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   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 <linux/unistd.h>
  34 #include <linux/io.h>
  35 #include <asm/system.h>
  36 #include <asm/atomic.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         struct ipipe_irqdesc *idesc;
  94         int m_ack, s = -1;
  95
  96         /*
  97          * Software-triggered IRQs do not need any ack.  The contents
  98          * of the register frame should only be used when processing
  99          * the timer interrupt, but not for handling any other
 100          * interrupt.
 101          */
 102         m_ack = (regs == NULL || irq == IRQ_SYSTMR || irq == IRQ_CORETMR);
 103         this_domain = __ipipe_current_domain;
 104         idesc = &this_domain->irqs[irq];
 105
 106         if (unlikely(test_bit(IPIPE_STICKY_FLAG, &idesc->control)))
 107                 head = &this_domain->p_link;
 108         else {
 109                 head = __ipipe_pipeline.next;
 110                 next_domain = list_entry(head, struct ipipe_domain, p_link);
 111                 idesc = &next_domain->irqs[irq];
 112                 if (likely(test_bit(IPIPE_WIRED_FLAG, &idesc->control))) {
 113                         if (!m_ack && idesc->acknowledge != NULL)
 114                                 idesc->acknowledge(irq, irq_to_desc(irq));
 115                         if (test_bit(IPIPE_SYNCDEFER_FLAG, &p->status))
 116                                 s = __test_and_set_bit(IPIPE_STALL_FLAG,
 117                                                        &p->status);
 118                         __ipipe_dispatch_wired(next_domain, irq);
 119                         goto out;
 120                 }
 121         }
 122
 123         /* Ack the interrupt. */
 124
 125         pos = head;
 126         while (pos != &__ipipe_pipeline) {
 127                 next_domain = list_entry(pos, struct ipipe_domain, p_link);
 128                 idesc = &next_domain->irqs[irq];
 129                 if (test_bit(IPIPE_HANDLE_FLAG, &idesc->control)) {
 130                         __ipipe_set_irq_pending(next_domain, irq);
 131                         if (!m_ack && idesc->acknowledge != NULL) {
 132                                 idesc->acknowledge(irq, irq_to_desc(irq));
 133                                 m_ack = 1;
 134                         }
 135                 }
 136                 if (!test_bit(IPIPE_PASS_FLAG, &idesc->control))
 137                         break;
 138                 pos = next_domain->p_link.next;
 139         }
 140
 141         /*
 142          * Now walk the pipeline, yielding control to the highest
 143          * priority domain that has pending interrupt(s) or
 144          * immediately to the current domain if the interrupt has been
 145          * marked as 'sticky'. This search does not go beyond the
 146          * current domain in the pipeline. We also enforce the
 147          * additional root stage lock (blackfin-specific).
 148          */
 149         if (test_bit(IPIPE_SYNCDEFER_FLAG, &p->status))
 150                 s = __test_and_set_bit(IPIPE_STALL_FLAG, &p->status);
 151
 152         /*
 153          * If the interrupt preempted the head domain, then do not
 154          * even try to walk the pipeline, unless an interrupt is
 155          * pending for it.
 156          */
 157         if (test_bit(IPIPE_AHEAD_FLAG, &this_domain->flags) &&
 158             ipipe_head_cpudom_var(irqpend_himask) == 0)
 159                 goto out;
 160
 161         __ipipe_walk_pipeline(head);
 162 out:
 163         if (!s)
 164                 __clear_bit(IPIPE_STALL_FLAG, &p->status);
 165 }
 166
 167 int __ipipe_check_root(void)
 168 {
 169         return ipipe_root_domain_p;
 170 }
 171
 172 void __ipipe_enable_irqdesc(struct ipipe_domain *ipd, unsigned irq)
 173 {
 174         struct irq_desc *desc = irq_to_desc(irq);
 175         int prio = __ipipe_get_irq_priority(irq);
 176
 177         desc->depth = 0;
 178         if (ipd != &ipipe_root &&
 179             atomic_inc_return(&__ipipe_irq_lvdepth[prio]) == 1)
 180                 __set_bit(prio, &__ipipe_irq_lvmask);
 181 }
 182 EXPORT_SYMBOL(__ipipe_enable_irqdesc);
 183
 184 void __ipipe_disable_irqdesc(struct ipipe_domain *ipd, unsigned irq)
 185 {
 186         int prio = __ipipe_get_irq_priority(irq);
 187
 188         if (ipd != &ipipe_root &&
 189             atomic_dec_and_test(&__ipipe_irq_lvdepth[prio]))
 190                 __clear_bit(prio, &__ipipe_irq_lvmask);
 191 }
 192 EXPORT_SYMBOL(__ipipe_disable_irqdesc);
 193
 194 void __ipipe_stall_root_raw(void)
 195 {
 196         /*
 197          * This code is called by the ins{bwl} routines (see
 198          * arch/blackfin/lib/ins.S), which are heavily used by the
 199          * network stack. It masks all interrupts but those handled by
 200          * non-root domains, so that we keep decent network transfer
 201          * rates for Linux without inducing pathological jitter for
 202          * the real-time domain.
 203          */
 204         __asm__ __volatile__ ("sti %0;" : : "d"(__ipipe_irq_lvmask));
 205
 206         __set_bit(IPIPE_STALL_FLAG,
 207                   &ipipe_root_cpudom_var(status));
 208 }
 209
 210 void __ipipe_unstall_root_raw(void)
 211 {
 212         __clear_bit(IPIPE_STALL_FLAG,
 213                     &ipipe_root_cpudom_var(status));
 214
 215         __asm__ __volatile__ ("sti %0;" : : "d"(bfin_irq_flags));
 216 }
 217
 218 int __ipipe_syscall_root(struct pt_regs *regs)
 219 {
 220         struct ipipe_percpu_domain_data *p;
 221         unsigned long flags;
 222         int ret;
 223
 224         /*
 225          * We need to run the IRQ tail hook whenever we don't
 226          * propagate a syscall to higher domains, because we know that
 227          * important operations might be pending there (e.g. Xenomai
 228          * deferred rescheduling).
 229          */
 230
 231         if (regs->orig_p0 < NR_syscalls) {
 232                 void (*hook)(void) = (void (*)(void))__ipipe_irq_tail_hook;
 233                 hook();
 234                 if ((current->flags & PF_EVNOTIFY) == 0)
 235                         return 0;
 236         }
 237
 238         /*
 239          * This routine either returns:
 240          * 0 -- if the syscall is to be passed to Linux;
 241          * >0 -- if the syscall should not be passed to Linux, and no
 242          * tail work should be performed;
 243          * <0 -- if the syscall should not be passed to Linux but the
 244          * tail work has to be performed (for handling signals etc).
 245          */
 246
 247         if (!__ipipe_event_monitored_p(IPIPE_EVENT_SYSCALL))
 248                 return 0;
 249
 250         ret = __ipipe_dispatch_event(IPIPE_EVENT_SYSCALL, regs);
 251
 252         local_irq_save_hw(flags);
 253
 254         if (!__ipipe_root_domain_p) {
 255                 local_irq_restore_hw(flags);
 256                 return 1;
 257         }
 258
 259         p = ipipe_root_cpudom_ptr();
 260         if ((p->irqpend_himask & IPIPE_IRQMASK_VIRT) != 0)
 261                 __ipipe_sync_pipeline(IPIPE_IRQMASK_VIRT);
 262
 263         local_irq_restore_hw(flags);
 264
 265         return -ret;
 266 }
 267
 268 unsigned long ipipe_critical_enter(void (*syncfn) (void))
 269 {
 270         unsigned long flags;
 271
 272         local_irq_save_hw(flags);
 273
 274         return flags;
 275 }
 276
 277 void ipipe_critical_exit(unsigned long flags)
 278 {
 279         local_irq_restore_hw(flags);
 280 }
 281
 282 static void __ipipe_no_irqtail(void)
 283 {
 284 }
 285
 286 int ipipe_get_sysinfo(struct ipipe_sysinfo *info)
 287 {
 288         info->ncpus = num_online_cpus();
 289         info->cpufreq = ipipe_cpu_freq();
 290         info->archdep.tmirq = IPIPE_TIMER_IRQ;
 291         info->archdep.tmfreq = info->cpufreq;
 292
 293         return 0;
 294 }
 295
 296 /*
 297  * ipipe_trigger_irq() -- Push the interrupt at front of the pipeline
 298  * just like if it has been actually received from a hw source. Also
 299  * works for virtual interrupts.
 300  */
 301 int ipipe_trigger_irq(unsigned irq)
 302 {
 303         unsigned long flags;
 304
 305 #ifdef CONFIG_IPIPE_DEBUG
 306         if (irq >= IPIPE_NR_IRQS ||
 307             (ipipe_virtual_irq_p(irq)
 308              && !test_bit(irq - IPIPE_VIRQ_BASE, &__ipipe_virtual_irq_map)))
 309                 return -EINVAL;
 310 #endif
 311
 312         local_irq_save_hw(flags);
 313         __ipipe_handle_irq(irq, NULL);
 314         local_irq_restore_hw(flags);
 315
 316         return 1;
 317 }
 318
 319 asmlinkage void __ipipe_sync_root(void)
 320 {
 321         void (*irq_tail_hook)(void) = (void (*)(void))__ipipe_irq_tail_hook;
 322         unsigned long flags;
 323
 324         BUG_ON(irqs_disabled());
 325
 326         local_irq_save_hw(flags);
 327
 328         if (irq_tail_hook)
 329                 irq_tail_hook();
 330
 331         clear_thread_flag(TIF_IRQ_SYNC);
 332
 333         if (ipipe_root_cpudom_var(irqpend_himask) != 0)
 334                 __ipipe_sync_pipeline(IPIPE_IRQMASK_ANY);
 335
 336         local_irq_restore_hw(flags);
 337 }
 338
 339 void ___ipipe_sync_pipeline(unsigned long syncmask)
 340 {
 341         if (__ipipe_root_domain_p &&
 342             test_bit(IPIPE_SYNCDEFER_FLAG, &ipipe_root_cpudom_var(status)))
 343                 return;
 344
 345         __ipipe_sync_stage(syncmask);
 346 }