Commit 20be66c1 authored by Sergiu Cuciurean's avatar Sergiu Cuciurean Committed by Jonathan Cameron
Browse files

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

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: default avatarSergiu Cuciurean <sergiu.cuciurean@analog.com>
Signed-off-by: default avatarAlexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20200916092535.76527-1-alexandru.ardelean@analog.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 2544ea7b

drivers/iio/dac/ti-dac7612.c

+12 −2
Original line number Diff line number Diff line
@@ -22,6 +22,14 @@ struct dac7612 { 
	struct gpio_desc *loaddacs;

	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

	 * 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])

		return 0;



	mutex_lock(&iio_dev->mlock);

	mutex_lock(&priv->lock);

	ret = dac7612_cmd_single(priv, chan->channel, val);

	mutex_unlock(&iio_dev->mlock);

	mutex_unlock(&priv->lock);



	return ret;

}
@@ -145,6 +153,8 @@ static int dac7612_probe(struct spi_device *spi) 
	iio_dev->num_channels = ARRAY_SIZE(priv->cache);

	iio_dev->name = spi_get_device_id(spi)->name;



	mutex_init(&priv->lock);



	for (i = 0; i < ARRAY_SIZE(priv->cache); i++) {

		ret = dac7612_cmd_single(priv, i, 0);

		if (ret)