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[34.81.118.25]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a3e3cc794asm180981205ad.70.2026.01.12.10.23.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Jan 2026 10:23:18 -0800 (PST) From: Kuan-Wei Chiu To: geert@linux-m68k.org, sre@kernel.org Cc: jserv@ccns.ncku.edu.tw, eleanor15x@gmail.com, linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-pm@vger.kernel.org, Kuan-Wei Chiu Subject: [PATCH 1/2] power: reset: Add QEMU virt-ctrl driver Date: Mon, 12 Jan 2026 18:22:56 +0000 Message-ID: <20260112182258.1851769-2-visitorckw@gmail.com> X-Mailer: git-send-email 2.52.0.457.g6b5491de43-goog In-Reply-To: <20260112182258.1851769-1-visitorckw@gmail.com> References: <20260112182258.1851769-1-visitorckw@gmail.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 registers a restart handler for system reboot and sets the global pm_power_off callback for system shutdown. 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 --- MAINTAINERS | 6 ++ drivers/power/reset/Kconfig | 10 +++ drivers/power/reset/Makefile | 1 + drivers/power/reset/qemu-virt-ctrl.c | 98 ++++++++++++++++++++++++++++ 4 files changed, 115 insertions(+) create mode 100644 drivers/power/reset/qemu-virt-ctrl.c diff --git a/MAINTAINERS b/MAINTAINERS index 0d044a58cbfe..2586e4162304 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -21179,6 +21179,12 @@ S: Maintained F: drivers/firmware/qemu_fw_cfg.c F: include/uapi/linux/qemu_fw_cfg.h +QEMU VIRT MACHINE SYSTEM CONTROLLER DRIVER +M: Kuan-Wei Chiu +L: linux-pm@vger.kernel.org +S: Maintained +F: drivers/power/reset/qemu-virt-ctrl.c + QLOGIC QL41xxx FCOE DRIVER M: Saurav Kashyap M: Javed Hasan diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig index f6c1bcbb57de..1ca1c2913cbc 100644 --- a/drivers/power/reset/Kconfig +++ b/drivers/power/reset/Kconfig @@ -354,4 +354,14 @@ config POWER_MLXBF help This driver supports reset or low power mode handling for Mellanox BlueField. +config POWER_RESET_QEMU_VIRT_CTRL + bool "QEMU Virt Machine System Controller" + depends on HAS_IOMEM + help + This driver supports the system reset and power off functionality + provided by the QEMU 'virt-ctrl' device. + + Say Y here if you are running Linux on a QEMU virtual machine that + provides this controller, such as the m68k virt machine. + endif diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile index 0e4ae6f6b5c5..d7ae97241a83 100644 --- a/drivers/power/reset/Makefile +++ b/drivers/power/reset/Makefile @@ -41,3 +41,4 @@ obj-$(CONFIG_SYSCON_REBOOT_MODE) += syscon-reboot-mode.o obj-$(CONFIG_POWER_RESET_SC27XX) += sc27xx-poweroff.o obj-$(CONFIG_NVMEM_REBOOT_MODE) += nvmem-reboot-mode.o obj-$(CONFIG_POWER_MLXBF) += pwr-mlxbf.o +obj-$(CONFIG_POWER_RESET_QEMU_VIRT_CTRL) += qemu-virt-ctrl.o diff --git a/drivers/power/reset/qemu-virt-ctrl.c b/drivers/power/reset/qemu-virt-ctrl.c new file mode 100644 index 000000000000..f1acd22172ce --- /dev/null +++ b/drivers/power/reset/qemu-virt-ctrl.c @@ -0,0 +1,98 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * QEMU Virt Machine System Controller Driver + * + * Copyright (C) 2026 Kuan-Wei Chiu + */ + +#include +#include +#include +#include + +/* Registers */ +#define VIRT_CTRL_REG_FEATURES 0x00 +#define VIRT_CTRL_REG_CMD 0x04 + +/* Commands */ +#define CMD_NOOP 0 +#define CMD_RESET 1 +#define CMD_HALT 2 +#define CMD_PANIC 3 + +struct qemu_virt_ctrl { + void __iomem *base; + struct notifier_block restart_nb; +}; + +static void __iomem *qemu_virt_ctrl_base; + +static void qemu_virt_ctrl_power_off(void) +{ + if (qemu_virt_ctrl_base) + iowrite32be(CMD_HALT, qemu_virt_ctrl_base + VIRT_CTRL_REG_CMD); +} + +static int qemu_virt_ctrl_restart(struct notifier_block *nb, unsigned long action, + void *data) +{ + struct qemu_virt_ctrl *vc = container_of(nb, struct qemu_virt_ctrl, restart_nb); + + iowrite32be(CMD_RESET, vc->base + VIRT_CTRL_REG_CMD); + + return NOTIFY_DONE; +} + +static int qemu_virt_ctrl_probe(struct platform_device *pdev) +{ + struct qemu_virt_ctrl *vc; + int ret; + + vc = devm_kzalloc(&pdev->dev, sizeof(*vc), GFP_KERNEL); + if (!vc) + return -ENOMEM; + + vc->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(vc->base)) + return PTR_ERR(vc->base); + + qemu_virt_ctrl_base = vc->base; + + vc->restart_nb.notifier_call = qemu_virt_ctrl_restart; + vc->restart_nb.priority = 128; + + ret = register_restart_handler(&vc->restart_nb); + if (ret) + return dev_err_probe(&pdev->dev, ret, + "cannot register restart handler\n"); + + if (!pm_power_off) + pm_power_off = qemu_virt_ctrl_power_off; + + platform_set_drvdata(pdev, vc); + + return 0; +} + +static void qemu_virt_ctrl_remove(struct platform_device *pdev) +{ + struct qemu_virt_ctrl *vc = platform_get_drvdata(pdev); + + unregister_restart_handler(&vc->restart_nb); + + if (pm_power_off == qemu_virt_ctrl_power_off) + pm_power_off = NULL; +} + +static struct platform_driver qemu_virt_ctrl_driver = { + .probe = qemu_virt_ctrl_probe, + .remove = qemu_virt_ctrl_remove, + .driver = { + .name = "qemu-virt-ctrl", + }, +}; +module_platform_driver(qemu_virt_ctrl_driver); + +MODULE_AUTHOR("Kuan-Wei Chiu "); +MODULE_DESCRIPTION("QEMU Virt Machine System Controller Driver"); +MODULE_LICENSE("GPL"); -- 2.52.0.457.g6b5491de43-goog