/*
 * cros_ec_debugfs - debug logs for Chrome OS EC
 *
 * Copyright 2015 Google, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/circ_buf.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/mfd/cros_ec.h>
#include <linux/mfd/cros_ec_commands.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/wait.h>

#include "cros_ec_dev.h"
#include "cros_ec_debugfs.h"

#define LOG_SHIFT               14
#define LOG_SIZE                (1 << LOG_SHIFT)
#define LOG_POLL_SEC            10

#define CIRC_ADD(idx, size, value)      (((idx) + (value)) & ((size) - 1))

/* struct cros_ec_debugfs - ChromeOS EC debugging information
 *
 * @ec: EC device this debugfs information belongs to
 * @dir: dentry for debugfs files
 * @log_buffer: circular buffer for console log information
 * @read_msg: preallocated EC command and buffer to read console log
 * @log_mutex: mutex to protect circular buffer
 * @log_wq: waitqueue for log readers
 * @log_poll_work: recurring task to poll EC for new console log data
 * @panicinfo_blob: panicinfo debugfs blob
 */
struct cros_ec_debugfs {
        struct cros_ec_dev *ec;
        struct dentry *dir;
        /* EC log */
        struct circ_buf log_buffer;
        struct cros_ec_command *read_msg;
        struct mutex log_mutex;
        wait_queue_head_t log_wq;
        struct delayed_work log_poll_work;
        /* EC panicinfo */
        struct debugfs_blob_wrapper panicinfo_blob;
};

/*
 * We need to make sure that the EC log buffer on the UART is large enough,
 * so that it is unlikely enough to overlow within LOG_POLL_SEC.
 */
static void cros_ec_console_log_work(struct work_struct *__work)
{
        struct cros_ec_debugfs *debug_info =
                container_of(to_delayed_work(__work),
                             struct cros_ec_debugfs,
                             log_poll_work);
        struct cros_ec_dev *ec = debug_info->ec;
        struct circ_buf *cb = &debug_info->log_buffer;
        struct cros_ec_command snapshot_msg = {
                .command = EC_CMD_CONSOLE_SNAPSHOT + ec->cmd_offset,
        };

        struct ec_params_console_read_v1 *read_params =
                (struct ec_params_console_read_v1 *)debug_info->read_msg->data;
        uint8_t *ec_buffer = (uint8_t *)debug_info->read_msg->data;
        int idx;
        int buf_space;
        int ret;

        ret = cros_ec_cmd_xfer(ec->ec_dev, &snapshot_msg);
        if (ret < 0) {
                dev_err(ec->dev, "EC communication failed\n");
                goto resched;
        }
        if (snapshot_msg.result != EC_RES_SUCCESS) {
                dev_err(ec->dev, "EC failed to snapshot the console log\n");
                goto resched;
        }

        /* Loop until we have read everything, or there's an error. */
        mutex_lock(&debug_info->log_mutex);
        buf_space = CIRC_SPACE(cb->head, cb->tail, LOG_SIZE);

        while (1) {
                if (!buf_space) {
                        dev_info_once(ec->dev,
                                      "Some logs may have been dropped...\n");
                        break;
                }

                memset(read_params, '\0', sizeof(*read_params));
                read_params->subcmd = CONSOLE_READ_RECENT;
                ret = cros_ec_cmd_xfer(ec->ec_dev, debug_info->read_msg);
                if (ret < 0) {
                        dev_err(ec->dev, "EC communication failed\n");
                        break;
                }
                if (debug_info->read_msg->result != EC_RES_SUCCESS) {
                        dev_err(ec->dev,
                                "EC failed to read the console log\n");
                        break;
                }

                /* If the buffer is empty, we're done here. */
                if (ret == 0 || ec_buffer[0] == '\0')
                        break;

                idx = 0;
                while (idx < ret && ec_buffer[idx] != '\0' && buf_space > 0) {
                        cb->buf[cb->head] = ec_buffer[idx];
                        cb->head = CIRC_ADD(cb->head, LOG_SIZE, 1);
                        idx++;
                        buf_space--;
                }

                wake_up(&debug_info->log_wq);
        }

        mutex_unlock(&debug_info->log_mutex);

resched:
        schedule_delayed_work(&debug_info->log_poll_work,
                              msecs_to_jiffies(LOG_POLL_SEC * 1000));
}

static int cros_ec_console_log_open(struct inode *inode, struct file *file)
{
        file->private_data = inode->i_private;

        return nonseekable_open(inode, file);
}

static ssize_t cros_ec_console_log_read(struct file *file, char __user *buf,
                                        size_t count, loff_t *ppos)
{
        struct cros_ec_debugfs *debug_info = file->private_data;
        struct circ_buf *cb = &debug_info->log_buffer;
        ssize_t ret;

        mutex_lock(&debug_info->log_mutex);

        while (!CIRC_CNT(cb->head, cb->tail, LOG_SIZE)) {
                if (file->f_flags & O_NONBLOCK) {
                        ret = -EAGAIN;
                        goto error;
                }

                mutex_unlock(&debug_info->log_mutex);

                ret = wait_event_interruptible(debug_info->log_wq,
                                        CIRC_CNT(cb->head, cb->tail, LOG_SIZE));
                if (ret < 0)
                        return ret;

                mutex_lock(&debug_info->log_mutex);
        }

        /* Only copy until the end of the circular buffer, and let userspace
         * retry to get the rest of the data.
         */
        ret = min_t(size_t, CIRC_CNT_TO_END(cb->head, cb->tail, LOG_SIZE),
                    count);

        if (copy_to_user(buf, cb->buf + cb->tail, ret)) {
                ret = -EFAULT;
                goto error;
        }

        cb->tail = CIRC_ADD(cb->tail, LOG_SIZE, ret);

error:
        mutex_unlock(&debug_info->log_mutex);
        return ret;
}

static unsigned int cros_ec_console_log_poll(struct file *file,
                                             poll_table *wait)
{
        struct cros_ec_debugfs *debug_info = file->private_data;
        unsigned int mask = 0;

        poll_wait(file, &debug_info->log_wq, wait);

        mutex_lock(&debug_info->log_mutex);
        if (CIRC_CNT(debug_info->log_buffer.head,
                     debug_info->log_buffer.tail,
                     LOG_SIZE))
                mask |= POLLIN | POLLRDNORM;
        mutex_unlock(&debug_info->log_mutex);

        return mask;
}

static int cros_ec_console_log_release(struct inode *inode, struct file *file)
{
        return 0;
}

const struct file_operations cros_ec_console_log_fops = {
        .owner = THIS_MODULE,
        .open = cros_ec_console_log_open,
        .read = cros_ec_console_log_read,
        .llseek = no_llseek,
        .poll = cros_ec_console_log_poll,
        .release = cros_ec_console_log_release,
};

static int ec_read_version_supported(struct cros_ec_dev *ec)
{
        struct ec_params_get_cmd_versions_v1 *params;
        struct ec_response_get_cmd_versions *response;
        int ret;

        struct cros_ec_command *msg;

        msg = kzalloc(sizeof(*msg) + max(sizeof(*params), sizeof(*response)),
                GFP_KERNEL);
        if (!msg)
                return 0;

        msg->command = EC_CMD_GET_CMD_VERSIONS + ec->cmd_offset;
        msg->outsize = sizeof(*params);
        msg->insize = sizeof(*response);

        params = (struct ec_params_get_cmd_versions_v1 *)msg->data;
        params->cmd = EC_CMD_CONSOLE_READ;
        response = (struct ec_response_get_cmd_versions *)msg->data;

        ret = cros_ec_cmd_xfer(ec->ec_dev, msg) >= 0 &&
                msg->result == EC_RES_SUCCESS &&
                (response->version_mask & EC_VER_MASK(1));

        kfree(msg);

        return ret;
}

static int cros_ec_create_console_log(struct cros_ec_debugfs *debug_info)
{
        struct cros_ec_dev *ec = debug_info->ec;
        char *buf;
        int read_params_size;
        int read_response_size;

        if (!ec_read_version_supported(ec)) {
                dev_warn(ec->dev,
                        "device does not support reading the console log\n");
                return 0;
        }

        buf = devm_kzalloc(ec->dev, LOG_SIZE, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        read_params_size = sizeof(struct ec_params_console_read_v1);
        read_response_size = ec->ec_dev->max_response;
        debug_info->read_msg = devm_kzalloc(ec->dev,
                sizeof(*debug_info->read_msg) +
                        max(read_params_size, read_response_size), GFP_KERNEL);
        if (!debug_info->read_msg)
                return -ENOMEM;

        debug_info->read_msg->version = 1;
        debug_info->read_msg->command = EC_CMD_CONSOLE_READ + ec->cmd_offset;
        debug_info->read_msg->outsize = read_params_size;
        debug_info->read_msg->insize = read_response_size;

        debug_info->log_buffer.buf = buf;
        debug_info->log_buffer.head = 0;
        debug_info->log_buffer.tail = 0;

        mutex_init(&debug_info->log_mutex);
        init_waitqueue_head(&debug_info->log_wq);

        if (!debugfs_create_file("console_log",
                                 S_IFREG | S_IRUGO,
                                 debug_info->dir,
                                 debug_info,
                                 &cros_ec_console_log_fops))
                return -ENOMEM;

        INIT_DELAYED_WORK(&debug_info->log_poll_work,
                          cros_ec_console_log_work);
        schedule_delayed_work(&debug_info->log_poll_work, 0);

        return 0;
}

static void cros_ec_cleanup_console_log(struct cros_ec_debugfs *debug_info)
{
        if (debug_info->log_buffer.buf) {
                cancel_delayed_work_sync(&debug_info->log_poll_work);
                mutex_destroy(&debug_info->log_mutex);
        }
}

static int cros_ec_create_panicinfo(struct cros_ec_debugfs *debug_info)
{
        struct cros_ec_device *ec_dev = debug_info->ec->ec_dev;
        int ret;
        struct cros_ec_command *msg;
        int insize;

        insize = ec_dev->max_response;

        msg = devm_kzalloc(debug_info->ec->dev,
                        sizeof(*msg) + insize, GFP_KERNEL);
        if (!msg)
                return -ENOMEM;

        msg->command = EC_CMD_GET_PANIC_INFO;
        msg->insize = insize;

        ret = cros_ec_cmd_xfer(ec_dev, msg);
        if (ret < 0) {
                dev_warn(debug_info->ec->dev, "Cannot read panicinfo.\n");
                ret = 0;
                goto free;
        }

        /* No panic data */
        if (ret == 0)
                goto free;

        debug_info->panicinfo_blob.data = msg->data;
        debug_info->panicinfo_blob.size = ret;

        if (!debugfs_create_blob("panicinfo",
                                 S_IFREG | S_IRUGO,
                                 debug_info->dir,
                                 &debug_info->panicinfo_blob)) {
                ret = -ENOMEM;
                goto free;
        }

        return 0;

free:
        devm_kfree(debug_info->ec->dev, msg);
        return ret;
}

int cros_ec_debugfs_init(struct cros_ec_dev *ec)
{
        struct cros_ec_platform *ec_platform = dev_get_platdata(ec->dev);
        const char *name = ec_platform->ec_name;
        struct cros_ec_debugfs *debug_info;
        int ret;

        debug_info = devm_kzalloc(ec->dev, sizeof(*debug_info), GFP_KERNEL);
        if (!debug_info)
                return -ENOMEM;

        debug_info->ec = ec;
        debug_info->dir = debugfs_create_dir(name, NULL);
        if (!debug_info->dir)
                return -ENOMEM;

        ret = cros_ec_create_panicinfo(debug_info);
        if (ret)
                goto remove_debugfs;

        ret = cros_ec_create_console_log(debug_info);
        if (ret)
                goto remove_debugfs;

        ec->debug_info = debug_info;

        return 0;

remove_debugfs:
        debugfs_remove_recursive(debug_info->dir);
        return ret;
}

void cros_ec_debugfs_remove(struct cros_ec_dev *ec)
{
        if (!ec->debug_info)
                return;

        debugfs_remove_recursive(ec->debug_info->dir);
        cros_ec_cleanup_console_log(ec->debug_info);
}