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author | Ingo Molnar <mingo@elte.hu> | 2012-02-07 08:59:29 (GMT) |
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committer | Ingo Molnar <mingo@elte.hu> | 2012-02-07 08:59:29 (GMT) |
commit | 290436c9c61ac983b1bd425da67242a4357c7701 (patch) | |
tree | 35e1f189b62eb50515600ad607d7fb57fc547870 /drivers/tty/serial/8250/8250_early.c | |
parent | 623ec991ce0e8cd5791bad656c162fa837635907 (diff) | |
parent | 62aa2b537c6f5957afd98e29f96897419ed5ebab (diff) | |
download | linux-fsl-qoriq-290436c9c61ac983b1bd425da67242a4357c7701.tar.xz |
Merge tag 'v3.3-rc2' into perf/core
Linux 3.3-rc2
Pick up the latest fixes.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'drivers/tty/serial/8250/8250_early.c')
-rw-r--r-- | drivers/tty/serial/8250/8250_early.c | 287 |
1 files changed, 287 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c new file mode 100644 index 0000000..eaafb98 --- /dev/null +++ b/drivers/tty/serial/8250/8250_early.c @@ -0,0 +1,287 @@ +/* + * Early serial console for 8250/16550 devices + * + * (c) Copyright 2004 Hewlett-Packard Development Company, L.P. + * Bjorn Helgaas <bjorn.helgaas@hp.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * Based on the 8250.c serial driver, Copyright (C) 2001 Russell King, + * and on early_printk.c by Andi Kleen. + * + * 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., "ttyS0", + * we locate the device directly by its MMIO or I/O port address. + * + * The user can specify the device directly, e.g., + * earlycon=uart8250,io,0x3f8,9600n8 + * earlycon=uart8250,mmio,0xff5e0000,115200n8 + * earlycon=uart8250,mmio32,0xff5e0000,115200n8 + * or + * console=uart8250,io,0x3f8,9600n8 + * console=uart8250,mmio,0xff5e0000,115200n8 + * console=uart8250,mmio32,0xff5e0000,115200n8 + */ + +#include <linux/tty.h> +#include <linux/init.h> +#include <linux/console.h> +#include <linux/serial_core.h> +#include <linux/serial_reg.h> +#include <linux/serial.h> +#include <linux/serial_8250.h> +#include <asm/io.h> +#include <asm/serial.h> +#ifdef CONFIG_FIX_EARLYCON_MEM +#include <asm/pgtable.h> +#include <asm/fixmap.h> +#endif + +struct early_serial8250_device { + struct uart_port port; + char options[16]; /* e.g., 115200n8 */ + unsigned int baud; +}; + +static struct early_serial8250_device early_device; + +static unsigned int __init serial_in(struct uart_port *port, int offset) +{ + switch (port->iotype) { + case UPIO_MEM: + return readb(port->membase + offset); + case UPIO_MEM32: + return readl(port->membase + (offset << 2)); + case UPIO_PORT: + return inb(port->iobase + offset); + default: + return 0; + } +} + +static void __init serial_out(struct uart_port *port, int offset, int value) +{ + switch (port->iotype) { + case UPIO_MEM: + writeb(value, port->membase + offset); + break; + case UPIO_MEM32: + writel(value, port->membase + (offset << 2)); + break; + case UPIO_PORT: + outb(value, port->iobase + offset); + break; + } +} + +#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE) + +static void __init wait_for_xmitr(struct uart_port *port) +{ + unsigned int status; + + for (;;) { + status = serial_in(port, UART_LSR); + if ((status & BOTH_EMPTY) == BOTH_EMPTY) + return; + cpu_relax(); + } +} + +static void __init serial_putc(struct uart_port *port, int c) +{ + wait_for_xmitr(port); + serial_out(port, UART_TX, c); +} + +static void __init early_serial8250_write(struct console *console, + const char *s, unsigned int count) +{ + struct uart_port *port = &early_device.port; + unsigned int ier; + + /* Save the IER and disable interrupts */ + ier = serial_in(port, UART_IER); + serial_out(port, UART_IER, 0); + + uart_console_write(port, s, count, serial_putc); + + /* Wait for transmitter to become empty and restore the IER */ + wait_for_xmitr(port); + serial_out(port, UART_IER, ier); +} + +static unsigned int __init probe_baud(struct uart_port *port) +{ + unsigned char lcr, dll, dlm; + unsigned int quot; + + lcr = serial_in(port, UART_LCR); + serial_out(port, UART_LCR, lcr | UART_LCR_DLAB); + dll = serial_in(port, UART_DLL); + dlm = serial_in(port, UART_DLM); + serial_out(port, UART_LCR, lcr); + + quot = (dlm << 8) | dll; + return (port->uartclk / 16) / quot; +} + +static void __init init_port(struct early_serial8250_device *device) +{ + struct uart_port *port = &device->port; + unsigned int divisor; + unsigned char c; + + serial_out(port, UART_LCR, 0x3); /* 8n1 */ + serial_out(port, UART_IER, 0); /* no interrupt */ + serial_out(port, UART_FCR, 0); /* no fifo */ + serial_out(port, UART_MCR, 0x3); /* DTR + RTS */ + + divisor = port->uartclk / (16 * device->baud); + c = serial_in(port, UART_LCR); + serial_out(port, UART_LCR, c | UART_LCR_DLAB); + serial_out(port, UART_DLL, divisor & 0xff); + serial_out(port, UART_DLM, (divisor >> 8) & 0xff); + serial_out(port, UART_LCR, c & ~UART_LCR_DLAB); +} + +static int __init parse_options(struct early_serial8250_device *device, + char *options) +{ + struct uart_port *port = &device->port; + int mmio, mmio32, length; + + if (!options) + return -ENODEV; + + port->uartclk = BASE_BAUD * 16; + + mmio = !strncmp(options, "mmio,", 5); + mmio32 = !strncmp(options, "mmio32,", 7); + if (mmio || mmio32) { + port->iotype = (mmio ? UPIO_MEM : UPIO_MEM32); + port->mapbase = simple_strtoul(options + (mmio ? 5 : 7), + &options, 0); + if (mmio32) + port->regshift = 2; +#ifdef CONFIG_FIX_EARLYCON_MEM + set_fixmap_nocache(FIX_EARLYCON_MEM_BASE, + port->mapbase & PAGE_MASK); + port->membase = + (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE); + port->membase += port->mapbase & ~PAGE_MASK; +#else + port->membase = ioremap_nocache(port->mapbase, 64); + if (!port->membase) { + printk(KERN_ERR "%s: Couldn't ioremap 0x%llx\n", + __func__, + (unsigned long long) port->mapbase); + return -ENOMEM; + } +#endif + } else if (!strncmp(options, "io,", 3)) { + port->iotype = UPIO_PORT; + port->iobase = simple_strtoul(options + 3, &options, 0); + mmio = 0; + } else + return -EINVAL; + + options = strchr(options, ','); + if (options) { + options++; + device->baud = simple_strtoul(options, NULL, 0); + length = min(strcspn(options, " "), sizeof(device->options)); + strncpy(device->options, options, length); + } else { + device->baud = probe_baud(port); + snprintf(device->options, sizeof(device->options), "%u", + device->baud); + } + + if (mmio || mmio32) + printk(KERN_INFO + "Early serial console at MMIO%s 0x%llx (options '%s')\n", + mmio32 ? "32" : "", + (unsigned long long)port->mapbase, + device->options); + else + printk(KERN_INFO + "Early serial console at I/O port 0x%lx (options '%s')\n", + port->iobase, + device->options); + + return 0; +} + +static struct console early_serial8250_console __initdata = { + .name = "uart", + .write = early_serial8250_write, + .flags = CON_PRINTBUFFER | CON_BOOT, + .index = -1, +}; + +static int __init early_serial8250_setup(char *options) +{ + struct early_serial8250_device *device = &early_device; + int err; + + if (device->port.membase || device->port.iobase) + return 0; + + err = parse_options(device, options); + if (err < 0) + return err; + + init_port(device); + return 0; +} + +int __init setup_early_serial8250_console(char *cmdline) +{ + char *options; + int err; + + options = strstr(cmdline, "uart8250,"); + if (!options) { + options = strstr(cmdline, "uart,"); + if (!options) + return 0; + } + + options = strchr(cmdline, ',') + 1; + err = early_serial8250_setup(options); + if (err < 0) + return err; + + register_console(&early_serial8250_console); + + return 0; +} + +int serial8250_find_port_for_earlycon(void) +{ + struct early_serial8250_device *device = &early_device; + struct uart_port *port = &device->port; + int line; + int ret; + + if (!device->port.membase && !device->port.iobase) + return -ENODEV; + + line = serial8250_find_port(port); + if (line < 0) + return -ENODEV; + + ret = update_console_cmdline("uart", 8250, + "ttyS", line, device->options); + if (ret < 0) + ret = update_console_cmdline("uart", 0, + "ttyS", line, device->options); + + return ret; +} + +early_param("earlycon", setup_early_serial8250_console); |