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/*
* Copyright (C) 2004-2010 Freescale Semiconductor, Inc. All Rights Reserved.
*/
/*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*/
/*!
* @file drivers/serial/mxc_uart_early.c
*
* @brief Driver for the Freescale Semiconductor MXC serial ports based on
* drivers/char/8250_early.c, Copyright 2004 Hewlett-Packard Development Company,
* L.P. by Bjorn Helgaasby.
*
* Early serial console for MXC UARTS.
*
* This is for use before the serial driver has initialized, in
* particular, before the UARTs have been discovered and named.
* Instead of specifying the console device as, e.g., "ttymxc0",
* we locate the device directly by its MMIO or I/O port address.
*
* The user can specify the device directly, e.g.,
* console=mxcuart,0x43f90000,115200n8
* or platform code can call early_uart_console_init() to set
* the early UART device.
*
* After the normal serial driver starts, we try to locate the
* matching ttymxc device and start a console there.
*/
/*
* Include Files
*/
#include <linux/tty.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/console.h>
#include <linux/serial_core.h>
#include <linux/serial_reg.h>
#include <linux/clk.h>
#include <mach/mxc_uart.h>
struct mxc_early_uart_device {
struct uart_port port;
char options[16]; /* e.g., 115200n8 */
unsigned int baud;
struct clk *clk;
};
static struct mxc_early_uart_device mxc_early_device __initdata;
/*
* Write out a character once the UART is ready
*/
static void __init mxcuart_console_write_char(struct uart_port *port, int ch)
{
unsigned int status;
do {
status = readl(port->membase + MXC_UARTUSR2);
} while ((status & MXC_UARTUSR2_TXFE) == 0);
writel(ch, port->membase + MXC_UARTUTXD);
}
/*!
* This function is called to write the console messages through the UART port.
*
* @param co the console structure
* @param s the log message to be written to the UART
* @param count length of the message
*/
void __init early_mxcuart_console_write(struct console *co, const char *s,
u_int count)
{
struct uart_port *port = &mxc_early_device.port;
volatile unsigned int status, oldcr1, oldcr2, oldcr3, cr2, cr3;
/*
* First save the control registers and then disable the interrupts
*/
oldcr1 = readl(port->membase + MXC_UARTUCR1);
oldcr2 = readl(port->membase + MXC_UARTUCR2);
oldcr3 = readl(port->membase + MXC_UARTUCR3);
cr2 =
oldcr2 & ~(MXC_UARTUCR2_ATEN | MXC_UARTUCR2_RTSEN |
MXC_UARTUCR2_ESCI);
cr3 =
oldcr3 & ~(MXC_UARTUCR3_DCD | MXC_UARTUCR3_RI |
MXC_UARTUCR3_DTRDEN);
writel(MXC_UARTUCR1_UARTEN, port->membase + MXC_UARTUCR1);
writel(cr2, port->membase + MXC_UARTUCR2);
writel(cr3, port->membase + MXC_UARTUCR3);
/* Transmit string */
uart_console_write(port, s, count, mxcuart_console_write_char);
/*
* Finally, wait for the transmitter to become empty
*/
do {
status = readl(port->membase + MXC_UARTUSR2);
} while (!(status & MXC_UARTUSR2_TXDC));
/*
* Restore the control registers
*/
writel(oldcr1, port->membase + MXC_UARTUCR1);
writel(oldcr2, port->membase + MXC_UARTUCR2);
writel(oldcr3, port->membase + MXC_UARTUCR3);
}
static unsigned int __init probe_baud(struct uart_port *port)
{
/* FIXME Return Default Baud Rate */
return 115200;
}
static int __init mxc_early_uart_setup(struct console *console, char *options)
{
struct mxc_early_uart_device *device = &mxc_early_device;
struct uart_port *port = &device->port;
int length;
if (device->port.membase || device->port.iobase)
return -ENODEV;
/* Enable Early MXC UART Clock */
clk_enable(device->clk);
port->uartclk = 5600000;
port->iotype = UPIO_MEM;
port->membase = ioremap(port->mapbase, SZ_4K);
if (options) {
device->baud = simple_strtoul(options, NULL, 0);
length = min(strlen(options), sizeof(device->options));
strncpy(device->options, options, length);
} else {
device->baud = probe_baud(port);
snprintf(device->options, sizeof(device->options), "%u",
device->baud);
}
printk(KERN_INFO
"MXC_Early serial console at MMIO 0x%x (options '%s')\n",
port->mapbase, device->options);
return 0;
}
static struct console mxc_early_uart_console __initdata = {
.name = "ttymxc",
.write = early_mxcuart_console_write,
.setup = mxc_early_uart_setup,
.flags = CON_PRINTBUFFER | CON_BOOT,
.index = -1,
};
int __init mxc_early_serial_console_init(unsigned long base, struct clk *clk)
{
mxc_early_device.clk = clk;
mxc_early_device.port.mapbase = base;
register_console(&mxc_early_uart_console);
return 0;
}
int __init mxc_early_uart_console_disable(void)
{
struct mxc_early_uart_device *device = &mxc_early_device;
struct uart_port *port = &device->port;
if (mxc_early_uart_console.index >= 0) {
iounmap(port->membase);
clk_disable(device->clk);
clk_put(device->clk);
}
return 0;
}
late_initcall(mxc_early_uart_console_disable);
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