linux/drivers/hid/intel-ish-hid/ishtp/loader.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * ISHTP firmware loader function
 *
 * Copyright (c) 2024, Intel Corporation.
 *
 * This module implements the functionality to load the main ISH firmware from the host, starting
 * with the Lunar Lake generation. It leverages a new method that enhances space optimization and
 * flexibility by dividing the ISH firmware into a bootloader and main firmware.
 *
 * Please refer to the [Documentation](Documentation/hid/intel-ish-hid.rst) for the details on
 * flows.
 *
 * Additionally, address potential error scenarios to ensure graceful failure handling.
 * - Firmware Image Not Found:
 *   Occurs when `request_firmware()` cannot locate the firmware image. The ISH firmware will
 *   remain in a state awaiting firmware loading from the host, with no further action from
 *   the ISHTP driver.
 *   Recovery: Re-insmod the ISH drivers allows for a retry of the firmware loading from the host.
 *
 * - DMA Buffer Allocation Failure:
 *   This happens if allocating a DMA buffer during `prepare_dma_bufs()` fails. The ISH firmware
 *   will stay in a waiting state, and the ISHTP driver will release any allocated DMA buffers and
 *   firmware without further actions.
 *   Recovery: Re-insmod the ISH drivers allows for a retry of the firmware loading from the host.
 *
 * - Incorrect Firmware Image:
 *   Using an incorrect firmware image will initiate the firmware loading process but will
 *   eventually be refused by the ISH firmware after three unsuccessful attempts, indicated by
 *   returning an error code. The ISHTP driver will stop attempting after three tries.
 *   Recovery: A platform reset is required to retry firmware loading from the host.
 */

#define dev_fmt(fmt) …

#include <linux/cacheflush.h>
#include <linux/container_of.h>
#include <linux/dev_printk.h>
#include <linux/dma-mapping.h>
#include <linux/errno.h>
#include <linux/firmware.h>
#include <linux/gfp_types.h>
#include <linux/math.h>
#include <linux/module.h>
#include <linux/pfn.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/wait.h>

#include "hbm.h"
#include "loader.h"

/**
 * loader_write_message() - Write a message to the ISHTP device
 * @dev: The ISHTP device
 * @buf: The buffer containing the message
 * @len: The length of the message
 *
 * Return: 0 on success, negative error code on failure
 */
static int loader_write_message(struct ishtp_device *dev, void *buf, int len)
{ … }

/**
 * loader_xfer_cmd() - Transfer a command to the ISHTP device
 * @dev: The ISHTP device
 * @req: The request buffer
 * @req_len: The length of the request
 * @resp: The response buffer
 * @resp_len: The length of the response
 *
 * Return: 0 on success, negative error code on failure
 */
static int loader_xfer_cmd(struct ishtp_device *dev, void *req, int req_len,
			   void *resp, int resp_len)
{ … }

/**
 * release_dma_bufs() - Release the DMA buffer for transferring firmware fragments
 * @dev: The ISHTP device
 * @fragment: The ISHTP firmware fragment descriptor
 * @dma_bufs: The array of DMA fragment buffers
 * @fragment_size: The size of a single DMA fragment
 */
static void release_dma_bufs(struct ishtp_device *dev,
			     struct loader_xfer_dma_fragment *fragment,
			     void **dma_bufs, u32 fragment_size)
{ … }

/**
 * prepare_dma_bufs() - Prepare the DMA buffer for transferring firmware fragments
 * @dev: The ISHTP device
 * @ish_fw: The ISH firmware
 * @fragment: The ISHTP firmware fragment descriptor
 * @dma_bufs: The array of DMA fragment buffers
 * @fragment_size: The size of a single DMA fragment
 * @fragment_count: Number of fragments
 *
 * Return: 0 on success, negative error code on failure
 */
static int prepare_dma_bufs(struct ishtp_device *dev,
			    const struct firmware *ish_fw,
			    struct loader_xfer_dma_fragment *fragment,
			    void **dma_bufs, u32 fragment_size, u32 fragment_count)
{ … }

/**
 * ishtp_loader_work() - Load the ISHTP firmware
 * @work: The work structure
 *
 * The ISH Loader attempts to load firmware by sending a series of commands
 * to the ISH device. If a command fails to be acknowledged by the ISH device,
 * the loader will retry sending the command, up to a maximum of
 * ISHTP_LOADER_RETRY_TIMES.
 *
 * After the maximum number of retries has been reached without success, the
 * ISH bootloader will return an error status code and will no longer respond
 * to the driver's commands. This behavior indicates that the ISH Loader has
 * encountered a critical error during the firmware loading process.
 *
 * In such a case, where the ISH bootloader is unresponsive after all retries
 * have been exhausted, a platform reset is required to restore communication
 * with the ISH device and to recover from this error state.
 */
void ishtp_loader_work(struct work_struct *work)
{ … }