// SPDX-License-Identifier: GPL-2.0-only
/*
 * AMD Secure Processor Seamless Firmware Servicing support.
 *
 * Copyright (C) 2025 Advanced Micro Devices, Inc.
 *
 * Author: Ashish Kalra <ashish.kalra@amd.com>
 */

#include <linux/firmware.h>

#include "sfs.h"
#include "sev-dev.h"

#define SFS_DEFAULT_TIMEOUT             (10 * MSEC_PER_SEC)
#define SFS_MAX_PAYLOAD_SIZE            (2 * 1024 * 1024)
#define SFS_NUM_2MB_PAGES_CMDBUF        (SFS_MAX_PAYLOAD_SIZE / PMD_SIZE)
#define SFS_NUM_PAGES_CMDBUF            (SFS_MAX_PAYLOAD_SIZE / PAGE_SIZE)

static DEFINE_MUTEX(sfs_ioctl_mutex);

static struct sfs_misc_dev *misc_dev;

static int send_sfs_cmd(struct sfs_device *sfs_dev, int msg)
{
        int ret;

        sfs_dev->command_buf->hdr.status = 0;
        sfs_dev->command_buf->hdr.sub_cmd_id = msg;

        ret = psp_extended_mailbox_cmd(sfs_dev->psp,
                                       SFS_DEFAULT_TIMEOUT,
                                       (struct psp_ext_request *)sfs_dev->command_buf);
        if (ret == -EIO) {
                dev_dbg(sfs_dev->dev,
                         "msg 0x%x failed with PSP error: 0x%x, extended status: 0x%x\n",
                         msg, sfs_dev->command_buf->hdr.status,
                         *(u32 *)sfs_dev->command_buf->buf);
        }

        return ret;
}

static int send_sfs_get_fw_versions(struct sfs_device *sfs_dev)
{
        /*
         * SFS_GET_FW_VERSIONS command needs the output buffer to be
         * initialized to 0xC7 in every byte.
         */
        memset(sfs_dev->command_buf->sfs_buffer, 0xc7, PAGE_SIZE);
        sfs_dev->command_buf->hdr.payload_size = 2 * PAGE_SIZE;

        return send_sfs_cmd(sfs_dev, PSP_SFS_GET_FW_VERSIONS);
}

static int send_sfs_update_package(struct sfs_device *sfs_dev, const char *payload_name)
{
        char payload_path[PAYLOAD_NAME_SIZE + sizeof("amd/")];
        const struct firmware *firmware;
        unsigned long package_size;
        int ret;

        /* Sanitize userspace provided payload name */
        if (!strnchr(payload_name, PAYLOAD_NAME_SIZE, '\0'))
                return -EINVAL;

        snprintf(payload_path, sizeof(payload_path), "amd/%s", payload_name);

        ret = firmware_request_nowarn(&firmware, payload_path, sfs_dev->dev);
        if (ret < 0) {
                dev_warn_ratelimited(sfs_dev->dev, "firmware request failed for %s (%d)\n",
                                     payload_path, ret);
                return -ENOENT;
        }

        /*
         * SFS Update Package command's input buffer contains TEE_EXT_CMD_BUFFER
         * followed by the Update Package and it should be 64KB aligned.
         */
        package_size = ALIGN(firmware->size + PAGE_SIZE, 0x10000U);

        /*
         * SFS command buffer is a pre-allocated 2MB buffer, fail update package
         * if SFS payload is larger than the pre-allocated command buffer.
         */
        if (package_size > SFS_MAX_PAYLOAD_SIZE) {
                dev_warn_ratelimited(sfs_dev->dev,
                         "SFS payload size %ld larger than maximum supported payload size of %u\n",
                         package_size, SFS_MAX_PAYLOAD_SIZE);
                release_firmware(firmware);
                return -E2BIG;
        }

        /*
         * Copy firmware data to a HV_Fixed memory region.
         */
        memcpy(sfs_dev->command_buf->sfs_buffer, firmware->data, firmware->size);
        sfs_dev->command_buf->hdr.payload_size = package_size;

        release_firmware(firmware);

        return send_sfs_cmd(sfs_dev, PSP_SFS_UPDATE);
}

static long sfs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
        struct sfs_user_get_fw_versions __user *sfs_get_fw_versions;
        struct sfs_user_update_package __user *sfs_update_package;
        struct psp_device *psp_master = psp_get_master_device();
        char payload_name[PAYLOAD_NAME_SIZE];
        struct sfs_device *sfs_dev;
        int ret = 0;

        if (!psp_master || !psp_master->sfs_data)
                return -ENODEV;

        sfs_dev = psp_master->sfs_data;

        guard(mutex)(&sfs_ioctl_mutex);

        switch (cmd) {
        case SFSIOCFWVERS:
                dev_dbg(sfs_dev->dev, "in SFSIOCFWVERS\n");

                sfs_get_fw_versions = (struct sfs_user_get_fw_versions __user *)arg;

                ret = send_sfs_get_fw_versions(sfs_dev);
                if (ret && ret != -EIO)
                        return ret;

                /*
                 * Return SFS status and extended status back to userspace
                 * if PSP status indicated success or command error.
                 */
                if (copy_to_user(&sfs_get_fw_versions->blob, sfs_dev->command_buf->sfs_buffer,
                                 PAGE_SIZE))
                        return -EFAULT;
                if (copy_to_user(&sfs_get_fw_versions->sfs_status,
                                 &sfs_dev->command_buf->hdr.status,
                                 sizeof(sfs_get_fw_versions->sfs_status)))
                        return -EFAULT;
                if (copy_to_user(&sfs_get_fw_versions->sfs_extended_status,
                                 &sfs_dev->command_buf->buf,
                                 sizeof(sfs_get_fw_versions->sfs_extended_status)))
                        return -EFAULT;
                break;
        case SFSIOCUPDATEPKG:
                dev_dbg(sfs_dev->dev, "in SFSIOCUPDATEPKG\n");

                sfs_update_package = (struct sfs_user_update_package __user *)arg;

                if (copy_from_user(payload_name, sfs_update_package->payload_name,
                                   PAYLOAD_NAME_SIZE))
                        return -EFAULT;

                ret = send_sfs_update_package(sfs_dev, payload_name);
                if (ret && ret != -EIO)
                        return ret;

                /*
                 * Return SFS status and extended status back to userspace
                 * if PSP status indicated success or command error.
                 */
                if (copy_to_user(&sfs_update_package->sfs_status,
                                 &sfs_dev->command_buf->hdr.status,
                                 sizeof(sfs_update_package->sfs_status)))
                        return -EFAULT;
                if (copy_to_user(&sfs_update_package->sfs_extended_status,
                                 &sfs_dev->command_buf->buf,
                                 sizeof(sfs_update_package->sfs_extended_status)))
                        return -EFAULT;
                break;
        default:
                ret = -EINVAL;
        }

        return ret;
}

static const struct file_operations sfs_fops = {
        .owner  = THIS_MODULE,
        .unlocked_ioctl = sfs_ioctl,
};

static void sfs_exit(struct kref *ref)
{
        misc_deregister(&misc_dev->misc);
        kfree(misc_dev);
        misc_dev = NULL;
}

void sfs_dev_destroy(struct psp_device *psp)
{
        struct sfs_device *sfs_dev = psp->sfs_data;

        if (!sfs_dev)
                return;

        /*
         * Change SFS command buffer back to the default "Write-Back" type.
         */
        set_memory_wb((unsigned long)sfs_dev->command_buf, SFS_NUM_PAGES_CMDBUF);

        snp_free_hv_fixed_pages(sfs_dev->page);

        if (sfs_dev->misc)
                kref_put(&misc_dev->refcount, sfs_exit);

        psp->sfs_data = NULL;
}

/* Based on sev_misc_init() */
static int sfs_misc_init(struct sfs_device *sfs)
{
        struct device *dev = sfs->dev;
        int ret;

        /*
         * SFS feature support can be detected on multiple devices but the SFS
         * FW commands must be issued on the master. During probe, we do not
         * know the master hence we create /dev/sfs on the first device probe.
         */
        if (!misc_dev) {
                struct miscdevice *misc;

                misc_dev = kzalloc_obj(*misc_dev);
                if (!misc_dev)
                        return -ENOMEM;

                misc = &misc_dev->misc;
                misc->minor = MISC_DYNAMIC_MINOR;
                misc->name = "sfs";
                misc->fops = &sfs_fops;
                misc->mode = 0600;

                ret = misc_register(misc);
                if (ret)
                        return ret;

                kref_init(&misc_dev->refcount);
        } else {
                kref_get(&misc_dev->refcount);
        }

        sfs->misc = misc_dev;
        dev_dbg(dev, "registered SFS device\n");

        return 0;
}

int sfs_dev_init(struct psp_device *psp)
{
        struct device *dev = psp->dev;
        struct sfs_device *sfs_dev;
        struct page *page;
        int ret = -ENOMEM;

        sfs_dev = devm_kzalloc(dev, sizeof(*sfs_dev), GFP_KERNEL);
        if (!sfs_dev)
                return -ENOMEM;

        /*
         * Pre-allocate 2MB command buffer for all SFS commands using
         * SNP HV_Fixed page allocator which also transitions the
         * SFS command buffer to HV_Fixed page state if SNP is enabled.
         */
        page = snp_alloc_hv_fixed_pages(SFS_NUM_2MB_PAGES_CMDBUF);
        if (!page) {
                dev_dbg(dev, "Command Buffer HV-Fixed page allocation failed\n");
                goto cleanup_dev;
        }
        sfs_dev->page = page;
        sfs_dev->command_buf = page_address(page);

        dev_dbg(dev, "Command buffer 0x%px to be marked as HV_Fixed\n", sfs_dev->command_buf);

        /*
         * SFS command buffer must be mapped as non-cacheable.
         */
        ret = set_memory_uc((unsigned long)sfs_dev->command_buf, SFS_NUM_PAGES_CMDBUF);
        if (ret) {
                dev_dbg(dev, "Set memory uc failed\n");
                goto cleanup_cmd_buf;
        }

        dev_dbg(dev, "Command buffer 0x%px marked uncacheable\n", sfs_dev->command_buf);

        psp->sfs_data = sfs_dev;
        sfs_dev->dev = dev;
        sfs_dev->psp = psp;

        ret = sfs_misc_init(sfs_dev);
        if (ret)
                goto cleanup_mem_attr;

        dev_notice(sfs_dev->dev, "SFS support is available\n");

        return 0;

cleanup_mem_attr:
        set_memory_wb((unsigned long)sfs_dev->command_buf, SFS_NUM_PAGES_CMDBUF);

cleanup_cmd_buf:
        snp_free_hv_fixed_pages(page);

cleanup_dev:
        psp->sfs_data = NULL;
        devm_kfree(dev, sfs_dev);

        return ret;
}