arch/blackfin/kernel/ipipe.c

   1 /* -*- linux-c -*-
   2  * linux/arch/blackfin/kernel/ipipe.c
   3  *
   4  * Copyright (C) 2005-2007 Philippe Gerum.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
   9  * USA; either version 2 of the License, or (at your option) any later
  10  * version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20  *
  21  * Architecture-dependent I-pipe support for the Blackfin.
  22  */
  23
  24 #include <linux/kernel.h>
  25 #include <linux/sched.h>
  26 #include <linux/module.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/percpu.h>
  29 #include <linux/bitops.h>
  30 #include <linux/slab.h>
  31 #include <linux/errno.h>
  32 #include <linux/kthread.h>
  33 #include <asm/unistd.h>
  34 #include <asm/system.h>
  35 #include <asm/atomic.h>
  36 #include <asm/io.h>
  37
  38 DEFINE_PER_CPU(struct pt_regs, __ipipe_tick_regs);
  39
  40 asmlinkage void asm_do_IRQ(unsigned int irq, struct pt_regs *regs);
  41
  42 static void __ipipe_no_irqtail(void);
  43
  44 unsigned long __ipipe_irq_tail_hook = (unsigned long)&__ipipe_no_irqtail;
  45 EXPORT_SYMBOL(__ipipe_irq_tail_hook);
  46
  47 unsigned long __ipipe_core_clock;
  48 EXPORT_SYMBOL(__ipipe_core_clock);
  49
  50 unsigned long __ipipe_freq_scale;
  51 EXPORT_SYMBOL(__ipipe_freq_scale);
  52
  53 atomic_t __ipipe_irq_lvdepth[IVG15 + 1];
  54
  55 unsigned long __ipipe_irq_lvmask = bfin_no_irqs;
  56 EXPORT_SYMBOL(__ipipe_irq_lvmask);
  57
  58 static void __ipipe_ack_irq(unsigned irq, struct irq_desc *desc)
  59 {
  60         desc->ipipe_ack(irq, desc);
  61 }
  62
  63 /*
  64  * __ipipe_enable_pipeline() -- We are running on the boot CPU, hw
  65  * interrupts are off, and secondary CPUs are still lost in space.
  66  */
  67 void __ipipe_enable_pipeline(void)
  68 {
  69         unsigned irq;
  70
  71         __ipipe_core_clock = get_cclk(); /* Fetch this once. */
  72         __ipipe_freq_scale = 1000000000UL / __ipipe_core_clock;
  73
  74         for (irq = 0; irq < NR_IRQS; ++irq)
  75                 ipipe_virtualize_irq(ipipe_root_domain,
  76                                      irq,
  77                                      (ipipe_irq_handler_t)&asm_do_IRQ,
  78                                      NULL,
  79                                      &__ipipe_ack_irq,
  80                                      IPIPE_HANDLE_MASK | IPIPE_PASS_MASK);
  81 }
  82
  83 /*
  84  * __ipipe_handle_irq() -- IPIPE's generic IRQ handler. An optimistic
  85  * interrupt protection log is maintained here for each domain. Hw
  86  * interrupts are masked on entry.
  87  */
  88 void __ipipe_handle_irq(unsigned irq, struct pt_regs *regs)
  89 {
  90         struct ipipe_percpu_domain_data *p = ipipe_root_cpudom_ptr();
  91         struct ipipe_domain *this_domain, *next_domain;
  92         struct list_head *head, *pos;
  93         int m_ack, s = -1;
  94
  95         /*
  96          * Software-triggered IRQs do not need any ack.  The contents
  97          * of the register frame should only be used when processing
  98          * the timer interrupt, but not for handling any other
  99          * interrupt.
 100          */
 101         m_ack = (regs == NULL || irq == IRQ_SYSTMR || irq == IRQ_CORETMR);
 102         this_domain = __ipipe_current_domain;
 103
 104         if (unlikely(test_bit(IPIPE_STICKY_FLAG, &this_domain->irqs[irq].control)))
 105                 head = &this_domain->p_link;
 106         else {
 107                 head = __ipipe_pipeline.next;
 108                 next_domain = list_entry(head, struct ipipe_domain, p_link);
 109                 if (likely(test_bit(IPIPE_WIRED_FLAG, &next_domain->irqs[irq].control))) {
 110                         if (!m_ack && next_domain->irqs[irq].acknowledge != NULL)
 111                                 next_domain->irqs[irq].acknowledge(irq, irq_to_desc(irq));
 112                         if (test_bit(IPIPE_SYNCDEFER_FLAG, &p->status))
 113                                 s = __test_and_set_bit(IPIPE_STALL_FLAG, &p->status);
 114                         __ipipe_dispatch_wired(next_domain, irq);
 115                         goto out;
 116                 }
 117         }
 118
 119         /* Ack the interrupt. */
 120
 121         pos = head;
 122         while (pos != &__ipipe_pipeline) {
 123                 next_domain = list_entry(pos, struct ipipe_domain, p_link);
 124                 if (test_bit(IPIPE_HANDLE_FLAG, &next_domain->irqs[irq].control)) {
 125                         __ipipe_set_irq_pending(next_domain, irq);
 126                         if (!m_ack && next_domain->irqs[irq].acknowledge != NULL) {
 127                                 next_domain->irqs[irq].acknowledge(irq, irq_to_desc(irq));
 128                                 m_ack = 1;
 129                         }
 130                 }
 131                 if (!test_bit(IPIPE_PASS_FLAG, &next_domain->irqs[irq].control))
 132                         break;
 133                 pos = next_domain->p_link.next;
 134         }
 135
 136         /*
 137          * Now walk the pipeline, yielding control to the highest
 138          * priority domain that has pending interrupt(s) or
 139          * immediately to the current domain if the interrupt has been
 140          * marked as 'sticky'. This search does not go beyond the
 141          * current domain in the pipeline. We also enforce the
 142          * additional root stage lock (blackfin-specific).
 143          */
 144         if (test_bit(IPIPE_SYNCDEFER_FLAG, &p->status))
 145                 s = __test_and_set_bit(IPIPE_STALL_FLAG, &p->status);
 146
 147         /*
 148          * If the interrupt preempted the head domain, then do not
 149          * even try to walk the pipeline, unless an interrupt is
 150          * pending for it.
 151          */
 152         if (test_bit(IPIPE_AHEAD_FLAG, &this_domain->flags) &&
 153             ipipe_head_cpudom_var(irqpend_himask) == 0)
 154                 goto out;
 155
 156         __ipipe_walk_pipeline(head);
 157 out:
 158         if (!s)
 159                 __clear_bit(IPIPE_STALL_FLAG, &p->status);
 160 }
 161
 162 int __ipipe_check_root(void)
 163 {
 164         return ipipe_root_domain_p;
 165 }
 166
 167 void __ipipe_enable_irqdesc(struct ipipe_domain *ipd, unsigned irq)
 168 {
 169         struct irq_desc *desc = irq_to_desc(irq);
 170         int prio = __ipipe_get_irq_priority(irq);
 171
 172         desc->depth = 0;
 173         if (ipd != &ipipe_root &&
 174             atomic_inc_return(&__ipipe_irq_lvdepth[prio]) == 1)
 175                 __set_bit(prio, &__ipipe_irq_lvmask);
 176 }
 177 EXPORT_SYMBOL(__ipipe_enable_irqdesc);
 178
 179 void __ipipe_disable_irqdesc(struct ipipe_domain *ipd, unsigned irq)
 180 {
 181         int prio = __ipipe_get_irq_priority(irq);
 182
 183         if (ipd != &ipipe_root &&
 184             atomic_dec_and_test(&__ipipe_irq_lvdepth[prio]))
 185                 __clear_bit(prio, &__ipipe_irq_lvmask);
 186 }
 187 EXPORT_SYMBOL(__ipipe_disable_irqdesc);
 188
 189 void __ipipe_stall_root_raw(void)
 190 {
 191         /*
 192          * This code is called by the ins{bwl} routines (see
 193          * arch/blackfin/lib/ins.S), which are heavily used by the
 194          * network stack. It masks all interrupts but those handled by
 195          * non-root domains, so that we keep decent network transfer
 196          * rates for Linux without inducing pathological jitter for
 197          * the real-time domain.
 198          */
 199         __asm__ __volatile__ ("sti %0;" : : "d"(__ipipe_irq_lvmask));
 200
 201         __set_bit(IPIPE_STALL_FLAG,
 202                   &ipipe_root_cpudom_var(status));
 203 }
 204
 205 void __ipipe_unstall_root_raw(void)
 206 {
 207         __clear_bit(IPIPE_STALL_FLAG,
 208                     &ipipe_root_cpudom_var(status));
 209
 210         __asm__ __volatile__ ("sti %0;" : : "d"(bfin_irq_flags));
 211 }
 212
 213 int __ipipe_syscall_root(struct pt_regs *regs)
 214 {
 215         struct ipipe_percpu_domain_data *p;
 216         unsigned long flags;
 217         int ret;
 218
 219         /*
 220          * We need to run the IRQ tail hook whenever we don't
 221          * propagate a syscall to higher domains, because we know that
 222          * important operations might be pending there (e.g. Xenomai
 223          * deferred rescheduling).
 224          */
 225
 226         if (regs->orig_p0 < NR_syscalls) {
 227                 void (*hook)(void) = (void (*)(void))__ipipe_irq_tail_hook;
 228                 hook();
 229                 if ((current->flags & PF_EVNOTIFY) == 0)
 230                         return 0;
 231         }
 232
 233         /*
 234          * This routine either returns:
 235          * 0 -- if the syscall is to be passed to Linux;
 236          * >0 -- if the syscall should not be passed to Linux, and no
 237          * tail work should be performed;
 238          * <0 -- if the syscall should not be passed to Linux but the
 239          * tail work has to be performed (for handling signals etc).
 240          */
 241
 242         if (!__ipipe_event_monitored_p(IPIPE_EVENT_SYSCALL))
 243                 return 0;
 244
 245         ret = __ipipe_dispatch_event(IPIPE_EVENT_SYSCALL, regs);
 246
 247         local_irq_save_hw(flags);
 248
 249         if (!__ipipe_root_domain_p) {
 250                 local_irq_restore_hw(flags);
 251                 return 1;
 252         }
 253
 254         p = ipipe_root_cpudom_ptr();
 255         if ((p->irqpend_himask & IPIPE_IRQMASK_VIRT) != 0)
 256                 __ipipe_sync_pipeline(IPIPE_IRQMASK_VIRT);
 257
 258         local_irq_restore_hw(flags);
 259
 260         return -ret;
 261 }
 262
 263 unsigned long ipipe_critical_enter(void (*syncfn) (void))
 264 {
 265         unsigned long flags;
 266
 267         local_irq_save_hw(flags);
 268
 269         return flags;
 270 }
 271
 272 void ipipe_critical_exit(unsigned long flags)
 273 {
 274         local_irq_restore_hw(flags);
 275 }
 276
 277 static void __ipipe_no_irqtail(void)
 278 {
 279 }
 280
 281 int ipipe_get_sysinfo(struct ipipe_sysinfo *info)
 282 {
 283         info->ncpus = num_online_cpus();
 284         info->cpufreq = ipipe_cpu_freq();
 285         info->archdep.tmirq = IPIPE_TIMER_IRQ;
 286         info->archdep.tmfreq = info->cpufreq;
 287
 288         return 0;
 289 }
 290
 291 /*
 292  * ipipe_trigger_irq() -- Push the interrupt at front of the pipeline
 293  * just like if it has been actually received from a hw source. Also
 294  * works for virtual interrupts.
 295  */
 296 int ipipe_trigger_irq(unsigned irq)
 297 {
 298         unsigned long flags;
 299
 300 #ifdef CONFIG_IPIPE_DEBUG
 301         if (irq >= IPIPE_NR_IRQS ||
 302             (ipipe_virtual_irq_p(irq)
 303              && !test_bit(irq - IPIPE_VIRQ_BASE, &__ipipe_virtual_irq_map)))
 304                 return -EINVAL;
 305 #endif
 306
 307         local_irq_save_hw(flags);
 308         __ipipe_handle_irq(irq, NULL);
 309         local_irq_restore_hw(flags);
 310
 311         return 1;
 312 }
 313
 314 asmlinkage void __ipipe_sync_root(void)
 315 {
 316         void (*irq_tail_hook)(void) = (void (*)(void))__ipipe_irq_tail_hook;
 317         unsigned long flags;
 318
 319         BUG_ON(irqs_disabled());
 320
 321         local_irq_save_hw(flags);
 322
 323         if (irq_tail_hook)
 324                 irq_tail_hook();
 325
 326         clear_thread_flag(TIF_IRQ_SYNC);
 327
 328         if (ipipe_root_cpudom_var(irqpend_himask) != 0)
 329                 __ipipe_sync_pipeline(IPIPE_IRQMASK_ANY);
 330
 331         local_irq_restore_hw(flags);
 332 }
 333
 334 void ___ipipe_sync_pipeline(unsigned long syncmask)
 335 {
 336         if (__ipipe_root_domain_p) {
 337                 if (test_bit(IPIPE_SYNCDEFER_FLAG, &ipipe_root_cpudom_var(status)))
 338                         return;
 339         }
 340
 341         __ipipe_sync_stage(syncmask);
 342 }
 343
 344 EXPORT_SYMBOL(show_stack);