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staging: iio: update locking method during frequency writes 

The driver needs to insure atomicity during frequency
changes of bus and device. The iiodev->mlock as used
was not doing that. Replace it with the drivers existing
buffer lock and introduce an auxiliary spi_write() that does
not hold the lock.

Signed-off-by: Gargi Sharma <gs051095@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Gargi Sharma 2017-03-30 15:03:46 +05:30 committed by Jonathan Cameron
parent 5e13b6f0e7
commit b71244b62b
1 changed files with 16 additions and 8 deletions
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24
drivers/staging/iio/meter/ade7754.c
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@ -96,7 +96,7 @@
/**
* struct ade7754_state - device instance specific data
* @us: actual spi_device
* @buf_lock: mutex to protect tx and rx
* @buf_lock: mutex to protect tx, rx and write frequency
* @tx: transmit buffer
* @rx: receive buffer
**/
@ -107,6 +107,17 @@ struct ade7754_state {
u8 rx[ADE7754_MAX_RX];
};
/* Unlocked version of ade7754_spi_write_reg_8 function */
static int __ade7754_spi_write_reg_8(struct device *dev, u8 reg_address, u8 val)
{
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct ade7754_state *st = iio_priv(indio_dev);
st->tx[0] = ADE7754_WRITE_REG(reg_address);
st->tx[1] = val;
return spi_write(st->us, st->tx, 2);
}
static int ade7754_spi_write_reg_8(struct device *dev, u8 reg_address, u8 val)
{
int ret;
@ -114,10 +125,7 @@ static int ade7754_spi_write_reg_8(struct device *dev, u8 reg_address, u8 val)
struct ade7754_state *st = iio_priv(indio_dev);
mutex_lock(&st->buf_lock);
st->tx[0] = ADE7754_WRITE_REG(reg_address);
st->tx[1] = val;
ret = spi_write(st->us, st->tx, 2);
ret = __ade7754_spi_write_reg_8(dev, reg_address, val);
mutex_unlock(&st->buf_lock);
return ret;
@ -512,7 +520,7 @@ static ssize_t ade7754_write_frequency(struct device *dev,
if (!val)
return -EINVAL;
mutex_lock(&indio_dev->mlock);
mutex_lock(&st->buf_lock);
t = 26000 / val;
if (t > 0)
@ -530,10 +538,10 @@ static ssize_t ade7754_write_frequency(struct device *dev,
reg &= ~(3 << 3);
reg |= t << 3;
ret = ade7754_spi_write_reg_8(dev, ADE7754_WAVMODE, reg);
ret = __ade7754_spi_write_reg_8(dev, ADE7754_WAVMODE, reg);
out:
mutex_unlock(&indio_dev->mlock);
mutex_unlock(&st->buf_lock);
return ret ? ret : len;
}