1/*
2 * PowerNV OPAL asynchronous completion interfaces
3 *
4 * Copyright 2013 IBM Corp.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#undef DEBUG
13
14#include <linux/kernel.h>
15#include <linux/init.h>
16#include <linux/slab.h>
17#include <linux/sched.h>
18#include <linux/semaphore.h>
19#include <linux/spinlock.h>
20#include <linux/wait.h>
21#include <linux/gfp.h>
22#include <linux/of.h>
23#include <asm/machdep.h>
24#include <asm/opal.h>
25
26#define N_ASYNC_COMPLETIONS	64
27
28static DECLARE_BITMAP(opal_async_complete_map, N_ASYNC_COMPLETIONS) = {~0UL};
29static DECLARE_BITMAP(opal_async_token_map, N_ASYNC_COMPLETIONS);
30static DECLARE_WAIT_QUEUE_HEAD(opal_async_wait);
31static DEFINE_SPINLOCK(opal_async_comp_lock);
32static struct semaphore opal_async_sem;
33static struct opal_msg *opal_async_responses;
34static unsigned int opal_max_async_tokens;
35
36int __opal_async_get_token(void)
37{
38	unsigned long flags;
39	int token;
40
41	spin_lock_irqsave(&opal_async_comp_lock, flags);
42	token = find_first_bit(opal_async_complete_map, opal_max_async_tokens);
43	if (token >= opal_max_async_tokens) {
44		token = -EBUSY;
45		goto out;
46	}
47
48	if (__test_and_set_bit(token, opal_async_token_map)) {
49		token = -EBUSY;
50		goto out;
51	}
52
53	__clear_bit(token, opal_async_complete_map);
54
55out:
56	spin_unlock_irqrestore(&opal_async_comp_lock, flags);
57	return token;
58}
59
60int opal_async_get_token_interruptible(void)
61{
62	int token;
63
64	/* Wait until a token is available */
65	if (down_interruptible(&opal_async_sem))
66		return -ERESTARTSYS;
67
68	token = __opal_async_get_token();
69	if (token < 0)
70		up(&opal_async_sem);
71
72	return token;
73}
74EXPORT_SYMBOL_GPL(opal_async_get_token_interruptible);
75
76int __opal_async_release_token(int token)
77{
78	unsigned long flags;
79
80	if (token < 0 || token >= opal_max_async_tokens) {
81		pr_err("%s: Passed token is out of range, token %d\n",
82				__func__, token);
83		return -EINVAL;
84	}
85
86	spin_lock_irqsave(&opal_async_comp_lock, flags);
87	__set_bit(token, opal_async_complete_map);
88	__clear_bit(token, opal_async_token_map);
89	spin_unlock_irqrestore(&opal_async_comp_lock, flags);
90
91	return 0;
92}
93
94int opal_async_release_token(int token)
95{
96	int ret;
97
98	ret = __opal_async_release_token(token);
99	if (ret)
100		return ret;
101
102	up(&opal_async_sem);
103
104	return 0;
105}
106EXPORT_SYMBOL_GPL(opal_async_release_token);
107
108int opal_async_wait_response(uint64_t token, struct opal_msg *msg)
109{
110	if (token >= opal_max_async_tokens) {
111		pr_err("%s: Invalid token passed\n", __func__);
112		return -EINVAL;
113	}
114
115	if (!msg) {
116		pr_err("%s: Invalid message pointer passed\n", __func__);
117		return -EINVAL;
118	}
119
120	wait_event(opal_async_wait, test_bit(token, opal_async_complete_map));
121	memcpy(msg, &opal_async_responses[token], sizeof(*msg));
122
123	return 0;
124}
125EXPORT_SYMBOL_GPL(opal_async_wait_response);
126
127static int opal_async_comp_event(struct notifier_block *nb,
128		unsigned long msg_type, void *msg)
129{
130	struct opal_msg *comp_msg = msg;
131	unsigned long flags;
132	uint64_t token;
133
134	if (msg_type != OPAL_MSG_ASYNC_COMP)
135		return 0;
136
137	token = be64_to_cpu(comp_msg->params[0]);
138	memcpy(&opal_async_responses[token], comp_msg, sizeof(*comp_msg));
139	spin_lock_irqsave(&opal_async_comp_lock, flags);
140	__set_bit(token, opal_async_complete_map);
141	spin_unlock_irqrestore(&opal_async_comp_lock, flags);
142
143	wake_up(&opal_async_wait);
144
145	return 0;
146}
147
148static struct notifier_block opal_async_comp_nb = {
149		.notifier_call	= opal_async_comp_event,
150		.next		= NULL,
151		.priority	= 0,
152};
153
154static int __init opal_async_comp_init(void)
155{
156	struct device_node *opal_node;
157	const __be32 *async;
158	int err;
159
160	opal_node = of_find_node_by_path("/ibm,opal");
161	if (!opal_node) {
162		pr_err("%s: Opal node not found\n", __func__);
163		err = -ENOENT;
164		goto out;
165	}
166
167	async = of_get_property(opal_node, "opal-msg-async-num", NULL);
168	if (!async) {
169		pr_err("%s: %s has no opal-msg-async-num\n",
170				__func__, opal_node->full_name);
171		err = -ENOENT;
172		goto out_opal_node;
173	}
174
175	opal_max_async_tokens = be32_to_cpup(async);
176	if (opal_max_async_tokens > N_ASYNC_COMPLETIONS)
177		opal_max_async_tokens = N_ASYNC_COMPLETIONS;
178
179	err = opal_message_notifier_register(OPAL_MSG_ASYNC_COMP,
180			&opal_async_comp_nb);
181	if (err) {
182		pr_err("%s: Can't register OPAL event notifier (%d)\n",
183				__func__, err);
184		goto out_opal_node;
185	}
186
187	opal_async_responses = kzalloc(
188			sizeof(*opal_async_responses) * opal_max_async_tokens,
189			GFP_KERNEL);
190	if (!opal_async_responses) {
191		pr_err("%s: Out of memory, failed to do asynchronous "
192				"completion init\n", __func__);
193		err = -ENOMEM;
194		goto out_opal_node;
195	}
196
197	/* Initialize to 1 less than the maximum tokens available, as we may
198	 * require to pop one during emergency through synchronous call to
199	 * __opal_async_get_token()
200	 */
201	sema_init(&opal_async_sem, opal_max_async_tokens - 1);
202
203out_opal_node:
204	of_node_put(opal_node);
205out:
206	return err;
207}
208machine_subsys_initcall(powernv, opal_async_comp_init);
209