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[platform][rosco-m68k] add proper support for the system data block

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A block of data left behind by the firmware to tell the system important
things such as the size of memory.
This commit is contained in:
Travis Geiselbrecht
2022-05-21 17:26:49 -07:00
parent 4695035505
commit d496ca1902
1 changed files with 38 additions and 17 deletions
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55
platform/rosco-m68k/platform.c
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@@ -14,14 +14,9 @@
#include <platform/debug.h>
#include <platform/timer.h>
#include <platform/rosco-m68k.h>
#include <string.h>
#include <sys/types.h>
#if WITH_LIB_MINIP
#include <lib/minip.h>
#endif
#include <kernel/novm.h>
#if WITH_LIB_CONSOLE
#include <lib/console.h>
#endif
#include "platform_p.h"
@@ -29,27 +24,53 @@
extern uint8_t __bss_end;
// firmware structure left behind by boot rom
// described at
// https://github.com/rosco-m68k/rosco_m68k/blob/develop/code/firmware/rosco_m68k_firmware/InterfaceReference.md
#define ROSCO_SDB_MAGIC (0xb105d47a)
struct rosco_system_data_block {
uint32_t magic;
uint32_t status;
uint16_t timer_tick_counter;
uint16_t system_flags;
uint32_t upticks_counter;
uint8_t easy68k_flag_echo_on;
uint8_t easy68k_flag_prompt_on;
uint8_t easy68k_flag_lf_display;
uint8_t timer_tick_internal;
uint32_t mem_size;
uint32_t default_uart_base;
uint32_t cpu_info;
};
STATIC_ASSERT(sizeof(struct rosco_system_data_block) == 0x20);
const volatile struct rosco_system_data_block *sdb = (void *)0x400;
void platform_early_init(void) {
duart_early_init();
dprintf(INFO, "ROSCO-M68K: firmware structure at 0x400 - 0x41f:\n");
hexdump((void *)0x400, 0x20);
uint32_t cpu_info = *(uint32_t *)0x41c;
printf("cpu family %u speed %u\n", cpu_info >> 29, cpu_info & 0x1fffffff);
// TODO: probe memory
// TODO: consider using firmware struct left around 0x400
// default to 1MB memory at 0
uint32_t membase = 0x0;
uint32_t memsize = 0x100000; // 1MB
if (sdb->magic != ROSCO_SDB_MAGIC) {
dprintf(INFO, "ROSCO-M68K: firmware failed magic check\n");
} else {
dprintf(INFO, "ROSCO-M68K: firmware structure at 0x400 - 0x41f:\n");
hexdump((void *)sdb, sizeof(*sdb));
printf("cpu family %u speed %u\n", sdb->cpu_info >> 29, sdb->cpu_info & 0x1fffffff);
memsize = sdb->mem_size;
}
dprintf(INFO, "ROSCO-M68K: memory base %#x size %#x\n", membase, memsize);
novm_add_arena("mem", membase, memsize);
// build a table of illegal instructions around 0 to try to catch bad branches
volatile uint16_t *ptr = 0;
for (int i = 0; i < 256; i++) {
ptr[i] = 0x4afa; // undefined opcode
uint16_t ins = 0x4afa;
for (uintptr_t i = 0; i < 256; i++) {
memcpy((void *)i, &ins, 2);
}
}