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/uaccess.h> /* for USER_DS macros */
  19 #include <asm/cacheflush.h>
  20
  21 void show_regs(struct pt_regs *regs)
  22 {
  23         printk(KERN_INFO " Registers dump: mode=%X\r\n", regs->pt_mode);
  24         printk(KERN_INFO " r1=%08lX, r2=%08lX, r3=%08lX, r4=%08lX\n",
  25                                 regs->r1, regs->r2, regs->r3, regs->r4);
  26         printk(KERN_INFO " r5=%08lX, r6=%08lX, r7=%08lX, r8=%08lX\n",
  27                                 regs->r5, regs->r6, regs->r7, regs->r8);
  28         printk(KERN_INFO " r9=%08lX, r10=%08lX, r11=%08lX, r12=%08lX\n",
  29                                 regs->r9, regs->r10, regs->r11, regs->r12);
  30         printk(KERN_INFO " r13=%08lX, r14=%08lX, r15=%08lX, r16=%08lX\n",
  31                                 regs->r13, regs->r14, regs->r15, regs->r16);
  32         printk(KERN_INFO " r17=%08lX, r18=%08lX, r19=%08lX, r20=%08lX\n",
  33                                 regs->r17, regs->r18, regs->r19, regs->r20);
  34         printk(KERN_INFO " r21=%08lX, r22=%08lX, r23=%08lX, r24=%08lX\n",
  35                                 regs->r21, regs->r22, regs->r23, regs->r24);
  36         printk(KERN_INFO " r25=%08lX, r26=%08lX, r27=%08lX, r28=%08lX\n",
  37                                 regs->r25, regs->r26, regs->r27, regs->r28);
  38         printk(KERN_INFO " r29=%08lX, r30=%08lX, r31=%08lX, rPC=%08lX\n",
  39                                 regs->r29, regs->r30, regs->r31, regs->pc);
  40         printk(KERN_INFO " msr=%08lX, ear=%08lX, esr=%08lX, fsr=%08lX\n",
  41                                 regs->msr, regs->ear, regs->esr, regs->fsr);
  42 }
  43
  44 void (*pm_idle)(void);
  45 void (*pm_power_off)(void) = NULL;
  46 EXPORT_SYMBOL(pm_power_off);
  47
  48 static int hlt_counter = 1;
  49
  50 void disable_hlt(void)
  51 {
  52         hlt_counter++;
  53 }
  54 EXPORT_SYMBOL(disable_hlt);
  55
  56 void enable_hlt(void)
  57 {
  58         hlt_counter--;
  59 }
  60 EXPORT_SYMBOL(enable_hlt);
  61
  62 static int __init nohlt_setup(char *__unused)
  63 {
  64         hlt_counter = 1;
  65         return 1;
  66 }
  67 __setup("nohlt", nohlt_setup);
  68
  69 static int __init hlt_setup(char *__unused)
  70 {
  71         hlt_counter = 0;
  72         return 1;
  73 }
  74 __setup("hlt", hlt_setup);
  75
  76 void default_idle(void)
  77 {
  78         if (likely(hlt_counter)) {
  79                 local_irq_disable();
  80                 stop_critical_timings();
  81                 cpu_relax();
  82                 start_critical_timings();
  83                 local_irq_enable();
  84         } else {
  85                 clear_thread_flag(TIF_POLLING_NRFLAG);
  86                 smp_mb__after_clear_bit();
  87                 local_irq_disable();
  88                 while (!need_resched())
  89                         cpu_sleep();
  90                 local_irq_enable();
  91                 set_thread_flag(TIF_POLLING_NRFLAG);
  92         }
  93 }
  94
  95 void cpu_idle(void)
  96 {
  97         set_thread_flag(TIF_POLLING_NRFLAG);
  98
  99         /* endless idle loop with no priority at all */
 100         while (1) {
 101                 void (*idle)(void) = pm_idle;
 102
 103                 if (!idle)
 104                         idle = default_idle;
 105
 106                 tick_nohz_stop_sched_tick(1);
 107                 while (!need_resched())
 108                         idle();
 109                 tick_nohz_restart_sched_tick();
 110
 111                 preempt_enable_no_resched();
 112                 schedule();
 113                 preempt_disable();
 114                 check_pgt_cache();
 115         }
 116 }
 117
 118 void flush_thread(void)
 119 {
 120 }
 121
 122 int copy_thread(unsigned long clone_flags, unsigned long usp,
 123                 unsigned long unused,
 124                 struct task_struct *p, struct pt_regs *regs)
 125 {
 126         struct pt_regs *childregs = task_pt_regs(p);
 127         struct thread_info *ti = task_thread_info(p);
 128
 129         *childregs = *regs;
 130         if (user_mode(regs))
 131                 childregs->r1 = usp;
 132         else
 133                 childregs->r1 = ((unsigned long) ti) + THREAD_SIZE;
 134
 135 #ifndef CONFIG_MMU
 136         memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
 137         ti->cpu_context.r1 = (unsigned long)childregs;
 138         ti->cpu_context.msr = (unsigned long)childregs->msr;
 139 #else
 140
 141         /* if creating a kernel thread then update the current reg (we don't
 142          * want to use the parent's value when restoring by POP_STATE) */
 143         if (kernel_mode(regs))
 144                 /* save new current on stack to use POP_STATE */
 145                 childregs->CURRENT_TASK = (unsigned long)p;
 146         /* if returning to user then use the parent's value of this register */
 147
 148         /* if we're creating a new kernel thread then just zeroing all
 149          * the registers. That's OK for a brand new thread.*/
 150         /* Pls. note that some of them will be restored in POP_STATE */
 151         if (kernel_mode(regs))
 152                 memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
 153         /* if this thread is created for fork/vfork/clone, then we want to
 154          * restore all the parent's context */
 155         /* in addition to the registers which will be restored by POP_STATE */
 156         else {
 157                 ti->cpu_context = *(struct cpu_context *)regs;
 158                 childregs->msr |= MSR_UMS;
 159         }
 160
 161         /* FIXME STATE_SAVE_PT_OFFSET; */
 162         ti->cpu_context.r1  = (unsigned long)childregs - STATE_SAVE_ARG_SPACE;
 163         /* we should consider the fact that childregs is a copy of the parent
 164          * regs which were saved immediately after entering the kernel state
 165          * before enabling VM. This MSR will be restored in switch_to and
 166          * RETURN() and we want to have the right machine state there
 167          * specifically this state must have INTs disabled before and enabled
 168          * after performing rtbd
 169          * compose the right MSR for RETURN(). It will work for switch_to also
 170          * excepting for VM and UMS
 171          * don't touch UMS , CARRY and cache bits
 172          * right now MSR is a copy of parent one */
 173         childregs->msr |= MSR_BIP;
 174         childregs->msr &= ~MSR_EIP;
 175         childregs->msr |= MSR_IE;
 176         childregs->msr &= ~MSR_VM;
 177         childregs->msr |= MSR_VMS;
 178         childregs->msr |= MSR_EE; /* exceptions will be enabled*/
 179
 180         ti->cpu_context.msr = (childregs->msr|MSR_VM);
 181         ti->cpu_context.msr &= ~MSR_UMS; /* switch_to to kernel mode */
 182 #endif
 183         ti->cpu_context.r15 = (unsigned long)ret_from_fork - 8;
 184
 185         if (clone_flags & CLONE_SETTLS)
 186                 ;
 187
 188         return 0;
 189 }
 190
 191 #ifndef CONFIG_MMU
 192 /*
 193  * Return saved PC of a blocked thread.
 194  */
 195 unsigned long thread_saved_pc(struct task_struct *tsk)
 196 {
 197         struct cpu_context *ctx =
 198                 &(((struct thread_info *)(tsk->stack))->cpu_context);
 199
 200         /* Check whether the thread is blocked in resume() */
 201         if (in_sched_functions(ctx->r15))
 202                 return (unsigned long)ctx->r15;
 203         else
 204                 return ctx->r14;
 205 }
 206 #endif
 207
 208 static void kernel_thread_helper(int (*fn)(void *), void *arg)
 209 {
 210         fn(arg);
 211         do_exit(-1);
 212 }
 213
 214 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 215 {
 216         struct pt_regs regs;
 217
 218         memset(&regs, 0, sizeof(regs));
 219         /* store them in non-volatile registers */
 220         regs.r5 = (unsigned long)fn;
 221         regs.r6 = (unsigned long)arg;
 222         local_save_flags(regs.msr);
 223         regs.pc = (unsigned long)kernel_thread_helper;
 224         regs.pt_mode = 1;
 225
 226         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
 227                         &regs, 0, NULL, NULL);
 228 }
 229 EXPORT_SYMBOL_GPL(kernel_thread);
 230
 231 unsigned long get_wchan(struct task_struct *p)
 232 {
 233 /* TBD (used by procfs) */
 234         return 0;
 235 }
 236
 237 /* Set up a thread for executing a new program */
 238 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
 239 {
 240         set_fs(USER_DS);
 241         regs->pc = pc;
 242         regs->r1 = usp;
 243         regs->pt_mode = 0;
 244 #ifdef CONFIG_MMU
 245         regs->msr |= MSR_UMS;
 246 #endif
 247 }
 248
 249 #ifdef CONFIG_MMU
 250 #include <linux/elfcore.h>
 251 /*
 252  * Set up a thread for executing a new program
 253  */
 254 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
 255 {
 256         return 0; /* MicroBlaze has no separate FPU registers */
 257 }
 258 #endif /* CONFIG_MMU */