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/*
* Copyright 2013 Google Inc.
*
* 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 <config.h>
#include <types.h>
#include <uart.h>
#include <arch/io.h>
#include <console/console.h> /* for __console definition */
#include <cpu/ti/am335x/uart.h>
#define EFR_ENHANCED_EN (1 << 4)
#define FCR_FIFO_EN (1 << 0)
#define MCR_TCR_TLR (1 << 6)
#define SYSC_SOFTRESET (1 << 1)
#define SYSS_RESETDONE (1 << 0)
#define LSR_RXFIFOE (1 << 0)
#define LSR_TXFIFOE (1 << 5)
/*
* Initialise the serial port with the given baudrate divisor. The settings
* are always 8 data bits, no parity, 1 stop bit, no start bits.
*/
static void am335x_uart_init(uint16_t div)
{
struct am335x_uart *uart = (struct am335x_uart *)
CONFIG_CONSOLE_SERIAL_UART_ADDRESS;
uint16_t lcr_orig, efr_orig, mcr_orig;
/* reset the UART */
write16(uart->sysc | SYSC_SOFTRESET, &uart->sysc);
while (!(read16(&uart->syss) & SYSS_RESETDONE))
;
/* 1. switch to register config mode B */
lcr_orig = read16(&uart->lcr);
write16(0xbf, &uart->lcr);
/*
* 2. Set EFR ENHANCED_EN bit. To access this bit, registers must
* be in TCR_TLR submode, meaning EFR[4] = 1 and MCR[6] = 1.
*/
efr_orig = read16(&uart->efr);
write16(efr_orig | EFR_ENHANCED_EN, &uart->efr);
/* 3. Switch to register config mode A */
write16(0x80, &uart->lcr);
/* 4. Enable register submode TCR_TLR to access the UARTi.UART_TLR */
mcr_orig = read16(&uart->mcr);
write16(mcr_orig | MCR_TCR_TLR, &uart->mcr);
/* 5. Enable the FIFO. For now we'll ignore FIFO triggers and DMA */
write16(FCR_FIFO_EN, &uart->fcr);
/* 6. Switch to configuration mode B */
write16(0xbf, &uart->lcr);
/* Skip steps 7 and 8 (setting up FIFO triggers for DMA) */
/* 9. Restore original EFR value */
write16(efr_orig, &uart->efr);
/* 10. Switch to config mode A */
write16(0x80, &uart->lcr);
/* 11. Restore original MCR value */
write16(mcr_orig, &uart->mcr);
/* 12. Restore original LCR value */
write16(lcr_orig, &uart->lcr);
/* Protocol, baud rate and interrupt settings */
/* 1. Disable UART access to DLL and DLH registers */
write16(read16(&uart->mdr1) | 0x7, &uart->mdr1);
/* 2. Switch to config mode B */
write16(0xbf, &uart->lcr);
/* 3. Enable access to IER[7:4] */
write16(efr_orig | EFR_ENHANCED_EN, &uart->efr);
/* 4. Switch to operational mode */
write16(0x0, &uart->lcr);
/* 5. Clear IER */
write16(0x0, &uart->ier);
/* 6. Switch to config mode B */
write16(0xbf, &uart->lcr);
/* 7. Set dll and dlh to the desired values (table 19-25) */
write16((div >> 8), &uart->dlh);
write16((div & 0xff), &uart->dll);
/* 8. Switch to operational mode to access ier */
write16(0x0, &uart->lcr);
/* 9. Clear ier to disable all interrupts */
write16(0x0, &uart->ier);
/* 10. Switch to config mode B */
write16(0xbf, &uart->lcr);
/* 11. Restore efr */
write16(efr_orig, &uart->efr);
/* 12. Set protocol formatting 8n1 (8 bit data, no parity, 1 stop bit) */
write16(0x3, &uart->lcr);
/* 13. Load the new UART mode */
write16(0x0, &uart->mdr1);
}
/*
* Read a single byte from the serial port. Returns 1 on success, 0
* otherwise. When the function is successful, the character read is
* written into its argument c.
*/
static unsigned char am335x_uart_rx_byte(void)
{
struct am335x_uart *uart =
(struct am335x_uart *)CONFIG_CONSOLE_SERIAL_UART_ADDRESS;
while (!(read16(&uart->lsr) & LSR_RXFIFOE));
return read8(&uart->rhr);
}
/*
* Output a single byte to the serial port.
*/
static void am335x_uart_tx_byte(unsigned char data)
{
struct am335x_uart *uart =
(struct am335x_uart *)CONFIG_CONSOLE_SERIAL_UART_ADDRESS;
while (!(read16(&uart->lsr) & LSR_TXFIFOE));
return write8(data, &uart->thr);
}
unsigned int uart_platform_refclk(void)
{
return 48000000;
}
static void am335x_uart_init_dev(void)
{
uint16_t div = (uint16_t) uart_baudrate_divisor(
default_baudrate(), uart_platform_refclk(), 16);
am335x_uart_init(div);
}
#if !defined(__PRE_RAM__)
uint32_t uartmem_getbaseaddr(void)
{
return CONFIG_CONSOLE_SERIAL_UART_ADDRESS;
}
static const struct console_driver exynos5_uart_console __console = {
.init = am335x_uart_init_dev,
.tx_byte = am335x_uart_tx_byte,
.rx_byte = am335x_uart_rx_byte,
};
#else
void uart_init(void)
{
am335x_uart_init_dev();
}
unsigned char uart_rx_byte(void)
{
return am335x_uart_rx_byte();
}
void uart_tx_byte(unsigned char data)
{
am335x_uart_tx_byte(data);
}
void uart_tx_flush(void) {
}
#endif
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