linux-kernel - [stable 4.19][PATCH 2/3] gpio: zynq: Report gpio direction at boot

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Message-Id: <20200210171827.29693-3-mathieu.poirier@linaro.org>
Date:   Mon, 10 Feb 2020 10:18:26 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [stable 4.19][PATCH 2/3] gpio: zynq: Report gpio direction at boot

From: Brandon Maier <Brandon.Maier@...lins.com>

commit 6169005ceb8c715582eca70df3912cd2b351ede2 upstream

The Zynq's gpios can be configured by the bootloader. But Linux will
erroneously report all gpios as inputs unless we implement
get_direction().

Signed-off-by: Brandon Maier <Brandon.Maier@...lins.com>
Tested-by: Michal Simek <michal.simek@...inx.com>
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
Cc: stable <stable@...r.kernel.org> # 4.19
Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
---
 drivers/gpio/gpio-zynq.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/gpio/gpio-zynq.c b/drivers/gpio/gpio-zynq.c
index a9238fb15013..5dec96155814 100644
--- a/drivers/gpio/gpio-zynq.c
+++ b/drivers/gpio/gpio-zynq.c
@@ -357,6 +357,28 @@ static int zynq_gpio_dir_out(struct gpio_chip *chip, unsigned int pin,
 	return 0;
 }
 
+/**
+ * zynq_gpio_get_direction - Read the direction of the specified GPIO pin
+ * @chip:	gpio_chip instance to be worked on
+ * @pin:	gpio pin number within the device
+ *
+ * This function returns the direction of the specified GPIO.
+ *
+ * Return: 0 for output, 1 for input
+ */
+static int zynq_gpio_get_direction(struct gpio_chip *chip, unsigned int pin)
+{
+	u32 reg;
+	unsigned int bank_num, bank_pin_num;
+	struct zynq_gpio *gpio = gpiochip_get_data(chip);
+
+	zynq_gpio_get_bank_pin(pin, &bank_num, &bank_pin_num, gpio);
+
+	reg = readl_relaxed(gpio->base_addr + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
+
+	return !(reg & BIT(bank_pin_num));
+}
+
 /**
  * zynq_gpio_irq_mask - Disable the interrupts for a gpio pin
  * @irq_data:	per irq and chip data passed down to chip functions
@@ -829,6 +851,7 @@ static int zynq_gpio_probe(struct platform_device *pdev)
 	chip->free = zynq_gpio_free;
 	chip->direction_input = zynq_gpio_dir_in;
 	chip->direction_output = zynq_gpio_dir_out;
+	chip->get_direction = zynq_gpio_get_direction;
 	chip->base = of_alias_get_id(pdev->dev.of_node, "gpio");
 	chip->ngpio = gpio->p_data->ngpio;
 
-- 
2.20.1