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Subject[PATCH] Staging: iio: ade7758: Expand buf_lock to cover both buffer
Date
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 'unlocked' __ade7758_spi_write_reg_8 and
__ade7758_spi_read_reg_8 functions to be used by ade7758_write_samp_freq
and ade7758_read_samp_freq which avoids nested locks and maintains
atomicity between bus and device frequency changes.

Signed-off-by: Shreeya Patel <shreeya.patel23498@gmail.com>
---
drivers/staging/iio/meter/ade7758.h | 2 +-
drivers/staging/iio/meter/ade7758_core.c | 49 +++++++++++++++++++++++---------
2 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/drivers/staging/iio/meter/ade7758.h b/drivers/staging/iio/meter/ade7758.h
index 6ae78d8..2de81b5 100644
--- a/drivers/staging/iio/meter/ade7758.h
+++ b/drivers/staging/iio/meter/ade7758.h
@@ -111,7 +111,7 @@
* @trig: data ready trigger registered with iio
* @tx: transmit buffer
* @rx: receive buffer
- * @buf_lock: mutex to protect tx and rx
+ * @buf_lock: mutex to protect tx, rx, read and write frequency
**/
struct ade7758_state {
struct spi_device *us;
diff --git a/drivers/staging/iio/meter/ade7758_core.c b/drivers/staging/iio/meter/ade7758_core.c
index 7b7ffe5..7f8f8c4 100644
--- a/drivers/staging/iio/meter/ade7758_core.c
+++ b/drivers/staging/iio/meter/ade7758_core.c
@@ -24,17 +24,26 @@
#include "meter.h"
#include "ade7758.h"

-int ade7758_spi_write_reg_8(struct device *dev, u8 reg_address, u8 val)
+/* Unlocked version of ade7758_spi_write_reg_8 function */
+int __ade7758_spi_write_reg_8(struct device *dev, u8 reg_address, u8 val)
{
- int ret;
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct ade7758_state *st = iio_priv(indio_dev);

- mutex_lock(&st->buf_lock);
st->tx[0] = ADE7758_WRITE_REG(reg_address);
st->tx[1] = val;

- ret = spi_write(st->us, st->tx, 2);
+ return spi_write(st->us, st->tx, 2);
+}
+
+int ade7758_spi_write_reg_8(struct device *dev, u8 reg_address, u8 val)
+{
+ int ret;
+ struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+ struct ade7758_state *st = iio_priv(indio_dev);
+
+ mutex_lock(&st->buf_lock);
+ ret = __ade7758_spi_write_reg_8(dev, reg_address, val);
mutex_unlock(&st->buf_lock);

return ret;
@@ -91,7 +100,8 @@ static int ade7758_spi_write_reg_24(struct device *dev, u8 reg_address,
return ret;
}

-int ade7758_spi_read_reg_8(struct device *dev, u8 reg_address, u8 *val)
+/* Unlocked version of ade7758_spi_read_reg_16 function */
+int __ade7758_spi_read_reg_8(struct device *dev, u8 reg_address, u8 *val)
{
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct ade7758_state *st = iio_priv(indio_dev);
@@ -111,7 +121,6 @@ int ade7758_spi_read_reg_8(struct device *dev, u8 reg_address, u8 *val)
},
};

- mutex_lock(&st->buf_lock);
st->tx[0] = ADE7758_READ_REG(reg_address);
st->tx[1] = 0;

@@ -124,7 +133,19 @@ int ade7758_spi_read_reg_8(struct device *dev, u8 reg_address, u8 *val)
*val = st->rx[0];

error_ret:
+ return ret;
+}
+
+int ade7758_spi_read_reg_8(struct device *dev, u8 reg_address, u8 *val)
+{
+ struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+ struct ade7758_state *st = iio_priv(indio_dev);
+ int ret;
+
+ mutex_lock(&st->buf_lock);
+ ret = __ade7758_spi_read_reg_8(dev, reg_address, val);
mutex_unlock(&st->buf_lock);
+
return ret;
}

@@ -470,7 +491,7 @@ static int ade7758_read_samp_freq(struct device *dev, int *val)
int ret;
u8 t;

- ret = ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, &t);
+ ret = __ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, &t);
if (ret)
return ret;

@@ -503,14 +524,14 @@ static int ade7758_write_samp_freq(struct device *dev, int val)
goto out;
}

- ret = ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, &reg);
+ ret = __ade7758_spi_read_reg_8(dev, ADE7758_WAVMODE, &reg);
if (ret)
goto out;

reg &= ~(5 << 3);
reg |= t << 5;

- ret = ade7758_spi_write_reg_8(dev, ADE7758_WAVMODE, reg);
+ ret = __ade7758_spi_write_reg_8(dev, ADE7758_WAVMODE, reg);

out:
return ret;
@@ -523,12 +544,13 @@ static int ade7758_read_raw(struct iio_dev *indio_dev,
long mask)
{
int ret;
+ struct ade7758_state *st = iio_priv(indio_dev);

switch (mask) {
case IIO_CHAN_INFO_SAMP_FREQ:
- mutex_lock(&indio_dev->mlock);
+ mutex_lock(&st->buf_lock);
ret = ade7758_read_samp_freq(&indio_dev->dev, val);
- mutex_unlock(&indio_dev->mlock);
+ mutex_unlock(&st->buf_lock);
return ret;
default:
return -EINVAL;
@@ -542,14 +564,15 @@ static int ade7758_write_raw(struct iio_dev *indio_dev,
int val, int val2, long mask)
{
int ret;
+ struct ade7758_state *st = iio_priv(indio_dev);

switch (mask) {
case IIO_CHAN_INFO_SAMP_FREQ:
if (val2)
return -EINVAL;
- mutex_lock(&indio_dev->mlock);
+ mutex_lock(&st->buf_lock);
ret = ade7758_write_samp_freq(&indio_dev->dev, val);
- mutex_unlock(&indio_dev->mlock);
+ mutex_unlock(&st->buf_lock);
return ret;
default:
return -EINVAL;
--
2.7.4
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