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view target-utils/libcommon/uartsel.c @ 407:19e5a3e2f9c0

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fcup-settime: moved time() retrieval a little closer to the output A fundamental problem with all simple time transfer tools is that there is always some delay between the time retrieval on the source system and that transmitted time being set on the destination, and the resulting time on the destination system is off by that delay amount. This delay cannot be fully eliminated when working in a simple environment like ours, but we should make our best effort to minimize it. In the present case, moving the atinterf_init() call before the time() retrieval should make a teensy-tiny improvement.
author Mychaela Falconia <falcon@freecalypso.org>
date Sat, 11 Aug 2018 21:52:17 +0000
parents 2942c5ef76ed
children
line wrap: on
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/*
 * uart_select_init() figures out which UART was used to load us
 * through the boot ROM, and sets things up for us to use the same
 * UART for our communication.
 */

#include "types.h"
#include "romvars.h"
#include "ns16550.h"
#include "halt.h"

extern struct ns16550_regs *uart_base;

static u16 rom_version;
static struct boot_rom_vars *rom_vars;
static char *uart_name;

uart_select_init()
{
	rom_version = *(const u16 *)0x1FFE;

	switch (rom_version) {
	case 0x0200:
		rom_vars = (struct boot_rom_vars *) 0x800504;
		break;
	case 0x0300:
		rom_vars = (struct boot_rom_vars *) 0x800518;
		break;
	default:
		_exit(HALTCODE_BOOTROMVER);
	}

	switch (rom_vars->uart_id) {
	case 0:
		uart_base = (struct ns16550_regs *) 0xFFFF5800;
		uart_name = "MODEM";
		break;
	case 1:
		uart_base = (struct ns16550_regs *) 0xFFFF5000;
		uart_name = "IrDA";
		break;
	default:
		_exit(HALTCODE_INVALIDUART);
	}
}

print_boot_rom_info()
{
	printf("Loaded via boot ROM v%04X, UART %d (%s) at baud rate #%d\n",
		rom_version, rom_vars->uart_id, uart_name,
		rom_vars->baud_rate_code);
	printf("CLKTCXO input autodetected to be %d MHz\n",
		rom_vars->clktcxo_13mhz ? 13 : 26);
}