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Commit 4d033556 authored by Feng Tang's avatar Feng Tang Committed by Ingo Molnar
Browse files

x86, earlyprintk: Add hsu early console for Intel Medfield platform 



Intel Medfield platform has a high speed UART device, which
could act as a early console. To enable early printk of HSU
console, simply add "earlyprintk=hsu" in kernel command line.

Currently we put the code in the early_printk_mrst.c as it is
also for Intel MID platforms like the mrst early console

Signed-off-by: default avatarFeng Tang <feng.tang@intel.com>
Acked-by: default avatarAlan Cox <alan@linux.intel.com>
Cc: greg@kroah.com
LKML-Reference: <1284361736-23011-5-git-send-email-feng.tang@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent c20b5c33

arch/x86/include/asm/mrst.h

+3 −0
Original line number Diff line number Diff line
@@ -47,4 +47,7 @@ extern enum mrst_timer_options mrst_timer_options; 


extern struct console early_mrst_console;

extern void mrst_early_console_init(void);



extern struct console early_hsu_console;

extern void hsu_early_console_init(void);

#endif /* _ASM_X86_MRST_H */

arch/x86/kernel/early_printk.c

+6 −0
Original line number Diff line number Diff line
@@ -245,6 +245,12 @@ static int __init setup_early_printk(char *buf) 
			mrst_early_console_init();

			early_console_register(&early_mrst_console, keep);

		}



		if (!strncmp(buf, "hsu", 3)) {

			hsu_early_console_init();

			early_console_register(&early_hsu_console, keep);

		}



#endif

		buf++;

	}

arch/x86/kernel/early_printk_mrst.c

+88 −1
Original line number Diff line number Diff line 
/*

 * early_printk_mrst.c - spi-uart early printk for Intel Moorestown platform

 * early_printk_mrst.c - early consoles for Intel MID platforms

 *

 * Copyright (c) 2008-2010, Intel Corporation

 *
@@ -9,9 +9,19 @@ 
 * of the License.

 */



/*

 * This file implements two early consoles named mrst and hsu.

 * mrst is based on Maxim3110 spi-uart device, it exists in both

 * Moorestown and Medfield platforms, while 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/kmsg_dump.h>

#include <linux/console.h>

#include <linux/kernel.h>

#include <linux/delay.h>

#include <linux/init.h>

#include <linux/io.h>
@@ -230,3 +240,80 @@ struct console early_mrst_console = { 
	.flags =	CON_PRINTBUFFER,

	.index =	-1,

};



/*

 * Following is the early console based on Medfield HSU (High

 * Speed UART) device.

 */

#define HSU_PORT2_PADDR		0xffa28180



static void __iomem *phsu;



void hsu_early_console_init(void)

{

	u8 lcr;



	phsu = (void *)set_fixmap_offset_nocache(FIX_EARLYCON_MEM_BASE,

							HSU_PORT2_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,

};