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
28 static DECLARE_BITMAP(opal_async_complete_map, N_ASYNC_COMPLETIONS) = {~0UL};
29 static DECLARE_BITMAP(opal_async_token_map, N_ASYNC_COMPLETIONS);
30 static DECLARE_WAIT_QUEUE_HEAD(opal_async_wait);
31 static DEFINE_SPINLOCK(opal_async_comp_lock);
32 static struct semaphore opal_async_sem;
33 static struct opal_msg *opal_async_responses;
34 static unsigned int opal_max_async_tokens;
35
__opal_async_get_token(void)36 int __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_zero_bit(opal_async_token_map, opal_max_async_tokens);
43 if (token >= opal_max_async_tokens) {
44 token = -EBUSY;
45 goto out;
46 }
47
48 if (!__test_and_clear_bit(token, opal_async_complete_map)) {
49 token = -EBUSY;
50 goto out;
51 }
52
53 __set_bit(token, opal_async_token_map);
54
55 out:
56 spin_unlock_irqrestore(&opal_async_comp_lock, flags);
57 return token;
58 }
59
opal_async_get_token_interruptible(void)60 int 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 }
74 EXPORT_SYMBOL_GPL(opal_async_get_token_interruptible);
75
__opal_async_release_token(int token)76 int __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
opal_async_release_token(int token)94 int 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 }
106 EXPORT_SYMBOL_GPL(opal_async_release_token);
107
opal_async_wait_response(uint64_t token,struct opal_msg * msg)108 int 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 }
125 EXPORT_SYMBOL_GPL(opal_async_wait_response);
126
opal_async_comp_event(struct notifier_block * nb,unsigned long msg_type,void * msg)127 static 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
148 static struct notifier_block opal_async_comp_nb = {
149 .notifier_call = opal_async_comp_event,
150 .next = NULL,
151 .priority = 0,
152 };
153
opal_async_comp_init(void)154 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
203 out_opal_node:
204 of_node_put(opal_node);
205 out:
206 return err;
207 }
208