[PATCH] gpio: sifive: use the correct register to read output values

[Niklas Cassel <Niklas.Cassel@xxxxxxx>]

From: Niklas Cassel <niklas.cassel@xxxxxxx>

Setting the output of a GPIO to 1 using gpiod_set_value(), followed by
reading the same GPIO using gpiod_get_value(), will currently yield an
incorrect result.

This is because the SiFive GPIO device stores the output values in reg_set,
not reg_dat.

Supply the flag BGPIOF_READ_OUTPUT_REG_SET to bgpio_init() so that the
generic driver reads the correct register.

Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxx>
---
The patch was tested on a canaan,k210 board (canaan,k210-gpiohs compatible
string). It would be nice with a Tested-by from someone with a SiFive board.

However, the u-boot driver for this device already behaves exactly the same
as this driver does after my patch, for all platforms using the driver.

 drivers/gpio/gpio-sifive.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-sifive.c b/drivers/gpio/gpio-sifive.c
index 403f9e833d6a..7d82388b4ab7 100644
--- a/drivers/gpio/gpio-sifive.c
+++ b/drivers/gpio/gpio-sifive.c
@@ -223,7 +223,7 @@ static int sifive_gpio_probe(struct platform_device *pdev)
 			 NULL,
 			 chip->base + SIFIVE_GPIO_OUTPUT_EN,
 			 chip->base + SIFIVE_GPIO_INPUT_EN,
-			 0);
+			 BGPIOF_READ_OUTPUT_REG_SET);
 	if (ret) {
 		dev_err(dev, "unable to init generic GPIO\n");
 		return ret;
-- 
2.34.1