gpio: davinci: implement .get_direction()

It's strongly recommended for GPIO drivers to always implement the
.get_direction() callback - even for fixed-direction controllers.

GPIO core will even emit a warning if the callback is missing, when
users try to read the direction of a pin.

Implement .get_direction() for gpio-davinci.

Reported-by: Michael Walle <[e-mail]>
Closes: https://lore.kernel.org/all/[e-mail]/
Reviewed-by: Linus Walleij <[e-mail]>
Fixes: a060b8c511ab ("gpiolib: implement low-level, shared GPIO support")
Tested-by: Michael Walle <[e-mail]> # on sa67
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bartosz Golaszewski <[e-mail]>

drivers/gpio/gpio-davinci.c

···
  * Copyright (c) 2007, MontaVista Software, Inc. <[e-mail]>
  */
 
+#include <linux/cleanup.h>
 #include <linux/gpio/driver.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
···
 	return __davinci_direction(chip, offset, true, value);
 }
 
+static int davinci_get_direction(struct gpio_chip *chip, unsigned int offset)
+{
+	struct davinci_gpio_controller *d = gpiochip_get_data(chip);
+	struct davinci_gpio_regs __iomem *g;
+	u32 mask = __gpio_mask(offset), val;
+	int bank = offset / 32;
+
+	g = d->regs[bank];
+
+	guard(spinlock_irqsave)(&d->lock);
+
+	val = readl_relaxed(&g->dir);
+
+	return (val & mask) ? GPIO_LINE_DIRECTION_IN : GPIO_LINE_DIRECTION_OUT;
+}
+
 /*
  * Read the pin's value (works even if it's set up as output);
  * returns zero/nonzero.
···
 	chips->chip.get = davinci_gpio_get;
 	chips->chip.direction_output = davinci_direction_out;
 	chips->chip.set = davinci_gpio_set;
+	chips->chip.get_direction = davinci_get_direction;
 
 	chips->chip.ngpio = ngpio;
 	chips->chip.base = -1;