spi: rockchip: fix missing error on unsupported SPI_CS_HIGH

Commit Message

Luca Ceresoli April 21, 2022, 9:32 p.m. UTC

The hardware (except for the ROCKCHIP_SPI_VER2_TYPE2 version) does not
support active-high native chip selects. However if such a CS is configured
the core does not error as it normally should, because the
'ctlr->use_gpio_descriptors = true' line in rockchip_spi_probe() makes the
core set SPI_CS_HIGH in ctlr->mode_bits.

In such a case the spi-rockchip driver operates normally but produces an
active-low chip select signal without notice.

There is no provision in the current core code to handle this
situation. Fix by adding a check in the ctlr->setup function (similarly to
what spi-atmel.c does).

This cannot be done reading the SPI_CS_HIGH but in ctlr->mode_bits because
that bit gets always set by the core for master mode (see above).

Fixes: eb1262e3cc8b ("spi: spi-rockchip: use num-cs property and ctlr->enable_gpiods")
Signed-off-by: Luca Ceresoli <[e-mail]>
---
 drivers/spi/spi-rockchip.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Mark Brown April 25, 2022, 5:24 p.m. UTC | #1

On Thu, 21 Apr 2022 23:32:51 +0200, Luca Ceresoli wrote:
> The hardware (except for the ROCKCHIP_SPI_VER2_TYPE2 version) does not
> support active-high native chip selects. However if such a CS is configured
> the core does not error as it normally should, because the
> 'ctlr->use_gpio_descriptors = true' line in rockchip_spi_probe() makes the
> core set SPI_CS_HIGH in ctlr->mode_bits.
> 
> In such a case the spi-rockchip driver operates normally but produces an
> active-low chip select signal without notice.
> 
> [...]

Applied to

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

Thanks!

[1/1] spi: rockchip: fix missing error on unsupported SPI_CS_HIGH
      commit: d5d933f09ac326aebad85bfb787cc786ad477711

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

Patch

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index cdc16eecaf6b..a08215eb9e14 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -196,6 +196,8 @@  struct rockchip_spi {
 
 	bool slave_abort;
 	bool cs_inactive; /* spi slave tansmition stop when cs inactive */
+	bool cs_high_supported; /* native CS supports active-high polarity */
+
 	struct spi_transfer *xfer; /* Store xfer temporarily */
 };
 
@@ -719,6 +721,11 @@  static int rockchip_spi_setup(struct spi_device *spi)
 	struct rockchip_spi *rs = spi_controller_get_devdata(spi->controller);
 	u32 cr0;
 
+	if (!spi->cs_gpiod && (spi->mode & SPI_CS_HIGH) && !rs->cs_high_supported) {
+		dev_warn(&spi->dev, "setup: non GPIO CS can't be active-high\n");
+		return -EINVAL;
+	}
+
 	pm_runtime_get_sync(rs->dev);
 
 	cr0 = readl_relaxed(rs->regs + ROCKCHIP_SPI_CTRLR0);
@@ -899,6 +906,7 @@  static int rockchip_spi_probe(struct platform_device *pdev)
 
 	switch (readl_relaxed(rs->regs + ROCKCHIP_SPI_VERSION)) {
 	case ROCKCHIP_SPI_VER2_TYPE2:
+		rs->cs_high_supported = true;
 		ctlr->mode_bits |= SPI_CS_HIGH;
 		if (ctlr->can_dma && slave_mode)
 			rs->cs_inactive = true;