--- /dev/null
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Carlo Szelinsky <github@szelinsky.de>
+Date: Sat, 30 May 2026 12:00:00 +0200
+Subject: watchdog: add Hasivo MCU watchdog driver
+
+Hardware watchdog driver for the external management MCU found on
+Hasivo / Horaco network switches, reachable over I2C. Without periodic
+keepalive the MCU resets the board every ~3 minutes.
+
+The driver arms the MCU at probe and registers a struct watchdog_device
+with WDOG_HW_RUNNING so the watchdog core feeds the chip via a kernel
+timer until userspace opens the watchdog node. Timeout is fixed at 15s;
+the hardware threshold is baked into MCU firmware and is not
+software-configurable.
+
+Signed-off-by: Carlo Szelinsky <github@szelinsky.de>
+Signed-off-by: Manuel Stocker <mensi@mensi.ch>
+---
+--- /dev/null
++++ b/Documentation/devicetree/bindings/watchdog/hasivo,mcu-wdt.yaml
+@@ -0,0 +1,45 @@
++# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
++%YAML 1.2
++---
++$id: http://devicetree.org/schemas/watchdog/hasivo,mcu-wdt.yaml#
++$schema: http://devicetree.org/meta-schemas/core.yaml#
++
++title: Hasivo / Horaco external management MCU watchdog
++
++maintainers:
++ - Carlo Szelinsky <github@szelinsky.de>
++ - Manuel Stocker <mensi@mensi.ch>
++
++description: |
++ Management microcontroller found on Hasivo and Horaco network switches,
++ exposed on the system I2C bus. Provides a hardware watchdog that must be
++ armed and periodically retriggered by the host via I2C writes.
++
++allOf:
++ - $ref: watchdog.yaml#
++
++properties:
++ compatible:
++ const: hasivo,mcu-wdt
++
++ reg:
++ maxItems: 1
++
++required:
++ - compatible
++ - reg
++
++unevaluatedProperties: false
++
++examples:
++ - |
++ i2c {
++ #address-cells = <1>;
++ #size-cells = <0>;
++
++ watchdog@6f {
++ compatible = "hasivo,mcu-wdt";
++ reg = <0x6f>;
++ };
++ };
++...
+--- a/drivers/watchdog/Kconfig
++++ b/drivers/watchdog/Kconfig
+@@ -302,6 +302,18 @@ config MENF21BMC_WATCHDOG
+ This driver can also be built as a module. If so the module
+ will be called menf21bmc_wdt.
+
++config HASIVO_MCU_WATCHDOG
++ tristate "Hasivo MCU Watchdog"
++ depends on I2C
++ select WATCHDOG_CORE
++ help
++ Hardware watchdog driver for the external management MCU found
++ on Hasivo and Horaco network switches, reachable over I2C. The
++ MCU resets the board unless it is periodically retriggered.
++
++ This driver can also be built as a module. If so the module
++ will be called hasivo-mcu-wdt.
++
+ config MENZ069_WATCHDOG
+ tristate "MEN 16Z069 Watchdog"
+ depends on MCB
+--- a/drivers/watchdog/Makefile
++++ b/drivers/watchdog/Makefile
+@@ -239,6 +239,7 @@ obj-$(CONFIG_NCT6694_WATCHDOG) += nct669
+ obj-$(CONFIG_ZIIRAVE_WATCHDOG) += ziirave_wdt.o
+ obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
+ obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
++obj-$(CONFIG_HASIVO_MCU_WATCHDOG) += hasivo-mcu-wdt.o
+ obj-$(CONFIG_MENZ069_WATCHDOG) += menz69_wdt.o
+ obj-$(CONFIG_RAVE_SP_WATCHDOG) += rave-sp-wdt.o
+ obj-$(CONFIG_STPMIC1_WATCHDOG) += stpmic1_wdt.o
+--- /dev/null
++++ b/drivers/watchdog/hasivo-mcu-wdt.c
+@@ -0,0 +1,177 @@
++// SPDX-License-Identifier: GPL-2.0-only
++/*
++ * Hasivo MCU Watchdog Driver
++ *
++ * Hardware watchdog driver for the external management MCU found on
++ * Hasivo / Horaco network switches. Communicates over I2C.
++ *
++ * Protocol reverse-engineered from the stock firmware ("imi" daemon +
++ * i2c-poe.ko kernel module):
++ * - Arm: write 0x4F -> reg 0x09 (unlock), 0x4F -> reg 0x0A
++ * - Disarm: write 0x4F -> reg 0x09 (unlock), 0x3F -> reg 0x0A
++ * - Keepalive: write 0xEE -> reg 0x0B (no unlock needed)
++ *
++ * Copyright (C) 2026 Manuel Stocker <mensi@mensi.ch>
++ * Copyright (C) 2026 Carlo Szelinsky <github@szelinsky.de>
++ */
++
++#include <linux/i2c.h>
++#include <linux/module.h>
++#include <linux/watchdog.h>
++
++#define HASIVO_REG_WDT_UNLOCK 0x09
++ #define HASIVO_WDT_UNLOCK_MAGIC 0x4f
++
++#define HASIVO_REG_WDT_CMD 0x0a
++ #define HASIVO_WDT_CMD_ARM 0x4f
++ #define HASIVO_WDT_CMD_DISARM 0x3f
++
++#define HASIVO_REG_WDT_KEEPALIVE 0x0b
++ #define HASIVO_WDT_KEEPALIVE_MAGIC 0xee
++
++/*
++ * Hardware timeout is fixed in MCU firmware and not software-
++ * configurable. Stock keepalive cadence is 2 s; the actual reset
++ * threshold is empirically in the 10-30 s range. Pick a conservative
++ * value so the kernel-core auto-feed (which fires at timeout/2) leaves
++ * generous slack.
++ */
++#define HASIVO_WDT_TIMEOUT 15
++
++struct hasivo_mcu {
++ struct i2c_client *client;
++ struct watchdog_device wdd;
++};
++
++static int hasivo_mcu_wdt_send_cmd(struct hasivo_mcu *mcu, u8 cmd)
++{
++ int ret;
++
++ ret = i2c_smbus_write_byte_data(mcu->client, HASIVO_REG_WDT_UNLOCK,
++ HASIVO_WDT_UNLOCK_MAGIC);
++ if (ret)
++ return ret;
++
++ return i2c_smbus_write_byte_data(mcu->client, HASIVO_REG_WDT_CMD, cmd);
++}
++
++static int hasivo_mcu_wdt_start(struct watchdog_device *wdd)
++{
++ struct hasivo_mcu *mcu = watchdog_get_drvdata(wdd);
++
++ return hasivo_mcu_wdt_send_cmd(mcu, HASIVO_WDT_CMD_ARM);
++}
++
++static int hasivo_mcu_wdt_stop(struct watchdog_device *wdd)
++{
++ struct hasivo_mcu *mcu = watchdog_get_drvdata(wdd);
++
++ return hasivo_mcu_wdt_send_cmd(mcu, HASIVO_WDT_CMD_DISARM);
++}
++
++static int hasivo_mcu_wdt_ping(struct watchdog_device *wdd)
++{
++ struct hasivo_mcu *mcu = watchdog_get_drvdata(wdd);
++
++ return i2c_smbus_write_byte_data(mcu->client,
++ HASIVO_REG_WDT_KEEPALIVE,
++ HASIVO_WDT_KEEPALIVE_MAGIC);
++}
++
++static const struct watchdog_info hasivo_mcu_wdt_info = {
++ .identity = "Hasivo MCU Watchdog",
++ .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
++};
++
++static const struct watchdog_ops hasivo_mcu_wdt_ops = {
++ .owner = THIS_MODULE,
++ .start = hasivo_mcu_wdt_start,
++ .stop = hasivo_mcu_wdt_stop,
++ .ping = hasivo_mcu_wdt_ping,
++};
++
++static int hasivo_mcu_probe(struct i2c_client *client)
++{
++ struct device *dev = &client->dev;
++ struct hasivo_mcu *mcu;
++ int ret;
++
++ mcu = devm_kzalloc(dev, sizeof(*mcu), GFP_KERNEL);
++ if (!mcu)
++ return -ENOMEM;
++
++ mcu->client = client;
++
++ /*
++ * Arm the watchdog. The stock bootloader normally leaves it
++ * already armed (and the chip's timer has been counting since
++ * then); re-arm explicitly so unexpected boot paths still leave
++ * it in a known state. It is not specified whether the arm
++ * sequence resets the chip's timeout counter, so send an
++ * explicit keepalive afterwards to guarantee a fresh window
++ * before the kernel-side feeder takes over at timeout/2.
++ */
++ ret = hasivo_mcu_wdt_send_cmd(mcu, HASIVO_WDT_CMD_ARM);
++ if (ret)
++ return dev_err_probe(dev, ret, "failed to arm watchdog\n");
++
++ ret = i2c_smbus_write_byte_data(client, HASIVO_REG_WDT_KEEPALIVE,
++ HASIVO_WDT_KEEPALIVE_MAGIC);
++ if (ret)
++ return dev_err_probe(dev, ret,
++ "initial watchdog ping failed\n");
++
++ mcu->wdd.info = &hasivo_mcu_wdt_info;
++ mcu->wdd.ops = &hasivo_mcu_wdt_ops;
++ mcu->wdd.parent = dev;
++ mcu->wdd.timeout = HASIVO_WDT_TIMEOUT;
++ mcu->wdd.min_timeout = HASIVO_WDT_TIMEOUT;
++ mcu->wdd.max_timeout = HASIVO_WDT_TIMEOUT;
++
++ /*
++ * Tell the watchdog core the hardware is already running so it
++ * pings via its own timer at timeout/2 until userspace (procd)
++ * opens /dev/watchdog0 and takes over.
++ */
++ set_bit(WDOG_HW_RUNNING, &mcu->wdd.status);
++
++ watchdog_set_drvdata(&mcu->wdd, mcu);
++ watchdog_stop_on_unregister(&mcu->wdd);
++
++ ret = devm_watchdog_register_device(dev, &mcu->wdd);
++ if (ret)
++ return dev_err_probe(dev, ret,
++ "failed to register watchdog\n");
++
++ dev_info(dev, "Hasivo MCU watchdog armed at 0x%02x (timeout %us)\n",
++ client->addr, mcu->wdd.timeout);
++
++ return 0;
++}
++
++static const struct of_device_id hasivo_mcu_of_match[] = {
++ { .compatible = "hasivo,mcu-wdt" },
++ { }
++};
++MODULE_DEVICE_TABLE(of, hasivo_mcu_of_match);
++
++static const struct i2c_device_id hasivo_mcu_id[] = {
++ { "hasivo-mcu-wdt" },
++ { }
++};
++MODULE_DEVICE_TABLE(i2c, hasivo_mcu_id);
++
++static struct i2c_driver hasivo_mcu_driver = {
++ .driver = {
++ .name = "hasivo-mcu-wdt",
++ .of_match_table = hasivo_mcu_of_match,
++ },
++ .probe = hasivo_mcu_probe,
++ .id_table = hasivo_mcu_id,
++};
++module_i2c_driver(hasivo_mcu_driver);
++
++MODULE_DESCRIPTION("Hasivo MCU Watchdog Driver");
++MODULE_LICENSE("GPL");
++MODULE_AUTHOR("Manuel Stocker <mensi@mensi.ch>");
++MODULE_AUTHOR("Carlo Szelinsky <github@szelinsky.de>");
projects / thirdparty / openwrt.git / commitdiff
