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/*
* early_printk_intel_mid.c - early consoles for Intel MID platforms
*
* Copyright (c) 2008-2010, Intel Corporation
*
* 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; version 2
* of the License.
*/
/*
* This file implements early console named hsu.
* hsu is based on a High Speed UART device which only exists in the Medfield
* platform
*/
#include <linux/serial_reg.h>
#include <linux/serial_mfd.h>
#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <asm/fixmap.h>
#include <asm/pgtable.h>
#include <asm/intel-mid.h>
/*
* Following is the early console based on Medfield HSU (High
* Speed UART) device.
*/
#define HSU_PORT_BASE 0xffa28080
static void __iomem *phsu;
void hsu_early_console_init(const char *s)
{
unsigned long paddr, port = 0;
u8 lcr;
/*
* Select the early HSU console port if specified by user in the
* kernel command line.
*/
if (*s && !kstrtoul(s, 10, &port))
port = clamp_val(port, 0, 2);
paddr = HSU_PORT_BASE + port * 0x80;
phsu = (void __iomem *)set_fixmap_offset_nocache(FIX_EARLYCON_MEM_BASE, paddr);
/* Disable FIFO */
writeb(0x0, phsu + UART_FCR);
/* Set to default 115200 bps, 8n1 */
lcr = readb(phsu + UART_LCR);
writeb((0x80 | lcr), phsu + UART_LCR);
writeb(0x18, phsu + UART_DLL);
writeb(lcr, phsu + UART_LCR);
writel(0x3600, phsu + UART_MUL*4);
writeb(0x8, phsu + UART_MCR);
writeb(0x7, phsu + UART_FCR);
writeb(0x3, phsu + UART_LCR);
/* Clear IRQ status */
readb(phsu + UART_LSR);
readb(phsu + UART_RX);
readb(phsu + UART_IIR);
readb(phsu + UART_MSR);
/* Enable FIFO */
writeb(0x7, phsu + UART_FCR);
}
#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
static void early_hsu_putc(char ch)
{
unsigned int timeout = 10000; /* 10ms */
u8 status;
while (--timeout) {
status = readb(phsu + UART_LSR);
if (status & BOTH_EMPTY)
break;
udelay(1);
}
/* Only write the char when there was no timeout */
if (timeout)
writeb(ch, phsu + UART_TX);
}
static void early_hsu_write(struct console *con, const char *str, unsigned n)
{
int i;
for (i = 0; i < n && *str; i++) {
if (*str == '\n')
early_hsu_putc('\r');
early_hsu_putc(*str);
str++;
}
}
struct console early_hsu_console = {
.name = "earlyhsu",
.write = early_hsu_write,
.flags = CON_PRINTBUFFER,
.index = -1,
};
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