xref: /openbmc/linux/arch/riscv/include/asm/processor.h (revision 176f011b)
1 /*
2  * Copyright (C) 2012 Regents of the University of California
3  *
4  *   This program is free software; you can redistribute it and/or
5  *   modify it under the terms of the GNU General Public License
6  *   as published by the Free Software Foundation, version 2.
7  *
8  *   This program is distributed in the hope that it will be useful,
9  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
10  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  *   GNU General Public License for more details.
12  */
13 
14 #ifndef _ASM_RISCV_PROCESSOR_H
15 #define _ASM_RISCV_PROCESSOR_H
16 
17 #include <linux/const.h>
18 
19 #include <asm/ptrace.h>
20 
21 /*
22  * This decides where the kernel will search for a free chunk of vm
23  * space during mmap's.
24  */
25 #define TASK_UNMAPPED_BASE	PAGE_ALIGN(TASK_SIZE >> 1)
26 
27 #define STACK_TOP		TASK_SIZE
28 #define STACK_TOP_MAX		STACK_TOP
29 #define STACK_ALIGN		16
30 
31 #ifndef __ASSEMBLY__
32 
33 struct task_struct;
34 struct pt_regs;
35 
36 /* CPU-specific state of a task */
37 struct thread_struct {
38 	/* Callee-saved registers */
39 	unsigned long ra;
40 	unsigned long sp;	/* Kernel mode stack */
41 	unsigned long s[12];	/* s[0]: frame pointer */
42 	struct __riscv_d_ext_state fstate;
43 };
44 
45 #define INIT_THREAD {					\
46 	.sp = sizeof(init_stack) + (long)&init_stack,	\
47 }
48 
49 #define task_pt_regs(tsk)						\
50 	((struct pt_regs *)(task_stack_page(tsk) + THREAD_SIZE		\
51 			    - ALIGN(sizeof(struct pt_regs), STACK_ALIGN)))
52 
53 #define KSTK_EIP(tsk)		(task_pt_regs(tsk)->sepc)
54 #define KSTK_ESP(tsk)		(task_pt_regs(tsk)->sp)
55 
56 
57 /* Do necessary setup to start up a newly executed thread. */
58 extern void start_thread(struct pt_regs *regs,
59 			unsigned long pc, unsigned long sp);
60 
61 /* Free all resources held by a thread. */
62 static inline void release_thread(struct task_struct *dead_task)
63 {
64 }
65 
66 extern unsigned long get_wchan(struct task_struct *p);
67 
68 
69 static inline void cpu_relax(void)
70 {
71 #ifdef __riscv_muldiv
72 	int dummy;
73 	/* In lieu of a halt instruction, induce a long-latency stall. */
74 	__asm__ __volatile__ ("div %0, %0, zero" : "=r" (dummy));
75 #endif
76 	barrier();
77 }
78 
79 static inline void wait_for_interrupt(void)
80 {
81 	__asm__ __volatile__ ("wfi");
82 }
83 
84 struct device_node;
85 int riscv_of_processor_hartid(struct device_node *node);
86 
87 extern void riscv_fill_hwcap(void);
88 
89 #endif /* __ASSEMBLY__ */
90 
91 #endif /* _ASM_RISCV_PROCESSOR_H */
92