linux-kernel - [PATCH v2 4/4] gpio: aspeed: Add open-source and open-drain support

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Date:   Fri,  7 Apr 2017 22:29:02 +0930
From:   Andrew Jeffery <andrew@...id.au>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Andrew Jeffery <andrew@...id.au>, Rob Herring <robh+dt@...nel.org>,
        Joel Stanley <joel@....id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, openbmc@...ts.ozlabs.org
Subject: [PATCH v2 4/4] gpio: aspeed: Add open-source and open-drain support

As per the datasheet, manage the IO and value states to implement
open-source/open-drain, but do this by falling back to gpiolib's
emulation.

This commit simply makes the behaviour explicit for clarity, rather than
relying on the implicit return of -ENOTSUPP to trigger the emulation.

Signed-off-by: Andrew Jeffery <andrew@...id.au>
---
 drivers/gpio/gpio-aspeed.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c
index 3327a48df862..ccea609676ee 100644
--- a/drivers/gpio/gpio-aspeed.c
+++ b/drivers/gpio/gpio-aspeed.c
@@ -761,6 +761,10 @@ static int aspeed_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
 			param == PIN_CONFIG_BIAS_PULL_DOWN ||
 			param == PIN_CONFIG_DRIVE_STRENGTH)
 		return pinctrl_gpio_set_config(offset, config);
+	else if (param == PIN_CONFIG_DRIVE_OPEN_DRAIN ||
+			param == PIN_CONFIG_DRIVE_OPEN_SOURCE)
+		/* Return -ENOTSUPP to trigger emulation, as per datasheet */
+		return -ENOTSUPP;
 
 	return -ENOTSUPP;
 }
-- 
2.9.3