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reset.S @ 328

Last change on this file since 328 was 314, checked in by cfuguet, 12 years ago
Erasing old comments in the reset.s file of the pre-loader
File size: 6.3 KB

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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 boot_ioc_init
32	.extern boot_putc
33	.extern boot_getc
34	.extern boot_puts
35	.extern boot_ioc_read
36	.extern boot_elf_loader
37	.extern boot_memcpy
38	.extern dtb_addr
39
40	.globl boot /* Make reset an external symbol */
41	.ent boot
42
43	.align 2
44	.set noreorder
45
46	boot:
47	b _boot /* 0xbfc0000 */
48	nop /* 0xbfc0004 */
49
50	/* Addresses of the functions provided by this pre-loader */
51
52	.word BOOT_VERSION /* 0xbfc0008 */
53	.word dtb_addr /* 0xbfc000c */
54	.word boot_putc /* 0xbfc0010 */
55	.word boot_getc /* 0xbfc0014 */
56	.word boot_puts /* 0xbfc0018 */
57	.word boot_ioc_read /* 0xbfc001C */
58	.word boot_elf_loader /* 0xbfc0020 */
59	.word boot_memcpy /* 0xbfc0024 */
60
61	_boot:
62	/* Disable interruptions, keep STATUSbev enabled */
63
64	li k0, (1 << 22)
65	mtc0 k0, CP0_STATUS
66
67	/* Computes proc_id, local_id, cluster_id, and cluster_increment */
68
69	mfc0 k0, CP0_EBASE
70	andi t0, k0, 0x3FF /* t0 <= proc_id (at most 1024 processors) */
71
72	move t3, t0
73
74	la k0, NB_PROCS /* k0 <= number of processors per cluster */
75	divu t3, k0
76	mfhi t1 /* t1 <= local_id = proc_id % NB_PROCS */
77	mflo t2 /* t2 <= cluster_id = proc_id / NB_PROCS */
78
79	la k0, NB_CLUSTERS
80	li t3, 0x80000000
81	divu t3, k0
82	mflo t4
83	sll t4, 1 /* t4 <= cluster_increment = 4G / NB_CLUSTERS */
84
85	mult t4, t2
86	mflo t5 /* t5 <= cluster_id * cluster_increment */
87
88	/* Initialization of the count register in the coprocessor 0 */
89
90	mtc0 zero, CP0_COUNT
91
92	/* In each cluster, the ICU base address depends on the cluster_id */
93
94	la t3, ICU_BASE
95	addu t3, t3, t5 /* t3 <= ICU_BASE + */
96	/* (cluster_id * cluster_increment) */
97
98	/**
99	* Compute the output index for the Write Triggered Interruption mask.
100	* Each processor enable the WTI for its irq output
101	* Each processor may have IRQ_PER_PROC private irq outputs from
102	* the XICU
103	*/
104
105	move t4, t1 /* t4 <= local_id */
106	li t5, IRQ_PER_PROC /* t5 <= IRQ_PER_PROC */
107	multu t4, t5
108	mflo t6 /* t6 <= IRQ_PER_PROC * local_id */
109	sll t4, t6, 2 /* t4 <= OUT_INDEX = t6 * 4 */
110
111	li t5, (0xC << 7) /* t5 <= FUNC = XICU_MSK_WTI */
112	or t4, t4, t5 /* t4 <= FUNC \| INDEX \| 00 */
113	or t5, t3, t4 /* t5 <= &XICU[MSK_WTI][OUT_INDEX] */
114
115	/* Compute and set WTI mask */
116
117	li t4, 1
118	sllv t4, t4, t1 /* Set XICU[MSK_WTI][INDEX][local_id] */
119	sw t4, 0(t5) /* XICU[MSK_WTI][INDEX] <= t4 */
120
121	/**
122	* We have:
123	* t0: global id
124	* t1: local id
125	* t2: cluster id
126	* t3: xicu base address
127	*
128	* Only processor 0 in cluster 0 executes the boot loader
129	*/
130
131	bne zero, t0, _reset_wait
132	nop
133
134	/* Initializes stack pointer */
135
136	la k1, seg_stack_base
137	li k0, BOOT_STACK_SIZE
138	addu sp, k1, k0 /* sp <= seg_stack_base + BOOT_STACK_SIZE */
139
140	#ifndef SOCLIB_IOC
141
142	/* Initialize the block device */
143
144	la k0, boot_ioc_init
145	jalr k0
146	nop
147
148	#endif
149
150	/**
151	* Jump to the boot elf loader routine
152	* Passing as argument the block number in which it must be
153	* the executable elf file to load
154	*/
155
156	la k0, boot_elf_loader
157	li a0, BOOT_LOADER_LBA
158	jalr k0
159	nop
160
161	/**
162	* We jump to the entry point address defined in the
163	* ELF file. This address is returned by boot_elf_loader function.
164	* All function arguments are 0
165	*/
166
167	move a0, zero
168	move a1, zero
169	move a2, zero
170	move a3, zero
171	jr v0
172	nop
173
174	/**
175	* Wait in low power consumption mode until the application wakes us.
176	* The application wakes up the non-boot CPUs using a IPI with a non-0
177	* value in the mailbox. This non-0 value is the address to jump to.
178	*/
179
180	_reset_wait:
181	/**
182	* We have:
183	* t0: global id
184	* t1: local id
185	* t2: cluster id
186	* t3: xicu base address
187	*/
188
189	sll t4, t1, 2 /* t4 <= local_id * 4 */
190	addu t5, t4, t3 /* t5 <= &XICU[WTI_REG][local_id] */
191
192	wait
193
194	lw k0, 0(t5) /* k0 <= XICU[WTI_REG][local_id] */
195	jr k0
196	nop
197
198	/* Exception entry point */
199	.org 0x0380
200	_excep:
201	mfc0 a0, CP0_STATUS /* first arg is status */
202	mfc0 a1, CP0_CAUSE /* second arg is cause */
203	mfc0 a2, CP0_EPC /* third argc is epc */
204	nop
205	j handle_except
206	nop
207
208	.end boot
209
210	.set reorder
211
212	/*
213	* vim: tabstop=4 : shiftwidth=4 : expandtab
214	*/

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