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Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] > > 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. > > E.g: echo 1 > /sys/bus/platform/devices/PALC0001\:00/pldr > > Signed-off-by: Jack Wu > --- > v2: > - Remove extra empty line > - Add missing includes and Remove unnecessary includes, sort includes alphabetically > - Remove noisy dev_info() > - Handle obj->type != ACPI_TYPE_BUFFER as error with proper return code > - Replace miscdevice/file_operations with sysfs attribute (DEVICE_ATTR_WO) to reduce boilerplate > - Propagate trigger_palc_pldr() return code to userspace > - Convert from acpi_driver to platform_driver > --- Generally speaking this looks much better. The only thing missing to me is documentation to go with it since it won't be obvious to a user what the "pldr" sysfs file represents. Also in that sense - if the ACPI PALC0001 device will always represent WWAN reset, then maybe the sysfs file should also be called wwan_reset instead of pldr (platform device reset). > --- > drivers/platform/x86/dell/Kconfig | 6 ++ > drivers/platform/x86/dell/Makefile | 2 + > .../platform/x86/dell/dell-dw5826e-reset.c | 83 +++++++++++++++++++ > 3 files changed, 91 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..52002578ed68 > --- /dev/null > +++ b/drivers/platform/x86/dell/dell-dw5826e-reset.c > @@ -0,0 +1,83 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * dell-dw5826e-reset.c - Dell DW5826e reset driver > + * > + * Copyright (C) 2026 Jackbb Wu > + */ > + > +#include > +#include > +#include > +#include > +#include > + > +static guid_t palc_dsm_guid = > + GUID_INIT(0x5a1a4bba, 0x8006, 0x487e, 0xbe, 0x0a, 0xac, 0xf5, 0xd8, 0xfd, 0xfe, 0x59); > + > +static int trigger_palc_pldr(struct device *dev, acpi_handle handle) > +{ > + union acpi_object *obj; > + int ret = 0; > + > + obj = acpi_evaluate_dsm(handle, &palc_dsm_guid, 1, 1, NULL); > + if (!obj) { > + dev_err(dev, "Failed to evaluate _DSM\n"); > + return -EIO; > + } > + > + if (obj->type != ACPI_TYPE_BUFFER) { > + dev_err(dev, "Unexpected _DSM return type: %d\n", obj->type); > + ret = -EINVAL; > + } > + > + ACPI_FREE(obj); > + return ret; > +} > + > +static ssize_t pldr_store(struct device *dev, struct device_attribute *attr, > + const char *buf, size_t count) > +{ > + acpi_handle handle = ACPI_HANDLE(dev); > + int ret; > + > + ret = trigger_palc_pldr(dev, handle); > + if (ret) > + return ret; > + > + return count; > +} > +static DEVICE_ATTR_WO(pldr); > + > +static struct attribute *palc_attrs[] = { > + &dev_attr_pldr.attr, > + NULL > +}; > +ATTRIBUTE_GROUPS(palc); > + > +static int palc_probe(struct platform_device *pdev) > +{ > + if (!ACPI_HANDLE(&pdev->dev)) > + return -ENODEV; > + > + return 0; > +} > + > +static const struct acpi_device_id palc_acpi_ids[] = { > + { "PALC0001", 0 }, > + { } > +}; > +MODULE_DEVICE_TABLE(acpi, palc_acpi_ids); > + > +static struct platform_driver palc_driver = { > + .driver = { > + .name = "dell-dw5826e-reset", > + .acpi_match_table = palc_acpi_ids, > + .dev_groups = palc_groups, > + }, > + .probe = palc_probe, > +}; > +module_platform_driver(palc_driver); > + > +MODULE_DESCRIPTION("Dell DW5826e reset driver"); > +MODULE_LICENSE("GPL"); > +MODULE_AUTHOR("JackBB Wu"); > -- > 2.34.1 > >