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linux/drivers/iio/adc/ti-adc0832.c
Jonathan Cameron 39e91f3be4 iio:adc:ti-adc0832 Fix alignment issue with timestamp 
One of a class of bugs pointed out by Lars in a recent review.
iio_push_to_buffers_with_timestamp assumes the buffer used is aligned
to the size of the timestamp (8 bytes).  This is not guaranteed in
this driver which uses an array of smaller elements on the stack.

We fix this issues by moving to a suitable structure in the iio_priv()
data with alignment explicitly requested.  This data is allocated
with kzalloc so no data can leak apart from previous readings.
Note that previously no data could leak 'including' previous readings
but I don't think it is an issue to potentially leak them like
this now does.

In this case the postioning of the timestamp is depends on what
other channels are enabled. As such we cannot use a structure to
make the alignment explicit as it would be missleading by suggesting
only one possible location for the timestamp.

Fixes: 815bbc8746 ("iio: ti-adc0832: add triggered buffer support")
Reported-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200722155103.979802-25-jic23@kernel.org
2020-09-21 20:01:51 +01:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* ADC0831/ADC0832/ADC0834/ADC0838 8-bit ADC driver
*
* Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
*
* Datasheet: https://www.ti.com/lit/ds/symlink/adc0832-n.pdf
*/
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#include <linux/iio/iio.h>
#include <linux/regulator/consumer.h>
#include <linux/iio/buffer.h>
#include <linux/iio/trigger.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.h>
enum {
adc0831,
adc0832,
adc0834,
adc0838,
};
struct adc0832 {
struct spi_device *spi;
struct regulator *reg;
struct mutex lock;
u8 mux_bits;
/*
* Max size needed: 16x 1 byte ADC data + 8 bytes timestamp
* May be shorter if not all channels are enabled subject
* to the timestamp remaining 8 byte aligned.
*/
u8 data[24] __aligned(8);
u8 tx_buf[2] ____cacheline_aligned;
u8 rx_buf[2];
};
#define ADC0832_VOLTAGE_CHANNEL(chan) \
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = chan, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
.scan_index = chan, \
.scan_type = { \
.sign = 'u', \
.realbits = 8, \
.storagebits = 8, \
}, \
}
#define ADC0832_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si) \
{ \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = (chan1), \
.channel2 = (chan2), \
.differential = 1, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
.scan_index = si, \
.scan_type = { \
.sign = 'u', \
.realbits = 8, \
.storagebits = 8, \
}, \
}
static const struct iio_chan_spec adc0831_channels[] = {
ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 0),
IIO_CHAN_SOFT_TIMESTAMP(1),
};
static const struct iio_chan_spec adc0832_channels[] = {
ADC0832_VOLTAGE_CHANNEL(0),
ADC0832_VOLTAGE_CHANNEL(1),
ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 2),
ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 3),
IIO_CHAN_SOFT_TIMESTAMP(4),
};
static const struct iio_chan_spec adc0834_channels[] = {
ADC0832_VOLTAGE_CHANNEL(0),
ADC0832_VOLTAGE_CHANNEL(1),
ADC0832_VOLTAGE_CHANNEL(2),
ADC0832_VOLTAGE_CHANNEL(3),
ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 4),
ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 5),
ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3, 6),
ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2, 7),
IIO_CHAN_SOFT_TIMESTAMP(8),
};
static const struct iio_chan_spec adc0838_channels[] = {
ADC0832_VOLTAGE_CHANNEL(0),
ADC0832_VOLTAGE_CHANNEL(1),
ADC0832_VOLTAGE_CHANNEL(2),
ADC0832_VOLTAGE_CHANNEL(3),
ADC0832_VOLTAGE_CHANNEL(4),
ADC0832_VOLTAGE_CHANNEL(5),
ADC0832_VOLTAGE_CHANNEL(6),
ADC0832_VOLTAGE_CHANNEL(7),
ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 9),
ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3, 10),
ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2, 11),
ADC0832_VOLTAGE_CHANNEL_DIFF(4, 5, 12),
ADC0832_VOLTAGE_CHANNEL_DIFF(5, 4, 13),
ADC0832_VOLTAGE_CHANNEL_DIFF(6, 7, 14),
ADC0832_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
IIO_CHAN_SOFT_TIMESTAMP(16),
};
static int adc0831_adc_conversion(struct adc0832 *adc)
{
struct spi_device *spi = adc->spi;
int ret;
ret = spi_read(spi, &adc->rx_buf, 2);
if (ret)
return ret;
/*
* Skip TRI-STATE and a leading zero
*/
return (adc->rx_buf[0] << 2 & 0xff) | (adc->rx_buf[1] >> 6);
}
static int adc0832_adc_conversion(struct adc0832 *adc, int channel,
bool differential)
{
struct spi_device *spi = adc->spi;
struct spi_transfer xfer = {
.tx_buf = adc->tx_buf,
.rx_buf = adc->rx_buf,
.len = 2,
};
int ret;
if (!adc->mux_bits)
return adc0831_adc_conversion(adc);
/* start bit */
adc->tx_buf[0] = 1 << (adc->mux_bits + 1);
/* single-ended or differential */
adc->tx_buf[0] |= differential ? 0 : (1 << adc->mux_bits);
/* odd / sign */
adc->tx_buf[0] |= (channel % 2) << (adc->mux_bits - 1);
/* select */
if (adc->mux_bits > 1)
adc->tx_buf[0] |= channel / 2;
/* align Data output BIT7 (MSB) to 8-bit boundary */
adc->tx_buf[0] <<= 1;
ret = spi_sync_transfer(spi, &xfer, 1);
if (ret)
return ret;
return adc->rx_buf[1];
}
static int adc0832_read_raw(struct iio_dev *iio,
struct iio_chan_spec const *channel, int *value,
int *shift, long mask)
{
struct adc0832 *adc = iio_priv(iio);
switch (mask) {
case IIO_CHAN_INFO_RAW:
mutex_lock(&adc->lock);
*value = adc0832_adc_conversion(adc, channel->channel,
channel->differential);
mutex_unlock(&adc->lock);
if (*value < 0)
return *value;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*value = regulator_get_voltage(adc->reg);
if (*value < 0)
return *value;
/* convert regulator output voltage to mV */
*value /= 1000;
*shift = 8;
return IIO_VAL_FRACTIONAL_LOG2;
}
return -EINVAL;
}
static const struct iio_info adc0832_info = {
.read_raw = adc0832_read_raw,
};
static irqreturn_t adc0832_trigger_handler(int irq, void *p)
{
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct adc0832 *adc = iio_priv(indio_dev);
int scan_index;
int i = 0;
mutex_lock(&adc->lock);
for_each_set_bit(scan_index, indio_dev->active_scan_mask,
indio_dev->masklength) {
const struct iio_chan_spec *scan_chan =
&indio_dev->channels[scan_index];
int ret = adc0832_adc_conversion(adc, scan_chan->channel,
scan_chan->differential);
if (ret < 0) {
dev_warn(&adc->spi->dev,
"failed to get conversion data\n");
goto out;
}
adc->data[i] = ret;
i++;
}
iio_push_to_buffers_with_timestamp(indio_dev, adc->data,
iio_get_time_ns(indio_dev));
out:
mutex_unlock(&adc->lock);
iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;
}
static int adc0832_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
struct adc0832 *adc;
int ret;
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
if (!indio_dev)
return -ENOMEM;
adc = iio_priv(indio_dev);
adc->spi = spi;
mutex_init(&adc->lock);
indio_dev->name = spi_get_device_id(spi)->name;
indio_dev->info = &adc0832_info;
indio_dev->modes = INDIO_DIRECT_MODE;
switch (spi_get_device_id(spi)->driver_data) {
case adc0831:
adc->mux_bits = 0;
indio_dev->channels = adc0831_channels;
indio_dev->num_channels = ARRAY_SIZE(adc0831_channels);
break;
case adc0832:
adc->mux_bits = 1;
indio_dev->channels = adc0832_channels;
indio_dev->num_channels = ARRAY_SIZE(adc0832_channels);
break;
case adc0834:
adc->mux_bits = 2;
indio_dev->channels = adc0834_channels;
indio_dev->num_channels = ARRAY_SIZE(adc0834_channels);
break;
case adc0838:
adc->mux_bits = 3;
indio_dev->channels = adc0838_channels;
indio_dev->num_channels = ARRAY_SIZE(adc0838_channels);
break;
default:
return -EINVAL;
}
adc->reg = devm_regulator_get(&spi->dev, "vref");
if (IS_ERR(adc->reg))
return PTR_ERR(adc->reg);
ret = regulator_enable(adc->reg);
if (ret)
return ret;
spi_set_drvdata(spi, indio_dev);
ret = iio_triggered_buffer_setup(indio_dev, NULL,
adc0832_trigger_handler, NULL);
if (ret)
goto err_reg_disable;
ret = iio_device_register(indio_dev);
if (ret)
goto err_buffer_cleanup;
return 0;
err_buffer_cleanup:
iio_triggered_buffer_cleanup(indio_dev);
err_reg_disable:
regulator_disable(adc->reg);
return ret;
}
static int adc0832_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = spi_get_drvdata(spi);
struct adc0832 *adc = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
iio_triggered_buffer_cleanup(indio_dev);
regulator_disable(adc->reg);
return 0;
}
static const struct of_device_id adc0832_dt_ids[] = {
{ .compatible = "ti,adc0831", },
{ .compatible = "ti,adc0832", },
{ .compatible = "ti,adc0834", },
{ .compatible = "ti,adc0838", },
{}
};
MODULE_DEVICE_TABLE(of, adc0832_dt_ids);
static const struct spi_device_id adc0832_id[] = {
{ "adc0831", adc0831 },
{ "adc0832", adc0832 },
{ "adc0834", adc0834 },
{ "adc0838", adc0838 },
{}
};
MODULE_DEVICE_TABLE(spi, adc0832_id);
static struct spi_driver adc0832_driver = {
.driver = {
.name = "adc0832",
.of_match_table = adc0832_dt_ids,
},
.probe = adc0832_probe,
.remove = adc0832_remove,
.id_table = adc0832_id,
};
module_spi_driver(adc0832_driver);
MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
MODULE_DESCRIPTION("ADC0831/ADC0832/ADC0834/ADC0838 driver");
MODULE_LICENSE("GPL v2");
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