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
__opal_async_release_token(int token)75 int __opal_async_release_token(int token)
76 {
77 unsigned long flags;
78
79 if (token < 0 || token >= opal_max_async_tokens) {
80 pr_err("%s: Passed token is out of range, token %d\n",
81 __func__, token);
82 return -EINVAL;
83 }
84
85 spin_lock_irqsave(&opal_async_comp_lock, flags);
86 __set_bit(token, opal_async_complete_map);
87 __clear_bit(token, opal_async_token_map);
88 spin_unlock_irqrestore(&opal_async_comp_lock, flags);
89
90 return 0;
91 }
92
opal_async_release_token(int token)93 int opal_async_release_token(int token)
94 {
95 int ret;
96
97 ret = __opal_async_release_token(token);
98 if (ret)
99 return ret;
100
101 up(&opal_async_sem);
102
103 return 0;
104 }
105
opal_async_wait_response(uint64_t token,struct opal_msg * msg)106 int opal_async_wait_response(uint64_t token, struct opal_msg *msg)
107 {
108 if (token >= opal_max_async_tokens) {
109 pr_err("%s: Invalid token passed\n", __func__);
110 return -EINVAL;
111 }
112
113 if (!msg) {
114 pr_err("%s: Invalid message pointer passed\n", __func__);
115 return -EINVAL;
116 }
117
118 wait_event(opal_async_wait, test_bit(token, opal_async_complete_map));
119 memcpy(msg, &opal_async_responses[token], sizeof(*msg));
120
121 return 0;
122 }
123
opal_async_comp_event(struct notifier_block * nb,unsigned long msg_type,void * msg)124 static int opal_async_comp_event(struct notifier_block *nb,
125 unsigned long msg_type, void *msg)
126 {
127 struct opal_msg *comp_msg = msg;
128 unsigned long flags;
129 uint64_t token;
130
131 if (msg_type != OPAL_MSG_ASYNC_COMP)
132 return 0;
133
134 token = be64_to_cpu(comp_msg->params[0]);
135 memcpy(&opal_async_responses[token], comp_msg, sizeof(*comp_msg));
136 spin_lock_irqsave(&opal_async_comp_lock, flags);
137 __set_bit(token, opal_async_complete_map);
138 spin_unlock_irqrestore(&opal_async_comp_lock, flags);
139
140 wake_up(&opal_async_wait);
141
142 return 0;
143 }
144
145 static struct notifier_block opal_async_comp_nb = {
146 .notifier_call = opal_async_comp_event,
147 .next = NULL,
148 .priority = 0,
149 };
150
opal_async_comp_init(void)151 static int __init opal_async_comp_init(void)
152 {
153 struct device_node *opal_node;
154 const __be32 *async;
155 int err;
156
157 opal_node = of_find_node_by_path("/ibm,opal");
158 if (!opal_node) {
159 pr_err("%s: Opal node not found\n", __func__);
160 err = -ENOENT;
161 goto out;
162 }
163
164 async = of_get_property(opal_node, "opal-msg-async-num", NULL);
165 if (!async) {
166 pr_err("%s: %s has no opal-msg-async-num\n",
167 __func__, opal_node->full_name);
168 err = -ENOENT;
169 goto out_opal_node;
170 }
171
172 opal_max_async_tokens = be32_to_cpup(async);
173 if (opal_max_async_tokens > N_ASYNC_COMPLETIONS)
174 opal_max_async_tokens = N_ASYNC_COMPLETIONS;
175
176 err = opal_message_notifier_register(OPAL_MSG_ASYNC_COMP,
177 &opal_async_comp_nb);
178 if (err) {
179 pr_err("%s: Can't register OPAL event notifier (%d)\n",
180 __func__, err);
181 goto out_opal_node;
182 }
183
184 opal_async_responses = kzalloc(
185 sizeof(*opal_async_responses) * opal_max_async_tokens,
186 GFP_KERNEL);
187 if (!opal_async_responses) {
188 pr_err("%s: Out of memory, failed to do asynchronous "
189 "completion init\n", __func__);
190 err = -ENOMEM;
191 goto out_opal_node;
192 }
193
194 /* Initialize to 1 less than the maximum tokens available, as we may
195 * require to pop one during emergency through synchronous call to
196 * __opal_async_get_token()
197 */
198 sema_init(&opal_async_sem, opal_max_async_tokens - 1);
199
200 out_opal_node:
201 of_node_put(opal_node);
202 out:
203 return err;
204 }
205 machine_subsys_initcall(powernv, opal_async_comp_init);
206