/*
 * Remote Processor Framework
 *
 * Copyright (C) 2011 Texas Instruments, Inc.
 * Copyright (C) 2011 Google, Inc.
 *
 * Ohad Ben-Cohen <ohad@wizery.com>
 * Mark Grosen <mgrosen@ti.com>
 * Brian Swetland <swetland@google.com>
 * Fernando Guzman Lugo <fernando.lugo@ti.com>
 * Suman Anna <s-anna@ti.com>
 * Robert Tivy <rtivy@ti.com>
 * Armando Uribe De Leon <x0095078@ti.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * 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.
 */

#define pr_fmt(fmt)    "%s: " fmt, __func__

#include <linux/kernel.h>
#include <linux/debugfs.h>
#include <linux/remoteproc.h>
#include <linux/device.h>
#include <linux/uaccess.h>

#include "remoteproc_internal.h"

/* remoteproc debugfs parent dir */
static struct dentry *rproc_dbg;

/*
 * Some remote processors may support dumping trace logs into a shared
 * memory buffer. We expose this trace buffer using debugfs, so users
 * can easily tell what's going on remotely.
 *
 * We will most probably improve the rproc tracing facilities later on,
 * but this kind of lightweight and simple mechanism is always good to have,
 * as it provides very early tracing with little to no dependencies at all.
 */
static ssize_t rproc_trace_read(struct file *filp, char __user *userbuf,
                                                size_t count, loff_t *ppos)
{
        struct rproc_mem_entry *trace = filp->private_data;
        int len = strnlen(trace->va, trace->len);

        return simple_read_from_buffer(userbuf, count, ppos, trace->va, len);
}

static const struct file_operations trace_rproc_ops = {
        .read = rproc_trace_read,
        .open = simple_open,
        .llseek = generic_file_llseek,
};

/*
 * A state-to-string lookup table, for exposing a human readable state
 * via debugfs. Always keep in sync with enum rproc_state
 */
static const char * const rproc_state_string[] = {
        "offline",
        "suspended",
        "running",
        "crashed",
        "invalid",
};

/* expose the state of the remote processor via debugfs */
static ssize_t rproc_state_read(struct file *filp, char __user *userbuf,
                                                size_t count, loff_t *ppos)
{
        struct rproc *rproc = filp->private_data;
        unsigned int state;
        char buf[30];
        int i;

        state = rproc->state > RPROC_LAST ? RPROC_LAST : rproc->state;

        i = scnprintf(buf, 30, "%.28s (%d)\n", rproc_state_string[state],
                                                        rproc->state);

        return simple_read_from_buffer(userbuf, count, ppos, buf, i);
}

static const struct file_operations rproc_state_ops = {
        .read = rproc_state_read,
        .open = simple_open,
        .llseek = generic_file_llseek,
};

/* expose the name of the remote processor via debugfs */
static ssize_t rproc_name_read(struct file *filp, char __user *userbuf,
                                                size_t count, loff_t *ppos)
{
        struct rproc *rproc = filp->private_data;
        /* need room for the name, a newline and a terminating null */
        char buf[100];
        int i;

        i = scnprintf(buf, sizeof(buf), "%.98s\n", rproc->name);

        return simple_read_from_buffer(userbuf, count, ppos, buf, i);
}

static const struct file_operations rproc_name_ops = {
        .read = rproc_name_read,
        .open = simple_open,
        .llseek = generic_file_llseek,
};

/* expose recovery flag via debugfs */
static ssize_t rproc_recovery_read(struct file *filp, char __user *userbuf,
                                   size_t count, loff_t *ppos)
{
        struct rproc *rproc = filp->private_data;
        char *buf = rproc->recovery_disabled ? "disabled\n" : "enabled\n";

        return simple_read_from_buffer(userbuf, count, ppos, buf, strlen(buf));
}

/*
 * By writing to the 'recovery' debugfs entry, we control the behavior of the
 * recovery mechanism dynamically. The default value of this entry is "enabled".
 *
 * The 'recovery' debugfs entry supports these commands:
 *
 * enabled:     When enabled, the remote processor will be automatically
 *              recovered whenever it crashes. Moreover, if the remote
 *              processor crashes while recovery is disabled, it will
 *              be automatically recovered too as soon as recovery is enabled.
 *
 * disabled:    When disabled, a remote processor will remain in a crashed
 *              state if it crashes. This is useful for debugging purposes;
 *              without it, debugging a crash is substantially harder.
 *
 * recover:     This function will trigger an immediate recovery if the
 *              remote processor is in a crashed state, without changing
 *              or checking the recovery state (enabled/disabled).
 *              This is useful during debugging sessions, when one expects
 *              additional crashes to happen after enabling recovery. In this
 *              case, enabling recovery will make it hard to debug subsequent
 *              crashes, so it's recommended to keep recovery disabled, and
 *              instead use the "recover" command as needed.
 */
static ssize_t
rproc_recovery_write(struct file *filp, const char __user *user_buf,
                     size_t count, loff_t *ppos)
{
        struct rproc *rproc = filp->private_data;
        char buf[10];
        int ret;

        if (count > sizeof(buf))
                return count;

        ret = copy_from_user(buf, user_buf, count);
        if (ret)
                return -EFAULT;

        /* remove end of line */
        if (buf[count - 1] == '\n')
                buf[count - 1] = '\0';

        if (!strncmp(buf, "enabled", count)) {
                rproc->recovery_disabled = false;
                /* if rproc has crashed, trigger recovery */
                if (rproc->state == RPROC_CRASHED)
                        rproc_trigger_recovery(rproc);
        } else if (!strncmp(buf, "disabled", count)) {
                rproc->recovery_disabled = true;
        } else if (!strncmp(buf, "recover", count)) {
                /* if rproc has crashed, trigger recovery */
                if (rproc->state == RPROC_CRASHED)
                        rproc_trigger_recovery(rproc);
        }

        return count;
}

static const struct file_operations rproc_recovery_ops = {
        .read = rproc_recovery_read,
        .write = rproc_recovery_write,
        .open = simple_open,
        .llseek = generic_file_llseek,
};

void rproc_remove_trace_file(struct dentry *tfile)
{
        debugfs_remove(tfile);
}

struct dentry *rproc_create_trace_file(const char *name, struct rproc *rproc,
                                        struct rproc_mem_entry *trace)
{
        struct dentry *tfile;

        tfile = debugfs_create_file(name, 0400, rproc->dbg_dir,
                                                trace, &trace_rproc_ops);
        if (!tfile) {
                dev_err(&rproc->dev, "failed to create debugfs trace entry\n");
                return NULL;
        }

        return tfile;
}

void rproc_delete_debug_dir(struct rproc *rproc)
{
        if (!rproc->dbg_dir)
                return;

        debugfs_remove_recursive(rproc->dbg_dir);
}

void rproc_create_debug_dir(struct rproc *rproc)
{
        struct device *dev = &rproc->dev;

        if (!rproc_dbg)
                return;

        rproc->dbg_dir = debugfs_create_dir(dev_name(dev), rproc_dbg);
        if (!rproc->dbg_dir)
                return;

        debugfs_create_file("name", 0400, rproc->dbg_dir,
                                        rproc, &rproc_name_ops);
        debugfs_create_file("state", 0400, rproc->dbg_dir,
                                        rproc, &rproc_state_ops);
        debugfs_create_file("recovery", 0400, rproc->dbg_dir,
                                        rproc, &rproc_recovery_ops);
}

void __init rproc_init_debugfs(void)
{
        if (debugfs_initialized()) {
                rproc_dbg = debugfs_create_dir(KBUILD_MODNAME, NULL);
                if (!rproc_dbg)
                        pr_err("can't create debugfs dir\n");
        }
}

void __exit rproc_exit_debugfs(void)
{
        debugfs_remove(rproc_dbg);
}