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/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "console.h"
#include "hooks.h"
#include "host_command.h"
#include "task.h"
#include "timer.h"
#include "util.h"
/* Event log FIFO */
#define UNIT_SIZE sizeof(struct ec_response_pd_log)
#define LOG_SIZE (CONFIG_USB_PD_LOG_SIZE/UNIT_SIZE)
static struct ec_response_pd_log log_events[LOG_SIZE];
BUILD_ASSERT(POWER_OF_TWO(LOG_SIZE));
/*
* The FIFO pointers are defined as following :
* "log_head" is the next available event to dequeue.
* "log_tail" is marking the end of the FIFO content (after last commited event)
* "log_tail_next" is the next available spot to enqueue events.
* The pointers are not wrapped until they are used, so we don't need an extra
* entry to disambiguate between full and empty FIFO.
*
* For concurrency, several tasks might try to enqueue events in parallel with
* pd_log_event(). Only one task is dequeuing events (host commands or VDM).
* When the FIFO is full, pd_log_event() will discard the oldest events,
* so "log_head" is incremented/decremented in a critical section since it is
* accessed from both pd_log_event() and pd_log_dequeue().
* log_tail_next is also protected as several writers can race to add an event
* to the queue.
* When a writer is done adding its event, it is updating log_tail,
* so the event can be consumed by pd_log_dequeue().
*/
static size_t log_head;
static size_t log_tail;
static size_t log_tail_next;
/* Size of one FIFO entry */
#define ENTRY_SIZE(payload_sz) (1+DIV_ROUND_UP((payload_sz), UNIT_SIZE))
void pd_log_event(uint8_t type, uint8_t size_port,
uint16_t data, void *payload)
{
struct ec_response_pd_log *r;
size_t payload_size = PD_LOG_SIZE(size_port);
size_t total_size = ENTRY_SIZE(payload_size);
size_t current_tail, first;
/* --- critical section : reserve queue space --- */
interrupt_disable();
current_tail = log_tail_next;
log_tail_next = current_tail + total_size;
interrupt_enable();
/* --- end of critical section --- */
/* Out of space : discard the oldest entry */
while ((LOG_SIZE - (current_tail - log_head)) < total_size) {
struct ec_response_pd_log *oldest;
/* --- critical section : atomically free-up space --- */
interrupt_disable();
oldest = log_events + (log_head & (LOG_SIZE - 1));
log_head += ENTRY_SIZE(PD_LOG_SIZE(oldest->size_port));
interrupt_enable();
/* --- end of critical section --- */
}
r = log_events + (current_tail & (LOG_SIZE - 1));
r->timestamp = get_time().val >> PD_LOG_TIMESTAMP_SHIFT;
r->type = type;
r->size_port = size_port;
r->data = data;
/* copy the payload into the FIFO */
first = MIN(total_size - 1, (LOG_SIZE -
(current_tail & (LOG_SIZE - 1))) - 1);
if (first)
memcpy(r->payload, payload, first * UNIT_SIZE);
if (first < total_size - 1)
memcpy(log_events, ((uint8_t *)payload) + first * UNIT_SIZE,
(total_size - first) * UNIT_SIZE);
/* mark the entry available in the queue if nobody is behind us */
if (current_tail == log_tail)
log_tail = log_tail_next;
}
static int pd_log_dequeue(struct ec_response_pd_log *r)
{
uint32_t now = get_time().val >> PD_LOG_TIMESTAMP_SHIFT;
unsigned total_size, first;
struct ec_response_pd_log *entry;
size_t current_head;
retry:
current_head = log_head;
/* The log FIFO is empty */
if (log_tail == current_head) {
memset(r, 0, UNIT_SIZE);
r->type = PD_EVENT_NO_ENTRY;
return UNIT_SIZE;
}
entry = log_events + (current_head & (LOG_SIZE - 1));
total_size = ENTRY_SIZE(PD_LOG_SIZE(entry->size_port));
first = MIN(total_size, LOG_SIZE - (current_head & (LOG_SIZE - 1)));
memcpy(r, entry, first * UNIT_SIZE);
if (first < total_size)
memcpy(r + first, log_events, (total_size-first) * UNIT_SIZE);
/* --- critical section : remove the entry from the queue --- */
interrupt_disable();
if (log_head != current_head) { /* our entry was thrown away */
interrupt_enable();
goto retry;
}
log_head += total_size;
interrupt_enable();
/* --- end of critical section --- */
/* fixup the timestamp : number of milliseconds in the past */
r->timestamp = now - r->timestamp;
return total_size * UNIT_SIZE;
}
#ifdef HAS_TASK_HOSTCMD
/* we are a PD MCU/EC, send back the events to the host */
static int hc_pd_get_log_entry(struct host_cmd_handler_args *args)
{
struct ec_response_pd_log *r = args->response;
args->response_size = pd_log_dequeue(r);
return EC_RES_SUCCESS;
}
DECLARE_HOST_COMMAND(EC_CMD_PD_GET_LOG_ENTRY,
hc_pd_get_log_entry,
EC_VER_MASK(0));
#else /* !HAS_TASK_HOSTCMD */
/* we are a PD accessory, send back the events as a VDM (VDO_CMD_GET_LOG) */
int pd_vdm_get_log_entry(uint32_t *payload)
{
struct ec_response_pd_log *r = (void *)&payload[1];
int byte_size;
byte_size = pd_log_dequeue(r);
return 1 + DIV_ROUND_UP(byte_size, sizeof(uint32_t));
}
#endif /* !HAS_TASK_HOSTCMD */
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