[PATCH v2 4/5] gpio: aaeon: Add GPIO driver for SRG-IMX8PL MCU
From: Thomas Perrot (Schneider Electric) <hidden>
Date: 2026-01-23 09:55:03
Also in:
imx, linux-devicetree, linux-gpio, linux-watchdog, lkml
Subsystem:
gpio subsystem, the rest · Maintainers:
Linus Walleij, Bartosz Golaszewski, Linus Torvalds
Add GPIO driver for the Aaeon SRG-IMX8PL embedded controller. This driver supports 7 GPO (General Purpose Output) pins and 12 GPIO pins that can be configured as inputs or outputs. The driver implements proper state management for GPO pins (which are output-only) and full direction control for GPIO pins. During probe, all pins are reset to a known state (GPOs low, GPIOs as inputs) to prevent undefined behavior across system reboots, as the MCU does not reset GPIO states on soft reboot. Co-developed-by: Jérémie Dautheribes (Schneider Electric) <redacted> Signed-off-by: Jérémie Dautheribes (Schneider Electric) <redacted> Signed-off-by: Thomas Perrot (Schneider Electric) <redacted> --- MAINTAINERS | 1 + drivers/gpio/Kconfig | 10 ++ drivers/gpio/Makefile | 1 + drivers/gpio/gpio-aaeon-mcu.c | 238 ++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 250 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 175c1e1b28b8151580ed340207d4a6fd59aa8853..28dd964cdf69bdcaec3eb82d6df851a2bad47415 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS@@ -191,6 +191,7 @@ M: Thomas Perrot <thomas.perrot@bootlin.com> R: Jérémie Dautheribes <jeremie.dautheribes@bootlin.com> S: Maintained F: Documentation/devicetree/bindings/mfd/aaeon,srg-imx8pl-mcu.yaml +F: drivers/gpio/gpio-aaeon-mcu.c F: drivers/mfd/aaeon-mcu.c F: include/linux/mfd/aaeon-mcu.h
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index c74da29253e810b51540684b1186e8f274066b69..6142d50b92b3d8c1fac8b0d81397dc22428fbb51 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig@@ -157,6 +157,16 @@ config GPIO_74XX_MMIO 8 bits: 74244 (Input), 74273 (Output) 16 bits: 741624 (Input), 7416374 (Output) +config GPIO_AAEON_MCU + tristate "Aaeon MCU GPIO support" + depends on MFD_AAEON_MCU + select GPIO_GENERIC + help + Select this option to enable GPIO support for the Aaeon SRG-IMX8PL + onboard MCU. This driver provides access to GPIO pins and GPO + (General Purpose Output) pins controlled by the microcontroller. + The driver handles both input and output configuration. + config GPIO_ALTERA tristate "Altera GPIO" select GPIOLIB_IRQCHIP
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 2421a8fd3733e0b06c2581262aaa9cd629f66c7d..1ba6318bc558743fbe5910966c2c8fc3f792efe9 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile@@ -29,6 +29,7 @@ obj-$(CONFIG_GPIO_104_IDI_48) += gpio-104-idi-48.o obj-$(CONFIG_GPIO_104_IDIO_16) += gpio-104-idio-16.o obj-$(CONFIG_GPIO_74X164) += gpio-74x164.o obj-$(CONFIG_GPIO_74XX_MMIO) += gpio-74xx-mmio.o +obj-$(CONFIG_GPIO_AAEON_MCU) += gpio-aaeon-mcu.o obj-$(CONFIG_GPIO_ADNP) += gpio-adnp.o obj-$(CONFIG_GPIO_ADP5520) += gpio-adp5520.o obj-$(CONFIG_GPIO_ADP5585) += gpio-adp5585.o
diff --git a/drivers/gpio/gpio-aaeon-mcu.c b/drivers/gpio/gpio-aaeon-mcu.c
new file mode 100644
index 0000000000000000000000000000000000000000..533eaf3e7f82f3b9e3f50a1a631c8e853adc1226
--- /dev/null
+++ b/drivers/gpio/gpio-aaeon-mcu.c@@ -0,0 +1,238 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Aaeon MCU GPIO driver + * + * Copyright (C) 2025 Bootlin + * Author: Jérémie Dautheribes <jeremie.dautheribes@bootlin.com> + * Author: Thomas Perrot <thomas.perrot@bootlin.com> + */ + +#include <linux/bitops.h> +#include <linux/device.h> +#include <linux/gpio/driver.h> +#include <linux/mfd/aaeon-mcu.h> +#include <linux/mod_devicetable.h> +#include <linux/module.h> +#include <linux/platform_device.h> + +#define AAEON_MCU_CONFIG_GPIO_INPUT 0x69 +#define AAEON_MCU_CONFIG_GPIO_OUTPUT 0x6F +#define AAEON_MCU_READ_GPIO 0x72 +#define AAEON_MCU_WRITE_GPIO 0x77 + +#define AAEON_MCU_CONTROL_GPO 0x6C + +#define MAX_GPIOS 12 +#define MAX_GPOS 7 + +struct aaeon_mcu_gpio { + struct gpio_chip gc; + struct device *dev; + DECLARE_BITMAP(dir_in, MAX_GPOS + MAX_GPIOS); + DECLARE_BITMAP(gpo_state, MAX_GPOS); +}; + +static int aaeon_mcu_gpio_config_input_cmd(struct aaeon_mcu_gpio *data, + unsigned int offset) +{ + u8 cmd[3], rsp; + + cmd[0] = AAEON_MCU_CONFIG_GPIO_INPUT; + cmd[1] = offset - 7; + cmd[2] = 0x00; + + return aaeon_mcu_i2c_xfer(data->dev, cmd, 3, &rsp, 1); +} + +static int aaeon_mcu_gpio_direction_input(struct gpio_chip *gc, unsigned int offset) +{ + struct aaeon_mcu_gpio *data = gpiochip_get_data(gc); + int ret; + + if (offset < MAX_GPOS) { + dev_err(gc->parent, "GPIO offset (%d) must be an output GPO\n", offset); + return -EOPNOTSUPP; + } + + ret = aaeon_mcu_gpio_config_input_cmd(data, offset); + if (ret < 0) + return ret; + + __set_bit(offset, data->dir_in); + + return 0; +} + +static int aaeon_mcu_gpio_config_output_cmd(struct aaeon_mcu_gpio *data, + unsigned int offset, + int value) +{ + u8 cmd[3], rsp; + int ret; + + cmd[0] = AAEON_MCU_CONFIG_GPIO_OUTPUT; + cmd[1] = offset - 7; + cmd[2] = 0x00; + + ret = aaeon_mcu_i2c_xfer(data->dev, cmd, 3, &rsp, 1); + if (ret < 0) + return ret; + + cmd[0] = AAEON_MCU_WRITE_GPIO; + /* cmd[1] = offset - 7; */ + cmd[2] = !!value; + + return aaeon_mcu_i2c_xfer(data->dev, cmd, 3, &rsp, 1); +} + +static int aaeon_mcu_gpio_direction_output(struct gpio_chip *gc, unsigned int offset, int value) +{ + struct aaeon_mcu_gpio *data = gpiochip_get_data(gc); + int ret; + + if (offset < MAX_GPOS) + return 0; + + ret = aaeon_mcu_gpio_config_output_cmd(data, offset, value); + if (ret < 0) + return ret; + + __clear_bit(offset, data->dir_in); + + return 0; +} + +static int aaeon_mcu_gpio_get_direction(struct gpio_chip *gc, unsigned int offset) +{ + struct aaeon_mcu_gpio *data = gpiochip_get_data(gc); + + return test_bit(offset, data->dir_in) ? + GPIO_LINE_DIRECTION_IN : GPIO_LINE_DIRECTION_OUT; +} + +static int aaeon_mcu_gpio_get(struct gpio_chip *gc, unsigned int offset) +{ + struct aaeon_mcu_gpio *data = gpiochip_get_data(gc); + u8 cmd[3], rsp; + int ret; + + if (offset < MAX_GPOS) + return test_bit(offset, data->gpo_state); + + cmd[0] = AAEON_MCU_READ_GPIO; + cmd[1] = offset - 7; + cmd[2] = 0x00; + + ret = aaeon_mcu_i2c_xfer(data->dev, cmd, 3, &rsp, 1); + if (ret < 0) + return ret; + + return rsp; +} + +static int aaeon_mcu_gpo_set_cmd(struct aaeon_mcu_gpio *data, unsigned int offset, int value) +{ + u8 cmd[3], rsp; + + cmd[0] = AAEON_MCU_CONTROL_GPO; + cmd[1] = offset + 1; + cmd[2] = !!value; + + return aaeon_mcu_i2c_xfer(data->dev, cmd, 3, &rsp, 1); +} + +static int aaeon_mcu_gpio_set_cmd(struct aaeon_mcu_gpio *data, unsigned int offset, int value) +{ + u8 cmd[3], rsp; + + cmd[0] = AAEON_MCU_WRITE_GPIO; + cmd[1] = offset - 7; + cmd[2] = !!value; + + return aaeon_mcu_i2c_xfer(data->dev, cmd, 3, &rsp, 1); +} + +static int aaeon_mcu_gpio_set(struct gpio_chip *gc, unsigned int offset, + int value) +{ + struct aaeon_mcu_gpio *data = gpiochip_get_data(gc); + + if (offset >= MAX_GPOS) + return aaeon_mcu_gpio_set_cmd(data, offset, value); + + if (aaeon_mcu_gpo_set_cmd(data, offset, value) == 0) + __assign_bit(offset, data->gpo_state, value); + + return 0; +} + +static const struct gpio_chip aaeon_mcu_chip = { + .label = "gpio-aaeon-mcu", + .owner = THIS_MODULE, + .get_direction = aaeon_mcu_gpio_get_direction, + .direction_input = aaeon_mcu_gpio_direction_input, + .direction_output = aaeon_mcu_gpio_direction_output, + .get = aaeon_mcu_gpio_get, + .set = aaeon_mcu_gpio_set, + .base = -1, + .ngpio = MAX_GPOS + MAX_GPIOS, + .can_sleep = true, +}; + +static void aaeon_mcu_gpio_reset(struct aaeon_mcu_gpio *data, struct device *dev) +{ + unsigned int i; + int ret; + + /* Reset all GPOs */ + for (i = 0; i < MAX_GPOS; i++) { + ret = aaeon_mcu_gpo_set_cmd(data, i, 0); + if (ret < 0) + dev_warn(dev, "Failed to reset GPO %u state: %d\n", i, ret); + __clear_bit(i, data->dir_in); + } + + /* Reset all GPIOs */ + for (i = MAX_GPOS; i < MAX_GPOS + MAX_GPIOS; i++) { + ret = aaeon_mcu_gpio_config_input_cmd(data, i); + if (ret < 0) + dev_warn(dev, "Failed to reset GPIO %u state: %d\n", i, ret); + __set_bit(i, data->dir_in); + } +} + +static int aaeon_mcu_gpio_probe(struct platform_device *pdev) +{ + struct aaeon_mcu_gpio *data; + + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + data->dev = pdev->dev.parent; + data->gc = aaeon_mcu_chip; + data->gc.parent = data->dev; + + /* + * Reset all GPIO states to a known configuration. The MCU does not + * reset GPIO state on soft reboot, only on power cycle (hard reboot). + * Without this reset, GPIOs would retain their previous state across + * reboots, which could lead to unexpected behavior. + */ + aaeon_mcu_gpio_reset(data, &pdev->dev); + + return devm_gpiochip_add_data(&pdev->dev, &data->gc, data); +} + +static struct platform_driver aaeon_mcu_gpio_driver = { + .driver = { + .name = "aaeon-mcu-gpio", + }, + .probe = aaeon_mcu_gpio_probe, +}; + +module_platform_driver(aaeon_mcu_gpio_driver); + +MODULE_DESCRIPTION("GPIO interface for Aaeon MCU"); +MODULE_AUTHOR("Jérémie Dautheribes <jeremie.dautheribes@bootlin.com>"); +MODULE_LICENSE("GPL");
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2.52.0