[PATCH v2 2/2] gpio: 74x164: Introduce the 'registers-default' property

[Fabio Estevam <festevam@gmail.com>]

From: Sandor Yu <sandor.yu@nxp.com>

On the imx7d-sdb board, there is one output pin of the 74x164 that
controls all peripherals power supply (PERI_3V).

This pin should be at high voltage level when the 74x164 is probed,
otherwise the modules dependent on PERI_3V3 will not be powered.

Add a new optional property called 'registers-default' that allows
describing the default output value for each shift register.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
---
Changes since v1:
- Use the more generic device_property_read_u8_array(), which
also works in ACPI.

 drivers/gpio/gpio-74x164.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpio/gpio-74x164.c b/drivers/gpio/gpio-74x164.c
index 05637d585152..a11637518774 100644
--- a/drivers/gpio/gpio-74x164.c
+++ b/drivers/gpio/gpio-74x164.c
@@ -141,6 +141,9 @@ static int gen_74x164_probe(struct spi_device *spi)
 	chip->registers = nregs;
 	chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers;
 
+	device_property_read_u8_array(&spi->dev, "registers-default",
+				      chip->buffer, chip->registers);
+
 	chip->gpio_chip.can_sleep = true;
 	chip->gpio_chip.parent = &spi->dev;
 	chip->gpio_chip.owner = THIS_MODULE;
-- 
2.17.1