len++] = cpu_to_be16(cmd);
}
/* Data for the 1st channel is not returned until the 3rd transfer */
len += 2;
for (i = 0; i < len; i++) {
if ((i + 2) < len)
st->ring_xfer[i].tx_buf = &st->tx_buf[i];
if (i >= 2)
st->ring_xfer[i].rx_buf = &st->rx_buf[i - 2];
st->ring_xfer[i].len = 2;
st->ring_xfer[i].cs_change = 1;
}
/* make sure last transfer's cs_change is not set */
st->ring_xfer[len - 1].cs_change = 0;
spi_message_init_with_transfers(&st->ring_msg, st->ring_xfer, len);
return 0;
}
static irqreturn_t ti_ads7950_trigger_handler(int irq, void *p)
{
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct ti_ads7950_state *st = iio_priv(indio_dev);
int ret;
ret = spi_sync(st->spi, &st->ring_msg);
if (ret < 0)
goto out;
iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
iio_get_time_ns(indio_dev));
out:
iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;
}
static int ti_ads7950_scan_direct(struct iio_dev *indio_dev, unsigned int ch)
{
struct ti_ads7950_state *st = iio_priv(indio_dev);
int ret, cmd;
mutex_lock(&indio_dev->mlock);
cmd = TI_ADS7950_CR_WRITE | TI_ADS7950_CR_CHAN(ch) | st->settings;
st->single_tx = cpu_to_be16(cmd);
ret = spi_sync(st->spi, &st->scan_single_msg);
if (ret)
goto out;
ret = be16_to_cpu(st->single_rx);
out:
mutex_unlock(&indio_dev->mlock);
return ret;
}
static int ti_ads7950_get_range(struct ti_ads7950_state *st)
{
int vref;
if (st->vref_mv) {
vref = st->vref_mv;
} else {
vref = regulator_get_voltage(st->reg);
if (vref < 0)
return vref;
vref /= 1000;
}
if (st->settings & TI_ADS7950_CR_RANGE_5V)
vref *= 2;
return vref;
}
static int ti_ads7950_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long m)
{
struct ti_ads7950_state *st = iio_priv(indio_dev);
int ret;
switch (m) {
case IIO_CHAN_INFO_RAW:
ret = ti_ads7950_scan_direct(indio_dev, chan->address);
if (ret < 0)
return ret;
if (chan->address != TI_ADS7950_EXTRACT(ret, 12, 4))
return -EIO;
*val = TI_ADS7950_EXTRACT(ret, chan->scan_type.shift,
chan->scan_type.realbits);
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
ret = ti_ads7950_get_range(st);
if (ret < 0)
return ret;
*val = ret;
*val2 = (1 << chan->scan_type.realbits) - 1;
return IIO_VAL_FRACTIONAL;
}
return -EINVAL;
}
static const struct iio_info ti_ads7950_info = {
.read_raw = &ti_ads7950_read_raw,
.update_scan_mode = ti_ads7950_update_scan_mode,
};
static int ti_ads7950_probe(struct spi_device *spi)
{
struct ti_ads7950_state *st;
struct iio_dev *indio_dev;
const struct ti_ads7950_chip_info *info;
int ret;
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
if (!indio_dev)
return -ENOMEM;
st = iio_priv(indio_dev);
spi_set_drvdata(spi, indio_dev);
st->spi = spi;
st->settings = TI_ADS7950_CR_MANUAL | TI_ADS7950_CR_RANGE_5V;
info = &ti_ads7950_chip_info[spi_get_device_id(spi)->driver_data];
indio_dev->name = spi_get_device_id(spi)->name;
indio_dev->dev.parent = &spi->dev;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = info->channels;
indio_dev->num_channels = info->num_channels;
indio_dev->info = &ti_ads7950_info;
/*
* Setup default message. The sample is read at the end of the first
* transfer, then it takes one full cycle to convert the sample and one
* more cycle to send the value. The conversion process is driven by
* the SPI clock, which is why we have 3 transfers. The middle one is
* just dummy data sent while the chip is converting the sample that
* was read at the end of the first transfer.
*/
st->scan_single_xfer[0].tx_buf = &st->single_tx;
st->scan_single_xfer[0].len = 2;
st->scan_single_xfer[0].cs_change = 1;
st->scan_single_xfer[1].tx_buf = &st->single_tx;
st->scan_single_xfer[1].len = 2;
st->scan_single_xfer[1].cs_change = 1;
st->scan_single_xfer[2].rx_buf = &st->single_rx;
st->scan_single_xfer[2].len = 2;
spi_message_init_with_transfers(&st->scan_single_msg,
st->scan_single_xfer, 3);
/* Use hard coded value for reference voltage in ACPI case */
if (ACPI_COMPANION(&spi->dev))
st->vref_mv = TI_ADS7950_VA_MV_ACPI_DEFAULT;
st->reg = devm_regulator_get(&spi->dev, "vref");
if (IS_ERR(st->reg)) {
dev_err(&spi->dev, "Failed get get regulator \"vref\"\n");
return PTR_ERR(st->reg);
}
ret = regulator_enable(st->reg);
if (ret) {
dev_err(&spi->dev, "Failed to enable regulator \"vref\"\n");
return ret;
}
ret = iio_triggered_buffer_setup(indio_dev, NULL,
&ti_ads7950_trigger_handler, NULL);
if (ret) {
dev_err(&spi->dev, "Failed to setup triggered buffer\n");
goto error_disable_reg;
}
ret = iio_device_register(indio_dev);
if (ret) {
dev_err(&spi->dev, "Failed to register iio device\n");
goto error_cleanup_ring;
}
return 0;
error_cleanup_ring:
iio_triggered_buffer_cleanup(indio_dev);
error_disable_reg:
regulator_disable(st->reg);
return ret;
}
static int ti_ads7950_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = spi_get_drvdata(spi);
struct ti_ads7950_state *st = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
iio_triggered_buffer_cleanup(indio_dev);
regulator_disable(st->reg);
return 0;
}
static const struct spi_device_id ti_ads7950_id[] = {
{ "ads7950", TI_ADS7950 },
{ "ads7951", TI_ADS7951 },
{ "ads7952", TI_ADS7952 },
{ "ads7953", TI_ADS7953 },
{ "ads7954", TI_ADS7954 },
{ "ads7955", TI_ADS7955 },
{ "ads7956", TI_ADS7956 },
{ "ads7957", TI_ADS7957 },
{ "ads7958", TI_ADS7958 },
{ "ads7959", TI_ADS7959 },
{ "ads7960", TI_ADS7960 },
{ "ads7961", TI_ADS7961 },
{ }
};
MODULE_DEVICE_TABLE(spi, ti_ads7950_id);
static const struct of_device_id ads7950_of_table[] = {
{ .compatible = "ti,ads7950", .data = &ti_ads7950_chip_info[TI_ADS7950] },
{ .compatible = "ti,ads7951", .data = &ti_ads7950_chip_info[TI_ADS7951] },
{ .compatible = "ti,ads7952", .data = &ti_ads7950_chip_info[TI_ADS7952] },
{ .compatible = "ti,ads7953", .data = &ti_ads7950_chip_info[TI_ADS7953] },
{ .compatible = "ti,ads7954", .data = &ti_ads7950_chip_info[TI_ADS7954] },
{ .compatible = "ti,ads7955", .data = &ti_ads7950_chip_info[TI_ADS7955] },
{ .compatible = "ti,ads7956", .data = &ti_ads7950_chip_info[TI_ADS7956] },
{ .compatible = "ti,ads7957", .data = &ti_ads7950_chip_info[TI_ADS7957] },
{ .compatible = "ti,ads7958", .data = &ti_ads7950_chip_info[TI_ADS7958] },
{ .compatible = "ti,ads7959", .data = &ti_ads7950_chip_info[TI_ADS7959] },
{ .compatible = "ti,ads7960", .data = &ti_ads7950_chip_info[TI_ADS7960] },
{ .compatible = "ti,ads7961", .data = &ti_ads7950_chip_info[TI_ADS7961] },
{ },
};
MODULE_DEVICE_TABLE(of, ads7950_of_table);
static struct spi_driver ti_ads7950_driver = {
.driver = {
.name = "ads7950",
.of_match_table = ads7950_of_table,
},
.probe = ti_ads7950_probe,
.remove = ti_ads7950_remove,
.id_table = ti_ads7950_id,
};
module_spi_driver(ti_ads7950_driver);
MODULE_AUTHOR("David Lechner <david@lechnology.com>");
MODULE_DESCRIPTION("TI TI_ADS7950 ADC");
MODULE_LICENSE("GPL v2");
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