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Linux/arch/powerpc/platforms/powernv/opal-async.c

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  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 
 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 
 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 
 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 
 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 
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 
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 
154 static 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 machine_subsys_initcall(powernv, opal_async_comp_init);
209 

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