linux-kernel - [PATCH 2/2] i2c: i2c-mux-gpio: Add support 'select-delay' property

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Date:   Wed, 13 Oct 2021 16:10:03 +0200
From:   Horatiu Vultur <horatiu.vultur@...rochip.com>
To:     <peda@...ntia.se>, <robh+dt@...nel.org>,
        <peter.korsgaard@...co.com>, <lars.povlsen@...rochip.com>,
        <linux-i2c@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     Horatiu Vultur <horatiu.vultur@...rochip.com>
Subject: [PATCH 2/2] i2c: i2c-mux-gpio: Add support 'select-delay' property

Use select-delay property to add a delay once the mux state is changed.
This is required on some platforms to allow the GPIO signals to get
stabilized.

Signed-off-by: Lars Povlsen <lars.povlsen@...rochip.com>
Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
---
 drivers/i2c/muxes/i2c-mux-gpio.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
index bac415a52b78..1cc69eb67221 100644
--- a/drivers/i2c/muxes/i2c-mux-gpio.c
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -13,6 +13,8 @@
 #include <linux/slab.h>
 #include <linux/bits.h>
 #include <linux/gpio/consumer.h>
+#include <linux/delay.h>
+
 /* FIXME: stop poking around inside gpiolib */
 #include "../../gpio/gpiolib.h"
 
@@ -20,6 +22,7 @@ struct gpiomux {
 	struct i2c_mux_gpio_platform_data data;
 	int ngpios;
 	struct gpio_desc **gpios;
+	int select_delay;
 };
 
 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
@@ -29,6 +32,8 @@ static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
 	values[0] = val;
 
 	gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values);
+	if (mux->select_delay)
+		udelay(mux->select_delay);
 }
 
 static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
@@ -153,6 +158,8 @@ static int i2c_mux_gpio_probe_fw(struct gpiomux *mux,
 	if (fwnode_property_read_u32(dev->fwnode, "idle-state", &mux->data.idle))
 		mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
 
+	fwnode_property_read_u32(dev->fwnode, "select-delay", &mux->select_delay);
+
 	return 0;
 }
 
-- 
2.33.0