1/*
2 * include/asm-xtensa/processor.h
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License.  See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 2001 - 2005 Tensilica Inc.
9 */
10
11#ifndef _XTENSA_PROCESSOR_H
12#define _XTENSA_PROCESSOR_H
13
14#include <variant/core.h>
15#include <platform/hardware.h>
16
17#include <linux/compiler.h>
18#include <asm/ptrace.h>
19#include <asm/types.h>
20#include <asm/regs.h>
21
22/* Assertions. */
23
24#if (XCHAL_HAVE_WINDOWED != 1)
25# error Linux requires the Xtensa Windowed Registers Option.
26#endif
27
28#define ARCH_SLAB_MINALIGN	XCHAL_DATA_WIDTH
29
30/*
31 * User space process size: 1 GB.
32 * Windowed call ABI requires caller and callee to be located within the same
33 * 1 GB region. The C compiler places trampoline code on the stack for sources
34 * that take the address of a nested C function (a feature used by glibc), so
35 * the 1 GB requirement applies to the stack as well.
36 */
37
38#ifdef CONFIG_MMU
39#define TASK_SIZE	__XTENSA_UL_CONST(0x40000000)
40#else
41#define TASK_SIZE	(PLATFORM_DEFAULT_MEM_START + PLATFORM_DEFAULT_MEM_SIZE)
42#endif
43
44#define STACK_TOP	TASK_SIZE
45#define STACK_TOP_MAX	STACK_TOP
46
47/*
48 * General exception cause assigned to debug exceptions. Debug exceptions go
49 * to their own vector, rather than the general exception vectors (user,
50 * kernel, double); and their specific causes are reported via DEBUGCAUSE
51 * rather than EXCCAUSE.  However it is sometimes convenient to redirect debug
52 * exceptions to the general exception mechanism.  To do this, an otherwise
53 * unused EXCCAUSE value was assigned to debug exceptions for this purpose.
54 */
55
56#define EXCCAUSE_MAPPED_DEBUG	63
57
58/*
59 * We use DEPC also as a flag to distinguish between double and regular
60 * exceptions. For performance reasons, DEPC might contain the value of
61 * EXCCAUSE for regular exceptions, so we use this definition to mark a
62 * valid double exception address.
63 * (Note: We use it in bgeui, so it should be 64, 128, or 256)
64 */
65
66#define VALID_DOUBLE_EXCEPTION_ADDRESS	64
67
68/* LOCKLEVEL defines the interrupt level that masks all
69 * general-purpose interrupts.
70 */
71#define LOCKLEVEL 1
72
73/* WSBITS and WBBITS are the width of the WINDOWSTART and WINDOWBASE
74 * registers
75 */
76#define WSBITS  (XCHAL_NUM_AREGS / 4)      /* width of WINDOWSTART in bits */
77#define WBBITS  (XCHAL_NUM_AREGS_LOG2 - 2) /* width of WINDOWBASE in bits */
78
79#ifndef __ASSEMBLY__
80
81/* Build a valid return address for the specified call winsize.
82 * winsize must be 1 (call4), 2 (call8), or 3 (call12)
83 */
84#define MAKE_RA_FOR_CALL(ra,ws)   (((ra) & 0x3fffffff) | (ws) << 30)
85
86/* Convert return address to a valid pc
87 * Note: We assume that the stack pointer is in the same 1GB ranges as the ra
88 */
89#define MAKE_PC_FROM_RA(ra,sp)    (((ra) & 0x3fffffff) | ((sp) & 0xc0000000))
90
91typedef struct {
92    unsigned long seg;
93} mm_segment_t;
94
95struct thread_struct {
96
97	/* kernel's return address and stack pointer for context switching */
98	unsigned long ra; /* kernel's a0: return address and window call size */
99	unsigned long sp; /* kernel's a1: stack pointer */
100
101	mm_segment_t current_ds;    /* see uaccess.h for example uses */
102
103	/* struct xtensa_cpuinfo info; */
104
105	unsigned long bad_vaddr; /* last user fault */
106	unsigned long bad_uaddr; /* last kernel fault accessing user space */
107	unsigned long error_code;
108
109	unsigned long ibreak[XCHAL_NUM_IBREAK];
110	unsigned long dbreaka[XCHAL_NUM_DBREAK];
111	unsigned long dbreakc[XCHAL_NUM_DBREAK];
112
113	/* Make structure 16 bytes aligned. */
114	int align[0] __attribute__ ((aligned(16)));
115};
116
117
118/*
119 * Default implementation of macro that returns current
120 * instruction pointer ("program counter").
121 */
122#define current_text_addr()  ({ __label__ _l; _l: &&_l;})
123
124
125/* This decides where the kernel will search for a free chunk of vm
126 * space during mmap's.
127 */
128#define TASK_UNMAPPED_BASE	(TASK_SIZE / 2)
129
130#define INIT_THREAD  \
131{									\
132	ra:		0, 						\
133	sp:		sizeof(init_stack) + (long) &init_stack,	\
134	current_ds:	{0},						\
135	/*info:		{0}, */						\
136	bad_vaddr:	0,						\
137	bad_uaddr:	0,						\
138	error_code:	0,						\
139}
140
141
142/*
143 * Do necessary setup to start up a newly executed thread.
144 * Note: We set-up ps as if we did a call4 to the new pc.
145 *       set_thread_state in signal.c depends on it.
146 */
147#define USER_PS_VALUE ((1 << PS_WOE_BIT) |				\
148                       (1 << PS_CALLINC_SHIFT) |			\
149                       (USER_RING << PS_RING_SHIFT) |			\
150                       (1 << PS_UM_BIT) |				\
151                       (1 << PS_EXCM_BIT))
152
153/* Clearing a0 terminates the backtrace. */
154#define start_thread(regs, new_pc, new_sp) \
155	regs->pc = new_pc; \
156	regs->ps = USER_PS_VALUE; \
157	regs->areg[1] = new_sp; \
158	regs->areg[0] = 0; \
159	regs->wmask = 1; \
160	regs->depc = 0; \
161	regs->windowbase = 0; \
162	regs->windowstart = 1;
163
164/* Forward declaration */
165struct task_struct;
166struct mm_struct;
167
168/* Free all resources held by a thread. */
169#define release_thread(thread) do { } while(0)
170
171/* Prepare to copy thread state - unlazy all lazy status */
172extern void prepare_to_copy(struct task_struct*);
173
174/* Create a kernel thread without removing it from tasklists */
175extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
176
177/* Copy and release all segment info associated with a VM */
178#define copy_segments(p, mm)	do { } while(0)
179#define release_segments(mm)	do { } while(0)
180#define forget_segments()	do { } while (0)
181
182#define thread_saved_pc(tsk)	(task_pt_regs(tsk)->pc)
183
184extern unsigned long get_wchan(struct task_struct *p);
185
186#define KSTK_EIP(tsk)		(task_pt_regs(tsk)->pc)
187#define KSTK_ESP(tsk)		(task_pt_regs(tsk)->areg[1])
188
189#define cpu_relax()  barrier()
190
191/* Special register access. */
192
193#define WSR(v,sr) __asm__ __volatile__ ("wsr %0,"__stringify(sr) :: "a"(v));
194#define RSR(v,sr) __asm__ __volatile__ ("rsr %0,"__stringify(sr) : "=a"(v));
195
196#define set_sr(x,sr) ({unsigned int v=(unsigned int)x; WSR(v,sr);})
197#define get_sr(sr) ({unsigned int v; RSR(v,sr); v; })
198
199#endif	/* __ASSEMBLY__ */
200#endif	/* _XTENSA_PROCESSOR_H */
201