KVM: Fix unlikely kvm_create vs decache_vcpus_on_cpu race
[linux-2.6] / drivers / char / snsc_event.c
1 /*
2  * SN Platform system controller communication support
3  *
4  * This file is subject to the terms and conditions of the GNU General Public
5  * License.  See the file "COPYING" in the main directory of this archive
6  * for more details.
7  *
8  * Copyright (C) 2004-2006 Silicon Graphics, Inc. All rights reserved.
9  */
10
11 /*
12  * System controller event handler
13  *
14  * These routines deal with environmental events arriving from the
15  * system controllers.
16  */
17
18 #include <linux/interrupt.h>
19 #include <linux/sched.h>
20 #include <linux/byteorder/generic.h>
21 #include <asm/sn/sn_sal.h>
22 #include <asm/unaligned.h>
23 #include "snsc.h"
24
25 static struct subch_data_s *event_sd;
26
27 void scdrv_event(unsigned long);
28 DECLARE_TASKLET(sn_sysctl_event, scdrv_event, 0);
29
30 /*
31  * scdrv_event_interrupt
32  *
33  * Pull incoming environmental events off the physical link to the
34  * system controller and put them in a temporary holding area in SAL.
35  * Schedule scdrv_event() to move them along to their ultimate
36  * destination.
37  */
38 static irqreturn_t
39 scdrv_event_interrupt(int irq, void *subch_data)
40 {
41         struct subch_data_s *sd = subch_data;
42         unsigned long flags;
43         int status;
44
45         spin_lock_irqsave(&sd->sd_rlock, flags);
46         status = ia64_sn_irtr_intr(sd->sd_nasid, sd->sd_subch);
47
48         if ((status > 0) && (status & SAL_IROUTER_INTR_RECV)) {
49                 tasklet_schedule(&sn_sysctl_event);
50         }
51         spin_unlock_irqrestore(&sd->sd_rlock, flags);
52         return IRQ_HANDLED;
53 }
54
55
56 /*
57  * scdrv_parse_event
58  *
59  * Break an event (as read from SAL) into useful pieces so we can decide
60  * what to do with it.
61  */
62 static int
63 scdrv_parse_event(char *event, int *src, int *code, int *esp_code, char *desc)
64 {
65         char *desc_end;
66         __be32 from_buf;
67
68         /* record event source address */
69         from_buf = get_unaligned((__be32 *)event);
70         *src = be32_to_cpup(&from_buf);
71         event += 4;                     /* move on to event code */
72
73         /* record the system controller's event code */
74         from_buf = get_unaligned((__be32 *)event);
75         *code = be32_to_cpup(&from_buf);
76         event += 4;                     /* move on to event arguments */
77
78         /* how many arguments are in the packet? */
79         if (*event++ != 2) {
80                 /* if not 2, give up */
81                 return -1;
82         }
83
84         /* parse out the ESP code */
85         if (*event++ != IR_ARG_INT) {
86                 /* not an integer argument, so give up */
87                 return -1;
88         }
89         from_buf = get_unaligned((__be32 *)event);
90         *esp_code = be32_to_cpup(&from_buf);
91         event += 4;
92
93         /* parse out the event description */
94         if (*event++ != IR_ARG_ASCII) {
95                 /* not an ASCII string, so give up */
96                 return -1;
97         }
98         event[CHUNKSIZE-1] = '\0';      /* ensure this string ends! */
99         event += 2;                     /* skip leading CR/LF */
100         desc_end = desc + sprintf(desc, "%s", event);
101
102         /* strip trailing CR/LF (if any) */
103         for (desc_end--;
104              (desc_end != desc) && ((*desc_end == 0xd) || (*desc_end == 0xa));
105              desc_end--) {
106                 *desc_end = '\0';
107         }
108
109         return 0;
110 }
111
112
113 /*
114  * scdrv_event_severity
115  *
116  * Figure out how urgent a message we should write to the console/syslog
117  * via printk.
118  */
119 static char *
120 scdrv_event_severity(int code)
121 {
122         int ev_class = (code & EV_CLASS_MASK);
123         int ev_severity = (code & EV_SEVERITY_MASK);
124         char *pk_severity = KERN_NOTICE;
125
126         switch (ev_class) {
127         case EV_CLASS_POWER:
128                 switch (ev_severity) {
129                 case EV_SEVERITY_POWER_LOW_WARNING:
130                 case EV_SEVERITY_POWER_HIGH_WARNING:
131                         pk_severity = KERN_WARNING;
132                         break;
133                 case EV_SEVERITY_POWER_HIGH_FAULT:
134                 case EV_SEVERITY_POWER_LOW_FAULT:
135                         pk_severity = KERN_ALERT;
136                         break;
137                 }
138                 break;
139         case EV_CLASS_FAN:
140                 switch (ev_severity) {
141                 case EV_SEVERITY_FAN_WARNING:
142                         pk_severity = KERN_WARNING;
143                         break;
144                 case EV_SEVERITY_FAN_FAULT:
145                         pk_severity = KERN_CRIT;
146                         break;
147                 }
148                 break;
149         case EV_CLASS_TEMP:
150                 switch (ev_severity) {
151                 case EV_SEVERITY_TEMP_ADVISORY:
152                         pk_severity = KERN_WARNING;
153                         break;
154                 case EV_SEVERITY_TEMP_CRITICAL:
155                         pk_severity = KERN_CRIT;
156                         break;
157                 case EV_SEVERITY_TEMP_FAULT:
158                         pk_severity = KERN_ALERT;
159                         break;
160                 }
161                 break;
162         case EV_CLASS_ENV:
163                 pk_severity = KERN_ALERT;
164                 break;
165         case EV_CLASS_TEST_FAULT:
166                 pk_severity = KERN_ALERT;
167                 break;
168         case EV_CLASS_TEST_WARNING:
169                 pk_severity = KERN_WARNING;
170                 break;
171         case EV_CLASS_PWRD_NOTIFY:
172                 pk_severity = KERN_ALERT;
173                 break;
174         }
175
176         return pk_severity;
177 }
178
179
180 /*
181  * scdrv_dispatch_event
182  *
183  * Do the right thing with an incoming event.  That's often nothing
184  * more than printing it to the system log.  For power-down notifications
185  * we start a graceful shutdown.
186  */
187 static void
188 scdrv_dispatch_event(char *event, int len)
189 {
190         static int snsc_shutting_down = 0;
191         int code, esp_code, src, class;
192         char desc[CHUNKSIZE];
193         char *severity;
194
195         if (scdrv_parse_event(event, &src, &code, &esp_code, desc) < 0) {
196                 /* ignore uninterpretible event */
197                 return;
198         }
199
200         /* how urgent is the message? */
201         severity = scdrv_event_severity(code);
202
203         class = (code & EV_CLASS_MASK);
204
205         if (class == EV_CLASS_PWRD_NOTIFY || code == ENV_PWRDN_PEND) {
206                 if (snsc_shutting_down)
207                         return;
208
209                 snsc_shutting_down = 1;
210
211                 /* give a message for each type of event */
212                 if (class == EV_CLASS_PWRD_NOTIFY)
213                         printk(KERN_NOTICE "Power off indication received."
214                                " Sending SIGPWR to init...\n");
215                 else if (code == ENV_PWRDN_PEND)
216                         printk(KERN_CRIT "WARNING: Shutting down the system"
217                                " due to a critical environmental condition."
218                                " Sending SIGPWR to init...\n");
219
220                 /* give a SIGPWR signal to init proc */
221                 kill_cad_pid(SIGPWR, 0);
222         } else {
223                 /* print to system log */
224                 printk("%s|$(0x%x)%s\n", severity, esp_code, desc);
225         }
226 }
227
228
229 /*
230  * scdrv_event
231  *
232  * Called as a tasklet when an event arrives from the L1.  Read the event
233  * from where it's temporarily stored in SAL and call scdrv_dispatch_event()
234  * to send it on its way.  Keep trying to read events until SAL indicates
235  * that there are no more immediately available.
236  */
237 void
238 scdrv_event(unsigned long dummy)
239 {
240         int status;
241         int len;
242         unsigned long flags;
243         struct subch_data_s *sd = event_sd;
244
245         /* anything to read? */
246         len = CHUNKSIZE;
247         spin_lock_irqsave(&sd->sd_rlock, flags);
248         status = ia64_sn_irtr_recv(sd->sd_nasid, sd->sd_subch,
249                                    sd->sd_rb, &len);
250
251         while (!(status < 0)) {
252                 spin_unlock_irqrestore(&sd->sd_rlock, flags);
253                 scdrv_dispatch_event(sd->sd_rb, len);
254                 len = CHUNKSIZE;
255                 spin_lock_irqsave(&sd->sd_rlock, flags);
256                 status = ia64_sn_irtr_recv(sd->sd_nasid, sd->sd_subch,
257                                            sd->sd_rb, &len);
258         }
259         spin_unlock_irqrestore(&sd->sd_rlock, flags);
260 }
261
262
263 /*
264  * scdrv_event_init
265  *
266  * Sets up a system controller subchannel to begin receiving event
267  * messages. This is sort of a specialized version of scdrv_open()
268  * in drivers/char/sn_sysctl.c.
269  */
270 void
271 scdrv_event_init(struct sysctl_data_s *scd)
272 {
273         int rv;
274
275         event_sd = kzalloc(sizeof (struct subch_data_s), GFP_KERNEL);
276         if (event_sd == NULL) {
277                 printk(KERN_WARNING "%s: couldn't allocate subchannel info"
278                        " for event monitoring\n", __FUNCTION__);
279                 return;
280         }
281
282         /* initialize subch_data_s fields */
283         event_sd->sd_nasid = scd->scd_nasid;
284         spin_lock_init(&event_sd->sd_rlock);
285
286         /* ask the system controllers to send events to this node */
287         event_sd->sd_subch = ia64_sn_sysctl_event_init(scd->scd_nasid);
288
289         if (event_sd->sd_subch < 0) {
290                 kfree(event_sd);
291                 printk(KERN_WARNING "%s: couldn't open event subchannel\n",
292                        __FUNCTION__);
293                 return;
294         }
295
296         /* hook event subchannel up to the system controller interrupt */
297         rv = request_irq(SGI_UART_VECTOR, scdrv_event_interrupt,
298                          IRQF_SHARED | IRQF_DISABLED,
299                          "system controller events", event_sd);
300         if (rv) {
301                 printk(KERN_WARNING "%s: irq request failed (%d)\n",
302                        __FUNCTION__, rv);
303                 ia64_sn_irtr_close(event_sd->sd_nasid, event_sd->sd_subch);
304                 kfree(event_sd);
305                 return;
306         }
307 }