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reset.S @ 554

Last change on this file since 554 was 554, checked in by bouyer, 11 years ago
Make sure the boot loader won't try to write to the ROM. Store read-write data in BSS along with the stack at seg_stack_base.
File size: 6.5 KB

Line
1	/**
2	* \file : reset.S
3	* \date : 01/12/2012
4	* \author: Cesar FUGUET & Manuel BOUYER & Alain Greiner
5	*
6	* This is a boot code for a generic multi-clusters / multi-processors
7	* TSAR architecture (up to 256 clusters / up to 4 processors per cluster).
8	* There is one XICU, one TTY, one DMA and one stack segment per cluster.
9	* segment base adresses = base + cluster_segment_increment*cluster_id
10	*
11	* - Each processor initializes the Status Register (SR) to disable interrupts.
12	* - Each processor initializes the Count Register.
13	* - Each processor initialises its private XICU Write Triggered Interruption
14	* mask register.
15	* - Only processor 0 initializes the stack pointer ($29).
16	* - Only processor 0 (boot processor) executes the boot_load_elf function to
17	* load in memory the boot loader stored in the block BOOT_LOADER_LBA of
18	* the disk.
19	* - All non-boot processors wait in a low power consumption mode that the
20	* processor 0 wakes them using the IPI (Inter Processor Interruption)
21	* functionality of the XICU device.
22	*/
23
24	#include <defs.h>
25	#include <mips32_registers.h>
26
27	.section .boot,"ax",@progbits
28
29	.extern seg_stack_base
30
31	.extern dtb_addr
32	.extern boot_putc
33	.extern boot_getc
34	.extern boot_ioc_read
35	.extern boot_elf_loader
36	.extern memcpy
37	.extern boot_puts
38	.extern boot_putx
39	.extern boot_putd
40	.extern boot_ioc_init
41	.extern versionstr
42
43	.globl boot /* Make reset an external symbol */
44	.ent boot
45
46	.align 2
47	.set noreorder
48
49	boot:
50	b _boot /* 0xbfc0000 */
51	nop /* 0xbfc0004 */
52
53	/* Addresses of the functions provided by this pre-loader */
54
55	.word BOOT_VERSION /* 0xbfc0008 */
56	.word dtb_addr /* 0xbfc000c */
57	.word boot_putc /* 0xbfc0010 */
58	.word boot_getc /* 0xbfc0014 */
59	.word boot_ioc_read /* 0xbfc0018 */
60	.word boot_elf_loader /* 0xbfc001C */
61	.word memcpy /* 0xbfc0020 */
62	.word boot_puts /* 0xbfc0024 */
63	.word boot_putx /* 0xbfc0028 */
64	.word boot_putd /* 0xbfc002C */
65
66	_boot:
67	/* Disable interruptions, keep STATUSbev enabled */
68
69	li k0, (1 << 22)
70	mtc0 k0, CP0_STATUS
71
72	/* Computes proc_id, local_id, cluster_id, and cluster_increment */
73
74	mfc0 k0, CP0_EBASE
75	andi t0, k0, 0x3FF /* t0 <= proc_id (at most 1024 processors) */
76
77	move t3, t0
78
79	la k0, NB_PROCS /* k0 <= number of processors per cluster */
80	divu t3, k0
81	mfhi t1 /* t1 <= local_id = proc_id % NB_PROCS */
82	mflo t2 /* t2 <= cluster_id = proc_id / NB_PROCS */
83
84	la k0, NB_CLUSTERS
85	li t3, 0x80000000
86	divu t3, k0
87	mflo t4
88	sll t4, 1 /* t4 <= cluster_increment = 4G / NB_CLUSTERS */
89
90	mult t4, t2
91	mflo t5 /* t5 <= cluster_id * cluster_increment */
92
93	/* Initialization of the count register in the coprocessor 0 */
94
95	mtc0 zero, CP0_COUNT
96
97	/* In each cluster, the ICU base address depends on the cluster_id */
98
99	la t3, ICU_BASE
100	addu t3, t3, t5 /* t3 <= ICU_BASE + */
101	/* (cluster_id * cluster_increment) */
102
103	/**
104	* Compute the output index for the Write Triggered Interruption mask.
105	* Each processor enable the WTI for its irq output
106	* Each processor may have IRQ_PER_PROC private irq outputs from
107	* the XICU
108	*/
109
110	move t4, t1 /* t4 <= local_id */
111	li t5, IRQ_PER_PROC /* t5 <= IRQ_PER_PROC */
112	multu t4, t5
113	mflo t6 /* t6 <= IRQ_PER_PROC * local_id */
114	sll t4, t6, 2 /* t4 <= OUT_INDEX = t6 * 4 */
115
116	li t5, (0xC << 7) /* t5 <= FUNC = XICU_MSK_WTI */
117	or t4, t4, t5 /* t4 <= FUNC \| INDEX \| 00 */
118	or t5, t3, t4 /* t5 <= &XICU[MSK_WTI][OUT_INDEX] */
119
120	/* Compute and set WTI mask */
121
122	li t4, 1
123	sllv t4, t4, t1 /* Set XICU[MSK_WTI][INDEX][local_id] */
124	sw t4, 0(t5) /* XICU[MSK_WTI][INDEX] <= t4 */
125
126	/**
127	* We have:
128	* t0: global id
129	* t1: local id
130	* t2: cluster id
131	* t3: xicu base address
132	*
133	* Only processor 0 in cluster 0 executes the boot loader
134	*/
135
136	bne zero, t0, _reset_wait
137	nop
138
139	/* Initializes stack pointer */
140
141	la sp, stk
142
143	la a0, versionstr
144	la k0, boot_puts
145	jalr k0
146	nop
147
148	#ifndef SOCLIB_IOC
149
150	/* Initialize the block device */
151
152	la k0, boot_ioc_init
153	jalr k0
154	nop
155
156	#endif
157
158	/**
159	* Jump to the boot elf loader routine
160	* Passing as argument the block number in which it must be
161	* the executable elf file to load
162	*/
163
164	la k0, boot_elf_loader
165	li a0, BOOT_LOADER_LBA
166	jalr k0
167	nop
168
169	/**
170	* We jump to the entry point address defined in the
171	* ELF file. This address is returned by boot_elf_loader function.
172	* All function arguments are 0
173	*/
174
175	move a0, zero
176	move a1, zero
177	move a2, zero
178	move a3, zero
179	jr v0
180	nop
181
182	/**
183	* Wait in low power consumption mode until the application wakes us.
184	* The application wakes up the non-boot CPUs using a IPI with a non-0
185	* value in the mailbox. This non-0 value is the address to jump to.
186	*/
187
188	_reset_wait:
189	/**
190	* We have:
191	* t0: global id
192	* t1: local id
193	* t2: cluster id
194	* t3: xicu base address
195	*/
196
197	sll t4, t1, 2 /* t4 <= local_id * 4 */
198	addu t5, t4, t3 /* t5 <= &XICU[WTI_REG][local_id] */
199
200	wait
201
202	lw k0, 0(t5) /* k0 <= XICU[WTI_REG][local_id] */
203	jr k0
204	nop
205
206	/* Exception entry point */
207	.org 0x0380
208	_excep:
209	mfc0 a0, CP0_STATUS /* first arg is status */
210	mfc0 a1, CP0_CAUSE /* second arg is cause */
211	mfc0 a2, CP0_EPC /* third argc is epc */
212	nop
213	j handle_except
214	nop
215
216	.end boot
217
218	.set reorder
219
220	.section .data
221	.space BOOT_STACK_SIZE
222	stk:
223	.space 1
224
225	/*
226	* vim: tabstop=4 : shiftwidth=4 : expandtab
227	*/

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