diff options
author | Katie Dunne <kdunne@mail.ccsf.edu> | 2017-09-18 15:52:40 -0700 |
---|---|---|
committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2017-09-24 15:52:03 +0100 |
commit | ba272e3bbeaee3b34ca6c616f7ad8d3c65f33f79 (patch) | |
tree | 9f31fd175d3f9fbd16310c7b520feebada0f72b2 /drivers/staging/iio | |
parent | 08969366afd99622bb315112179933f7ded4b066 (diff) |
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>
Diffstat (limited to 'drivers/staging/iio')
-rw-r--r-- | drivers/staging/iio/meter/ade7759.c | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/drivers/staging/iio/meter/ade7759.c b/drivers/staging/iio/meter/ade7759.c index 7639e90d1c94..cd75f60aded3 100644 --- a/drivers/staging/iio/meter/ade7759.c +++ b/drivers/staging/iio/meter/ade7759.c @@ -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 **/ @@ -89,19 +89,30 @@ static int ade7759_spi_write_reg_8(struct device *dev, return ret; } -static int ade7759_spi_write_reg_16(struct device *dev, +/*Unlocked version of ade7759_spi_write_reg_16 function */ +static int __ade7759_spi_write_reg_16(struct device *dev, u8 reg_address, u16 value) { - int ret; struct iio_dev *indio_dev = dev_to_iio_dev(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); + return spi_write(st->us, st->tx, 3); +} + +static int ade7759_spi_write_reg_16(struct device *dev, + u8 reg_address, + u16 value) +{ + int ret; + struct iio_dev *indio_dev = dev_to_iio_dev(dev); + struct ade7759_state *st = iio_priv(indio_dev); + + mutex_lock(&st->buf_lock); + 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; } |