linux-kernel - [PATCH v2 9/9] gpiolib: of: add a quirk for reset line polarity for Himax LCDs

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Date:   Fri, 14 Oct 2022 10:54:33 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>,
        Linus Walleij <linus.walleij@...aro.org>
Cc:     linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        Alexander Stein <alexander.stein@...tq-group.com>,
        linux-kernel@...r.kernel.org,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-gpio@...r.kernel.org
Subject: [PATCH v2 9/9] gpiolib: of: add a quirk for reset line polarity for Himax LCDs

Existing DTS that use legacy (non-standard) property name for the reset
line "gpios-reset" also specify incorrect polarity (0 which maps to
"active high"). Add a quirk to force polarity to "active low" so that
once driver is converted to gpiod API that pays attention to line
polarity it will work properly.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
 drivers/gpio/gpiolib-of.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 805222a2e6bc..26d57465fec9 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -152,11 +152,47 @@ static void of_gpio_quirk_polarity(const struct device_node *np,
 	}
 }
 
+/*
+ * This quirk does static polarity overrides in cases where existing
+ * DTS specified incorrect polarity.
+ */
+static void of_gpio_try_fixup_polarity(const struct device_node *np,
+				       const char *propname,
+				       enum of_gpio_flags *flags)
+{
+	static const struct {
+		const char *compatible;
+		const char *propname;
+		bool active_high;
+	} gpios[] = {
+#if !IS_ENABLED(CONFIG_LCD_HX8357)
+		/*
+		 * Himax LCD controllers used incorrectly named
+		 * "gpios-reset" property and also specified wrong
+		 * polarity.
+		 */
+		{ "himax,hx8357",	"gpios-reset",	false },
+		{ "himax,hx8369",	"gpios-reset",	false },
+#endif
+	};
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(gpios); i++) {
+		if (of_device_is_compatible(np, gpios[i].compatible) &&
+		    !strcmp(propname, gpios[i].propname)) {
+			of_gpio_quirk_polarity(np, gpios[i].active_high, flags);
+			break;
+		}
+	}
+}
+
 static void of_gpio_flags_quirks(const struct device_node *np,
 				 const char *propname,
 				 enum of_gpio_flags *flags,
 				 int index)
 {
+	of_gpio_try_fixup_polarity(np, propname, flags);
+
 	/*
 	 * Some GPIO fixed regulator quirks.
 	 * Note that active low is the default.

-- 
b4 0.11.0-dev-5166b