NVIDIA: SAUCE: MEDIATEK: pinctrl: mediatek: Add eint hotplug driver

This driver is used to manage PCIe link for NVIDIA ConnectX-7 (CX7)
hot-plug/unplug on DGX Spark. We need to disable PCIe link when
CX7 cable plug out happens and enable pcie link when
CX7 cable plug in happens.

It also creates a sysfs entry to emulate cable plug in/out
behavior as below:

plug in - echo 1 > /sys/devices/platform/MTKP0001:00/cx7_dbg/plugin
plug out - echo 0 > /sys/devices/platform/MTKP0001:00/cx7_dbg/plugin

We also implement uevent to notify user-space applications when a
cable is plugged in or removed. Below are the details of our process:

* cable plug-in:
report plug-in uevent (driver)
enable pcie link (application)
rescan devices (application)

* cable removal:
report removal uevent (driver)
remove devices (application)
disable pcie link (application)

Signed-off-by: Vaibhav Vyas <vavyas@nvidia.com>
Signed-off-by: Jerry.Guo <jerry.guo@mediatek.com>
Signed-off-by: Yenchia Chen <yenchia.chen@mediatek.com>
Signed-off-by: Shubhi Garg <shgarg@nvidia.com>
Signed-off-by: Abhishek Sahu <abhsahu@nvidia.com>
Signed-off-by: Surabhi Chythanya Kumar <schythanyaku@nvidia.com>

Author: schythanyaku

debian.nvidia-6.14/config/annotations

@@ -224,6 +224,7 @@ CONFIG_CC_HAS_SIGN_RETURN_ADDRESS               policy<{'arm64': '-'}>
 CONFIG_CC_VERSION_TEXT                          policy<{'amd64': '"x86_64-linux-gnu-gcc-13 (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0"', 'arm64': '"aarch64-linux-gnu-gcc-13 (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0"'}>
 CONFIG_CGROUP_RESCTRL                           policy<{'amd64': '-', 'arm64': '-'}>
 CONFIG_CPUFREQ_ARCH_CUR_FREQ                    policy<{'amd64': 'y'}>
+CONFIG_EINT_MTK_HP                              policy<{'arm64': 'm'}>
 CONFIG_DRM_PANIC_SCREEN_QR_CODE                 policy<{'amd64': '-', 'arm64': '-'}>
 CONFIG_EC_HUAWEI_GAOKUN                         policy<{'arm64': 'n'}>
 CONFIG_FTRACE_SORT_STARTUP_TEST                 policy<{'amd64': 'n', 'arm64': 'n'}>

drivers/pinctrl/mediatek/Kconfig

@@ -10,6 +10,15 @@ config EINT_MTK
 	default y if PINCTRL_MTK || PINCTRL_MTK_MOORE
 	default PINCTRL_MTK_PARIS
 
+config EINT_MTK_HP
+	tristate "MediaTek HP Driver"
+	depends on EINT_MTK
+	help
+	  Say yes here to support NICs cable plug in/out test.
+	  It will disable pcie link when plug out and enable
+	  pcie link after plug in cable.
+	  This is particularly useful for MediaTek MT8901 SoC.
+
 config PINCTRL_MTK
 	bool
 	depends on OF

drivers/pinctrl/mediatek/Makefile

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 # Core
 obj-$(CONFIG_EINT_MTK)			+= mtk-eint.o
+obj-$(CONFIG_EINT_MTK_HP)		+= mtk-eint-hotplug.o
 obj-$(CONFIG_PINCTRL_MTK)		+= pinctrl-mtk-common.o
 obj-$(CONFIG_PINCTRL_MTK_V2)		+= pinctrl-mtk-common-v2.o
 obj-$(CONFIG_PINCTRL_MTK_MTMIPS)	+= pinctrl-mtmips.o