[PATCH 4.5 059/101] spi: spi-ti-qspi: Handle truncated frames properly

Greg Kroah-Hartman
2016-05-17T01:27:07Z

From: Ben Hutchings <ben.hutchings@codethink.co.uk>

commit 1ff7760ff66b98ef244bf0e5e2bd5310651205ad upstream.

We clamp frame_len_words to a maximum of 4096, but do not actually
limit the number of words written or read through the DATA registers
or the length added to spi_message::actual_length. This results in
silent data corruption for commands longer than this maximum.

Recalculate the length of each transfer, taking frame_len_words into
account. Use this length in qspi_{read,write}_msg(), and to increment
spi_message::actual_length.

Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/spi/spi-ti-qspi.c | 32 ++++++++++++++++++++------------
1 file changed, 20 insertions(+), 12 deletions(-)

--- a/drivers/spi/spi-ti-qspi.c
+++ b/drivers/spi/spi-ti-qspi.c
@@ -225,16 +225,16 @@ static inline int ti_qspi_poll_wc(struct
return -ETIMEDOUT;
}

-static int qspi_write_msg(struct ti_qspi *qspi, struct spi_transfer *t)
+static int qspi_write_msg(struct ti_qspi *qspi, struct spi_transfer *t,
+ int count)
{
- int wlen, count, xfer_len;
+ int wlen, xfer_len;
unsigned int cmd;
const u8 *txbuf;
u32 data;

txbuf = t->tx_buf;
cmd = qspi->cmd | QSPI_WR_SNGL;
- count = t->len;
wlen = t->bits_per_word >> 3; /* in bytes */
xfer_len = wlen;

@@ -294,9 +294,10 @@ static int qspi_write_msg(struct ti_qspi
return 0;
}

-static int qspi_read_msg(struct ti_qspi *qspi, struct spi_transfer *t)
+static int qspi_read_msg(struct ti_qspi *qspi, struct spi_transfer *t,
+ int count)
{
- int wlen, count;
+ int wlen;
unsigned int cmd;
u8 *rxbuf;

@@ -313,7 +314,6 @@ static int qspi_read_msg(struct ti_qspi
cmd |= QSPI_RD_SNGL;
break;
}
- count = t->len;
wlen = t->bits_per_word >> 3; /* in bytes */

while (count) {
@@ -344,12 +344,13 @@ static int qspi_read_msg(struct ti_qspi
return 0;
}

-static int qspi_transfer_msg(struct ti_qspi *qspi, struct spi_transfer *t)
+static int qspi_transfer_msg(struct ti_qspi *qspi, struct spi_transfer *t,
+ int count)
{
int ret;

if (t->tx_buf) {
- ret = qspi_write_msg(qspi, t);
+ ret = qspi_write_msg(qspi, t, count);
if (ret) {
dev_dbg(qspi->dev, "Error while writing\n");
return ret;
@@ -357,7 +358,7 @@ static int qspi_transfer_msg(struct ti_q
}

if (t->rx_buf) {
- ret = qspi_read_msg(qspi, t);
+ ret = qspi_read_msg(qspi, t, count);
if (ret) {
dev_dbg(qspi->dev, "Error while reading\n");
return ret;
@@ -374,7 +375,8 @@ static int ti_qspi_start_transfer_one(st
struct spi_device *spi = m->spi;
struct spi_transfer *t;
int status = 0, ret;
- unsigned int frame_len_words;
+ unsigned int frame_len_words, transfer_len_words;
+ int wlen;

/* setup device control reg */
qspi->dc = 0;
@@ -404,14 +406,20 @@ static int ti_qspi_start_transfer_one(st
qspi->cmd = ((qspi->cmd & ~QSPI_WLEN_MASK) |
QSPI_WLEN(t->bits_per_word));

- ret = qspi_transfer_msg(qspi, t);
+ wlen = t->bits_per_word >> 3;
+ transfer_len_words = min(t->len / wlen, frame_len_words);
+
+ ret = qspi_transfer_msg(qspi, t, transfer_len_words * wlen);
if (ret) {
dev_dbg(qspi->dev, "transfer message failed\n");
mutex_unlock(&qspi->list_lock);
return -EINVAL;
}

- m->actual_length += t->len;
+ m->actual_length += transfer_len_words * wlen;
+ frame_len_words -= transfer_len_words;
+ if (frame_len_words == 0)
+ break;
}

mutex_unlock(&qspi->list_lock);