Re: [PATCH] platform/x86: dell-dw5826e: Add reset driver for DW5826e
From: 吳逼逼
Date: Fri Apr 10 2026 - 05:58:39 EST
About good place:
drivers/reset/ is for the reset controller subsystem
(reset_controller_dev), which provides reset signals consumed by other
subsystem drivers.
This driver doesn't fit that model — it exposes a Dell
platform-specific ACPI _DSM method (PALC0001) to userspace for
triggering a PLDR reset on the DW5826e WWAN module. Since this is a
Dell-specific ACPI interface that only exists on Dell laptops,
drivers/platform/x86/dell/ is the appropriate location, consistent
with other Dell platform drivers
About other issue:
I fixed them in v2 and upload It
Thanks.
Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx> 於 2026年4月8日週三 下午9:46寫道：
>
> On Wed, 8 Apr 2026, Jack Wu wrote:
>
> > 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@xxxxxxxxxx>
> > ---
> > 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
>
> Another thing,
>
> I wonder if this is good place for this, as kernel also has drivers/reset/.
>
> --
> i.
>
> > +
> > 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@xxxxxxxxxx>
> > + *
> > + */
> > +
> > +#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");
> >
>