Commit ecba1eaa authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Bartosz Golaszewski
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gpio: rcar: Optimize GPIO pin state read on R-Car Gen3 



Currently, the R-Car GPIO driver treats R-Car Gen2 and R-Car Gen3 GPIO
controllers the same.  However, there exist small differences, like the
behavior of the General Input Register (INDT):
  - On R-Car Gen1, R-Car Gen2, and RZ/G1, INDT only reflects the state
    of an input pin if the GPIO is configured for input,
  - On R-Car Gen3 and RZ/G2, INDT always reflects the state of the input
    pins.
Hence to accommodate all variants, the driver does not use the INDT
register to read the status of a GPIO line when configured for output,
at the expense of doing 2 or 3 register reads instead of 1.

Given register accesses are slow, change the .get() and .get_multiple()
callbacks to always use INDT to read pin state on SoCs where this is
supported.

Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: default avatarYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
parent 2a84708c

drivers/gpio/gpio-rcar.c

+20 −5
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ struct gpio_rcar_bank_info { 
struct gpio_rcar_info {

	bool has_outdtsel;

	bool has_both_edge_trigger;

	bool has_always_in;

};



struct gpio_rcar_priv {
@@ -302,9 +303,11 @@ static int gpio_rcar_get(struct gpio_chip *chip, unsigned offset) 
	struct gpio_rcar_priv *p = gpiochip_get_data(chip);

	u32 bit = BIT(offset);



	/* testing on r8a7790 shows that INDT does not show correct pin state

	 * when configured as output, so use OUTDT in case of output pins */

	if (gpio_rcar_read(p, INOUTSEL) & bit)

	/*

	 * Before R-Car Gen3, INDT does not show correct pin state when

	 * configured as output, so use OUTDT in case of output pins

	 */

	if (!p->info.has_always_in && (gpio_rcar_read(p, INOUTSEL) & bit))

		return !!(gpio_rcar_read(p, OUTDT) & bit);

	else

		return !!(gpio_rcar_read(p, INDT) & bit);
@@ -324,6 +327,11 @@ static int gpio_rcar_get_multiple(struct gpio_chip *chip, unsigned long *mask, 
	if (!bankmask)

		return 0;



	if (p->info.has_always_in) {

		bits[0] = gpio_rcar_read(p, INDT) & bankmask;

		return 0;

	}



	spin_lock_irqsave(&p->lock, flags);

	outputs = gpio_rcar_read(p, INOUTSEL);

	m = outputs & bankmask;
@@ -383,11 +391,19 @@ static int gpio_rcar_direction_output(struct gpio_chip *chip, unsigned offset, 
static const struct gpio_rcar_info gpio_rcar_info_gen1 = {

	.has_outdtsel = false,

	.has_both_edge_trigger = false,

	.has_always_in = false,

};



static const struct gpio_rcar_info gpio_rcar_info_gen2 = {

	.has_outdtsel = true,

	.has_both_edge_trigger = true,

	.has_always_in = false,

};



static const struct gpio_rcar_info gpio_rcar_info_gen3 = {

	.has_outdtsel = true,

	.has_both_edge_trigger = true,

	.has_always_in = true,

};



static const struct of_device_id gpio_rcar_of_table[] = {
@@ -399,8 +415,7 @@ static const struct of_device_id gpio_rcar_of_table[] = { 
		.data = &gpio_rcar_info_gen2,

	}, {

		.compatible = "renesas,rcar-gen3-gpio",

		/* Gen3 GPIO is identical to Gen2. */

		.data = &gpio_rcar_info_gen2,

		.data = &gpio_rcar_info_gen3,

	}, {

		.compatible = "renesas,gpio-rcar",

		.data = &gpio_rcar_info_gen1,