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linux-next/drivers/iio/adc/nau7802.c
Quentin Schulz 44072b2c8d iio: adc: nau7802: Expose possible gains in sysfs 
The Nuvoton NAU7802 ADC is able to adjust its gain but prior knowledge of
its possible values was required to adjust it. Users had to guess the
possible gain values based on the ADC datasheet or on this driver's code.

This exposes the possible values in the in_voltage_scale_available file of
each nau7802 ADC device. The gain is set for the whole ADC and is therefore
not configurable by channel. Thus, there exists only one
in_voltage_scale_available file for each nau7802 ADC device even if it has
two separate channels.

Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
2016-05-21 20:15:04 +01:00

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/*
* Driver for the Nuvoton NAU7802 ADC
*
* Copyright 2013 Free Electrons
*
* Licensed under the GPLv2 or later.
*/
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/wait.h>
#include <linux/log2.h>
#include <linux/of.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#define NAU7802_REG_PUCTRL 0x00
#define NAU7802_PUCTRL_RR(x) (x << 0)
#define NAU7802_PUCTRL_RR_BIT NAU7802_PUCTRL_RR(1)
#define NAU7802_PUCTRL_PUD(x) (x << 1)
#define NAU7802_PUCTRL_PUD_BIT NAU7802_PUCTRL_PUD(1)
#define NAU7802_PUCTRL_PUA(x) (x << 2)
#define NAU7802_PUCTRL_PUA_BIT NAU7802_PUCTRL_PUA(1)
#define NAU7802_PUCTRL_PUR(x) (x << 3)
#define NAU7802_PUCTRL_PUR_BIT NAU7802_PUCTRL_PUR(1)
#define NAU7802_PUCTRL_CS(x) (x << 4)
#define NAU7802_PUCTRL_CS_BIT NAU7802_PUCTRL_CS(1)
#define NAU7802_PUCTRL_CR(x) (x << 5)
#define NAU7802_PUCTRL_CR_BIT NAU7802_PUCTRL_CR(1)
#define NAU7802_PUCTRL_AVDDS(x) (x << 7)
#define NAU7802_PUCTRL_AVDDS_BIT NAU7802_PUCTRL_AVDDS(1)
#define NAU7802_REG_CTRL1 0x01
#define NAU7802_CTRL1_VLDO(x) (x << 3)
#define NAU7802_CTRL1_GAINS(x) (x)
#define NAU7802_CTRL1_GAINS_BITS 0x07
#define NAU7802_REG_CTRL2 0x02
#define NAU7802_CTRL2_CHS(x) (x << 7)
#define NAU7802_CTRL2_CRS(x) (x << 4)
#define NAU7802_SAMP_FREQ_320 0x07
#define NAU7802_CTRL2_CHS_BIT NAU7802_CTRL2_CHS(1)
#define NAU7802_REG_ADC_B2 0x12
#define NAU7802_REG_ADC_B1 0x13
#define NAU7802_REG_ADC_B0 0x14
#define NAU7802_REG_ADC_CTRL 0x15
#define NAU7802_MIN_CONVERSIONS 6
struct nau7802_state {
struct i2c_client *client;
s32 last_value;
struct mutex lock;
struct mutex data_lock;
u32 vref_mv;
u32 conversion_count;
u32 min_conversions;
u8 sample_rate;
u32 scale_avail[8];
struct completion value_ok;
};
#define NAU7802_CHANNEL(chan) { \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = (chan), \
.scan_index = (chan), \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
BIT(IIO_CHAN_INFO_SAMP_FREQ) \
}
static const struct iio_chan_spec nau7802_chan_array[] = {
NAU7802_CHANNEL(0),
NAU7802_CHANNEL(1),
};
static const u16 nau7802_sample_freq_avail[] = {10, 20, 40, 80,
10, 10, 10, 320};
static ssize_t nau7802_show_scales(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct nau7802_state *st = iio_priv(dev_to_iio_dev(dev));
int i, len = 0;
for (i = 0; i < ARRAY_SIZE(st->scale_avail); i++)
len += scnprintf(buf + len, PAGE_SIZE - len, "0.%09d ",
st->scale_avail[i]);
buf[len-1] = '\n';
return len;
}
static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("10 40 80 320");
static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO, nau7802_show_scales,
NULL, 0);
static struct attribute *nau7802_attributes[] = {
&iio_const_attr_sampling_frequency_available.dev_attr.attr,
&iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
NULL
};
static const struct attribute_group nau7802_attribute_group = {
.attrs = nau7802_attributes,
};
static int nau7802_set_gain(struct nau7802_state *st, int gain)
{
int ret;
mutex_lock(&st->lock);
st->conversion_count = 0;
ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_CTRL1);
if (ret < 0)
goto nau7802_sysfs_set_gain_out;
ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_CTRL1,
(ret & (~NAU7802_CTRL1_GAINS_BITS)) |
gain);
nau7802_sysfs_set_gain_out:
mutex_unlock(&st->lock);
return ret;
}
static int nau7802_read_conversion(struct nau7802_state *st)
{
int data;
mutex_lock(&st->data_lock);
data = i2c_smbus_read_byte_data(st->client, NAU7802_REG_ADC_B2);
if (data < 0)
goto nau7802_read_conversion_out;
st->last_value = data << 16;
data = i2c_smbus_read_byte_data(st->client, NAU7802_REG_ADC_B1);
if (data < 0)
goto nau7802_read_conversion_out;
st->last_value |= data << 8;
data = i2c_smbus_read_byte_data(st->client, NAU7802_REG_ADC_B0);
if (data < 0)
goto nau7802_read_conversion_out;
st->last_value |= data;
st->last_value = sign_extend32(st->last_value, 23);
nau7802_read_conversion_out:
mutex_unlock(&st->data_lock);
return data;
}
/*
* Conversions are synchronised on the rising edge of NAU7802_PUCTRL_CS_BIT
*/
static int nau7802_sync(struct nau7802_state *st)
{
int ret;
ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_PUCTRL);
if (ret < 0)
return ret;
ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_PUCTRL,
ret | NAU7802_PUCTRL_CS_BIT);
return ret;
}
static irqreturn_t nau7802_eoc_trigger(int irq, void *private)
{
struct iio_dev *indio_dev = private;
struct nau7802_state *st = iio_priv(indio_dev);
int status;
status = i2c_smbus_read_byte_data(st->client, NAU7802_REG_PUCTRL);
if (status < 0)
return IRQ_HANDLED;
if (!(status & NAU7802_PUCTRL_CR_BIT))
return IRQ_NONE;
if (nau7802_read_conversion(st) < 0)
return IRQ_HANDLED;
/*
* Because there is actually only one ADC for both channels, we have to
* wait for enough conversions to happen before getting a significant
* value when changing channels and the values are far apart.
*/
if (st->conversion_count < NAU7802_MIN_CONVERSIONS)
st->conversion_count++;
if (st->conversion_count >= NAU7802_MIN_CONVERSIONS)
complete_all(&st->value_ok);
return IRQ_HANDLED;
}
static int nau7802_read_irq(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val)
{
struct nau7802_state *st = iio_priv(indio_dev);
int ret;
reinit_completion(&st->value_ok);
enable_irq(st->client->irq);
nau7802_sync(st);
/* read registers to ensure we flush everything */
ret = nau7802_read_conversion(st);
if (ret < 0)
goto read_chan_info_failure;
/* Wait for a conversion to finish */
ret = wait_for_completion_interruptible_timeout(&st->value_ok,
msecs_to_jiffies(1000));
if (ret == 0)
ret = -ETIMEDOUT;
if (ret < 0)
goto read_chan_info_failure;
disable_irq(st->client->irq);
*val = st->last_value;
return IIO_VAL_INT;
read_chan_info_failure:
disable_irq(st->client->irq);
return ret;
}
static int nau7802_read_poll(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val)
{
struct nau7802_state *st = iio_priv(indio_dev);
int ret;
nau7802_sync(st);
/* read registers to ensure we flush everything */
ret = nau7802_read_conversion(st);
if (ret < 0)
return ret;
/*
* Because there is actually only one ADC for both channels, we have to
* wait for enough conversions to happen before getting a significant
* value when changing channels and the values are far appart.
*/
do {
ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_PUCTRL);
if (ret < 0)
return ret;
while (!(ret & NAU7802_PUCTRL_CR_BIT)) {
if (st->sample_rate != NAU7802_SAMP_FREQ_320)
msleep(20);
else
mdelay(4);
ret = i2c_smbus_read_byte_data(st->client,
NAU7802_REG_PUCTRL);
if (ret < 0)
return ret;
}
ret = nau7802_read_conversion(st);
if (ret < 0)
return ret;
if (st->conversion_count < NAU7802_MIN_CONVERSIONS)
st->conversion_count++;
} while (st->conversion_count < NAU7802_MIN_CONVERSIONS);
*val = st->last_value;
return IIO_VAL_INT;
}
static int nau7802_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct nau7802_state *st = iio_priv(indio_dev);
int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
mutex_lock(&st->lock);
/*
* Select the channel to use
* - Channel 1 is value 0 in the CHS register
* - Channel 2 is value 1 in the CHS register
*/
ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_CTRL2);
if (ret < 0) {
mutex_unlock(&st->lock);
return ret;
}
if (((ret & NAU7802_CTRL2_CHS_BIT) && !chan->channel) ||
(!(ret & NAU7802_CTRL2_CHS_BIT) &&
chan->channel)) {
st->conversion_count = 0;
ret = i2c_smbus_write_byte_data(st->client,
NAU7802_REG_CTRL2,
NAU7802_CTRL2_CHS(chan->channel) |
NAU7802_CTRL2_CRS(st->sample_rate));
if (ret < 0) {
mutex_unlock(&st->lock);
return ret;
}
}
if (st->client->irq)
ret = nau7802_read_irq(indio_dev, chan, val);
else
ret = nau7802_read_poll(indio_dev, chan, val);
mutex_unlock(&st->lock);
return ret;
case IIO_CHAN_INFO_SCALE:
ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_CTRL1);
if (ret < 0)
return ret;
/*
* We have 24 bits of signed data, that means 23 bits of data
* plus the sign bit
*/
*val = st->vref_mv;
*val2 = 23 + (ret & NAU7802_CTRL1_GAINS_BITS);
return IIO_VAL_FRACTIONAL_LOG2;
case IIO_CHAN_INFO_SAMP_FREQ:
*val = nau7802_sample_freq_avail[st->sample_rate];
*val2 = 0;
return IIO_VAL_INT;
default:
break;
}
return -EINVAL;
}
static int nau7802_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
struct nau7802_state *st = iio_priv(indio_dev);
int i, ret;
switch (mask) {
case IIO_CHAN_INFO_SCALE:
for (i = 0; i < ARRAY_SIZE(st->scale_avail); i++)
if (val2 == st->scale_avail[i])
return nau7802_set_gain(st, i);
break;
case IIO_CHAN_INFO_SAMP_FREQ:
for (i = 0; i < ARRAY_SIZE(nau7802_sample_freq_avail); i++)
if (val == nau7802_sample_freq_avail[i]) {
mutex_lock(&st->lock);
st->sample_rate = i;
st->conversion_count = 0;
ret = i2c_smbus_write_byte_data(st->client,
NAU7802_REG_CTRL2,
NAU7802_CTRL2_CRS(st->sample_rate));
mutex_unlock(&st->lock);
return ret;
}
break;
default:
break;
}
return -EINVAL;
}
static int nau7802_write_raw_get_fmt(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
long mask)
{
return IIO_VAL_INT_PLUS_NANO;
}
static const struct iio_info nau7802_info = {
.driver_module = THIS_MODULE,
.read_raw = &nau7802_read_raw,
.write_raw = &nau7802_write_raw,
.write_raw_get_fmt = nau7802_write_raw_get_fmt,
.attrs = &nau7802_attribute_group,
};
static int nau7802_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct iio_dev *indio_dev;
struct nau7802_state *st;
struct device_node *np = client->dev.of_node;
int i, ret;
u8 data;
u32 tmp = 0;
if (!client->dev.of_node) {
dev_err(&client->dev, "No device tree node available.\n");
return -EINVAL;
}
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st));
if (indio_dev == NULL)
return -ENOMEM;
st = iio_priv(indio_dev);
i2c_set_clientdata(client, indio_dev);
indio_dev->dev.parent = &client->dev;
indio_dev->name = dev_name(&client->dev);
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->info = &nau7802_info;
st->client = client;
/* Reset the device */
ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_PUCTRL,
NAU7802_PUCTRL_RR_BIT);
if (ret < 0)
return ret;
/* Enter normal operation mode */
ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_PUCTRL,
NAU7802_PUCTRL_PUD_BIT);
if (ret < 0)
return ret;
/*
* After about 200 usecs, the device should be ready and then
* the Power Up bit will be set to 1. If not, wait for it.
*/
udelay(210);
ret = i2c_smbus_read_byte_data(st->client, NAU7802_REG_PUCTRL);
if (ret < 0)
return ret;
if (!(ret & NAU7802_PUCTRL_PUR_BIT))
return ret;
of_property_read_u32(np, "nuvoton,vldo", &tmp);
st->vref_mv = tmp;
data = NAU7802_PUCTRL_PUD_BIT | NAU7802_PUCTRL_PUA_BIT |
NAU7802_PUCTRL_CS_BIT;
if (tmp >= 2400)
data |= NAU7802_PUCTRL_AVDDS_BIT;
ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_PUCTRL, data);
if (ret < 0)
return ret;
ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_ADC_CTRL, 0x30);
if (ret < 0)
return ret;
if (tmp >= 2400) {
data = NAU7802_CTRL1_VLDO((4500 - tmp) / 300);
ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_CTRL1,
data);
if (ret < 0)
return ret;
}
/* Populate available ADC input ranges */
for (i = 0; i < ARRAY_SIZE(st->scale_avail); i++)
st->scale_avail[i] = (((u64)st->vref_mv) * 1000000000ULL)
>> (23 + i);
init_completion(&st->value_ok);
/*
* The ADC fires continuously and we can't do anything about
* it. So we need to have the IRQ disabled by default, and we
* will enable them back when we will need them..
*/
if (client->irq) {
ret = request_threaded_irq(client->irq,
NULL,
nau7802_eoc_trigger,
IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
client->dev.driver->name,
indio_dev);
if (ret) {
/*
* What may happen here is that our IRQ controller is
* not able to get level interrupt but this is required
* by this ADC as when going over 40 sample per second,
* the interrupt line may stay high between conversions.
* So, we continue no matter what but we switch to
* polling mode.
*/
dev_info(&client->dev,
"Failed to allocate IRQ, using polling mode\n");
client->irq = 0;
} else
disable_irq(client->irq);
}
if (!client->irq) {
/*
* We are polling, use the fastest sample rate by
* default
*/
st->sample_rate = NAU7802_SAMP_FREQ_320;
ret = i2c_smbus_write_byte_data(st->client, NAU7802_REG_CTRL2,
NAU7802_CTRL2_CRS(st->sample_rate));
if (ret)
goto error_free_irq;
}
/* Setup the ADC channels available on the board */
indio_dev->num_channels = ARRAY_SIZE(nau7802_chan_array);
indio_dev->channels = nau7802_chan_array;
mutex_init(&st->lock);
mutex_init(&st->data_lock);
ret = iio_device_register(indio_dev);
if (ret < 0) {
dev_err(&client->dev, "Couldn't register the device.\n");
goto error_device_register;
}
return 0;
error_device_register:
mutex_destroy(&st->lock);
mutex_destroy(&st->data_lock);
error_free_irq:
if (client->irq)
free_irq(client->irq, indio_dev);
return ret;
}
static int nau7802_remove(struct i2c_client *client)
{
struct iio_dev *indio_dev = i2c_get_clientdata(client);
struct nau7802_state *st = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
mutex_destroy(&st->lock);
mutex_destroy(&st->data_lock);
if (client->irq)
free_irq(client->irq, indio_dev);
return 0;
}
static const struct i2c_device_id nau7802_i2c_id[] = {
{ "nau7802", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, nau7802_i2c_id);
static const struct of_device_id nau7802_dt_ids[] = {
{ .compatible = "nuvoton,nau7802" },
{},
};
MODULE_DEVICE_TABLE(of, nau7802_dt_ids);
static struct i2c_driver nau7802_driver = {
.probe = nau7802_probe,
.remove = nau7802_remove,
.id_table = nau7802_i2c_id,
.driver = {
.name = "nau7802",
.of_match_table = nau7802_dt_ids,
},
};
module_i2c_driver(nau7802_driver);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Nuvoton NAU7802 ADC Driver");
MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
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