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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2011 Advanced Micro Devices, Inc.
* Copyright (C) 2014 Edward O'Callaghan <eocallaghan@alterapraxis.com>
* Copyright (C) 2014 Felix Held <felix-coreboot@felixheld.de>
*
* 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 2 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, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/*
* A generic romstage (pre-ram) driver for Nuvoton variant Super I/O chips.
*
* The following is derived directly from the vendor Nuvoton's data-sheets:
*
* To toggle between `configuration mode` and `normal operation mode` as to
* manipulate the various LDN's in Nuvoton Super I/O's we are required to
* pass magic numbers `passwords keys`.
*
* NUVOTON_ENTRY_KEY := enable configuration : 0x87
* NUVOTON_EXIT_KEY := disable configuration : 0xAA
*
* To modify a LDN's configuration register, we use the index port to select
* the index of the LDN and then write to the data port to alter the
* parameters. A default index, data port pair is 0x4E, 0x4F respectively, a
* user modified pair is 0x2E, 0x2F respectively.
*
*/
#include <arch/io.h>
#include <device/pnp.h>
#include <stdint.h>
#include "nuvoton.h"
#define NUVOTON_ENTRY_KEY 0x87
#define NUVOTON_EXIT_KEY 0xAA
/* Enable configuration: pass entry key '0x87' into index port dev
* two times. */
static void pnp_enter_conf_state(device_t dev)
{
u16 port = dev >> 8;
outb(NUVOTON_ENTRY_KEY, port);
outb(NUVOTON_ENTRY_KEY, port);
}
/* Disable configuration: pass exit key '0xAA' into index port dev. */
static void pnp_exit_conf_state(device_t dev)
{
u16 port = dev >> 8;
outb(NUVOTON_EXIT_KEY, port);
}
/* Bring up early serial debugging output before the RAM is initialized. */
void nuvoton_enable_serial(device_t dev, u16 iobase)
{
pnp_enter_conf_state(dev);
pnp_set_logical_device(dev);
pnp_set_enable(dev, 0);
pnp_set_iobase(dev, PNP_IDX_IO0, iobase);
pnp_set_enable(dev, 1);
pnp_exit_conf_state(dev);
}
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