[PATCH v9] platform/chrome: Add ChromeOS ACPI device driver
From: Muhammad Usama Anjum
Date: Fri May 06 2022 - 05:57:39 EST
From: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
The x86 Chromebooks have the ChromeOS ACPI device. This driver attaches
to the ChromeOS ACPI device and exports the values reported by ACPI in a
sysfs directory. This data isn't present in ACPI tables when read
through ACPI tools, hence a driver is needed to do it. The driver gets
data from firmware using the ACPI component of the kernel. The ACPI values
are presented in string form (numbers as decimal values) or binary
blobs, and can be accessed as the contents of the appropriate read only
files in the standard ACPI device's sysfs directory tree. This data is
consumed by the ChromeOS user space.
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Cc: Hans de Goede <hdegoede@xxxxxxxxxx>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
Co-developed-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
Signed-off-by: Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>
---
The driver's implementation has been changed completely after Greg's
comment. I've updated the authorship of the module to myself. Enric,
Please let me know if yuo are comfortable with this.
Changes in v9:
- Changed the implementation completely
- Move the driver to drivers/platform/chrome
- Remove Acked-by Rafael as driver has changed
- Corrected some typos
- Changed the author of the module
Changes in v8:
- Change struct platform_driver name from chromeos_acpi_driver to
chromeos_acpi_device_driver
Changes in v7:
- Rename acpi_chromeos Kconfig option to chromeos_acpi
- Change this acpi driver to platform driver
- Minor cosmetic changes
There were the following concerns on v4 which have been delt with in
v5/v6:
- Remove BINF.{0,1,4} from sysfs as they are reserved and not used
anymore
- Reword the description of MECK
- Change function name from chromeos_acpi_alloc_name() to
chromeos_acpi_gen_file_name()
- Remove local variable obj in chromeos_acpi_add_method()
- Replace usage of dev_info() to dev_dbg()
- Improve the description of the patch
- Add the firmware interface document which serves as primary
documentation and garantees that this interface will not change
- GGL0001 is valid PNP ID of the Google. PNP ID can be used with the
ACPI devices. Consensus was developed on it in discussion of v4.
Changes in v6:
- Correct authorship and path email's From
- Add changelog between v4 and v5 in detail
- Add copywrite year 2022
- Improve the description and add concerns from V4 which have been fixed
Changes in v5:
- Improve the description of the patch
- Document firmware interface
- Update sysfs interface documentation
- Remove binf{0,1,4} as they have been deprecated
- Update some cleanup logic in case of error
- Remove freeing of chromeos_acpi.root explicitely in
chromeos_acpi_device_remove() as it'll be automatically freed by
chromeos_acpi_remove_groups()
- If sysfs_create_groups() fails in chromeos_acpi_process_mlst(),
cleanup all groups
- Cosmetic changes
Changes in v4:
https://lore.kernel.org/lkml/20200413134611.478441-1-enric.balletbo@xxxxxxxxxxxxx/t/
- Add COMPILE_TEST to increase build coverage.
- Add sysfs ABI documentation.
- Rebased on top of 5.7-rc1 and solve conflicts.
- Cc ACPI maintainers.
Changes in v3:
- Use attribute groups instead of adding files "by hand".
- Do not use "raw" kobject to create directories.
- Do not abuse of the platform_device interface. Remove it.
Changes in v2:
- Note that this version is a total rework, with those major changes:
- Use lists to track dinamically allocated attributes and groups.
- Use sysfs binary attributes to store the ACPI contents.
- Remove all the functionalities except the one that creates the sysfs files.
---
.../ABI/testing/sysfs-driver-chromeos-acpi | 126 ++++++
.../acpi/chromeos-acpi-device.rst | 363 ++++++++++++++++++
Documentation/firmware-guide/acpi/index.rst | 1 +
drivers/platform/chrome/Kconfig | 11 +
drivers/platform/chrome/Makefile | 1 +
drivers/platform/chrome/chromeos_acpi.c | 277 +++++++++++++
6 files changed, 779 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-driver-chromeos-acpi
create mode 100644 Documentation/firmware-guide/acpi/chromeos-acpi-device.rst
create mode 100644 drivers/platform/chrome/chromeos_acpi.c
diff --git a/Documentation/ABI/testing/sysfs-driver-chromeos-acpi b/Documentation/ABI/testing/sysfs-driver-chromeos-acpi
new file mode 100644
index 0000000000000..5b59ef9d7b371
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-chromeos-acpi
@@ -0,0 +1,126 @@
+What: /sys/bus/platform/devices/GGL0001:*/BINF.2
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows information about the current boot of
+ the active EC firmware.
+ * 0 - Read only (recovery) firmware.
+ * 1 - Rewritable firmware.
+
+What: /sys/bus/platform/devices/GGL0001:*/BINF.3
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows information about the current boot of
+ the active main firmware type.
+ * 0 - Recovery.
+ * 1 - Normal.
+ * 2 - Developer.
+ * 3 - Netboot (factory installation only).
+
+What: /sys/bus/platform/devices/GGL0001:*/CHSW
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows the switch position for the Chrome OS specific
+ hardware switches.
+ * 0 - No changes.
+ * 2 - Recovery button was pressed when firmware booted.
+ * 4 - Recovery button was pressed when EC firmware booted.
+ * 32 - Developer switch was enabled when firmware booted.
+ * 512 - Firmware write protection was disabled when firmware
+ booted.
+
+What: /sys/bus/platform/devices/GGL0001:*/FMAP
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows the physical memory address of the start of
+ the main processor firmware flashmap.
+
+What: /sys/bus/platform/devices/GGL0001:*/FRID
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows the firmware version for the read-only portion
+ of the main processor firmware.
+
+What: /sys/bus/platform/devices/GGL0001:*/FWID
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows the firmware version for the rewritable portion
+ of the main processor firmware.
+
+What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.0
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows the type of the GPIO signal for the Chrome OS
+ specific GPIO assignments.
+ * 1 - Recovery button.
+ * 2 - Developer mode switch.
+ * 3 - Firmware write protection switch.
+ * 256 to 511 - Debug header GPIO 0 to GPIO 255.
+
+What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.1
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows the signal attributes of the GPIO signal.
+ * 0 - Signal is active low.
+ * 1 - Signal is active high.
+
+What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.2
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows the GPIO number on the specified GPIO
+ controller.
+
+What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.3
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows the name of the GPIO controller.
+
+What: /sys/bus/platform/devices/GGL0001:*/HWID
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows the hardware ID for the Chromebook.
+
+What: /sys/bus/platform/devices/GGL0001:*/MECK
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This binary file returns the SHA-1 or SHA-256 hash that is
+ read out of the Management Engine extended registers during
+ boot. The hash is exported vi ACPI so the OS can verify that
+ the Management Engine firmware has not changed. If Management
+ Engine is not present, or if the firmware was unable to read the
+ extended registers, this buffer size can be zero.
+
+What: /sys/bus/platform/devices/GGL0001:*/VBNV.0
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows the offset in CMOS bank 0 of the verified boot
+ non-volatile storage block, counting from the first writable
+ CMOS byte (that is, 'offset = 0' is the byte following the 14
+ bytes of clock data).
+
+What: /sys/bus/platform/devices/GGL0001:*/VBNV.1
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This file shows the size in bytes of the verified boot
+ non-volatile storage block.
+
+What: /sys/bus/platform/devices/GGL0001:*/VDAT
+Date: May 2022
+KernelVersion: 5.19
+Description:
+ This binary file returns the verified boot data block shared
+ between the firmware verification step and the kernel
+ verification step.
diff --git a/Documentation/firmware-guide/acpi/chromeos-acpi-device.rst b/Documentation/firmware-guide/acpi/chromeos-acpi-device.rst
new file mode 100644
index 0000000000000..f37fc90ce340e
--- /dev/null
+++ b/Documentation/firmware-guide/acpi/chromeos-acpi-device.rst
@@ -0,0 +1,363 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================
+Chrome OS ACPI Device
+=====================
+
+Hardware functionality specific to Chrome OS is exposed through a Chrome OS ACPI device.
+The plug and play ID of a Chrome OS ACPI device is GGL0001. GGL is a valid PNP ID of Google.
+PNP ID can be used with the ACPI devices according to the guidelines. The following ACPI
+objects are supported:
+
+.. flat-table:: Supported ACPI Objects
+ :widths: 1 2
+ :header-rows: 1
+
+ * - Object
+ - Description
+
+ * - CHSW
+ - Chrome OS switch positions
+
+ * - HWID
+ - Chrome OS hardware ID
+
+ * - FWID
+ - Chrome OS firmware version
+
+ * - FRID
+ - Chrome OS read-only firmware version
+
+ * - BINF
+ - Chrome OS boot information
+
+ * - GPIO
+ - Chrome OS GPIO assignments
+
+ * - VBNV
+ - Chrome OS NVRAM locations
+
+ * - VDTA
+ - Chrome OS verified boot data
+
+ * - FMAP
+ - Chrome OS flashmap base address
+
+ * - MLST
+ - Chrome OS method list
+
+CHSW (Chrome OS switch positions)
+=================================
+This control method returns the switch positions for Chrome OS specific hardware switches.
+
+Arguments:
+----------
+None
+
+Result code:
+------------
+An integer containing the switch positions as bitfields:
+
+.. flat-table::
+ :widths: 1 2
+
+ * - 0x00000002
+ - Recovery button was pressed when x86 firmware booted.
+
+ * - 0x00000004
+ - Recovery button was pressed when EC firmware booted. (required if EC EEPROM is
+ rewritable; otherwise optional)
+
+ * - 0x00000020
+ - Developer switch was enabled when x86 firmware booted.
+
+ * - 0x00000200
+ - Firmware write protection was disabled when x86 firmware booted. (required if
+ firmware write protection is controlled through x86 BIOS; otherwise optional)
+
+All other bits are reserved and should be set to 0.
+
+HWID (Chrome OS hardware ID)
+============================
+This control method returns the hardware ID for the Chromebook.
+
+Arguments:
+----------
+None
+
+Result code:
+------------
+A null-terminated ASCII string containing the hardware ID from the Model-Specific Data area of
+EEPROM.
+
+Note that the hardware ID can be up to 256 characters long, including the terminating null.
+
+FWID (Chrome OS firmware version)
+=================================
+This control method returns the firmware version for the rewritable portion of the main
+processor firmware.
+
+Arguments:
+----------
+None
+
+Result code:
+------------
+A null-terminated ASCII string containing the complete firmware version for the rewritable
+portion of the main processor firmware.
+
+FRID (Chrome OS read-only firmware version)
+===========================================
+This control method returns the firmware version for the read-only portion of the main
+processor firmware.
+
+Arguments:
+----------
+None
+
+Result code:
+------------
+A null-terminated ASCII string containing the complete firmware version for the read-only
+(bootstrap + recovery ) portion of the main processor firmware.
+
+BINF (Chrome OS boot information)
+=================================
+This control method returns information about the current boot.
+
+Arguments:
+----------
+None
+
+Result code:
+------------
+
+.. code-block::
+
+ Package {
+ Reserved1
+ Reserved2
+ Active EC Firmware
+ Active Main Firmware Type
+ Reserved5
+ }
+
+.. flat-table::
+ :widths: 1 1 2
+ :header-rows: 1
+
+ * - Field
+ - Format
+ - Description
+
+ * - Reserved1
+ - DWORD
+ - Set to 256 (0x100). This indicates this field is no longer used.
+
+ * - Reserved2
+ - DWORD
+ - Set to 256 (0x100). This indicates this field is no longer used.
+
+ * - Active EC firmware
+ - DWORD
+ - The EC firmware which was used during boot.
+
+ - 0 - Read-only (recovery) firmware
+ - 1 - Rewritable firmware.
+
+ Set to 0 if EC firmware is always read-only.
+
+ * - Active Main Firmware Type
+ - DWORD
+ - The main firmware type which was used during boot.
+
+ - 0 - Recovery
+ - 1 - Normal
+ - 2 - Developer
+ - 3 - netboot (factory installation only)
+
+ Other values are reserved.
+
+ * - Reserved5
+ - DWORD
+ - Set to 256 (0x100). This indicates this field is no longer used.
+
+GPIO (Chrome OS GPIO assignments)
+=================================
+This control method returns information about Chrome OS specific GPIO assignments for
+Chrome OS hardware, so the kernel can directly control that hardware.
+
+Arguments:
+----------
+None
+
+Result code:
+------------
+.. code-block::
+
+ Package {
+ Package {
+ // First GPIO assignment
+ Signal Type //DWORD
+ Attributes //DWORD
+ Controller Offset //DWORD
+ Controller Name //ASCIIZ
+ },
+ ...
+ Package {
+ // Last GPIO assignment
+ Signal Type //DWORD
+ Attributes //DWORD
+ Controller Offset //DWORD
+ Controller Name //ASCIIZ
+ }
+ }
+
+Where ASCIIZ means a null-terminated ASCII string.
+
+.. flat-table::
+ :widths: 1 1 2
+ :header-rows: 1
+
+ * - Field
+ - Format
+ - Description
+
+ * - Signal Type
+ - DWORD
+ - Type of GPIO signal
+
+ - 0x00000001 - Recovery button
+ - 0x00000002 - Developer mode switch
+ - 0x00000003 - Firmware write protection switch
+ - 0x00000100 - Debug header GPIO 0
+ - ...
+ - 0x000001FF - Debug header GPIO 255
+
+ Other values are reserved.
+
+ * - Attributes
+ - DWORD
+ - Signal attributes as bitfields:
+
+ - 0x00000001 - Signal is active-high (for button, a GPIO value
+ of 1 means the button is pressed; for switches, a GPIO value
+ of 1 means the switch is enabled). If this bit is 0, the signal
+ is active low. Set to 0 for debug header GPIOs.
+
+ * - Controller Offset
+ - DWORD
+ - GPIO number on the specified controller.
+
+ * - Controller Name
+ - ASCIIZ
+ - Name of the controller for the GPIO.
+ Currently supported names:
+ "NM10" - Intel NM10 chip
+
+VBNV (Chrome OS NVRAM locations)
+================================
+This control method returns information about the NVRAM (CMOS) locations used to
+communicate with the BIOS.
+
+Arguments:
+----------
+None
+
+Result code:
+------------
+.. code-block::
+
+ Package {
+ NV Storage Block Offset //DWORD
+ NV Storage Block Size //DWORD
+ }
+
+.. flat-table::
+ :widths: 1 1 2
+ :header-rows: 1
+
+ * - Field
+ - Format
+ - Description
+
+ * - NV Storage Block Offset
+ - DWORD
+ - Offset in CMOS bank 0 of the verified boot non-volatile storage block, counting from
+ the first writable CMOS byte (that is, offset=0 is the byte following the 14 bytes of
+ clock data).
+
+ * - NV Storage Block Size
+ - DWORD
+ - Size in bytes of the verified boot non-volatile storage block.
+
+FMAP (Chrome OS flashmap address)
+=================================
+This control method returns the physical memory address of the start of the main processor
+firmware flashmap.
+
+Arguments:
+----------
+None
+
+NoneResult code:
+----------------
+A DWORD containing the physical memory address of the start of the main processor firmware
+flashmap.
+
+VDTA (Chrome OS verified boot data)
+===================================
+This control method returns the verified boot data block shared between the firmware
+verification step and the kernel verification step.
+
+Arguments:
+----------
+None
+
+Result code:
+------------
+A buffer containing the verified boot data block.
+
+MECK (Management Engine Checksum)
+=================================
+This control method returns the SHA-1 or SHA-256 hash that is read out of the Management
+Engine extended registers during boot. The hash is exported via ACPI so the OS can verify that
+the ME firmware has not changed. If Management Engine is not present, or if the firmware was
+unable to read the extended registers, this buffer can be zero.
+
+Arguments:
+----------
+None
+
+Result code:
+------------
+A buffer containing the ME hash.
+
+MLST (Chrome OS method list)
+============================
+This control method returns a list of the other control methods supported by the Chrome OS
+hardware device.
+
+Arguments:
+----------
+None
+
+Result code:
+------------
+A package containing a list of null-terminated ASCII strings, one for each control method
+supported by the Chrome OS hardware device, not including the MLST method itself.
+For this version of the specification, the result is:
+
+.. code-block::
+
+ Package {
+ "CHSW",
+ "FWID",
+ "HWID",
+ "FRID",
+ "BINF",
+ "GPIO",
+ "VBNV",
+ "FMAP",
+ "VDTA",
+ "MECK"
+ }
diff --git a/Documentation/firmware-guide/acpi/index.rst b/Documentation/firmware-guide/acpi/index.rst
index b053b0c3d6969..b6a42f4ffe032 100644
--- a/Documentation/firmware-guide/acpi/index.rst
+++ b/Documentation/firmware-guide/acpi/index.rst
@@ -29,3 +29,4 @@ ACPI Support
non-d0-probe
extcon-intel-int3496
intel-pmc-mux
+ chromeos-acpi-device
diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index 75e93efd669f0..ca2bc1121a29e 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -15,6 +15,17 @@ menuconfig CHROME_PLATFORMS
if CHROME_PLATFORMS
+config CHROMEOS_ACPI
+ tristate "ChromeOS specific ACPI extensions"
+ depends on ACPI || COMPILE_TEST
+ help
+ This driver provides the firmware interface for the services
+ exported through the ChromeOS interfaces when using ChromeOS
+ ACPI firmware.
+
+ If you have an ACPI-compatible Chromebook, say Y or M here.
+ The module will be called chromeos_acpi.
+
config CHROMEOS_LAPTOP
tristate "Chrome OS Laptop"
depends on I2C && DMI && X86
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index 6420ca129548e..52f5a2dde8b81 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -4,6 +4,7 @@
CFLAGS_cros_ec_trace.o:= -I$(src)
CFLAGS_cros_ec_sensorhub_ring.o:= -I$(src)
+obj-$(CONFIG_CHROMEOS_ACPI) += chromeos_acpi.o
obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
obj-$(CONFIG_CHROMEOS_PRIVACY_SCREEN) += chromeos_privacy_screen.o
obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o
diff --git a/drivers/platform/chrome/chromeos_acpi.c b/drivers/platform/chrome/chromeos_acpi.c
new file mode 100644
index 0000000000000..6fda8aa846ad7
--- /dev/null
+++ b/drivers/platform/chrome/chromeos_acpi.c
@@ -0,0 +1,277 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ChromeOS specific ACPI extensions
+ *
+ * Copyright 2022 Google LLC
+ *
+ * This driver attaches to the ChromeOS ACPI device and then exports the
+ * values reported by the ACPI in a sysfs directory. All values are
+ * presented in the string form (numbers as decimal values) and can be
+ * accessed as the contents of the appropriate read only files in the
+ * sysfs directory tree.
+ */
+#include <linux/acpi.h>
+#include <linux/platform_device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+
+#define ACPI_ATTR_NAME_LEN 4
+
+#define DEV_ATTR(_var, _name) \
+ static struct device_attribute dev_attr_##_var = { \
+ .attr = { .name = _name, .mode = 0444 }, \
+ .show = chromeos_first_level_attr_show \
+ };
+
+#define GPIO_ATTR_GROUP(_group, _name, _num) \
+ static umode_t attr_is_visible_gpio_##_num(struct kobject *kobj, \
+ struct attribute *attr, int n) \
+ { \
+ if (_num < chromeos_acpi_gpio_groups) \
+ return attr->mode; \
+ else \
+ return 0; \
+ } \
+ static ssize_t chromeos_attr_show_gpio_##_num(struct device *dev, \
+ struct device_attribute *attr, \
+ char *buf) \
+ { \
+ char name[ACPI_ATTR_NAME_LEN + 1]; \
+ int ret, num; \
+ \
+ ret = parse_attr_name(attr->attr.name, name, &num); \
+ if (ret) \
+ return ret; \
+ ret = chromeos_acpi_evaluate_method(dev, _num, num, name, buf); \
+ if (ret < 0) \
+ ret = 0; \
+ return ret; \
+ } \
+ static struct device_attribute dev_attr_0_##_group = { \
+ .attr = { .name = "GPIO.0", .mode = 0444 }, \
+ .show = chromeos_attr_show_gpio_##_num \
+ }; \
+ static struct device_attribute dev_attr_1_##_group = { \
+ .attr = { .name = "GPIO.1", .mode = 0444 }, \
+ .show = chromeos_attr_show_gpio_##_num \
+ }; \
+ static struct device_attribute dev_attr_2_##_group = { \
+ .attr = { .name = "GPIO.2", .mode = 0444 }, \
+ .show = chromeos_attr_show_gpio_##_num \
+ }; \
+ static struct device_attribute dev_attr_3_##_group = { \
+ .attr = { .name = "GPIO.3", .mode = 0444 }, \
+ .show = chromeos_attr_show_gpio_##_num \
+ }; \
+ static struct attribute *attrs_##_group[] = { \
+ &dev_attr_0_##_group.attr, \
+ &dev_attr_1_##_group.attr, \
+ &dev_attr_2_##_group.attr, \
+ &dev_attr_3_##_group.attr, \
+ NULL \
+ }; \
+ static const struct attribute_group attr_group_##_group = { \
+ .name = _name, \
+ .is_visible = attr_is_visible_gpio_##_num, \
+ .attrs = attrs_##_group \
+ };
+
+static unsigned int chromeos_acpi_gpio_groups;
+
+/* Parse the ACPI package and return the data related to that attribute */
+static int chromeos_acpi_handle_package(struct device *dev, union acpi_object *obj,
+ int pkg_num, int sub_pkg_num, char *name, char *buf)
+{
+ union acpi_object *element = obj->package.elements;
+ int length = -EINVAL;
+
+ if (pkg_num >= obj->package.count)
+ return -EINVAL;
+ element += pkg_num;
+
+ if (element->type == ACPI_TYPE_PACKAGE) {
+ if (sub_pkg_num >= element->package.count)
+ return -EINVAL;
+ // select sub element inside this package
+ element = element->package.elements;
+ element += sub_pkg_num;
+ }
+
+ switch (element->type) {
+ case ACPI_TYPE_INTEGER:
+ length = sysfs_emit(buf, "%d", (int)element->integer.value);
+ break;
+ case ACPI_TYPE_STRING:
+ length = sysfs_emit(buf, "%s", element->string.pointer);
+ break;
+ case ACPI_TYPE_BUFFER:
+ length = sysfs_emit(buf, "%s", element->buffer.pointer);
+ break;
+ default:
+ dev_err(dev, "element type %d not supported\n", element->type);
+ break;
+ }
+
+ return length;
+}
+
+static int chromeos_acpi_evaluate_method(struct device *dev, int pkg_num, int sub_pkg_num,
+ char *name, char *buf)
+{
+ struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+ acpi_status status;
+ int ret = -EINVAL;
+
+ status = acpi_evaluate_object(ACPI_HANDLE(dev), name, NULL, &output);
+ if (ACPI_FAILURE(status)) {
+ dev_err(dev, "failed to retrieve %s. %s\n", name, acpi_format_exception(status));
+ return ret;
+ }
+
+ if (((union acpi_object *)output.pointer)->type == ACPI_TYPE_PACKAGE)
+ ret = chromeos_acpi_handle_package(dev, output.pointer, pkg_num, sub_pkg_num,
+ name, buf);
+
+ kfree(output.pointer);
+ return ret;
+}
+
+static int parse_attr_name(const char *name, char *attr_name, int *attr_num)
+{
+ int ret = 0;
+
+ strscpy(attr_name, name, ACPI_ATTR_NAME_LEN + 1);
+
+ if (strlen(name) > ACPI_ATTR_NAME_LEN)
+ ret = kstrtoint(&name[ACPI_ATTR_NAME_LEN + 1], 0, attr_num);
+
+ return ret;
+}
+
+static ssize_t chromeos_first_level_attr_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ char attr_name[ACPI_ATTR_NAME_LEN + 1];
+ int ret, attr_num = 0;
+
+ ret = parse_attr_name(attr->attr.name, attr_name, &attr_num);
+ if (ret)
+ return 0;
+ ret = chromeos_acpi_evaluate_method(dev, attr_num, 0, attr_name, buf);
+ if (ret < 0)
+ ret = 0;
+ return ret;
+}
+
+static unsigned int get_gpio_pkg_num(struct device *dev)
+{
+ struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+ acpi_status status;
+ unsigned int count = 0;
+ char *name = "GPIO";
+
+ status = acpi_evaluate_object(ACPI_HANDLE(dev), name, NULL, &output);
+ if (ACPI_FAILURE(status)) {
+ dev_err(dev, "failed to retrieve %s. %s\n", name, acpi_format_exception(status));
+ return count;
+ }
+
+ if (((union acpi_object *)output.pointer)->type == ACPI_TYPE_PACKAGE)
+ count = ((union acpi_object *)output.pointer)->package.count;
+
+ kfree(output.pointer);
+ return count;
+}
+
+DEV_ATTR(binf2, "BINF.2")
+DEV_ATTR(binf3, "BINF.3")
+DEV_ATTR(chsw, "CHSW")
+DEV_ATTR(fmap, "FMAP")
+DEV_ATTR(frid, "FRID")
+DEV_ATTR(fwid, "FWID")
+DEV_ATTR(hwid, "HWID")
+DEV_ATTR(meck, "MECK")
+DEV_ATTR(vbnv0, "VBNV.0")
+DEV_ATTR(vbnv1, "VBNV.1")
+DEV_ATTR(vdat, "VDAT")
+
+static struct attribute *first_level_attrs[] = {
+ &dev_attr_binf2.attr,
+ &dev_attr_binf3.attr,
+ &dev_attr_chsw.attr,
+ &dev_attr_fmap.attr,
+ &dev_attr_frid.attr,
+ &dev_attr_fwid.attr,
+ &dev_attr_hwid.attr,
+ &dev_attr_meck.attr,
+ &dev_attr_vbnv0.attr,
+ &dev_attr_vbnv1.attr,
+ &dev_attr_vdat.attr,
+ NULL
+};
+
+static const struct attribute_group first_level_attr_group = {
+ .attrs = first_level_attrs,
+};
+
+/* Every platform can have different number of GPIO attribute groups.
+ * Define upper limit groups. At run time, the platform decides to show
+ * the present number of groups only, others are hidden.
+ */
+GPIO_ATTR_GROUP(gpio0, "GPIO.0", 0)
+GPIO_ATTR_GROUP(gpio1, "GPIO.1", 1)
+GPIO_ATTR_GROUP(gpio2, "GPIO.2", 2)
+GPIO_ATTR_GROUP(gpio3, "GPIO.3", 3)
+GPIO_ATTR_GROUP(gpio4, "GPIO.4", 4)
+GPIO_ATTR_GROUP(gpio5, "GPIO.5", 5)
+GPIO_ATTR_GROUP(gpio6, "GPIO.6", 6)
+GPIO_ATTR_GROUP(gpio7, "GPIO.7", 7)
+
+static const struct attribute_group *chromeos_acpi_all_groups[] = {
+ &first_level_attr_group,
+ &attr_group_gpio0,
+ &attr_group_gpio1,
+ &attr_group_gpio2,
+ &attr_group_gpio3,
+ &attr_group_gpio4,
+ &attr_group_gpio5,
+ &attr_group_gpio6,
+ &attr_group_gpio7,
+ NULL
+};
+
+static int chromeos_acpi_device_probe(struct platform_device *pdev)
+{
+ chromeos_acpi_gpio_groups = get_gpio_pkg_num(&pdev->dev);
+
+ /* If platform has more GPIO attribute groups than the number of
+ * groups this driver supports, give out a warning message.
+ */
+ if (chromeos_acpi_gpio_groups > (ARRAY_SIZE(chromeos_acpi_all_groups) - 2))
+ dev_warn(&(pdev->dev), "Only %ld GPIO attr groups supported by the driver out of total %d.\n",
+ (ARRAY_SIZE(chromeos_acpi_all_groups) - 2), chromeos_acpi_gpio_groups);
+ return 0;
+}
+
+/* GGL is valid PNP ID of Google. PNP ID can be used with the ACPI devices. */
+static const struct acpi_device_id chromeos_device_ids[] = {
+ { "GGL0001", 0 },
+ {}
+};
+MODULE_DEVICE_TABLE(acpi, chromeos_device_ids);
+
+static struct platform_driver chromeos_acpi_device_driver = {
+ .probe = chromeos_acpi_device_probe,
+ .driver = {
+ .name = KBUILD_MODNAME,
+ .dev_groups = chromeos_acpi_all_groups,
+ .acpi_match_table = ACPI_PTR(chromeos_device_ids)
+ }
+};
+module_platform_driver(chromeos_acpi_device_driver);
+
+MODULE_AUTHOR("Muhammad Usama Anjum <usama.anjum@xxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ChromeOS specific ACPI extensions");
--
2.30.2