source: soft/giet_vm/giet_kernel/ctx_handler.h @ 693

Last change on this file since 693 was 648, checked in by alain, 9 years ago

Introducing support for the new mechanism to start tasks.

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File size: 7.6 KB
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1/////////////////////////////////////////////////////////////////////////////////
2// File     : ctx_handler.h
3// Date     : 01/04/2012
4// Authors  : alain greiner & joel porquet
5// Copyright (c) UPMC-LIP6
6/////////////////////////////////////////////////////////////////////////////////
7// The ctx_handler.h and ctx_handler.c files are part of the GIET-VM nano-kernel.
8// This code is used to support context switch when several tasks are executing
9// in time multiplexing on a single processor.
10// The tasks are statically allocated to a processor in the boot phase, and
11// there is one private scheduler per processor. Each sheduler occupies 8K bytes,
12// and contains up to 14 task contexts (task_id is from 0 to 13).
13// The task context [13] is reserved for the "idle" task that does nothing, and
14// is launched by the scheduler when there is no other runable task.
15/////////////////////////////////////////////////////////////////////////////////
16// A task context is an array of 64 uint32 words => 256 bytes.
17// It contains copies of processor registers (when the task is preempted)
18// and some general informations associated to a task, such as the private
19// peripheral channels allocated to the task, the vspace index, the various
20// task index (local / global / application), and the runnable status.
21/////////////////////////////////////////////////////////////////////////////////
22// ctx[0] <- ***   |ctx[8] <- $8     |ctx[16]<- $16    |ctx[24]<- $24
23// ctx[1] <- $1    |ctx[9] <- $9     |ctx[17]<- $17    |ctx[25]<- $25
24// ctx[2] <- $2    |ctx[10]<- $10    |ctx[18]<- $18    |ctx[26]<- LO
25// ctx[3] <- $3    |ctx[11]<- $11    |ctx[19]<- $19    |ctx[27]<- HI
26// ctx[4] <- $4    |ctx[12]<- $12    |ctx[20]<- $20    |ctx[28]<- $28
27// ctx[5] <- $5    |ctx[13]<- $13    |ctx[21]<- $21    |ctx[29]<- SP
28// ctx[6] <- $6    |ctx[14]<- $14    |ctx[22]<- $22    |ctx[30]<- $30
29// ctx[7] <- $7    |ctx[15]<- $15    |ctx[23]<- $23    |ctx[31]<- RA
30//
31// ctx[32]<- EPC   |ctx[40]<- TTY    |ctx[48]<- TRDID  |ctx[56]<- ***
32// ctx[33]<- CR    |ctx[41]<- CMA_FB |ctx[49]<- GTID   |ctx[57]<- ***
33// ctx[34]<- SR    |ctx[42]<- CMA_RX |ctx[50]<- NORUN  |ctx[58]<- ***
34// ctx[35]<- BVAR  |ctx[43]<- CMA_TX |ctx[51]<- COPROC |ctx[59]<- ***
35// ctx[36]<- PTAB  |ctx[44]<- NIC_RX |ctx[52]<- ENTRY  |ctx[60]<- ***
36// ctx[37]<- LTID  |ctx[45]<- NIC_TX |ctx[53]<- ***    |ctx[61]<- ***
37// ctx[38]<- VSID  |ctx[46]<- TIM    |ctx[54]<- ***    |ctx[62]<- ***
38// ctx[39]<- PTPR  |ctx[47]<- HBA    |ctx[55]<- ***    |ctx[63]<- ***
39/////////////////////////////////////////////////////////////////////////////////
40
41#ifndef _CTX_HANDLER_H
42#define _CTX_HANDLER_H
43
44#include <giet_config.h>
45
46/////////////////////////////////////////////////////////////////////////////////
47//    Definition of the task context slots indexes
48/////////////////////////////////////////////////////////////////////////////////
49
50#define CTX_SP_ID        29    // Stack Pointer
51#define CTX_RA_ID        31    // Return Address
52
53#define CTX_EPC_ID       32    // Exception Program Counter (CP0)
54#define CTX_CR_ID        33    // Cause Register (CP0)
55#define CTX_SR_ID        34    // Status Register (CP0)
56#define CTX_BVAR_ID      35        // Bad Virtual Address Register (CP0)
57#define CTX_PTAB_ID      36    // Page Table Virtual address
58#define CTX_LTID_ID      37    // Local  Task Index (in scheduler)
59#define CTX_VSID_ID      38    // Vspace Index     
60#define CTX_PTPR_ID      39    // Page Table Pointer Register (PADDR>>13)
61
62#define CTX_TTY_ID       40    // private TTY channel index 
63#define CTX_CMA_FB_ID    41    // private CMA channel index for FBF write
64#define CTX_CMA_RX_ID    42    // private CMA channel index for NIC_TX
65#define CTX_CMA_TX_ID    43    // private CMA channel index for NIC_RX
66#define CTX_NIC_RX_ID    44    // private NIC channel index RX transfer
67#define CTX_NIC_TX_ID    45    // private NIC channel index TX transfer
68#define CTX_TIM_ID       46    // ptivate TIM channel index
69#define CTX_HBA_ID       47    // private HBA channel index
70
71#define CTX_TRDID_ID     48    // Thread Task Index in vspace
72#define CTX_GTID_ID      49    // Global Task Index in all system
73#define CTX_NORUN_ID     50    // bit-vector : task runable if all zero
74#define CTX_COPROC_ID    51    // cluster_xy : coprocessor coordinates
75#define CTX_ENTRY_ID     52    // Virtual address of task entry point
76
77/////////////////////////////////////////////////////////////////////////////////
78//    Definition of the NORUN bit-vector masks
79/////////////////////////////////////////////////////////////////////////////////
80
81#define NORUN_MASK_TASK       0x00000001   // Task not active 
82#define NORUN_MASK_IOC        0x00000002   // Task blocked on IOC transfer
83#define NORUN_MASK_COPROC     0x00000004   // Task blocked on COPROC transfer
84
85/////////////////////////////////////////////////////////////////////////////////
86//    Definition of the scheduler structure
87/////////////////////////////////////////////////////////////////////////////////
88
89typedef struct static_scheduler_s
90{
91    unsigned int context[14][64];      // at most 14 task (including idle_task)
92    unsigned int tasks;                // actual number of tasks
93    unsigned int current;              // current task index
94    unsigned int hwi_vector[32];       // hardware interrupt vector
95    unsigned int pti_vector[32];       // timer    interrupt vector
96    unsigned int wti_vector[32];       // software interrupt vector
97    unsigned int reserved[30];         // padding to 4 Kbytes
98    unsigned int idle_stack[1024];     // private stack for idle stack (4Kbytes)
99} static_scheduler_t;
100
101#define IDLE_TASK_INDEX        13
102
103
104/////////////////////////////////////////////////////////////////////////////////
105//               Extern Functions
106/////////////////////////////////////////////////////////////////////////////////
107
108/////////////////////////////////////////////////////////////////////////////////
109// This function performs a context switch between the running task
110// and  another task, using a round-robin sheduling policy between all
111// tasks allocated to a given processor (static allocation).
112// It selects the next runable task to resume execution.
113// If the only runable task is the current task, return without context switch.
114// If there is no runable task, the scheduler switch to the default "idle" task.
115// The return address contained in $31 is saved in the current task context
116// (in the ctx[31] slot), and the function actually returns to the address
117// contained in the ctx[31] slot of the next task context.
118/////////////////////////////////////////////////////////////////////////////////
119extern void _ctx_switch();
120
121/////////////////////////////////////////////////////////////////////////////////
122// The address of this function is used to initialise the return address
123// in the "idle" task context.
124/////////////////////////////////////////////////////////////////////////////////
125extern void _ctx_eret();
126
127/////////////////////////////////////////////////////////////////////////////////
128// This function is executed task when no other task can be executed.
129/////////////////////////////////////////////////////////////////////////////////
130extern void _idle_task();
131
132/////////////////////////////////////////////////////////////////////////////////
133// This function displays the context of a task identified by the processor
134// coordinates (x,y,p), and by the local task index ltid.
135// The string argument can be used for debug.
136/////////////////////////////////////////////////////////////////////////////////
137extern void _ctx_display( unsigned int x,
138                          unsigned int y,
139                          unsigned int p,
140                          unsigned int ltid,
141                          char*        string );
142
143#endif
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