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ad9d2cd065
Add a new driver for the 'virt-ctrl' device found on QEMU virt machines (e.g. m68k). This device provides a simple interface for system reset and power off [1]. This driver utilizes the modern system-off API to register callbacks for both system restart and power off. It also registers a reboot notifier to catch SYS_HALT events, ensuring that LINUX_REBOOT_CMD_HALT is properly handled. It is designed to be generic and can be reused by other architectures utilizing this QEMU device. Link: https://gitlab.com/qemu-project/qemu/-/blob/v10.2.0/hw/misc/virt_ctrl.c [1] Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com> Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com> Link: https://patch.msgid.link/20260412211952.3564033-2-visitorckw@gmail.com Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
123 lines
2.9 KiB
C
123 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* QEMU Virt Machine System Controller Driver
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*
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* Copyright (C) 2026 Kuan-Wei Chiu <visitorckw@gmail.com>
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*/
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include <linux/platform_device.h>
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#include <linux/reboot.h>
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/* Registers */
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#define VIRT_CTRL_REG_FEATURES 0x00
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#define VIRT_CTRL_REG_CMD 0x04
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/* Commands */
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#define CMD_NOOP 0
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#define CMD_RESET 1
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#define CMD_HALT 2
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#define CMD_PANIC 3
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struct qemu_virt_ctrl {
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void __iomem *base;
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struct notifier_block reboot_nb;
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};
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static inline void virt_ctrl_write32(u32 val, void __iomem *addr)
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{
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if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
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iowrite32be(val, addr);
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else
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iowrite32(val, addr);
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}
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static int qemu_virt_ctrl_power_off(struct sys_off_data *data)
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{
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struct qemu_virt_ctrl *ctrl = data->cb_data;
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virt_ctrl_write32(CMD_HALT, ctrl->base + VIRT_CTRL_REG_CMD);
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return NOTIFY_DONE;
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}
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static int qemu_virt_ctrl_restart(struct sys_off_data *data)
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{
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struct qemu_virt_ctrl *ctrl = data->cb_data;
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virt_ctrl_write32(CMD_RESET, ctrl->base + VIRT_CTRL_REG_CMD);
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return NOTIFY_DONE;
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}
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static int qemu_virt_ctrl_reboot_notify(struct notifier_block *nb,
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unsigned long action, void *data)
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{
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struct qemu_virt_ctrl *ctrl = container_of(nb, struct qemu_virt_ctrl, reboot_nb);
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if (action == SYS_HALT)
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virt_ctrl_write32(CMD_HALT, ctrl->base + VIRT_CTRL_REG_CMD);
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return NOTIFY_DONE;
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}
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static int qemu_virt_ctrl_probe(struct platform_device *pdev)
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{
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struct qemu_virt_ctrl *ctrl;
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int ret;
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ctrl = devm_kzalloc(&pdev->dev, sizeof(*ctrl), GFP_KERNEL);
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if (!ctrl)
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return -ENOMEM;
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ctrl->base = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(ctrl->base))
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return PTR_ERR(ctrl->base);
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ret = devm_register_sys_off_handler(&pdev->dev,
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SYS_OFF_MODE_RESTART,
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SYS_OFF_PRIO_DEFAULT,
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qemu_virt_ctrl_restart,
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ctrl);
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if (ret)
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return dev_err_probe(&pdev->dev, ret,
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"cannot register restart handler\n");
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ret = devm_register_sys_off_handler(&pdev->dev,
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SYS_OFF_MODE_POWER_OFF,
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SYS_OFF_PRIO_DEFAULT,
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qemu_virt_ctrl_power_off,
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ctrl);
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if (ret)
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return dev_err_probe(&pdev->dev, ret,
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"cannot register power-off handler\n");
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ctrl->reboot_nb.notifier_call = qemu_virt_ctrl_reboot_notify;
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ret = devm_register_reboot_notifier(&pdev->dev, &ctrl->reboot_nb);
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if (ret)
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return dev_err_probe(&pdev->dev, ret, "cannot register reboot notifier\n");
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return 0;
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}
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static const struct platform_device_id qemu_virt_ctrl_id[] = {
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{ "qemu-virt-ctrl", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(platform, qemu_virt_ctrl_id);
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static struct platform_driver qemu_virt_ctrl_driver = {
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.probe = qemu_virt_ctrl_probe,
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.driver = {
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.name = "qemu-virt-ctrl",
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},
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.id_table = qemu_virt_ctrl_id,
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};
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module_platform_driver(qemu_virt_ctrl_driver);
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MODULE_AUTHOR("Kuan-Wei Chiu <visitorckw@gmail.com>");
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MODULE_DESCRIPTION("QEMU Virt Machine System Controller Driver");
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MODULE_LICENSE("GPL");
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