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/*
* Copyright (c) 2011 The Chromium OS Authors.
*
* See file CREDITS for list of people who contributed to this
* project.
*
* 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., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <common.h>
#include <ns16550.h>
#include <asm/gpio.h>
#include <asm/arch/pinmux.h>
#include <asm/arch/uart-spi-switch.h>
#include <asm/arch/tegra2.h>
#include <asm/arch/tegra2_spi.h>
/* position of the UART/SPI select switch */
enum spi_uart_switch {
SWITCH_UNKNOWN,
SWITCH_SPI,
SWITCH_UART,
SWITCH_BOTH
};
/* Information about the spi/uart switch */
struct spi_uart {
int gpio; /* GPIO to control switch */
NS16550_t regs; /* Address of UART affected */
u32 port; /* Port number of UART affected */
};
static struct spi_uart local;
static enum spi_uart_switch switch_pos; /* Current switch position */
static void get_config(struct spi_uart *config)
{
#if defined CONFIG_SPI_CORRUPTS_UART
config->gpio = CONFIG_UART_DISABLE_GPIO;
config->regs = (NS16550_t)CONFIG_SPI_CORRUPTS_UART;
config->port = CONFIG_SPI_CORRUPTS_UART_NR;
#else
config->gpio = -1;
#endif
}
/*
* Init the UART / SPI switch. This can be called before relocation so we must
* not access BSS.
*/
void gpio_early_init_uart(void)
{
struct spi_uart config;
get_config(&config);
if (config.gpio != -1) {
/* Cannot provide a label prior to relocation */
gpio_request(config.gpio, NULL);
gpio_direction_output(config.gpio, 0);
}
}
/*
* Configure the UART / SPI switch.
*/
void gpio_config_uart(void)
{
get_config(&local);
if (local.gpio != -1) {
gpio_direction_output(local.gpio, 0);
switch_pos = SWITCH_UART;
} else {
/*
* If we're here we don't have a SPI switch; go ahead and
* enable the SPI now. We didn't in spi_init() so we wouldn't
* kill the UART.
*/
pinmux_set_func(PINGRP_GMC, PMUX_FUNC_SFLASH);
switch_pos = SWITCH_BOTH;
}
}
static void spi_uart_switch(struct spi_uart *config,
enum spi_uart_switch new_pos)
{
if (switch_pos == SWITCH_BOTH || new_pos == switch_pos)
return;
/* if the UART was selected, allow it to drain */
if (switch_pos == SWITCH_UART)
NS16550_drain(config->regs, config->port);
/* We need to dynamically change the pinmux, shared w/UART RXD/CTS */
pinmux_set_func(PINGRP_GMC, new_pos == SWITCH_SPI ?
PMUX_FUNC_SFLASH : PMUX_FUNC_UARTD);
/*
* On Seaboard, MOSI/MISO are shared w/UART.
* Use GPIO I3 (UART_DISABLE) to tristate UART during SPI activity.
* Enable UART later (cs_deactivate) so we can use it for U-Boot comms.
*/
gpio_direction_output(config->gpio, new_pos == SWITCH_SPI);
switch_pos = new_pos;
/* if the SPI was selected, clear any junk bytes in the UART */
if (switch_pos == SWITCH_UART) {
/* TODO: What if it is part-way through clocking in junk? */
udelay(100);
NS16550_clear(config->regs, config->port);
}
}
void pinmux_select_uart(NS16550_t regs)
{
/* Also prevents calling spi_uart_switch() before relocation */
if (regs == local.regs)
spi_uart_switch(&local, SWITCH_UART);
}
void pinmux_select_spi(void)
{
spi_uart_switch(&local, SWITCH_SPI);
}
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