[PATCH] platform/x86: dell-dw5826e: Add reset driver for DW5826e

[Jack Wu <wojackbb@gmail.com>]

If the DW5826e is in a frozen state and unable to receive USB commands,
this driver provides a method for the user to reset the DW5826e via ACPI.

Signed-off-by: Jack Wu <jackbb_wu@compal.com>
---
 drivers/platform/x86/dell/Kconfig             |   6 +
 drivers/platform/x86/dell/Makefile            |   2 +
 .../platform/x86/dell/dell-dw5826e-reset.c    | 120 ++++++++++++++++++
 3 files changed, 128 insertions(+)
 create mode 100644 drivers/platform/x86/dell/dell-dw5826e-reset.c

diff --git a/drivers/platform/x86/dell/Kconfig b/drivers/platform/x86/dell/Kconfig
index 738c108c2163..c4540c837a88 100644
--- a/drivers/platform/x86/dell/Kconfig
+++ b/drivers/platform/x86/dell/Kconfig
@@ -276,4 +276,10 @@ config DELL_WMI_SYSMAN
 	  To compile this driver as a module, choose M here: the module will
 	  be called dell-wmi-sysman.
 
+config DELL_DW5826E_RESET
+	tristate "Dell DW5826e PLDR reset support"
+	default m
+	depends on ACPI
+	help
+	  This adds support for the Dell DW5826e PLDR reset via ACPI
 endif # X86_PLATFORM_DRIVERS_DELL
diff --git a/drivers/platform/x86/dell/Makefile b/drivers/platform/x86/dell/Makefile
index c7501c25e627..8150283cfd1d 100644
--- a/drivers/platform/x86/dell/Makefile
+++ b/drivers/platform/x86/dell/Makefile
@@ -28,3 +28,5 @@ obj-$(CONFIG_DELL_WMI_DESCRIPTOR)		+= dell-wmi-descriptor.o
 obj-$(CONFIG_DELL_WMI_DDV)			+= dell-wmi-ddv.o
 obj-$(CONFIG_DELL_WMI_LED)			+= dell-wmi-led.o
 obj-$(CONFIG_DELL_WMI_SYSMAN)			+= dell-wmi-sysman/
+obj-$(CONFIG_DELL_DW5826E_RESET)		+= dell-dw5826e-reset.o
+
diff --git a/drivers/platform/x86/dell/dell-dw5826e-reset.c b/drivers/platform/x86/dell/dell-dw5826e-reset.c
new file mode 100644
index 000000000000..28865a123c63
--- /dev/null
+++ b/drivers/platform/x86/dell/dell-dw5826e-reset.c
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  dell-dw5826e-reset.c - Dell DW5826e reset driver
+ *
+ *  Copyright (C) 2026 Jackbb Wu <jackbb.wu@compal.com>
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/acpi.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+
+static guid_t palc_dsm_guid =
+	GUID_INIT(0x5a1a4bba, 0x8006, 0x487e, 0xbe, 0x0a, 0xac, 0xf5, 0xd8, 0xfd, 0xfe, 0x59);
+
+struct palc_dev {
+	struct device *dev;
+	acpi_handle handle;
+	struct miscdevice miscdev;
+};
+
+static int trigger_palc_pldr(struct palc_dev *palc)
+{
+	union acpi_object *obj;
+
+	dev_info(palc->dev, "Triggering PLDR via ACPI _DSM Function 1...\n");
+
+	obj = acpi_evaluate_dsm(palc->handle, &palc_dsm_guid, 1, 1, NULL);
+
+	if (!obj) {
+		dev_err(palc->dev, "Failed to evaluate _DSM\n");
+		return -EIO;
+	}
+
+	if (obj->type == ACPI_TYPE_BUFFER)
+		dev_info(palc->dev, "PLDR _DSM executed successfully\n");
+
+	ACPI_FREE(obj);
+	return 0;
+}
+
+static ssize_t palc_write(struct file *filp, const char __user *buf, size_t count, loff_t *ppos)
+{
+	struct palc_dev *palc = filp->private_data;
+
+	trigger_palc_pldr(palc);
+
+	return count;
+}
+
+static int palc_open(struct inode *inode, struct file *filp)
+{
+	struct palc_dev *palc = container_of(filp->private_data, struct palc_dev, miscdev);
+
+	filp->private_data = palc;
+	return 0;
+}
+
+static const struct file_operations palc_fops = {
+	.owner  = THIS_MODULE,
+	.open   = palc_open,
+	.write  = palc_write,
+};
+
+static int palc_acpi_probe(struct acpi_device *adev)
+{
+	struct palc_dev *palc;
+
+	palc = devm_kzalloc(&adev->dev, sizeof(*palc), GFP_KERNEL);
+	if (!palc)
+		return -ENOMEM;
+
+	palc->dev    = &adev->dev;
+	palc->handle = adev->handle;
+
+	palc->miscdev.minor  = MISC_DYNAMIC_MINOR;
+	palc->miscdev.name   = "reset_palc";
+	palc->miscdev.fops   = &palc_fops;
+	palc->miscdev.parent = &adev->dev;
+
+	if (misc_register(&palc->miscdev))
+		return -EINVAL;
+
+	dev_set_drvdata(&adev->dev, palc);
+
+	dev_info(&adev->dev, "DW5826e Reset Device (PALC0001) Driver Loaded\n");
+	return 0;
+}
+
+static void palc_acpi_remove(struct acpi_device *adev)
+{
+	struct palc_dev *palc = dev_get_drvdata(&adev->dev);
+
+	if (palc)
+		misc_deregister(&palc->miscdev);
+}
+
+static const struct acpi_device_id palc_acpi_ids[] = {
+	{ "PALC0001", 0 },
+	{ "", 0 }
+};
+
+static struct acpi_driver palc_acpi_driver = {
+	.name  = "palc_reset",
+	.ids   = palc_acpi_ids,
+	.ops = {
+		.add    = palc_acpi_probe,
+		.remove = palc_acpi_remove,
+	},
+};
+
+MODULE_DEVICE_TABLE(acpi, palc_acpi_ids);
+module_acpi_driver(palc_acpi_driver);
+
+MODULE_DESCRIPTION("Dell DW5826e reset driver");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("JackBB Wu");
-- 
2.34.1