Hi, On 9/3/21 2:38 AM, Daniel Dadap wrote: > A number of upcoming notebook computer designs drive the internal > display panel's backlight PWM through the Embedded Controller (EC). > This EC-based backlight control can be plumbed through to an ACPI > "WMAA" method interface, which in turn can be wrapped by WMI with > the GUID handle 603E9613-EF25-4338-A3D0-C46177516DB7. > > Add a new driver, aliased to the WMAA WMI GUID, to expose a sysfs > backlight class driver to control backlight levels on systems with > EC-driven backlights. > > Signed-off-by: Daniel Dadap <ddadap@xxxxxxxxxx> > Reviewed-By: Thomas Weißschuh <linux@xxxxxxxxxxxxxx> Thank you for your patch, I've applied this patch to my review-hans branch: https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans Note it will show up in my review-hans branch once I've pushed my local branch there, which might take a while. Once I've run some tests on this branch the patches there will be added to the platform-drivers-x86/for-next branch and eventually will be included in the pdx86 pull-request to Linus for the next merge-window. Regards, Hans > --- > > v2: Convert to WMI subsystem driver, suggested by Mario Limonciello > <mario.limonciello@xxxxxxxxxxx>; various cleanups suggested by > Barnabás Pőcze <pobrn@xxxxxxxxxxxxxx> > v3: Address assorted style nits raised by Andy Shevchenko > <andy.shevchenko@xxxxxxxxx> in response to a related patch; remove > additional behavior change to WMI subsystem from patch series as > recommended by Hans de Goede <hdegoede@xxxxxxxxxx> > v4: Use MODULE_DEVICE_TABLE() (Thomas Weißschuh <thomas@xxxxxxxx>) > Fix scope of internal driver state; various style fixes (Barnabás > Pőcze, Andy Shevchenko) > Use devm_backlight_device_register() (Barnabás Pőcze) > Add kerneldoc comments for enums and structs (Andy Shevchenko) > v5: Remove Aaron Plattner as author, as suggested by Aaron Plattner > <aplattner@xxxxxxxxxx> > Register as BACKLIGHT_FIRMWARE rather than BACKLIGHT_PLATFORM; > Return negative errno if .get_brightness() fails (Thomas Weißschuh) > Assorted style improvements (Andy Shevchenko, Thomas Weißschuh) > v6: Make behavior of callers of wmi_call_wmaa() more consistent; > simplify potentially confusing description in Kconfig help text > (Thomas Weißschuh) > > MAINTAINERS | 6 + > drivers/platform/x86/Kconfig | 16 ++ > drivers/platform/x86/Makefile | 1 + > drivers/platform/x86/wmaa-backlight-wmi.c | 205 ++++++++++++++++++++++ > 4 files changed, 228 insertions(+) > create mode 100644 drivers/platform/x86/wmaa-backlight-wmi.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index bbaecde94aa0..fd7362a86c6d 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -20008,6 +20008,12 @@ L: linux-wireless@xxxxxxxxxxxxxxx > S: Odd fixes > F: drivers/net/wireless/wl3501* > > +WMAA BACKLIGHT DRIVER > +M: Daniel Dadap <ddadap@xxxxxxxxxx> > +L: platform-driver-x86@xxxxxxxxxxxxxxx > +S: Supported > +F: drivers/platform/x86/wmaa-backlight-wmi.c > + > WOLFSON MICROELECTRONICS DRIVERS > L: patches@xxxxxxxxxxxxxxxxxxxxx > S: Supported > diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig > index d12db6c316ea..00f021eda25c 100644 > --- a/drivers/platform/x86/Kconfig > +++ b/drivers/platform/x86/Kconfig > @@ -113,6 +113,22 @@ config PEAQ_WMI > help > Say Y here if you want to support WMI-based hotkeys on PEAQ 2-in-1s. > > +config WMAA_BACKLIGHT_WMI > + tristate "ACPI WMAA Backlight Driver" > + depends on ACPI_WMI > + depends on BACKLIGHT_CLASS_DEVICE > + help > + This driver provides a sysfs backlight interface for notebook > + systems which expose the WMAA ACPI method and an associated WMI > + wrapper to drive LCD backlight levels through the Embedded Controller > + (EC). > + > + Say Y or M here if you want to control the backlight on a notebook > + system with an EC-driven backlight using the ACPI WMAA method. > + > + If you choose to compile this driver as a module the module will be > + called wmaa-backlight-wmi. > + > config XIAOMI_WMI > tristate "Xiaomi WMI key driver" > depends on ACPI_WMI > diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile > index 7ee369aab10d..109c1714237d 100644 > --- a/drivers/platform/x86/Makefile > +++ b/drivers/platform/x86/Makefile > @@ -14,6 +14,7 @@ obj-$(CONFIG_INTEL_WMI_SBL_FW_UPDATE) += intel-wmi-sbl-fw-update.o > obj-$(CONFIG_INTEL_WMI_THUNDERBOLT) += intel-wmi-thunderbolt.o > obj-$(CONFIG_MXM_WMI) += mxm-wmi.o > obj-$(CONFIG_PEAQ_WMI) += peaq-wmi.o > +obj-$(CONFIG_WMAA_BACKLIGHT_WMI) += wmaa-backlight-wmi.o > obj-$(CONFIG_XIAOMI_WMI) += xiaomi-wmi.o > obj-$(CONFIG_GIGABYTE_WMI) += gigabyte-wmi.o > > diff --git a/drivers/platform/x86/wmaa-backlight-wmi.c b/drivers/platform/x86/wmaa-backlight-wmi.c > new file mode 100644 > index 000000000000..f5c4f8337c2c > --- /dev/null > +++ b/drivers/platform/x86/wmaa-backlight-wmi.c > @@ -0,0 +1,205 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved. > + */ > + > +#include <linux/acpi.h> > +#include <linux/backlight.h> > +#include <linux/mod_devicetable.h> > +#include <linux/module.h> > +#include <linux/types.h> > +#include <linux/wmi.h> > + > +/** > + * enum wmaa_method - WMI method IDs for ACPI WMAA > + * @WMAA_METHOD_LEVEL: Get or set the brightness level, > + * or get the maximum brightness level. > + * @WMAA_METHOD_SOURCE: Get the source for backlight control. > + */ > +enum wmaa_method { > + WMAA_METHOD_LEVEL = 1, > + WMAA_METHOD_SOURCE = 2, > + WMAA_METHOD_MAX > +}; > + > +/** > + * enum wmaa_mode - Operation mode for ACPI WMAA method > + * @WMAA_MODE_GET: Get the current brightness level or source. > + * @WMAA_MODE_SET: Set the brightness level. > + * @WMAA_MODE_GET_MAX_LEVEL: Get the maximum brightness level. This is only > + * valid when the WMI method is %WMAA_METHOD_LEVEL. > + */ > +enum wmaa_mode { > + WMAA_MODE_GET = 0, > + WMAA_MODE_SET = 1, > + WMAA_MODE_GET_MAX_LEVEL = 2, > + WMAA_MODE_MAX > +}; > + > +/** > + * enum wmaa_source - Backlight brightness control source identification > + * @WMAA_SOURCE_GPU: Backlight brightness is controlled by the GPU. > + * @WMAA_SOURCE_EC: Backlight brightness is controlled by the system's > + * Embedded Controller (EC). > + * @WMAA_SOURCE_AUX: Backlight brightness is controlled over the DisplayPort > + * AUX channel. > + */ > +enum wmaa_source { > + WMAA_SOURCE_GPU = 1, > + WMAA_SOURCE_EC = 2, > + WMAA_SOURCE_AUX = 3, > + WMAA_SOURCE_MAX > +}; > + > +/** > + * struct wmaa_args - arguments for the ACPI WMAA method > + * @mode: Pass in an &enum wmaa_mode value to select between getting or > + * setting a value. > + * @val: In parameter for value to set when operating in %WMAA_MODE_SET > + * mode. Not used in %WMAA_MODE_GET or %WMAA_MODE_GET_MAX_LEVEL mode. > + * @ret: Out parameter returning retrieved value when operating in > + * %WMAA_MODE_GET or %WMAA_MODE_GET_MAX_LEVEL mode. Not used in > + * %WMAA_MODE_SET mode. > + * @ignored: Padding; not used. The ACPI method expects a 24 byte params struct. > + * > + * This is the parameters structure for the ACPI WMAA method as wrapped by WMI. > + * The value passed in to @val or returned by @ret will be a brightness value > + * when the WMI method ID is %WMAA_METHOD_LEVEL, or an &enum wmaa_source value > + * when the WMI method ID is %WMAA_METHOD_SOURCE. > + */ > +struct wmaa_args { > + u32 mode; > + u32 val; > + u32 ret; > + u32 ignored[3]; > +}; > + > +/** > + * wmi_call_wmaa() - helper function for calling ACPI WMAA via its WMI wrapper > + * @w: Pointer to the struct wmi_device identified by %WMAA_WMI_GUID > + * @id: The method ID for the ACPI WMAA method (e.g. %WMAA_METHOD_LEVEL or > + * %WMAA_METHOD_SOURCE) > + * @mode: The operation to perform on the ACPI WMAA method (e.g. %WMAA_MODE_SET > + * or %WMAA_MODE_GET) > + * @val: Pointer to a value passed in by the caller when @mode is > + * %WMAA_MODE_SET, or a value passed out to the caller when @mode is > + * %WMAA_MODE_GET or %WMAA_MODE_GET_MAX_LEVEL. > + * > + * Returns 0 on success, or a negative error number on failure. > + */ > +static int wmi_call_wmaa(struct wmi_device *w, enum wmaa_method id, enum wmaa_mode mode, u32 *val) > +{ > + struct wmaa_args args = { > + .mode = mode, > + .val = 0, > + .ret = 0, > + }; > + struct acpi_buffer buf = { (acpi_size)sizeof(args), &args }; > + acpi_status status; > + > + if (id < WMAA_METHOD_LEVEL || id >= WMAA_METHOD_MAX || > + mode < WMAA_MODE_GET || mode >= WMAA_MODE_MAX) > + return -EINVAL; > + > + if (mode == WMAA_MODE_SET) > + args.val = *val; > + > + status = wmidev_evaluate_method(w, 0, id, &buf, &buf); > + if (ACPI_FAILURE(status)) { > + dev_err(&w->dev, "ACPI WMAA failed: %s\n", > + acpi_format_exception(status)); > + return -EIO; > + } > + > + if (mode != WMAA_MODE_SET) > + *val = args.ret; > + > + return 0; > +} > + > +static int wmaa_backlight_update_status(struct backlight_device *bd) > +{ > + struct wmi_device *wdev = bl_get_data(bd); > + > + return wmi_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_SET, > + &bd->props.brightness); > +} > + > +static int wmaa_backlight_get_brightness(struct backlight_device *bd) > +{ > + struct wmi_device *wdev = bl_get_data(bd); > + u32 level; > + int ret; > + > + ret = wmi_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_GET, &level); > + if (ret < 0) > + return ret; > + > + return level; > +} > + > +static const struct backlight_ops wmaa_backlight_ops = { > + .update_status = wmaa_backlight_update_status, > + .get_brightness = wmaa_backlight_get_brightness, > +}; > + > +static int wmaa_backlight_wmi_probe(struct wmi_device *wdev, const void *ctx) > +{ > + struct backlight_properties props = {}; > + struct backlight_device *bdev; > + u32 source; > + int ret; > + > + ret = wmi_call_wmaa(wdev, WMAA_METHOD_SOURCE, WMAA_MODE_GET, &source); > + if (ret) > + return ret; > + > + /* > + * This driver is only to be used when brightness control is handled > + * by the EC; otherwise, the GPU driver(s) should control brightness. > + */ > + if (source != WMAA_SOURCE_EC) > + return -ENODEV; > + > + /* > + * Identify this backlight device as a firmware device so that it can > + * be prioritized over any exposed GPU-driven raw device(s). > + */ > + props.type = BACKLIGHT_FIRMWARE; > + > + ret = wmi_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_GET_MAX_LEVEL, > + &props.max_brightness); > + if (ret) > + return ret; > + > + ret = wmi_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_GET, > + &props.brightness); > + if (ret) > + return ret; > + > + bdev = devm_backlight_device_register(&wdev->dev, "wmaa_backlight", > + &wdev->dev, wdev, > + &wmaa_backlight_ops, &props); > + return PTR_ERR_OR_ZERO(bdev); > +} > + > +#define WMAA_WMI_GUID "603E9613-EF25-4338-A3D0-C46177516DB7" > + > +static const struct wmi_device_id wmaa_backlight_wmi_id_table[] = { > + { .guid_string = WMAA_WMI_GUID }, > + { } > +}; > +MODULE_DEVICE_TABLE(wmi, wmaa_backlight_wmi_id_table); > + > +static struct wmi_driver wmaa_backlight_wmi_driver = { > + .driver = { > + .name = "wmaa-backlight", > + }, > + .probe = wmaa_backlight_wmi_probe, > + .id_table = wmaa_backlight_wmi_id_table, > +}; > +module_wmi_driver(wmaa_backlight_wmi_driver); > + > +MODULE_AUTHOR("Daniel Dadap <ddadap@xxxxxxxxxx>"); > +MODULE_DESCRIPTION("WMAA Backlight WMI driver"); > +MODULE_LICENSE("GPL"); >
