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: Andreas Kaessens <akaessens@xxxxxxxxx> Signed-off-by: Darian Biastoch <d.biastoch@xxxxxxxxx> --- drivers/pinctrl/pinctrl-mcp23s08.c | 3 +++ drivers/pinctrl/pinctrl-mcp23s08.h | 1 + 2 files changed, 4 insertions(+) diff --git a/drivers/pinctrl/pinctrl-mcp23s08.c b/drivers/pinctrl/pinctrl-mcp23s08.c index 799d596a1a4b..8ab254170d99 100644 --- a/drivers/pinctrl/pinctrl-mcp23s08.c +++ b/drivers/pinctrl/pinctrl-mcp23s08.c @@ -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. */ diff --git a/drivers/pinctrl/pinctrl-mcp23s08.h b/drivers/pinctrl/pinctrl-mcp23s08.h index 90dc27081a3c..b8d15939e0c2 100644 --- a/drivers/pinctrl/pinctrl-mcp23s08.h +++ b/drivers/pinctrl/pinctrl-mcp23s08.h @@ -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; -- 2.25.1
