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/*
* PowerNV OPAL asynchronous completion interfaces
*
* Copyright 2013 IBM Corp.
*
* 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.
*/
#undef DEBUG
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/semaphore.h>
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/gfp.h>
#include <linux/of.h>
#include <asm/opal.h>
#define N_ASYNC_COMPLETIONS 64
static DECLARE_BITMAP(opal_async_complete_map, N_ASYNC_COMPLETIONS) = {~0UL};
static DECLARE_BITMAP(opal_async_token_map, N_ASYNC_COMPLETIONS);
static DECLARE_WAIT_QUEUE_HEAD(opal_async_wait);
static DEFINE_SPINLOCK(opal_async_comp_lock);
static struct semaphore opal_async_sem;
static struct opal_msg *opal_async_responses;
static unsigned int opal_max_async_tokens;
int __opal_async_get_token(void)
{
unsigned long flags;
int token;
spin_lock_irqsave(&opal_async_comp_lock, flags);
token = find_first_bit(opal_async_complete_map, opal_max_async_tokens);
if (token >= opal_max_async_tokens) {
token = -EBUSY;
goto out;
}
if (__test_and_set_bit(token, opal_async_token_map)) {
token = -EBUSY;
goto out;
}
__clear_bit(token, opal_async_complete_map);
out:
spin_unlock_irqrestore(&opal_async_comp_lock, flags);
return token;
}
int opal_async_get_token_interruptible(void)
{
int token;
/* Wait until a token is available */
if (down_interruptible(&opal_async_sem))
return -ERESTARTSYS;
token = __opal_async_get_token();
if (token < 0)
up(&opal_async_sem);
return token;
}
int __opal_async_release_token(int token)
{
unsigned long flags;
if (token < 0 || token >= opal_max_async_tokens) {
pr_err("%s: Passed token is out of range, token %d\n",
__func__, token);
return -EINVAL;
}
spin_lock_irqsave(&opal_async_comp_lock, flags);
__set_bit(token, opal_async_complete_map);
__clear_bit(token, opal_async_token_map);
spin_unlock_irqrestore(&opal_async_comp_lock, flags);
return 0;
}
int opal_async_release_token(int token)
{
int ret;
ret = __opal_async_release_token(token);
if (ret)
return ret;
up(&opal_async_sem);
return 0;
}
int opal_async_wait_response(uint64_t token, struct opal_msg *msg)
{
if (token >= opal_max_async_tokens) {
pr_err("%s: Invalid token passed\n", __func__);
return -EINVAL;
}
if (!msg) {
pr_err("%s: Invalid message pointer passed\n", __func__);
return -EINVAL;
}
wait_event(opal_async_wait, test_bit(token, opal_async_complete_map));
memcpy(msg, &opal_async_responses[token], sizeof(*msg));
return 0;
}
static int opal_async_comp_event(struct notifier_block *nb,
unsigned long msg_type, void *msg)
{
struct opal_msg *comp_msg = msg;
unsigned long flags;
if (msg_type != OPAL_MSG_ASYNC_COMP)
return 0;
memcpy(&opal_async_responses[comp_msg->params[0]], comp_msg,
sizeof(*comp_msg));
spin_lock_irqsave(&opal_async_comp_lock, flags);
__set_bit(comp_msg->params[0], opal_async_complete_map);
spin_unlock_irqrestore(&opal_async_comp_lock, flags);
wake_up(&opal_async_wait);
return 0;
}
static struct notifier_block opal_async_comp_nb = {
.notifier_call = opal_async_comp_event,
.next = NULL,
.priority = 0,
};
static int __init opal_async_comp_init(void)
{
struct device_node *opal_node;
const __be32 *async;
int err;
opal_node = of_find_node_by_path("/ibm,opal");
if (!opal_node) {
pr_err("%s: Opal node not found\n", __func__);
err = -ENOENT;
goto out;
}
async = of_get_property(opal_node, "opal-msg-async-num", NULL);
if (!async) {
pr_err("%s: %s has no opal-msg-async-num\n",
__func__, opal_node->full_name);
err = -ENOENT;
goto out_opal_node;
}
opal_max_async_tokens = be32_to_cpup(async);
if (opal_max_async_tokens > N_ASYNC_COMPLETIONS)
opal_max_async_tokens = N_ASYNC_COMPLETIONS;
err = opal_message_notifier_register(OPAL_MSG_ASYNC_COMP,
&opal_async_comp_nb);
if (err) {
pr_err("%s: Can't register OPAL event notifier (%d)\n",
__func__, err);
goto out_opal_node;
}
opal_async_responses = kzalloc(
sizeof(*opal_async_responses) * opal_max_async_tokens,
GFP_KERNEL);
if (!opal_async_responses) {
pr_err("%s: Out of memory, failed to do asynchronous "
"completion init\n", __func__);
err = -ENOMEM;
goto out_opal_node;
}
/* Initialize to 1 less than the maximum tokens available, as we may
* require to pop one during emergency through synchronous call to
* __opal_async_get_token()
*/
sema_init(&opal_async_sem, opal_max_async_tokens - 1);
out_opal_node:
of_node_put(opal_node);
out:
return err;
}
subsys_initcall(opal_async_comp_init);
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