linux-kernel - [PATCH v1 1/1] spi: Assume GPIO CS active high in ACPI case

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210510141022.56499-1-andriy.shevchenko@linux.intel.com>
Date:   Mon, 10 May 2021 17:10:22 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Mark Brown <broonie@...nel.org>, linux-spi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Liguang Zhang <zhangliguang@...ux.alibaba.com>,
        Jay Fang <f.fangjian@...wei.com>,
        Sven Van Asbroeck <thesven73@...il.com>,
        Xin Hao <xhao@...ux.alibaba.com>
Subject: [PATCH v1 1/1] spi: Assume GPIO CS active high in ACPI case

Currently GPIO CS handling, when descriptors are in use, doesn't
take into consideration that in ACPI case the default polarity
is active high and can't be altered. Instead we have to use the
per-chip definition provided by SPISerialBus() resource.

Fixes: 766c6b63aa04 ("spi: fix client driver breakages when using GPIO descriptors")
Cc: Liguang Zhang <zhangliguang@...ux.alibaba.com>
Cc: Jay Fang <f.fangjian@...wei.com>
Cc: Sven Van Asbroeck <thesven73@...il.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Tested-by: Xin Hao <xhao@...ux.alibaba.com>
---
 drivers/spi/spi.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 956dce3aafca..f56e0212ee97 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -820,12 +820,23 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
 
 	if (spi->cs_gpiod || gpio_is_valid(spi->cs_gpio)) {
 		if (!(spi->mode & SPI_NO_CS)) {
+			/*
+			 * Historically ACPI has no means of the GPIO polarity and thus
+			 * the SPISerialBus() resource defines it on the per-chip basis.
+			 * In order to avoid a chain of negations, the GPIO polarity is
+			 * considered being Active High. Even for the cases when _DSD()
+			 * is involved (in the updated versions of ACPI) the GPIO CS
+			 * polarity must be defined Active High to avoid ambiguity.
+			 * That's why we use enable, that takes SPI_CS_HIGH into account.
+			 */
+			bool value = has_acpi_companion(&spi->dev) ? !enable : activate;
+
 			if (spi->cs_gpiod)
-				/* polarity handled by gpiolib */
-				gpiod_set_value_cansleep(spi->cs_gpiod, activate);
+				/* Polarity handled by GPIO library */
+				gpiod_set_value_cansleep(spi->cs_gpiod, value);
 			else
 				/*
-				 * invert the enable line, as active low is
+				 * Invert the enable line, as active low is
 				 * default for SPI.
 				 */
 				gpio_set_value_cansleep(spi->cs_gpio, !enable);
-- 
2.30.2