On Tue, Mar 03, 2026 at 06:12:59AM +0000, Jingyuan Liang wrote:
> From: Angela Czubak <[email protected]>
>
> Detect SPI HID devices described in ACPI.
>
> Signed-off-by: Angela Czubak <[email protected]>
> Signed-off-by: Jingyuan Liang <[email protected]>
> ---
> drivers/hid/spi-hid/Kconfig | 15 +++
> drivers/hid/spi-hid/Makefile | 1 +
> drivers/hid/spi-hid/spi-hid-acpi.c | 253
> +++++++++++++++++++++++++++++++++++++
> drivers/hid/spi-hid/spi-hid-core.c | 27 +---
> drivers/hid/spi-hid/spi-hid.h | 44 +++++++
> 5 files changed, 316 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/hid/spi-hid/Kconfig b/drivers/hid/spi-hid/Kconfig
> index 836fdefe8345..114b1e00da39 100644
> --- a/drivers/hid/spi-hid/Kconfig
> +++ b/drivers/hid/spi-hid/Kconfig
> @@ -10,6 +10,21 @@ menuconfig SPI_HID
>
> if SPI_HID
>
> +config SPI_HID_ACPI
> + tristate "HID over SPI transport layer ACPI driver"
> + depends on ACPI
> + select SPI_HID_CORE
> + help
> + Say Y here if you use a keyboard, a touchpad, a touchscreen, or any
> + other HID based devices which are connected to your computer via SPI.
> + This driver supports ACPI-based systems.
> +
> + If unsure, say N.
> +
> + This support is also available as a module. If so, the module
> + will be called spi-hid-acpi. It will also build/depend on the
> + module spi-hid.
> +
> config SPI_HID_CORE
> tristate
> endif
> diff --git a/drivers/hid/spi-hid/Makefile b/drivers/hid/spi-hid/Makefile
> index 92e24cddbfc2..753c7b7a7844 100644
> --- a/drivers/hid/spi-hid/Makefile
> +++ b/drivers/hid/spi-hid/Makefile
> @@ -7,3 +7,4 @@
>
> obj-$(CONFIG_SPI_HID_CORE) += spi-hid.o
> spi-hid-objs = spi-hid-core.o
> +obj-$(CONFIG_SPI_HID_ACPI) += spi-hid-acpi.o
> diff --git a/drivers/hid/spi-hid/spi-hid-acpi.c
> b/drivers/hid/spi-hid/spi-hid-acpi.c
> new file mode 100644
> index 000000000000..612e74fe72f9
> --- /dev/null
> +++ b/drivers/hid/spi-hid/spi-hid-acpi.c
> @@ -0,0 +1,253 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * HID over SPI protocol, ACPI related code
> + *
> + * Copyright (c) 2021 Microsoft Corporation
> + * Copyright (c) 2026 Google LLC
> + *
> + * This code was forked out of the HID over SPI core code, which is partially
> + * based on "HID over I2C protocol implementation:
> + *
> + * Copyright (c) 2012 Benjamin Tissoires <[email protected]>
> + * Copyright (c) 2012 Ecole Nationale de l'Aviation Civile, France
> + * Copyright (c) 2012 Red Hat, Inc
> + *
> + * which in turn is partially based on "USB HID support for Linux":
> + *
> + * Copyright (c) 1999 Andreas Gal
> + * Copyright (c) 2000-2005 Vojtech Pavlik <[email protected]>
> + * Copyright (c) 2005 Michael Haboustak <[email protected]> for Concept2,
> Inc
> + * Copyright (c) 2007-2008 Oliver Neukum
> + * Copyright (c) 2006-2010 Jiri Kosina
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/reset.h>
> +#include <linux/uuid.h>
> +
> +#include "spi-hid.h"
> +
> +/* Config structure is filled with data from ACPI */
> +struct spi_hid_acpi_config {
> + struct spihid_ops ops;
> +
> + struct spi_hid_conf property_conf;
> + u32 post_power_on_delay_ms;
> + u32 minimal_reset_delay_ms;
> + struct acpi_device *adev;
> +};
> +
> +/* HID SPI Device: 6e2ac436-0fcf41af-a265-b32a220dcfab */
> +static guid_t spi_hid_guid =
> + GUID_INIT(0x6E2AC436, 0x0FCF, 0x41AF,
> + 0xA2, 0x65, 0xB3, 0x2A, 0x22, 0x0D, 0xCF, 0xAB);
> +
> +static int spi_hid_acpi_populate_config(struct spi_hid_acpi_config *conf,
> + struct acpi_device *adev)
> +{
> + acpi_handle handle = acpi_device_handle(adev);
> + union acpi_object *obj;
> +
> + conf->adev = adev;
> +
> + /* Revision 3 for HID over SPI V1, see specification. */
> + obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 1, NULL,
> + ACPI_TYPE_INTEGER);
> + if (!obj) {
> + acpi_handle_err(handle,
> + "Error _DSM call to get HID input report header
> address failed");
> + return -ENODEV;
> + }
> + conf->property_conf.input_report_header_address = obj->integer.value;
> + ACPI_FREE(obj);
> +
> + obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 2, NULL,
> + ACPI_TYPE_INTEGER);
> + if (!obj) {
> + acpi_handle_err(handle,
> + "Error _DSM call to get HID input report body
> address failed");
> + return -ENODEV;
> + }
> + conf->property_conf.input_report_body_address = obj->integer.value;
> + ACPI_FREE(obj);
> +
> + obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 3, NULL,
> + ACPI_TYPE_INTEGER);
> + if (!obj) {
> + acpi_handle_err(handle,
> + "Error _DSM call to get HID output report
> header address failed");
> + return -ENODEV;
> + }
> + conf->property_conf.output_report_address = obj->integer.value;
> + ACPI_FREE(obj);
> +
> + obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 4, NULL,
> + ACPI_TYPE_BUFFER);
> + if (!obj) {
> + acpi_handle_err(handle,
> + "Error _DSM call to get HID read opcode
> failed");
> + return -ENODEV;
> + }
> + if (obj->buffer.length == 1) {
> + conf->property_conf.read_opcode = obj->buffer.pointer[0];
> + } else {
> + acpi_handle_err(handle,
> + "Error _DSM call to get HID read opcode, too
> long buffer");
> + ACPI_FREE(obj);
> + return -ENODEV;
> + }
> + ACPI_FREE(obj);
> +
> + obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 5, NULL,
> + ACPI_TYPE_BUFFER);
> + if (!obj) {
> + acpi_handle_err(handle,
> + "Error _DSM call to get HID write opcode
> failed");
> + return -ENODEV;
> + }
> + if (obj->buffer.length == 1) {
> + conf->property_conf.write_opcode = obj->buffer.pointer[0];
> + } else {
> + acpi_handle_err(handle,
> + "Error _DSM call to get HID write opcode, too
> long buffer");
> + ACPI_FREE(obj);
> + return -ENODEV;
> + }
> + ACPI_FREE(obj);
> +
> + /* Value not provided in ACPI,*/
> + conf->post_power_on_delay_ms = 5;
> + conf->minimal_reset_delay_ms = 150;
> +
> + if (!acpi_has_method(handle, "_RST")) {
> + acpi_handle_err(handle, "No reset method for acpi handle");
> + return -ENODEV;
I would return -EINVAL as we have the device with right _DSM but without
mandated by the spec _RST.
> + }
> +
> + /* FIXME: not reading hid-over-spi-flags, multi-SPI not supported */
> +
> + return 0;
> +}
> +
> +static int spi_hid_acpi_power_none(struct spihid_ops *ops)
> +{
> + return 0;
> +}
> +
> +static int spi_hid_acpi_power_down(struct spihid_ops *ops)
> +{
> + struct spi_hid_acpi_config *conf = container_of(ops,
> + struct
> spi_hid_acpi_config,
> + ops);
> +
> + return acpi_device_set_power(conf->adev, ACPI_STATE_D3);
> +}
> +
> +static int spi_hid_acpi_power_up(struct spihid_ops *ops)
> +{
> + struct spi_hid_acpi_config *conf = container_of(ops,
> + struct
> spi_hid_acpi_config,
> + ops);
> + int error;
> +
> + error = acpi_device_set_power(conf->adev, ACPI_STATE_D0);
> + if (error) {
> + dev_err(&conf->adev->dev, "Error could not power up ACPI
> device: %d.", error);
> + return error;
> + }
> +
> + if (conf->post_power_on_delay_ms)
> + msleep(conf->post_power_on_delay_ms);
> +
> + return 0;
> +}
> +
> +static int spi_hid_acpi_assert_reset(struct spihid_ops *ops)
> +{
> + return 0;
> +}
> +
> +static int spi_hid_acpi_deassert_reset(struct spihid_ops *ops)
> +{
> + struct spi_hid_acpi_config *conf = container_of(ops,
> + struct
> spi_hid_acpi_config,
> + ops);
> +
> + return device_reset(&conf->adev->dev);
> +}
> +
> +static void spi_hid_acpi_sleep_minimal_reset_delay(struct spihid_ops *ops)
> +{
> + struct spi_hid_acpi_config *conf = container_of(ops,
> + struct
> spi_hid_acpi_config,
> + ops);
> + usleep_range(1000 * conf->minimal_reset_delay_ms,
> + 1000 * (conf->minimal_reset_delay_ms + 1));
I'd probably use "fsleep(conf->minimal_reset_delay_ms * 1000)".
> +}
> +
> +static int spi_hid_acpi_probe(struct spi_device *spi)
> +{
> + struct device *dev = &spi->dev;
> + struct acpi_device *adev;
> + struct spi_hid_acpi_config *config;
> + int error;
> +
> + adev = ACPI_COMPANION(dev);
> + if (!adev) {
> + dev_err(dev, "Error could not get ACPI device.");
> + return -ENODEV;
> + }
> +
> + config = devm_kzalloc(dev, sizeof(struct spi_hid_acpi_config),
> + GFP_KERNEL);
> + if (!config)
> + return -ENOMEM;
> +
> + if (acpi_device_power_manageable(adev)) {
> + config->ops.power_up = spi_hid_acpi_power_up;
> + config->ops.power_down = spi_hid_acpi_power_down;
> + } else {
> + config->ops.power_up = spi_hid_acpi_power_none;
> + config->ops.power_down = spi_hid_acpi_power_none;
> + }
> + config->ops.assert_reset = spi_hid_acpi_assert_reset;
> + config->ops.deassert_reset = spi_hid_acpi_deassert_reset;
> + config->ops.sleep_minimal_reset_delay =
> + spi_hid_acpi_sleep_minimal_reset_delay;
> +
> + error = spi_hid_acpi_populate_config(config, adev);
> + if (error) {
> + dev_err(dev, "%s: unable to populate config data.", __func__);
> + return error;
> + }
I would add a blank line.
> + return spi_hid_core_probe(spi, &config->ops, &config->property_conf);
> +}
> +
> +static const struct acpi_device_id spi_hid_acpi_match[] = {
> + { "ACPI0C51", 0 },
> + { "PNP0C51", 0 },
> + { },
No comma on sentinels.
> +};
> +MODULE_DEVICE_TABLE(acpi, spi_hid_acpi_match);
> +
> +static struct spi_driver spi_hid_acpi_driver = {
> + .driver = {
> + .name = "spi_hid_acpi",
> + .owner = THIS_MODULE,
> + .acpi_match_table = ACPI_PTR(spi_hid_acpi_match),
This is dependent on ACPI, so no need to sue ACPI_PTR().
> + .probe_type = PROBE_PREFER_ASYNCHRONOUS,
> + .dev_groups = spi_hid_groups,
> + },
> + .probe = spi_hid_acpi_probe,
> + .remove = spi_hid_core_remove,
> +};
> +
> +module_spi_driver(spi_hid_acpi_driver);
> +
> +MODULE_DESCRIPTION("HID over SPI ACPI transport driver");
> +MODULE_AUTHOR("Angela Czubak <[email protected]>");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/hid/spi-hid/spi-hid-core.c
> b/drivers/hid/spi-hid/spi-hid-core.c
> index e3273846267e..02beb209a92d 100644
> --- a/drivers/hid/spi-hid/spi-hid-core.c
> +++ b/drivers/hid/spi-hid/spi-hid-core.c
> @@ -43,6 +43,9 @@
> #include <linux/wait.h>
> #include <linux/workqueue.h>
>
> +#include "spi-hid.h"
> +#include "spi-hid-core.h"
> +
> /* Protocol constants */
> #define SPI_HID_READ_APPROVAL_CONSTANT 0xff
> #define SPI_HID_INPUT_HEADER_SYNC_BYTE 0x5a
> @@ -105,30 +108,6 @@ struct spi_hid_output_report {
> u8 *content;
> };
>
> -/* struct spi_hid_conf - Conf provided to the core */
> -struct spi_hid_conf {
> - u32 input_report_header_address;
> - u32 input_report_body_address;
> - u32 output_report_address;
> - u8 read_opcode;
> - u8 write_opcode;
> -};
> -
> -/**
> - * struct spihid_ops - Ops provided to the core
> - * @power_up: do sequencing to power up the device
> - * @power_down: do sequencing to power down the device
> - * @assert_reset: do sequencing to assert the reset line
> - * @deassert_reset: do sequencing to deassert the reset line
> - */
> -struct spihid_ops {
> - int (*power_up)(struct spihid_ops *ops);
> - int (*power_down)(struct spihid_ops *ops);
> - int (*assert_reset)(struct spihid_ops *ops);
> - int (*deassert_reset)(struct spihid_ops *ops);
> - void (*sleep_minimal_reset_delay)(struct spihid_ops *ops);
> -};
> -
> static struct hid_ll_driver spi_hid_ll_driver;
>
> static void spi_hid_populate_read_approvals(const struct spi_hid_conf *conf,
> diff --git a/drivers/hid/spi-hid/spi-hid.h b/drivers/hid/spi-hid/spi-hid.h
> new file mode 100644
> index 000000000000..1fdd45262647
> --- /dev/null
> +++ b/drivers/hid/spi-hid/spi-hid.h
> @@ -0,0 +1,44 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2021 Microsoft Corporation
> + * Copyright (c) 2026 Google LLC
> + */
> +
> +#ifndef SPI_HID_H
> +#define SPI_HID_H
> +
> +#include <linux/spi/spi.h>
> +#include <linux/sysfs.h>
> +
> +/* struct spi_hid_conf - Conf provided to the core */
> +struct spi_hid_conf {
> + u32 input_report_header_address;
> + u32 input_report_body_address;
> + u32 output_report_address;
> + u8 read_opcode;
> + u8 write_opcode;
> +};
> +
> +/**
> + * struct spihid_ops - Ops provided to the core
> + * @power_up: do sequencing to power up the device
> + * @power_down: do sequencing to power down the device
> + * @assert_reset: do sequencing to assert the reset line
> + * @deassert_reset: do sequencing to deassert the reset line
> + */
> +struct spihid_ops {
> + int (*power_up)(struct spihid_ops *ops);
> + int (*power_down)(struct spihid_ops *ops);
> + int (*assert_reset)(struct spihid_ops *ops);
> + int (*deassert_reset)(struct spihid_ops *ops);
> + void (*sleep_minimal_reset_delay)(struct spihid_ops *ops);
> +};
> +
> +int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
> + struct spi_hid_conf *conf);
> +
> +void spi_hid_core_remove(struct spi_device *spi);
> +
> +extern const struct attribute_group *spi_hid_groups[];
> +
> +#endif /* SPI_HID_H */
I am not sure if this belongs to this patch or if it should be better in
the patch introducing the main driver from the beginning.
For the ACPI part:
Reviewed-by: Dmitry Torokhov <[email protected]>
Thanks.
--
Dmitry
