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