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/**
* @file svc.c
* Handler code for SVC calls
*
* Copyright (C) 2018 Clyne Sullivan
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <stdint.h>
#include "gpio.h"
#include "clock.h"
#include "task.h"
extern void gpio_svc(uint32_t, uint32_t *, uint32_t *);
extern void clock_svc(uint32_t, uint32_t *, uint32_t *);
extern void task_svc(uint32_t, uint32_t *, uint32_t *);
extern void vfs_svc(uint32_t, uint32_t *, uint32_t *args);
void SVC_Handler(void) {
uint32_t *stack;
// Get the appropriate stack (either kernel or process)
asm("\
tst lr, #4; \
ite eq; \
mrseq %0, msp; \
mrsne %0, psp; \
" : "=r" (stack));
int svc_number = ((char *)stack[6])[-2];
uint32_t min_number = stack[0];
uint32_t *ret = (uint32_t *)stack[1];
uint32_t *args = (uint32_t *)stack[2];
switch (svc_number) {
case -1: // TODO why?
case 0: /* Task-related calls
* 0 - _exit
* 1 - fork
* 2 - getpid
* 3 - waitpid
* 4 - sbrk (TODO poor implementation)
* 5 - execve
*/
task_svc(min_number, ret, args);
break;
case 1: /* GPIO-related calls
* 0 - gpio_mode
* 1 - gpio_type
* 2 - gpio_pupd
* 3 - gpio_speed
* 4 - gpio_dout
* 5 - gpio_din
*/
gpio_svc(min_number, ret, args);
break;
case 2: /* Clock-related calls
* 0 - delay
* 1 - udelay
* 2 - ticks
*/
clock_svc(min_number, ret, args);
break;
case 3: /* Filesystem-related calls
* 0 - mount
* 1 - open
* 2 - close
* 3 - read
* 4 - write
*/
vfs_svc(min_number, ret, args);
break;
default:
break;
}
}
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