diff options
Diffstat (limited to 'drivers/serial/mxc_uart_early.c')
| -rw-r--r-- | drivers/serial/mxc_uart_early.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/drivers/serial/mxc_uart_early.c b/drivers/serial/mxc_uart_early.c new file mode 100644 index 000000000000..f4b6493a9a64 --- /dev/null +++ b/drivers/serial/mxc_uart_early.c @@ -0,0 +1,184 @@ +/* + * 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); |