linux/arch/openrisc/kernel/process.c
Sebastian Macke e29d11c699 openrisc: Initial support for the idle state
This patch adds basic support for the idle state of the cpu.
The patch overrides the regular idle function, enables the interupts,
checks for the power management unit and enables the cpu doze mode
if available.

Signed-off-by: Sebastian Macke <sebastian@macke.de>
[shorne@gmail.com: Fixed checkpatch, blankline after declarations]
Signed-off-by: Stafford Horne <shorne@gmail.com>
2017-02-25 04:14:35 +09:00

288 lines
7.5 KiB
C

/*
* OpenRISC process.c
*
* Linux architectural port borrowing liberally from similar works of
* others. All original copyrights apply as per the original source
* declaration.
*
* Modifications for the OpenRISC architecture:
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* This file handles the architecture-dependent parts of process handling...
*/
#define __KERNEL_SYSCALLS__
#include <stdarg.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/elfcore.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/init_task.h>
#include <linux/mqueue.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/spr_defs.h>
#include <linux/smp.h>
/*
* Pointer to Current thread info structure.
*
* Used at user space -> kernel transitions.
*/
struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, };
void machine_restart(void)
{
printk(KERN_INFO "*** MACHINE RESTART ***\n");
__asm__("l.nop 1");
}
/*
* Similar to machine_power_off, but don't shut off power. Add code
* here to freeze the system for e.g. post-mortem debug purpose when
* possible. This halt has nothing to do with the idle halt.
*/
void machine_halt(void)
{
printk(KERN_INFO "*** MACHINE HALT ***\n");
__asm__("l.nop 1");
}
/* If or when software power-off is implemented, add code here. */
void machine_power_off(void)
{
printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
__asm__("l.nop 1");
}
/*
* Send the doze signal to the cpu if available.
* Make sure, that all interrupts are enabled
*/
void arch_cpu_idle(void)
{
local_irq_enable();
if (mfspr(SPR_UPR) & SPR_UPR_PMP)
mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME);
}
void (*pm_power_off) (void) = machine_power_off;
/*
* When a process does an "exec", machine state like FPU and debug
* registers need to be reset. This is a hook function for that.
* Currently we don't have any such state to reset, so this is empty.
*/
void flush_thread(void)
{
}
void show_regs(struct pt_regs *regs)
{
extern void show_registers(struct pt_regs *regs);
show_regs_print_info(KERN_DEFAULT);
/* __PHX__ cleanup this mess */
show_registers(regs);
}
unsigned long thread_saved_pc(struct task_struct *t)
{
return (unsigned long)user_regs(t->stack)->pc;
}
void release_thread(struct task_struct *dead_task)
{
}
/*
* Copy the thread-specific (arch specific) info from the current
* process to the new one p
*/
extern asmlinkage void ret_from_fork(void);
/*
* copy_thread
* @clone_flags: flags
* @usp: user stack pointer or fn for kernel thread
* @arg: arg to fn for kernel thread; always NULL for userspace thread
* @p: the newly created task
* @regs: CPU context to copy for userspace thread; always NULL for kthread
*
* At the top of a newly initialized kernel stack are two stacked pt_reg
* structures. The first (topmost) is the userspace context of the thread.
* The second is the kernelspace context of the thread.
*
* A kernel thread will not be returning to userspace, so the topmost pt_regs
* struct can be uninitialized; it _does_ need to exist, though, because
* a kernel thread can become a userspace thread by doing a kernel_execve, in
* which case the topmost context will be initialized and used for 'returning'
* to userspace.
*
* The second pt_reg struct needs to be initialized to 'return' to
* ret_from_fork. A kernel thread will need to set r20 to the address of
* a function to call into (with arg in r22); userspace threads need to set
* r20 to NULL in which case ret_from_fork will just continue a return to
* userspace.
*
* A kernel thread 'fn' may return; this is effectively what happens when
* kernel_execve is called. In that case, the userspace pt_regs must have
* been initialized (which kernel_execve takes care of, see start_thread
* below); ret_from_fork will then continue its execution causing the
* 'kernel thread' to return to userspace as a userspace thread.
*/
int
copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long arg, struct task_struct *p)
{
struct pt_regs *userregs;
struct pt_regs *kregs;
unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
unsigned long top_of_kernel_stack;
top_of_kernel_stack = sp;
p->set_child_tid = p->clear_child_tid = NULL;
/* Locate userspace context on stack... */
sp -= STACK_FRAME_OVERHEAD; /* redzone */
sp -= sizeof(struct pt_regs);
userregs = (struct pt_regs *) sp;
/* ...and kernel context */
sp -= STACK_FRAME_OVERHEAD; /* redzone */
sp -= sizeof(struct pt_regs);
kregs = (struct pt_regs *)sp;
if (unlikely(p->flags & PF_KTHREAD)) {
memset(kregs, 0, sizeof(struct pt_regs));
kregs->gpr[20] = usp; /* fn, kernel thread */
kregs->gpr[22] = arg;
} else {
*userregs = *current_pt_regs();
if (usp)
userregs->sp = usp;
/*
* For CLONE_SETTLS set "tp" (r10) to the TLS pointer passed to sys_clone.
*
* The kernel entry is:
* int clone (long flags, void *child_stack, int *parent_tid,
* int *child_tid, struct void *tls)
*
* This makes the source r7 in the kernel registers.
*/
if (clone_flags & CLONE_SETTLS)
userregs->gpr[10] = userregs->gpr[7];
userregs->gpr[11] = 0; /* Result from fork() */
kregs->gpr[20] = 0; /* Userspace thread */
}
/*
* _switch wants the kernel stack page in pt_regs->sp so that it
* can restore it to thread_info->ksp... see _switch for details.
*/
kregs->sp = top_of_kernel_stack;
kregs->gpr[9] = (unsigned long)ret_from_fork;
task_thread_info(p)->ksp = (unsigned long)kregs;
return 0;
}
/*
* Set up a thread for executing a new program
*/
void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
{
unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
memset(regs, 0, sizeof(struct pt_regs));
regs->pc = pc;
regs->sr = sr;
regs->sp = sp;
}
/* Fill in the fpu structure for a core dump. */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
{
/* TODO */
return 0;
}
extern struct thread_info *_switch(struct thread_info *old_ti,
struct thread_info *new_ti);
extern int lwa_flag;
struct task_struct *__switch_to(struct task_struct *old,
struct task_struct *new)
{
struct task_struct *last;
struct thread_info *new_ti, *old_ti;
unsigned long flags;
local_irq_save(flags);
/* current_set is an array of saved current pointers
* (one for each cpu). we need them at user->kernel transition,
* while we save them at kernel->user transition
*/
new_ti = new->stack;
old_ti = old->stack;
lwa_flag = 0;
current_thread_info_set[smp_processor_id()] = new_ti;
last = (_switch(old_ti, new_ti))->task;
local_irq_restore(flags);
return last;
}
/*
* Write out registers in core dump format, as defined by the
* struct user_regs_struct
*/
void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
{
dest[0] = 0; /* r0 */
memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
dest[32] = regs->pc;
dest[33] = regs->sr;
dest[34] = 0;
dest[35] = 0;
}
unsigned long get_wchan(struct task_struct *p)
{
/* TODO */
return 0;
}