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iio: dac: ti-dac7612: Replace indio_dev->mlock with own device lock

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As part of the general cleanup of indio_dev->mlock, this change replaces
it with a local lock on the device's state from potential concurrent write
accesses from userspace. The write operation requires an SPI write, then
toggling of a GPIO, so the lock aims to protect the sanity of the entire
sequence of operation.

This is part of a bigger cleanup.
Link: https://lore.kernel.org/linux-iio/CA+U=Dsoo6YABe5ODLp+eFNPGFDjk5ZeQEceGkqjxXcVEhLWubw@mail.gmail.com/

Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20200916092535.76527-1-alexandru.ardelean@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Sergiu Cuciurean 2020-09-16 12:25:35 +03:00 committed by Jonathan Cameron
parent 2544ea7bd0
commit 20be66c193
1 changed files with 12 additions and 2 deletions
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14
drivers/iio/dac/ti-dac7612.c
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@ -22,6 +22,14 @@ struct dac7612 {
struct gpio_desc *loaddacs; struct gpio_desc *loaddacs;
uint16_t cache[2]; uint16_t cache[2];
/*
* Lock to protect the state of the device from potential concurrent
* write accesses from userspace. The write operation requires an
* SPI write, then toggling of a GPIO, so the lock aims to protect
* the sanity of the entire sequence of operation.
*/
struct mutex lock;
/* /*
* DMA (thus cache coherency maintenance) requires the * DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines. * transfer buffers to live in their own cache lines.
@ -101,9 +109,9 @@ static int dac7612_write_raw(struct iio_dev *iio_dev,
if (val == priv->cache[chan->channel]) if (val == priv->cache[chan->channel])
return 0; return 0;
mutex_lock(&iio_dev->mlock); mutex_lock(&priv->lock);
ret = dac7612_cmd_single(priv, chan->channel, val); ret = dac7612_cmd_single(priv, chan->channel, val);
mutex_unlock(&iio_dev->mlock); mutex_unlock(&priv->lock);
return ret; return ret;
} }
@ -145,6 +153,8 @@ static int dac7612_probe(struct spi_device *spi)
iio_dev->num_channels = ARRAY_SIZE(priv->cache); iio_dev->num_channels = ARRAY_SIZE(priv->cache);
iio_dev->name = spi_get_device_id(spi)->name; iio_dev->name = spi_get_device_id(spi)->name;
mutex_init(&priv->lock);
for (i = 0; i < ARRAY_SIZE(priv->cache); i++) { for (i = 0; i < ARRAY_SIZE(priv->cache); i++) {
ret = dac7612_cmd_single(priv, i, 0); ret = dac7612_cmd_single(priv, i, 0);
if (ret) if (ret)