![Gustavo A. R. Silva](/assets/img/avatar_default.png)
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293
("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
226 lines
6.9 KiB
C
226 lines
6.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* ChromeOS Wilco Embedded Controller
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*
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* Copyright 2018 Google LLC
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*/
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#ifndef WILCO_EC_H
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#define WILCO_EC_H
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#include <linux/mutex.h>
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#include <linux/types.h>
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/* Message flags for using the mailbox() interface */
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#define WILCO_EC_FLAG_NO_RESPONSE BIT(0) /* EC does not respond */
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/* Normal commands have a maximum 32 bytes of data */
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#define EC_MAILBOX_DATA_SIZE 32
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struct device;
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struct resource;
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struct platform_device;
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/**
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* struct wilco_ec_device - Wilco Embedded Controller handle.
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* @dev: Device handle.
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* @mailbox_lock: Mutex to ensure one mailbox command at a time.
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* @io_command: I/O port for mailbox command. Provided by ACPI.
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* @io_data: I/O port for mailbox data. Provided by ACPI.
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* @io_packet: I/O port for mailbox packet data. Provided by ACPI.
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* @data_buffer: Buffer used for EC communication. The same buffer
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* is used to hold the request and the response.
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* @data_size: Size of the data buffer used for EC communication.
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* @debugfs_pdev: The child platform_device used by the debugfs sub-driver.
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* @rtc_pdev: The child platform_device used by the RTC sub-driver.
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* @charger_pdev: Child platform_device used by the charger config sub-driver.
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* @telem_pdev: The child platform_device used by the telemetry sub-driver.
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*/
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struct wilco_ec_device {
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struct device *dev;
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struct mutex mailbox_lock;
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struct resource *io_command;
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struct resource *io_data;
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struct resource *io_packet;
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void *data_buffer;
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size_t data_size;
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struct platform_device *debugfs_pdev;
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struct platform_device *rtc_pdev;
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struct platform_device *charger_pdev;
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struct platform_device *telem_pdev;
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};
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/**
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* struct wilco_ec_request - Mailbox request message format.
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* @struct_version: Should be %EC_MAILBOX_PROTO_VERSION
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* @checksum: Sum of all bytes must be 0.
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* @mailbox_id: Mailbox identifier, specifies the command set.
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* @mailbox_version: Mailbox interface version %EC_MAILBOX_VERSION
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* @reserved: Set to zero.
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* @data_size: Length of following data.
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*/
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struct wilco_ec_request {
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u8 struct_version;
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u8 checksum;
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u16 mailbox_id;
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u8 mailbox_version;
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u8 reserved;
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u16 data_size;
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} __packed;
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/**
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* struct wilco_ec_response - Mailbox response message format.
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* @struct_version: Should be %EC_MAILBOX_PROTO_VERSION
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* @checksum: Sum of all bytes must be 0.
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* @result: Result code from the EC. Non-zero indicates an error.
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* @data_size: Length of the response data buffer.
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* @reserved: Set to zero.
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* @data: Response data buffer. Max size is %EC_MAILBOX_DATA_SIZE_EXTENDED.
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*/
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struct wilco_ec_response {
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u8 struct_version;
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u8 checksum;
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u16 result;
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u16 data_size;
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u8 reserved[2];
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u8 data[];
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} __packed;
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/**
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* enum wilco_ec_msg_type - Message type to select a set of command codes.
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* @WILCO_EC_MSG_LEGACY: Legacy EC messages for standard EC behavior.
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* @WILCO_EC_MSG_PROPERTY: Get/Set/Sync EC controlled NVRAM property.
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* @WILCO_EC_MSG_TELEMETRY: Request telemetry data from the EC.
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*/
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enum wilco_ec_msg_type {
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WILCO_EC_MSG_LEGACY = 0x00f0,
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WILCO_EC_MSG_PROPERTY = 0x00f2,
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WILCO_EC_MSG_TELEMETRY = 0x00f5,
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};
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/**
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* struct wilco_ec_message - Request and response message.
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* @type: Mailbox message type.
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* @flags: Message flags, e.g. %WILCO_EC_FLAG_NO_RESPONSE.
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* @request_size: Number of bytes to send to the EC.
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* @request_data: Buffer containing the request data.
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* @response_size: Number of bytes to read from EC.
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* @response_data: Buffer containing the response data, should be
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* response_size bytes and allocated by caller.
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*/
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struct wilco_ec_message {
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enum wilco_ec_msg_type type;
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u8 flags;
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size_t request_size;
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void *request_data;
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size_t response_size;
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void *response_data;
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};
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/**
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* wilco_ec_mailbox() - Send request to the EC and receive the response.
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* @ec: Wilco EC device.
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* @msg: Wilco EC message.
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*
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* Return: Number of bytes received or negative error code on failure.
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*/
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int wilco_ec_mailbox(struct wilco_ec_device *ec, struct wilco_ec_message *msg);
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/**
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* wilco_keyboard_leds_init() - Set up the keyboard backlight LEDs.
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* @ec: EC device to query.
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*
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* After this call, the keyboard backlight will be exposed through a an LED
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* device at /sys/class/leds.
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*
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* This may sleep because it uses wilco_ec_mailbox().
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*
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* Return: 0 on success, negative error code on failure.
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*/
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int wilco_keyboard_leds_init(struct wilco_ec_device *ec);
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/*
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* A Property is typically a data item that is stored to NVRAM
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* by the EC. Each of these data items has an index associated
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* with it, known as the Property ID (PID). Properties may have
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* variable lengths, up to a max of WILCO_EC_PROPERTY_MAX_SIZE
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* bytes. Properties can be simple integers, or they may be more
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* complex binary data.
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*/
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#define WILCO_EC_PROPERTY_MAX_SIZE 4
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/**
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* struct ec_property_set_msg - Message to get or set a property.
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* @property_id: Which property to get or set.
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* @length: Number of bytes of |data| that are used.
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* @data: Actual property data.
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*/
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struct wilco_ec_property_msg {
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u32 property_id;
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int length;
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u8 data[WILCO_EC_PROPERTY_MAX_SIZE];
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};
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/**
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* wilco_ec_get_property() - Retrieve a property from the EC.
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* @ec: Embedded Controller device.
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* @prop_msg: Message for request and response.
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*
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* The property_id field of |prop_msg| should be filled before calling this
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* function. The result will be stored in the data and length fields.
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*
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* Return: 0 on success, negative error code on failure.
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*/
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int wilco_ec_get_property(struct wilco_ec_device *ec,
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struct wilco_ec_property_msg *prop_msg);
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/**
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* wilco_ec_set_property() - Store a property on the EC.
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* @ec: Embedded Controller device.
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* @prop_msg: Message for request and response.
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*
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* The property_id, length, and data fields of |prop_msg| should be
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* filled before calling this function.
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*
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* Return: 0 on success, negative error code on failure.
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*/
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int wilco_ec_set_property(struct wilco_ec_device *ec,
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struct wilco_ec_property_msg *prop_msg);
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/**
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* wilco_ec_get_byte_property() - Retrieve a byte-size property from the EC.
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* @ec: Embedded Controller device.
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* @property_id: Which property to retrieve.
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* @val: The result value, will be filled by this function.
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*
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* Return: 0 on success, negative error code on failure.
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*/
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int wilco_ec_get_byte_property(struct wilco_ec_device *ec, u32 property_id,
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u8 *val);
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/**
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* wilco_ec_get_byte_property() - Store a byte-size property on the EC.
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* @ec: Embedded Controller device.
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* @property_id: Which property to store.
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* @val: Value to store.
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*
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* Return: 0 on success, negative error code on failure.
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*/
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int wilco_ec_set_byte_property(struct wilco_ec_device *ec, u32 property_id,
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u8 val);
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/**
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* wilco_ec_add_sysfs() - Create sysfs entries
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* @ec: Wilco EC device
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*
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* wilco_ec_remove_sysfs() needs to be called afterwards
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* to perform the necessary cleanup.
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*
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* Return: 0 on success or negative error code on failure.
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*/
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int wilco_ec_add_sysfs(struct wilco_ec_device *ec);
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void wilco_ec_remove_sysfs(struct wilco_ec_device *ec);
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#endif /* WILCO_EC_H */
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