Commit 865f6d19 authored by Ray Jui's avatar Ray Jui Committed by Mark Brown
Browse files

spi: spidev: Use separate TX and RX bounce buffers 



By using separate TX and RX bounce buffers, we avoid potential cache
flush and invalidation sequence issue that may be encountered when a
single bounce buffer is shared between TX and RX

Signed-off-by: default avatarRay Jui <rjui@broadcom.com>
Reviewed-by: default avatarJD (Jiandong) Zheng <jdzheng@broadcom.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent a2285b8c

drivers/spi/spidev.c

+52 −27
Original line number Diff line number Diff line
@@ -82,10 +82,11 @@ struct spidev_data { 
	struct spi_device	*spi;

	struct list_head	device_entry;



	/* buffer is NULL unless this device is open (users > 0) */

	/* TX/RX buffers are NULL unless this device is open (users > 0) */

	struct mutex		buf_lock;

	unsigned		users;

	u8			*buffer;

	u8			*tx_buffer;

	u8			*rx_buffer;

};



static LIST_HEAD(device_list);
@@ -135,7 +136,7 @@ static inline ssize_t 
spidev_sync_write(struct spidev_data *spidev, size_t len)

{

	struct spi_transfer	t = {

			.tx_buf		= spidev->buffer,

			.tx_buf		= spidev->tx_buffer,

			.len		= len,

		};

	struct spi_message	m;
@@ -149,7 +150,7 @@ static inline ssize_t 
spidev_sync_read(struct spidev_data *spidev, size_t len)

{

	struct spi_transfer	t = {

			.rx_buf		= spidev->buffer,

			.rx_buf		= spidev->rx_buffer,

			.len		= len,

		};

	struct spi_message	m;
@@ -179,7 +180,7 @@ spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) 
	if (status > 0) {

		unsigned long	missing;



		missing = copy_to_user(buf, spidev->buffer, status);

		missing = copy_to_user(buf, spidev->rx_buffer, status);

		if (missing == status)

			status = -EFAULT;

		else
@@ -206,7 +207,7 @@ spidev_write(struct file *filp, const char __user *buf, 
	spidev = filp->private_data;



	mutex_lock(&spidev->buf_lock);

	missing = copy_from_user(spidev->buffer, buf, count);

	missing = copy_from_user(spidev->tx_buffer, buf, count);

	if (missing == 0)

		status = spidev_sync_write(spidev, count);

	else
@@ -224,7 +225,7 @@ static int spidev_message(struct spidev_data *spidev, 
	struct spi_transfer	*k_tmp;

	struct spi_ioc_transfer *u_tmp;

	unsigned		n, total;

	u8			*buf;

	u8			*tx_buf, *rx_buf;

	int			status = -EFAULT;



	spi_message_init(&msg);
@@ -236,7 +237,8 @@ static int spidev_message(struct spidev_data *spidev, 
	 * We walk the array of user-provided transfers, using each one

	 * to initialize a kernel version of the same transfer.

	 */

	buf = spidev->buffer;

	tx_buf = spidev->tx_buffer;

	rx_buf = spidev->rx_buffer;

	total = 0;

	for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;

			n;
@@ -250,20 +252,21 @@ static int spidev_message(struct spidev_data *spidev, 
		}



		if (u_tmp->rx_buf) {

			k_tmp->rx_buf = buf;

			k_tmp->rx_buf = rx_buf;

			if (!access_ok(VERIFY_WRITE, (u8 __user *)

						(uintptr_t) u_tmp->rx_buf,

						u_tmp->len))

				goto done;

		}

		if (u_tmp->tx_buf) {

			k_tmp->tx_buf = buf;

			if (copy_from_user(buf, (const u8 __user *)

			k_tmp->tx_buf = tx_buf;

			if (copy_from_user(tx_buf, (const u8 __user *)

						(uintptr_t) u_tmp->tx_buf,

					u_tmp->len))

				goto done;

		}

		buf += k_tmp->len;

		tx_buf += k_tmp->len;

		rx_buf += k_tmp->len;



		k_tmp->cs_change = !!u_tmp->cs_change;

		k_tmp->tx_nbits = u_tmp->tx_nbits;
@@ -290,17 +293,17 @@ static int spidev_message(struct spidev_data *spidev, 
		goto done;



	/* copy any rx data out of bounce buffer */

	buf = spidev->buffer;

	rx_buf = spidev->rx_buffer;

	for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {

		if (u_tmp->rx_buf) {

			if (__copy_to_user((u8 __user *)

					(uintptr_t) u_tmp->rx_buf, buf,

					(uintptr_t) u_tmp->rx_buf, rx_buf,

					u_tmp->len)) {

				status = -EFAULT;

				goto done;

			}

		}

		buf += u_tmp->len;

		rx_buf += u_tmp->len;

	}

	status = total;
@@ -508,22 +511,41 @@ static int spidev_open(struct inode *inode, struct file *filp) 
			break;

		}

	}

	if (status == 0) {

		if (!spidev->buffer) {

			spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);

			if (!spidev->buffer) {



	if (status) {

		pr_debug("spidev: nothing for minor %d\n", iminor(inode));

		goto err_find_dev;

	}



	if (!spidev->tx_buffer) {

		spidev->tx_buffer = kmalloc(bufsiz, GFP_KERNEL);

		if (!spidev->tx_buffer) {

				dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");

				status = -ENOMEM;

			goto err_find_dev;

			}

		}

		if (status == 0) {



	if (!spidev->rx_buffer) {

		spidev->rx_buffer = kmalloc(bufsiz, GFP_KERNEL);

		if (!spidev->rx_buffer) {

			dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");

			status = -ENOMEM;

			goto err_alloc_rx_buf;

		}

	}



	spidev->users++;

	filp->private_data = spidev;

	nonseekable_open(inode, filp);

		}

	} else

		pr_debug("spidev: nothing for minor %d\n", iminor(inode));



	mutex_unlock(&device_list_lock);

	return 0;



err_alloc_rx_buf:

	kfree(spidev->tx_buffer);

	spidev->tx_buffer = NULL;

err_find_dev:

	mutex_unlock(&device_list_lock);

	return status;

}
@@ -542,8 +564,11 @@ static int spidev_release(struct inode *inode, struct file *filp) 
	if (!spidev->users) {

		int		dofree;



		kfree(spidev->buffer);

		spidev->buffer = NULL;

		kfree(spidev->tx_buffer);

		spidev->tx_buffer = NULL;



		kfree(spidev->rx_buffer);

		spidev->rx_buffer = NULL;



		/* ... after we unbound from the underlying device? */

		spin_lock_irq(&spidev->spi_lock);

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