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Staging: iio: meter: ade7759: update locking method for write frequency 

iio_dev->mlock is to be used only by the IIO core for protecting
device mode changes between INDIO_DIRECT and INDIO_BUFFER.

This patch replaces the use of mlock with the already established
buf_lock mutex.

Introducing an 'unlocked' spi_write_reg_16 function to be used by
ade7759_write_frequency avoids nested locks and maintains atomicity
between bus and device frequency changes.

Based on the solution found in ade7754 patch here:
https://marc.info/?l=linux-iio&m=149086659008991&w=2

Signed-off-by: Katie Dunne <kdunne@mail.ccsf.edu>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Katie Dunne 2017-09-18 15:52:40 -07:00 committed by Jonathan Cameron
parent 08969366af
commit ba272e3bbe
1 changed files with 19 additions and 8 deletions
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27
drivers/staging/iio/meter/ade7759.c
View File

@ -60,7 +60,7 @@
/**
* struct ade7759_state - device instance specific data
* @us: actual spi_device
* @buf_lock: mutex to protect tx and rx
* @buf_lock: mutex to protect tx and rx and write frequency
* @tx: transmit buffer
* @rx: receive buffer
**/
@ -89,6 +89,20 @@ static int ade7759_spi_write_reg_8(struct device *dev,
return ret;
}
/*Unlocked version of ade7759_spi_write_reg_16 function */
static int __ade7759_spi_write_reg_16(struct device *dev,
u8 reg_address,
u16 value)
{
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct ade7759_state *st = iio_priv(indio_dev);
st->tx[0] = ADE7759_WRITE_REG(reg_address);
st->tx[1] = (value >> 8) & 0xFF;
st->tx[2] = value & 0xFF;
return spi_write(st->us, st->tx, 3);
}
static int ade7759_spi_write_reg_16(struct device *dev,
u8 reg_address,
u16 value)
@ -98,10 +112,7 @@ static int ade7759_spi_write_reg_16(struct device *dev,
struct ade7759_state *st = iio_priv(indio_dev);
mutex_lock(&st->buf_lock);
st->tx[0] = ADE7759_WRITE_REG(reg_address);
st->tx[1] = (value >> 8) & 0xFF;
st->tx[2] = value & 0xFF;
ret = spi_write(st->us, st->tx, 3);
ret = __ade7759_spi_write_reg_16(dev, reg_address, value);
mutex_unlock(&st->buf_lock);
return ret;
@ -429,7 +440,7 @@ static ssize_t ade7759_write_frequency(struct device *dev,
if (!val)
return -EINVAL;
mutex_lock(&indio_dev->mlock);
mutex_lock(&st->buf_lock);
t = 27900 / val;
if (t > 0)
@ -447,10 +458,10 @@ static ssize_t ade7759_write_frequency(struct device *dev,
reg &= ~(3 << 13);
reg |= t << 13;
ret = ade7759_spi_write_reg_16(dev, ADE7759_MODE, reg);
ret = __ade7759_spi_write_reg_16(dev, ADE7759_MODE, reg);
out:
mutex_unlock(&indio_dev->mlock);
mutex_unlock(&st->buf_lock);
return ret ? ret : len;
}