/*
 * This file is part of the coreboot project.
 *
 * Copyright (C) 2011 The ChromiumOS Authors.  All rights reserved.
 * Copyright (C) 2017 Siemens AG
 *
 * 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; version 2 of the License.
 *
 * 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.
 */

#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <console/console.h>
#include <cbmem.h>
#include <symbols.h>
#include <timer.h>
#include <timestamp.h>
#include <arch/early_variables.h>
#include <rules.h>
#include <smp/node.h>

#define MAX_TIMESTAMPS 192

/* When changing this number, adjust TIMESTAMP() size ASSERT() in memlayout.h */
#define MAX_BSS_TIMESTAMP_CACHE 16

struct __packed timestamp_cache {
	uint32_t cache_state;
	struct timestamp_table table;
	/* The struct timestamp_table has a 0 length array as its last field.
	 * The  following 'entries' array serves as the storage space for the
	 * cache when allocated in the BSS. */
	struct timestamp_entry entries[MAX_BSS_TIMESTAMP_CACHE];
};

DECLARE_OPTIONAL_REGION(timestamp);

#if defined(__PRE_RAM__)
#define USE_TIMESTAMP_REGION (_timestamp_size > 0)
#else
#define USE_TIMESTAMP_REGION 0
#endif

/* The cache location will sit in BSS when in ramstage. */
#define TIMESTAMP_CACHE_IN_BSS ENV_RAMSTAGE

#define HAS_CBMEM (ENV_ROMSTAGE || ENV_RAMSTAGE || ENV_POSTCAR)

/* Storage of cache entries during ramstage prior to cbmem coming online. */
static struct timestamp_cache timestamp_cache;

enum {
	TIMESTAMP_CACHE_UNINITIALIZED = 0,
	TIMESTAMP_CACHE_INITIALIZED,
	TIMESTAMP_CACHE_NOT_NEEDED,
};

static void timestamp_cache_init(struct timestamp_cache *ts_cache,
				 uint64_t base)
{
	ts_cache->table.num_entries = 0;
	ts_cache->table.max_entries = MAX_BSS_TIMESTAMP_CACHE;
	ts_cache->table.base_time = base;
	ts_cache->cache_state = TIMESTAMP_CACHE_INITIALIZED;

	if (USE_TIMESTAMP_REGION)
		ts_cache->table.max_entries = (_timestamp_size -
			offsetof(struct timestamp_cache, entries))
			/ sizeof(struct timestamp_entry);
}

static struct timestamp_cache *timestamp_cache_get(void)
{
	struct timestamp_cache *ts_cache = NULL;

	if (TIMESTAMP_CACHE_IN_BSS) {
		ts_cache = &timestamp_cache;
	} else if (USE_TIMESTAMP_REGION) {
		if (_timestamp_size < sizeof(*ts_cache))
			BUG();
		ts_cache = car_get_var_ptr((void *)_timestamp);
	}

	return ts_cache;
}

static struct timestamp_table *timestamp_alloc_cbmem_table(void)
{
	struct timestamp_table *tst;

	tst = cbmem_add(CBMEM_ID_TIMESTAMP,
			sizeof(struct timestamp_table) +
			MAX_TIMESTAMPS * sizeof(struct timestamp_entry));

	if (!tst)
		return NULL;

	tst->base_time = 0;
	tst->max_entries = MAX_TIMESTAMPS;
	tst->num_entries = 0;

	return tst;
}

/* Determine if one should proceed into timestamp code. This is for protecting
 * systems that have multiple processors running in romstage -- namely AMD
 * based x86 platforms. */
static int timestamp_should_run(void)
{
	/* Only check boot_cpu() in other stages than ramstage on x86. */
	if ((!ENV_RAMSTAGE && IS_ENABLED(CONFIG_ARCH_X86)) && !boot_cpu())
		return 0;

	return 1;
}

static struct timestamp_table *timestamp_table_get(void)
{
	MAYBE_STATIC struct timestamp_table *ts_table = NULL;
	struct timestamp_cache *ts_cache;

	if (!timestamp_should_run())
		return NULL;

	if (ts_table != NULL)
		return ts_table;

	ts_cache = timestamp_cache_get();

	if (ts_cache == NULL) {
		if (HAS_CBMEM)
			ts_table = cbmem_find(CBMEM_ID_TIMESTAMP);
		return ts_table;
	}

	/* Cache is required. */
	if (ts_cache->cache_state != TIMESTAMP_CACHE_NOT_NEEDED)
		return &ts_cache->table;

	/* Cache shouldn't be used but there's no backing store. */
	if (!HAS_CBMEM)
		return NULL;

	ts_table = cbmem_find(CBMEM_ID_TIMESTAMP);

	return ts_table;
}

static const char *timestamp_name(enum timestamp_id id)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(timestamp_ids); i++) {
		if (timestamp_ids[i].id == id)
			return timestamp_ids[i].name;
	}

	return "Unknown timestamp ID";
}

static void timestamp_add_table_entry(struct timestamp_table *ts_table,
				      enum timestamp_id id, uint64_t ts_time)
{
	struct timestamp_entry *tse;

	if (ts_table->num_entries >= ts_table->max_entries)
		return;

	tse = &ts_table->entries[ts_table->num_entries++];
	tse->entry_id = id;
	tse->entry_stamp = ts_time - ts_table->base_time;

	if (IS_ENABLED(CONFIG_TIMESTAMPS_ON_CONSOLE))
		printk(BIOS_SPEW, "Timestamp - %s: %" PRIu64 "\n",
				timestamp_name(id), ts_time);

	if (ts_table->num_entries == ts_table->max_entries)
		printk(BIOS_ERR, "ERROR: Timestamp table full\n");
}

void timestamp_add(enum timestamp_id id, uint64_t ts_time)
{
	struct timestamp_table *ts_table;

	ts_table = timestamp_table_get();

	if (!ts_table) {
		printk(BIOS_ERR, "ERROR: No timestamp table found\n");
		return;
	}

	timestamp_add_table_entry(ts_table, id, ts_time);
}

void timestamp_add_now(enum timestamp_id id)
{
	timestamp_add(id, timestamp_get());
}

void timestamp_init(uint64_t base)
{
	struct timestamp_cache *ts_cache;

	if (!timestamp_should_run())
		return;

	ts_cache = timestamp_cache_get();

	if (!ts_cache) {
		printk(BIOS_ERR, "ERROR: No timestamp cache to init\n");
		return;
	}

	/* Timestamps could have already been recovered.
	 * In those circumstances honor the cache which sits in BSS
	 * as it has already been initialized. */
	if (ENV_RAMSTAGE &&
	    ts_cache->cache_state != TIMESTAMP_CACHE_UNINITIALIZED)
		return;

	timestamp_cache_init(ts_cache, base);
}

static void timestamp_sync_cache_to_cbmem(int is_recovery)
{
	uint32_t i;
	struct timestamp_cache *ts_cache;
	struct timestamp_table *ts_cache_table;
	struct timestamp_table *ts_cbmem_table = NULL;

	if (!timestamp_should_run())
		return;

	ts_cache = timestamp_cache_get();

	/* No timestamp cache found */
	if (ts_cache == NULL) {
		printk(BIOS_ERR, "ERROR: No timestamp cache found\n");
		return;
	}

	ts_cache_table = &ts_cache->table;

	/* cbmem is being recovered. */
	if (is_recovery) {
		/* x86 resume path expects timestamps to be reset. */
		if (IS_ENABLED(CONFIG_ARCH_ROMSTAGE_X86_32) && ENV_ROMSTAGE)
			ts_cbmem_table = timestamp_alloc_cbmem_table();
		else {
			/* Find existing table in cbmem. */
			ts_cbmem_table = cbmem_find(CBMEM_ID_TIMESTAMP);
			/* No existing timestamp table. */
			if (ts_cbmem_table == NULL)
				ts_cbmem_table = timestamp_alloc_cbmem_table();
		}
	} else
		/* First time sync. Add new table. */
		ts_cbmem_table = timestamp_alloc_cbmem_table();

	if (ts_cbmem_table == NULL) {
		printk(BIOS_ERR, "ERROR: No timestamp table allocated\n");
		return;
	}

	/*
	 * There's no need to worry about the base_time fields being out of
	 * sync because only the following configuration is used/supported:
	 *
	 *    Timestamps get initialized before ramstage, which implies
	 *    CBMEM initialization in romstage.
	 *    This requires the board to define a TIMESTAMP() region in its
	 *    memlayout.ld (default on x86). The base_time from timestamp_init()
	 *    (usually called from bootblock.c on most non-x86 boards) persists
	 *    in that region until it gets synced to CBMEM in romstage.
	 *    In ramstage, the BSS cache's base_time will be 0 until the second
	 *    sync, which will adjust the timestamps in there to the correct
	 *    base_time (from CBMEM) with the timestamp_add_table_entry() below.
	 *
	 * If you try to initialize timestamps before ramstage but don't define
	 * a TIMESTAMP region, all operations will fail (safely), and coreboot
	 * will behave as if timestamps only get initialized in ramstage.
	 *
	 * If timestamps only get initialized in ramstage, the base_time from
	 * timestamp_init() will get ignored and all timestamps will be 0-based.
	 */
	for (i = 0; i < ts_cache_table->num_entries; i++) {
		struct timestamp_entry *tse = &ts_cache_table->entries[i];
		timestamp_add_table_entry(ts_cbmem_table, tse->entry_id,
					  tse->entry_stamp);
	}

	/* Freshly added cbmem table has base_time 0. Inherit cache base_time */
	if (ts_cbmem_table->base_time == 0)
		ts_cbmem_table->base_time = ts_cache_table->base_time;

	/* Seed the timestamp tick frequency in ramstage. */
	if (ENV_RAMSTAGE)
		ts_cbmem_table->tick_freq_mhz = timestamp_tick_freq_mhz();

	/* Cache no longer required. */
	ts_cache_table->num_entries = 0;
	ts_cache->cache_state = TIMESTAMP_CACHE_NOT_NEEDED;
}

void timestamp_rescale_table(uint16_t N, uint16_t M)
{
	uint32_t i;
	struct timestamp_table *ts_table;

	if (!timestamp_should_run())
		return;

	if (N == 0 || M == 0)
		return;

	ts_table = timestamp_table_get();

	/* No timestamp table found */
	if (ts_table == NULL) {
		printk(BIOS_ERR, "ERROR: No timestamp table found\n");
		return;
	}

	ts_table->base_time /= M;
	ts_table->base_time *= N;
	for (i = 0; i < ts_table->num_entries; i++) {
		struct timestamp_entry *tse = &ts_table->entries[i];
		tse->entry_stamp /= M;
		tse->entry_stamp *= N;
	}
}

/*
 * Get the time in microseconds since boot (or more precise: since timestamp
 * table was initialized).
 */
uint32_t get_us_since_boot(void)
{
	struct timestamp_table *ts = timestamp_table_get();

	if (ts == NULL || ts->tick_freq_mhz == 0)
		return 0;
	return (timestamp_get() - ts->base_time) / ts->tick_freq_mhz;
}

ROMSTAGE_CBMEM_INIT_HOOK(timestamp_sync_cache_to_cbmem)
RAMSTAGE_CBMEM_INIT_HOOK(timestamp_sync_cache_to_cbmem)

/* Provide default timestamp implementation using monotonic timer. */
uint64_t  __weak timestamp_get(void)
{
	struct mono_time t1, t2;

	if (!IS_ENABLED(CONFIG_HAVE_MONOTONIC_TIMER))
		return 0;

	mono_time_set_usecs(&t1, 0);
	timer_monotonic_get(&t2);

	return mono_time_diff_microseconds(&t1, &t2);
}

/* Like timestamp_get() above this matches up with microsecond granularity. */
int __weak timestamp_tick_freq_mhz(void)
{
	return 1;
}