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[v2] spi: spidev: mask SPI_CS_HIGH in SPI_IOC_RD_MODE

Message ID 20221130162927.539512-1-alexander.sverdlin@siemens.com
State Accepted
Commit 7dbfa445ff7393d1c4c066c1727c9e0af1251958
Headers show
Series [v2] spi: spidev: mask SPI_CS_HIGH in SPI_IOC_RD_MODE | expand

Commit Message

Sverdlin, Alexander Nov. 30, 2022, 4:29 p.m. UTC 
From: Alexander Sverdlin <alexander.sverdlin@siemens.com>

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>
---
Changelog:
v2:
- fix SPI_IOC_RD_MODE32 as well

 drivers/spi/spidev.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

Comments

Mark Brown Dec. 1, 2022, 12:20 p.m. UTC | #1 
On Wed, 30 Nov 2022 17:29:27 +0100, A. Sverdlin wrote:
> From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> 
> 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.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: spidev: mask SPI_CS_HIGH in SPI_IOC_RD_MODE
      commit: 7dbfa445ff7393d1c4c066c1727c9e0af1251958

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark
diff mbox series

Patch

diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index b2775d82d2d7b..6313e7d0cdf87 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,