virtex.c
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/*
* The platform specific code for virtex devices since a boot loader is not
* always used.
*
* (C) Copyright 2008 Xilinx, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*/
#include "ops.h"
#include "io.h"
#include "stdio.h"
#define UART_DLL 0 /* Out: Divisor Latch Low */
#define UART_DLM 1 /* Out: Divisor Latch High */
#define UART_FCR 2 /* Out: FIFO Control Register */
#define UART_FCR_CLEAR_RCVR 0x02 /* Clear the RCVR FIFO */
#define UART_FCR_CLEAR_XMIT 0x04 /* Clear the XMIT FIFO */
#define UART_LCR 3 /* Out: Line Control Register */
#define UART_MCR 4 /* Out: Modem Control Register */
#define UART_MCR_RTS 0x02 /* RTS complement */
#define UART_MCR_DTR 0x01 /* DTR complement */
#define UART_LCR_DLAB 0x80 /* Divisor latch access bit */
#define UART_LCR_WLEN8 0x03 /* Wordlength: 8 bits */
static int virtex_ns16550_console_init(void *devp)
{
unsigned char *reg_base;
u32 reg_shift, reg_offset, clk, spd;
u16 divisor;
int n;
if (dt_get_virtual_reg(devp, (void **)®_base, 1) < 1)
return -1;
n = getprop(devp, "reg-offset", ®_offset, sizeof(reg_offset));
if (n == sizeof(reg_offset))
reg_base += reg_offset;
n = getprop(devp, "reg-shift", ®_shift, sizeof(reg_shift));
if (n != sizeof(reg_shift))
reg_shift = 0;
n = getprop(devp, "current-speed", (void *)&spd, sizeof(spd));
if (n != sizeof(spd))
spd = 9600;
/* should there be a default clock rate?*/
n = getprop(devp, "clock-frequency", (void *)&clk, sizeof(clk));
if (n != sizeof(clk))
return -1;
divisor = clk / (16 * spd);
/* Access baud rate */
out_8(reg_base + (UART_LCR << reg_shift), UART_LCR_DLAB);
/* Baud rate based on input clock */
out_8(reg_base + (UART_DLL << reg_shift), divisor & 0xFF);
out_8(reg_base + (UART_DLM << reg_shift), divisor >> 8);
/* 8 data, 1 stop, no parity */
out_8(reg_base + (UART_LCR << reg_shift), UART_LCR_WLEN8);
/* RTS/DTR */
out_8(reg_base + (UART_MCR << reg_shift), UART_MCR_RTS | UART_MCR_DTR);
/* Clear transmitter and receiver */
out_8(reg_base + (UART_FCR << reg_shift),
UART_FCR_CLEAR_XMIT | UART_FCR_CLEAR_RCVR);
return 0;
}
/* For virtex, the kernel may be loaded without using a bootloader and if so
some UARTs need more setup than is provided in the normal console init
*/
int platform_specific_init(void)
{
void *devp;
char devtype[MAX_PROP_LEN];
char path[MAX_PATH_LEN];
devp = finddevice("/chosen");
if (devp == NULL)
return -1;
if (getprop(devp, "linux,stdout-path", path, MAX_PATH_LEN) > 0) {
devp = finddevice(path);
if (devp == NULL)
return -1;
if ((getprop(devp, "device_type", devtype, sizeof(devtype)) > 0)
&& !strcmp(devtype, "serial")
&& (dt_is_compatible(devp, "ns16550")))
virtex_ns16550_console_init(devp);
}
return 0;
}