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boot_entry.S @ 1

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1	/*************************************************************************************************
2	* This file contains the entry point of the ALMOS-MK boot-loader for TSAR architecture. *
3	* It supports a generic multi-clusters / multi-processors architecture *
4	* *
5	* - The number of clusters is defined by the (X_SIZE, Y_SIZE) parameters in the *
6	* hard_config.h file (up to 256 clusters). *
7	* - The number of processors per cluster is defined by the NB_PROCS_MAX parameter in the *
8	* hard_config.h file (up to 4 processors per cluster). *
9	* *
10	* This assembly code is executed by all cores. It has 2 versions (in order to see if the *
11	* contention created by the ARCHINFO core descriptor table scanning loops is acceptable): *
12	* with or without the assumption that the core hardware identifier gid has a fixed format: *
13	* *
14	* - Version with fixed format: gid == (((x << Y_WIDTH) + y) << PADDR_WIDTH) + lid *
15	* It does 3 things: *
16	* + It initializes the stack pointer depending on the lid extracted from the gid, *
17	* using the BOOT_STACK_BASE and BOOT_STACK_SIZE parameters defined in the *
18	* 'boot_config.h' file, *
19	* + It changes the value of the address extension registers using the cxy extracted *
20	* from the gid, *
21	* + It jumps to the boot_loader() function defined in the 'boot.c' file and passes 2 *
22	* arguments which are the cxy and lid of each core to this function. *
23	* *
24	* - Version without fixed format *
25	* It has to perform an additional step in order to extract the (cxy,lid) values from the *
26	* arch_info.bin structure that has been loaded in the cluster (0,0) memory by the bscpu. *
27	* + Each core other than the bscpu scans the core descriptor table in the arch_info.bin *
28	* structure to make an associative search on the (gid), and get the (cxy,lid). *
29	* + It initializes the stack pointer depending on the lid, using the BOOT_STACK_BASE *
30	* and BOOT_STACK_SIZE parameters defined in the 'boot_config.h' file, *
31	* + It changes the value of the address extension registers using cxy obtained *
32	* previously, *
33	* + It jumps to the boot_loader() function defined in the 'boot.c' file and passes 2 *
34	* arguments which are the cxy and lid of each core to this function. *
35	*************************************************************************************************/
36
37	#include "mips32_registers.h"
38	#include "hard_config.h"
39	#include "boot_config.h"
40
41	.section .text, "ax", @progbits
42
43	.globl boot_entry
44	.ent boot_entry
45
46	.align 2
47	.set noreorder
48
49	boot_entry:
50
51	#if USE_FIXED_FORMAT
52
53	/*************
54	* VERSION 1 *
55	*************/
56
57	/*
58	* Get (cxy, lid) values from gid contained in coprocessor0 register.
59	*/
60
61	mfc0 k0, CP0_PROCID
62	andi k0, k0, 0xFFF /* k0 <= gid */
63	andi t1, k0, ((1 << PADDR_WIDTH) - 1) /* t1 <= lid */
64	srl t2, k0, PADDR_WIDTH /* t2 <= cxy */
65
66	/*
67	* Initializing stack pointer from previously retrieved lid value.
68	*/
69
70	la t0, BOOT_STACK_BASE /* t0 <= BOOT_STACK_BASE */
71	li k1, BOOT_STACK_SIZE /* k1 <= BOOT_STACK_SIZE */
72	multu k1, t1
73	mflo k0, /* k0 <= BOOT_STACK_SIZE * lid */
74	subu sp, t0, k0 /* P[cxy,lid] stack top initialized */
75
76	/*
77	* Switching to local DSPACE by changing the value of the address extension registers.
78	*/
79
80	mtc2 t2, CP2_DATA_PADDR_EXT
81
82	/*
83	* Jumping to boot_loader() function after passing 2 arguments in the registers.
84	*/
85
86	or a0, zero, t1 /* a0 <= lid */
87	or a1, zero, t2 /* a1 <= cxy */
88	la ra, boot_loader
89	jr ra
90	nop
91
92	#else
93
94	/*************
95	* VERSION 2 *
96	*************/
97
98	/*
99	* Testing if this is bscpu.
100	*/
101
102	mfc0 k0, CP0_PROCID
103	andi k0, k0, 0xFFF /* k0 <= gid */
104
105	li t1, BOOT_CORE_GID /* t1 <= bscpu gid */
106	or t3, zero, zero /* t3 <= bscpu lid = 0 */
107	beq k0, t1, bscpu_exit /* if bscpu, skip scanning core tbl */
108	li t4, BOOT_CORE_CXY /* t4 <= bscpu cxy */
109
110	/*
111	* Getting base address of the core descriptor table in 'arch_info.bin' file.
112	*/
113
114	la t0, ARCHINFO_BASE /* t0 <= ARCHINFO_BASE */
115	li t1, 0x80 /* t1 <= ARCHINFO_HEADER_SIZE */
116	addu t2, t0, t1 /* t2 <= ARCHINFO_CORE_BASE */
117
118	/*
119	* Scanning the core descriptor table if this is not bscpu. TODO If not found?
120	*/
121
122	li t3, 0x8 /* t3 <= ARCHINFO_CORE_SIZE */
123
124	scanning_core_table:
125	lw t1, 0(t2) /* t1 <= archinfo_core.gid */
126	bne t1, k0, scanning_core_table /* if (t1 != k0) => loop */
127	addu t2, t2, t3 /* t2 <= @ next archinfo_core */
128
129	/*
130	* Getting (cxy, lid) values from the found core descriptor.
131	*/
132
133	lw t3, -8(t2) /* t3 <= lid */
134	lw t4, -4(t2) /* t4 <= cxy */
135
136	/*
137	* Initializing stack pointer from previously retrieved lid value.
138	*/
139
140	bscpu_exit:
141	la t0, BOOT_STACK_BASE /* t0 <= BOOT_STACK_BASE */
142	li k1, BOOT_STACK_SIZE /* k1 <= BOOT_STACK_SIZE */
143	multu k1, t3
144	mflo k0 /* k0 <= BOOT_STACK_SIZE * lid */
145	subu sp, t0, k0 /* P[cxy,lid] stack top initialized */
146
147	/*
148	* Switching to local DSPACE by changing the value of the address extension registers.
149	*/
150
151	mtc2 t4, CP2_DATA_PADDR_EXT
152
153	/*
154	* Jumping to boot_loader() function after passing 2 arguments in the registers.
155	*/
156
157	or a0, zero, t3 /* a0 <= lid */
158	or a1, zero, t4 /* a1 <= cxy */
159	la ra, boot_loader
160	jr ra
161	nop
162
163	#endif
164
165	.end boot_entry
166
167	.set reorder

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