Commit 4e73bfa3 authored by Andreas Kaessens's avatar Andreas Kaessens Committed by Linus Walleij
Browse files

pinctrl: mcp23s08: Add optional reset GPIO 

The MCP23x port expander RESET# line can be connected to a host GPIO.
The optional reset-gpio must be set to LOW if the reset is asserted
at probing time.

On page 5 in the datasheet [0] the "Device Active After Reset high"
time is specified at 0 µs. Therefore no waiting is needed after the
reset transition.

[0] https://ww1.microchip.com/downloads/en/DeviceDoc/20001952C.pdf



Signed-off-by: default avatarAndreas Kaessens <akaessens@gmail.com>
Signed-off-by: default avatarDarian Biastoch <d.biastoch@gmail.com>
Link: https://lore.kernel.org/r/20210610132438.3085841-1-akaessens@gmail.com


Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent ca199e19

drivers/pinctrl/pinctrl-mcp23s08.c

+3 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#include <linux/module.h>

#include <linux/export.h>

#include <linux/gpio/driver.h>

#include <linux/gpio/consumer.h>

#include <linux/slab.h>

#include <asm/byteorder.h>

#include <linux/interrupt.h>
@@ -558,6 +559,8 @@ int mcp23s08_probe_one(struct mcp23s08 *mcp, struct device *dev, 
	mcp->chip.parent = dev;

	mcp->chip.owner = THIS_MODULE;



	mcp->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);



	/* verify MCP_IOCON.SEQOP = 0, so sequential reads work,

	 * and MCP_IOCON.HAEN = 1, so we work with all chips.

	 */

drivers/pinctrl/pinctrl-mcp23s08.h

+1 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ struct mcp23s08 { 


	struct pinctrl_dev	*pctldev;

	struct pinctrl_desc	pinctrl_desc;

	struct gpio_desc        *reset_gpio;

};



extern const struct regmap_config mcp23x08_regmap;