Commit a0b977a3 authored by Bastien Curutchet's avatar Bastien Curutchet Committed by Jakub Kicinski
Browse files

net: dsa: microchip: Set SPI as bus interface during reset for KSZ8463 



At reset, the KSZ8463 uses a strap-based configuration to set SPI as
bus interface. SPI is the only bus supported by the driver. If the
required pull-ups/pull-downs are missing (by mistake or by design to
save power) the pins may float and the configuration can go wrong
preventing any communication with the switch.

Introduce a ksz8463_configure_straps_spi() function called during the
device reset. It relies on the 'straps-rxd-gpios' OF property and the
'reset' pinmux configuration to enforce SPI as bus interface.

Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
Signed-off-by: default avatarBastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>
Link: https://patch.msgid.link/20250918-ksz-strap-pins-v3-3-16662e881728@bootlin.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent e469b87e

drivers/net/dsa/microchip/ksz_common.c

+45 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/of_mdio.h>

#include <linux/of_net.h>

#include <linux/micrel_phy.h>

#include <linux/pinctrl/consumer.h>

#include <net/dsa.h>

#include <net/ieee8021q.h>

#include <net/pkt_cls.h>
@@ -5345,6 +5346,38 @@ static int ksz_parse_drive_strength(struct ksz_device *dev) 
	return 0;

}



static int ksz8463_configure_straps_spi(struct ksz_device *dev)

{

	struct pinctrl *pinctrl;

	struct gpio_desc *rxd0;

	struct gpio_desc *rxd1;



	rxd0 = devm_gpiod_get_index_optional(dev->dev, "straps-rxd", 0, GPIOD_OUT_LOW);

	if (IS_ERR(rxd0))

		return PTR_ERR(rxd0);



	rxd1 = devm_gpiod_get_index_optional(dev->dev, "straps-rxd", 1, GPIOD_OUT_HIGH);

	if (IS_ERR(rxd1))

		return PTR_ERR(rxd1);



	if (!rxd0 && !rxd1)

		return 0;



	if ((rxd0 && !rxd1) || (rxd1 && !rxd0))

		return -EINVAL;



	pinctrl = devm_pinctrl_get_select(dev->dev, "reset");

	if (IS_ERR(pinctrl))

		return PTR_ERR(pinctrl);



	return 0;

}



static int ksz8463_release_straps_spi(struct ksz_device *dev)

{

	return pinctrl_select_default_state(dev->dev);

}



int ksz_switch_register(struct ksz_device *dev)

{

	const struct ksz_chip_data *info;
@@ -5360,10 +5393,22 @@ int ksz_switch_register(struct ksz_device *dev) 
		return PTR_ERR(dev->reset_gpio);



	if (dev->reset_gpio) {

		if (of_device_is_compatible(dev->dev->of_node, "microchip,ksz8463")) {

			ret = ksz8463_configure_straps_spi(dev);

			if (ret)

				return ret;

		}



		gpiod_set_value_cansleep(dev->reset_gpio, 1);

		usleep_range(10000, 12000);

		gpiod_set_value_cansleep(dev->reset_gpio, 0);

		msleep(100);



		if (of_device_is_compatible(dev->dev->of_node, "microchip,ksz8463")) {

			ret = ksz8463_release_straps_spi(dev);

			if (ret)

				return ret;

		}

	}



	mutex_init(&dev->dev_mutex);