arch/microblaze/kernel/process.c

   1 /*
   2  * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
   3  * Copyright (C) 2008-2009 PetaLogix
   4  * Copyright (C) 2006 Atmark Techno, Inc.
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License. See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/sched.h>
  13 #include <linux/pm.h>
  14 #include <linux/tick.h>
  15 #include <linux/bitops.h>
  16 #include <asm/system.h>
  17 #include <asm/pgalloc.h>
  18 #include <asm/cacheflush.h>
  19
  20 void show_regs(struct pt_regs *regs)
  21 {
  22         printk(KERN_INFO " Registers dump: mode=%X\r\n", regs->pt_mode);
  23         printk(KERN_INFO " r1=%08lX, r2=%08lX, r3=%08lX, r4=%08lX\n",
  24                                 regs->r1, regs->r2, regs->r3, regs->r4);
  25         printk(KERN_INFO " r5=%08lX, r6=%08lX, r7=%08lX, r8=%08lX\n",
  26                                 regs->r5, regs->r6, regs->r7, regs->r8);
  27         printk(KERN_INFO " r9=%08lX, r10=%08lX, r11=%08lX, r12=%08lX\n",
  28                                 regs->r9, regs->r10, regs->r11, regs->r12);
  29         printk(KERN_INFO " r13=%08lX, r14=%08lX, r15=%08lX, r16=%08lX\n",
  30                                 regs->r13, regs->r14, regs->r15, regs->r16);
  31         printk(KERN_INFO " r17=%08lX, r18=%08lX, r19=%08lX, r20=%08lX\n",
  32                                 regs->r17, regs->r18, regs->r19, regs->r20);
  33         printk(KERN_INFO " r21=%08lX, r22=%08lX, r23=%08lX, r24=%08lX\n",
  34                                 regs->r21, regs->r22, regs->r23, regs->r24);
  35         printk(KERN_INFO " r25=%08lX, r26=%08lX, r27=%08lX, r28=%08lX\n",
  36                                 regs->r25, regs->r26, regs->r27, regs->r28);
  37         printk(KERN_INFO " r29=%08lX, r30=%08lX, r31=%08lX, rPC=%08lX\n",
  38                                 regs->r29, regs->r30, regs->r31, regs->pc);
  39         printk(KERN_INFO " msr=%08lX, ear=%08lX, esr=%08lX, fsr=%08lX\n",
  40                                 regs->msr, regs->ear, regs->esr, regs->fsr);
  41 }
  42
  43 void (*pm_idle)(void);
  44 void (*pm_power_off)(void) = NULL;
  45 EXPORT_SYMBOL(pm_power_off);
  46
  47 static int hlt_counter = 1;
  48
  49 void disable_hlt(void)
  50 {
  51         hlt_counter++;
  52 }
  53 EXPORT_SYMBOL(disable_hlt);
  54
  55 void enable_hlt(void)
  56 {
  57         hlt_counter--;
  58 }
  59 EXPORT_SYMBOL(enable_hlt);
  60
  61 static int __init nohlt_setup(char *__unused)
  62 {
  63         hlt_counter = 1;
  64         return 1;
  65 }
  66 __setup("nohlt", nohlt_setup);
  67
  68 static int __init hlt_setup(char *__unused)
  69 {
  70         hlt_counter = 0;
  71         return 1;
  72 }
  73 __setup("hlt", hlt_setup);
  74
  75 void default_idle(void)
  76 {
  77         if (!hlt_counter) {
  78                 clear_thread_flag(TIF_POLLING_NRFLAG);
  79                 smp_mb__after_clear_bit();
  80                 local_irq_disable();
  81                 while (!need_resched())
  82                         cpu_sleep();
  83                 local_irq_enable();
  84                 set_thread_flag(TIF_POLLING_NRFLAG);
  85         } else
  86                 while (!need_resched())
  87                         cpu_relax();
  88 }
  89
  90 void cpu_idle(void)
  91 {
  92         set_thread_flag(TIF_POLLING_NRFLAG);
  93
  94         /* endless idle loop with no priority at all */
  95         while (1) {
  96                 void (*idle)(void) = pm_idle;
  97
  98                 if (!idle)
  99                         idle = default_idle;
 100
 101                 tick_nohz_stop_sched_tick(1);
 102                 while (!need_resched())
 103                         idle();
 104                 tick_nohz_restart_sched_tick();
 105
 106                 preempt_enable_no_resched();
 107                 schedule();
 108                 preempt_disable();
 109                 check_pgt_cache();
 110         }
 111 }
 112
 113 void flush_thread(void)
 114 {
 115 }
 116
 117 int copy_thread(unsigned long clone_flags, unsigned long usp,
 118                 unsigned long unused,
 119                 struct task_struct *p, struct pt_regs *regs)
 120 {
 121         struct pt_regs *childregs = task_pt_regs(p);
 122         struct thread_info *ti = task_thread_info(p);
 123
 124         *childregs = *regs;
 125         if (user_mode(regs))
 126                 childregs->r1 = usp;
 127         else
 128                 childregs->r1 = ((unsigned long) ti) + THREAD_SIZE;
 129
 130 #ifndef CONFIG_MMU
 131         memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
 132         ti->cpu_context.r1 = (unsigned long)childregs;
 133         ti->cpu_context.msr = (unsigned long)childregs->msr;
 134 #else
 135
 136         /* if creating a kernel thread then update the current reg (we don't
 137          * want to use the parent's value when restoring by POP_STATE) */
 138         if (kernel_mode(regs))
 139                 /* save new current on stack to use POP_STATE */
 140                 childregs->CURRENT_TASK = (unsigned long)p;
 141         /* if returning to user then use the parent's value of this register */
 142
 143         /* if we're creating a new kernel thread then just zeroing all
 144          * the registers. That's OK for a brand new thread.*/
 145         /* Pls. note that some of them will be restored in POP_STATE */
 146         if (kernel_mode(regs))
 147                 memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
 148         /* if this thread is created for fork/vfork/clone, then we want to
 149          * restore all the parent's context */
 150         /* in addition to the registers which will be restored by POP_STATE */
 151         else {
 152                 ti->cpu_context = *(struct cpu_context *)regs;
 153                 childregs->msr |= MSR_UMS;
 154         }
 155
 156         /* FIXME STATE_SAVE_PT_OFFSET; */
 157         ti->cpu_context.r1  = (unsigned long)childregs - STATE_SAVE_ARG_SPACE;
 158         /* we should consider the fact that childregs is a copy of the parent
 159          * regs which were saved immediately after entering the kernel state
 160          * before enabling VM. This MSR will be restored in switch_to and
 161          * RETURN() and we want to have the right machine state there
 162          * specifically this state must have INTs disabled before and enabled
 163          * after performing rtbd
 164          * compose the right MSR for RETURN(). It will work for switch_to also
 165          * excepting for VM and UMS
 166          * don't touch UMS , CARRY and cache bits
 167          * right now MSR is a copy of parent one */
 168         childregs->msr |= MSR_BIP;
 169         childregs->msr &= ~MSR_EIP;
 170         childregs->msr |= MSR_IE;
 171         childregs->msr &= ~MSR_VM;
 172         childregs->msr |= MSR_VMS;
 173         childregs->msr |= MSR_EE; /* exceptions will be enabled*/
 174
 175         ti->cpu_context.msr = (childregs->msr|MSR_VM);
 176         ti->cpu_context.msr &= ~MSR_UMS; /* switch_to to kernel mode */
 177 #endif
 178         ti->cpu_context.r15 = (unsigned long)ret_from_fork - 8;
 179
 180         if (clone_flags & CLONE_SETTLS)
 181                 ;
 182
 183         return 0;
 184 }
 185
 186 #ifndef CONFIG_MMU
 187 /*
 188  * Return saved PC of a blocked thread.
 189  */
 190 unsigned long thread_saved_pc(struct task_struct *tsk)
 191 {
 192         struct cpu_context *ctx =
 193                 &(((struct thread_info *)(tsk->stack))->cpu_context);
 194
 195         /* Check whether the thread is blocked in resume() */
 196         if (in_sched_functions(ctx->r15))
 197                 return (unsigned long)ctx->r15;
 198         else
 199                 return ctx->r14;
 200 }
 201 #endif
 202
 203 static void kernel_thread_helper(int (*fn)(void *), void *arg)
 204 {
 205         fn(arg);
 206         do_exit(-1);
 207 }
 208
 209 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 210 {
 211         struct pt_regs regs;
 212
 213         memset(&regs, 0, sizeof(regs));
 214         /* store them in non-volatile registers */
 215         regs.r5 = (unsigned long)fn;
 216         regs.r6 = (unsigned long)arg;
 217         local_save_flags(regs.msr);
 218         regs.pc = (unsigned long)kernel_thread_helper;
 219         regs.pt_mode = 1;
 220
 221         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
 222                         &regs, 0, NULL, NULL);
 223 }
 224 EXPORT_SYMBOL_GPL(kernel_thread);
 225
 226 unsigned long get_wchan(struct task_struct *p)
 227 {
 228 /* TBD (used by procfs) */
 229         return 0;
 230 }
 231
 232 /* Set up a thread for executing a new program */
 233 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
 234 {
 235         set_fs(USER_DS);
 236         regs->pc = pc;
 237         regs->r1 = usp;
 238         regs->pt_mode = 0;
 239 #ifdef CONFIG_MMU
 240         regs->msr |= MSR_UMS;
 241 #endif
 242 }
 243
 244 #ifdef CONFIG_MMU
 245 #include <linux/elfcore.h>
 246 /*
 247  * Set up a thread for executing a new program
 248  */
 249 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
 250 {
 251         return 0; /* MicroBlaze has no separate FPU registers */
 252 }
 253 #endif /* CONFIG_MMU */