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spi: spidev: mask SPI_CS_HIGH in SPI_IOC_RD_MODE 

[ Upstream commit 7dbfa445ff ]

Commit f3186dd876 ("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 138c9c32f0
("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: f3186dd876 ("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>
This commit is contained in:
Alexander Sverdlin 2022-11-30 17:29:27 +01:00 committed by Greg Kroah-Hartman
parent b6d27d9250
commit f58888434d
1 changed files with 16 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
drivers/spi/spidev.c
View File

@ -376,12 +376,23 @@ 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,