[PATCH 4.9 15/22] gpio: max7301: fix driver for use with CONFIG_VMAP_STACK

Greg Kroah-Hartman
2018-12-28T12:19:11Z

From: Christophe Leroy <christophe.leroy@c-s.fr>

commit abf221d2f51b8ce7b9959a8953f880a8b0a1400d upstream.

spi_read() and spi_write() require DMA-safe memory. When
CONFIG_VMAP_STACK is selected, those functions cannot be used
with buffers on stack.

This patch replaces calls to spi_read() and spi_write() by
spi_write_then_read() which doesn't require DMA-safe buffers.

Fixes: 0c36ec314735 ("gpio: gpio driver for max7301 SPI GPIO expander")
Cc: <stable@vger.kernel.org>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpio/gpio-max7301.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)

--- a/drivers/gpio/gpio-max7301.c
+++ b/drivers/gpio/gpio-max7301.c
@@ -25,7 +25,7 @@ static int max7301_spi_write(struct devi
struct spi_device *spi = to_spi_device(dev);
u16 word = ((reg & 0x7F) << 8) | (val & 0xFF);

- return spi_write(spi, (const u8 *)&word, sizeof(word));
+ return spi_write_then_read(spi, &word, sizeof(word), NULL, 0);
}

/* A read from the MAX7301 means two transfers; here, one message each */
@@ -37,14 +37,8 @@ static int max7301_spi_read(struct devic
struct spi_device *spi = to_spi_device(dev);

word = 0x8000 | (reg << 8);
- ret = spi_write(spi, (const u8 *)&word, sizeof(word));
- if (ret)
- return ret;
- /*
- * This relies on the fact, that a transfer with NULL tx_buf shifts out
- * zero bytes (=NOOP for MAX7301)
- */
- ret = spi_read(spi, (u8 *)&word, sizeof(word));
+ ret = spi_write_then_read(spi, &word, sizeof(word), &word,
+ sizeof(word));
if (ret)
return ret;
return word & 0xff;