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