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>
diff --git a/drivers/staging/iio/meter/ade7759.c b/drivers/staging/iio/meter/ade7759.c
index 7639e90..cd75f60 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
**/
@@ -89,6 +89,20 @@
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 @@
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 @@
if (!val)
return -EINVAL;
- mutex_lock(&indio_dev->mlock);
+ mutex_lock(&st->buf_lock);
t = 27900 / val;
if (t > 0)
@@ -447,10 +458,10 @@
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;
}