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