m68k: virt: Switch to qemu-virt-ctrl driver

Register the "qemu-virt-ctrl" platform device during board
initialization to utilize the new generic power/reset driver.

Consequently, remove the legacy reset and power-off implementations
specific to the virt machine. The platform's mach_reset callback is
updated to call do_kernel_restart(), bridging the legacy m68k reboot
path to the generic kernel restart handler framework for this machine.

To prevent any regressions in reboot or power-off functionality when
the driver is not built-in, explicitly select POWER_RESET and
POWER_RESET_QEMU_VIRT_CTRL for the VIRT machine in Kconfig.machine.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://patch.msgid.link/20260412211952.3564033-3-visitorckw@gmail.com
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Author: visitorckw

arch/m68k/Kconfig.machine

@@ -133,6 +133,8 @@ config VIRT
 	select GOLDFISH_TIMER
 	select GOLDFISH_TTY
 	select M68040
+	select POWER_RESET
+	select POWER_RESET_QEMU_VIRT_CTRL
 	select RTC_CLASS
 	select RTC_DRV_GOLDFISH
 	select TTY

arch/m68k/virt/config.c

@@ -13,18 +13,6 @@
 
 struct virt_booter_data virt_bi_data;
 
-#define VIRT_CTRL_REG_FEATURES	0x00
-#define VIRT_CTRL_REG_CMD	0x04
-
-static struct resource ctrlres;
-
-enum {
-	CMD_NOOP,
-	CMD_RESET,
-	CMD_HALT,
-	CMD_PANIC,
-};
-
 static void virt_get_model(char *str)
 {
 	/* str is 80 characters long */
@@ -33,25 +21,9 @@ static void virt_get_model(char *str)
 		(u8)(virt_bi_data.qemu_version >> 16),
 		(u8)(virt_bi_data.qemu_version >> 8));
 }
-
-static void virt_halt(void)
-{
-	void __iomem *base = (void __iomem *)virt_bi_data.ctrl.mmio;
-
-	iowrite32be(CMD_HALT, base + VIRT_CTRL_REG_CMD);
-	local_irq_disable();
-	while (1)
-		;
-}
-
 static void virt_reset(void)
 {
-	void __iomem *base = (void __iomem *)virt_bi_data.ctrl.mmio;
-
-	iowrite32be(CMD_RESET, base + VIRT_CTRL_REG_CMD);
-	local_irq_disable();
-	while (1)
-		;
+	do_kernel_restart(NULL);
 }
 
 /*
@@ -113,20 +85,8 @@ void __init config_virt(void)
 		 virt_bi_data.tty.mmio);
 	setup_earlycon(earlycon);
 
-	ctrlres = (struct resource)
-		   DEFINE_RES_MEM_NAMED(virt_bi_data.ctrl.mmio, 0x100,
-					"virtctrl");
-
-	if (request_resource(&iomem_resource, &ctrlres)) {
-		pr_err("Cannot allocate virt controller resource\n");
-		return;
-	}
-
 	mach_init_IRQ = virt_init_IRQ;
 	mach_sched_init = virt_sched_init;
 	mach_get_model = virt_get_model;
 	mach_reset = virt_reset;
-	mach_halt = virt_halt;
-
-	register_platform_power_off(virt_halt);
 }

arch/m68k/virt/platform.c

@@ -30,7 +30,10 @@ static int __init virt_platform_init(void)
 		DEFINE_RES_MEM(virt_bi_data.rtc.mmio + 0x1000, 0x1000),
 		DEFINE_RES_IRQ(virt_bi_data.rtc.irq + 1),
 	};
-	struct platform_device *pdev1, *pdev2;
+	const struct resource virt_ctrl_res[] = {
+		DEFINE_RES_MEM(virt_bi_data.ctrl.mmio, 0x100),
+	};
+	struct platform_device *pdev1, *pdev2, *pdev3;
 	struct platform_device *pdevs[VIRTIO_BUS_NB];
 	unsigned int i;
 	int ret = 0;
@@ -57,19 +60,30 @@ static int __init virt_platform_init(void)
 		goto err_unregister_tty;
 	}
 
+	pdev3 = platform_device_register_simple("qemu-virt-ctrl",
+						PLATFORM_DEVID_NONE,
+						virt_ctrl_res,
+						ARRAY_SIZE(virt_ctrl_res));
+	if (IS_ERR(pdev3)) {
+		ret = PTR_ERR(pdev3);
+		goto err_unregister_rtc;
+	}
+
 	for (i = 0; i < VIRTIO_BUS_NB; i++) {
 		pdevs[i] = virt_virtio_init(i);
 		if (IS_ERR(pdevs[i])) {
 			ret = PTR_ERR(pdevs[i]);
-			goto err_unregister_rtc_virtio;
+			goto err_unregister_virtio;
 		}
 	}
 
 	return 0;
 
-err_unregister_rtc_virtio:
+err_unregister_virtio:
 	while (i > 0)
 		platform_device_unregister(pdevs[--i]);
+	platform_device_unregister(pdev3);
+err_unregister_rtc:
 	platform_device_unregister(pdev2);
 err_unregister_tty:
 	platform_device_unregister(pdev1);