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Subject[PATCH AUTOSEL 5.4 011/187] gpio: Handle counting of Freescale chipselects
Date
From: Linus Walleij <linus.walleij@linaro.org>

[ Upstream commit 71b8f600b034c7f5780f6fb311dabfe331c64feb ]

We have a special quirk to handle the Freescale
nonstandard SPI chipselect GPIOs in the gpiolib-of.c
file, but it currently only handles the case where
the GPIOs are actually requested (gpiod_*get()).

We also need to handle that the SPI core attempts
to count the GPIOs before use, and that needs a
similar quirk in the OF part of the library.

Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Reported-by: Christophe Leroy <christophe.leroy@c-s.fr>
Fixes: 0f0581b24bd0 ("spi: fsl: Convert to use CS GPIO descriptors")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Christophe Leroy <christophe.leroy@c-s.fr>
Link: https://lore.kernel.org/r/20191128083718.39177-2-linus.walleij@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpio/gpiolib-of.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 80ea49f570f4..43ffec3a6fbb 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -23,6 +23,29 @@
#include "gpiolib.h"
#include "gpiolib-of.h"

+/**
+ * of_gpio_spi_cs_get_count() - special GPIO counting for SPI
+ * Some elder GPIO controllers need special quirks. Currently we handle
+ * the Freescale GPIO controller with bindings that doesn't use the
+ * established "cs-gpios" for chip selects but instead rely on
+ * "gpios" for the chip select lines. If we detect this, we redirect
+ * the counting of "cs-gpios" to count "gpios" transparent to the
+ * driver.
+ */
+int of_gpio_spi_cs_get_count(struct device *dev, const char *con_id)
+{
+ struct device_node *np = dev->of_node;
+
+ if (!IS_ENABLED(CONFIG_SPI_MASTER))
+ return 0;
+ if (!con_id || strcmp(con_id, "cs"))
+ return 0;
+ if (!of_device_is_compatible(np, "fsl,spi") &&
+ !of_device_is_compatible(np, "aeroflexgaisler,spictrl"))
+ return 0;
+ return of_gpio_named_count(np, "gpios");
+}
+
/*
* This is used by external users of of_gpio_count() from <linux/of_gpio.h>
*
@@ -35,6 +58,10 @@ int of_gpio_get_count(struct device *dev, const char *con_id)
char propname[32];
unsigned int i;

+ ret = of_gpio_spi_cs_get_count(dev, con_id);
+ if (ret > 0)
+ return ret;
+
for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
if (con_id)
snprintf(propname, sizeof(propname), "%s-%s",
--
2.20.1
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