[PATCH 6.1 0449/1146] spi: spidev: mask SPI_CS_HIGH in SPI_IOC_RD_MODE

Greg Kroah-Hartman
2022-12-28T15:58:00Z

From: Alexander Sverdlin <alexander.sverdlin@siemens.com>

[ Upstream commit 7dbfa445ff7393d1c4c066c1727c9e0af1251958 ]

Commit f3186dd87669 ("spi: Optionally use GPIO descriptors for CS GPIOs")
has changed the user-space interface so that bogus SPI_CS_HIGH started
to appear in the mask returned by SPI_IOC_RD_MODE even for active-low CS
pins. Commit 138c9c32f090
("spi: spidev: Fix CS polarity if GPIO descriptors are used") fixed only
SPI_IOC_WR_MODE part of the problem. Let's fix SPI_IOC_RD_MODE
symmetrically.

Test case:

#include <sys/ioctl.h>
#include <fcntl.h>
#include <linux/spi/spidev.h>

int main(int argc, char **argv)
{
char modew = SPI_CPHA;
char moder;
int f = open("/dev/spidev0.0", O_RDWR);

if (f < 0)
return 1;

ioctl(f, SPI_IOC_WR_MODE, &modew);
ioctl(f, SPI_IOC_RD_MODE, &moder);

return moder == modew ? 0 : 2;
}

Fixes: f3186dd87669 ("spi: Optionally use GPIO descriptors for CS GPIOs")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Link: https://lore.kernel.org/r/20221130162927.539512-1-alexander.sverdlin@siemens.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/spi/spidev.c | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index b2775d82d2d7..6313e7d0cdf8 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -377,12 +377,23 @@ spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
switch (cmd) {
/* read requests */
case SPI_IOC_RD_MODE:
- retval = put_user(spi->mode & SPI_MODE_MASK,
- (__u8 __user *)arg);
- break;
case SPI_IOC_RD_MODE32:
- retval = put_user(spi->mode & SPI_MODE_MASK,
- (__u32 __user *)arg);
+ tmp = spi->mode;
+
+ {
+ struct spi_controller *ctlr = spi->controller;
+
+ if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
+ ctlr->cs_gpiods[spi->chip_select])
+ tmp &= ~SPI_CS_HIGH;
+ }
+
+ if (cmd == SPI_IOC_RD_MODE)
+ retval = put_user(tmp & SPI_MODE_MASK,
+ (__u8 __user *)arg);
+ else
+ retval = put_user(tmp & SPI_MODE_MASK,
+ (__u32 __user *)arg);
break;
case SPI_IOC_RD_LSB_FIRST:
retval = put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0,
--
2.35.1