diff options
Diffstat (limited to 'drivers/tty/serial/earlycon.c')
| -rw-r--r-- | drivers/tty/serial/earlycon.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c new file mode 100644 index 00000000000..a514ee6f540 --- /dev/null +++ b/drivers/tty/serial/earlycon.c @@ -0,0 +1,172 @@ +/* + * Copyright (C) 2014 Linaro Ltd. + * Author: Rob Herring <robh@kernel.org> + * + * Based on 8250 earlycon: + * (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. + */ +#include <linux/console.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/serial_core.h> +#include <linux/sizes.h> +#include <linux/mod_devicetable.h> + +#ifdef CONFIG_FIX_EARLYCON_MEM +#include <asm/fixmap.h> +#endif + +#include <asm/serial.h> + +static struct console early_con = { + .name = "uart", /* 8250 console switch requires this name */ + .flags = CON_PRINTBUFFER | CON_BOOT, + .index = -1, +}; + +static struct earlycon_device early_console_dev = { + .con = &early_con, +}; + +static const struct of_device_id __earlycon_of_table_sentinel + __used __section(__earlycon_of_table_end); + +static void __iomem * __init earlycon_map(unsigned long paddr, size_t size) +{ + void __iomem *base; +#ifdef CONFIG_FIX_EARLYCON_MEM + set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK); + base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE); + base += paddr & ~PAGE_MASK; +#else + base = ioremap(paddr, size); +#endif + if (!base) + pr_err("%s: Couldn't map 0x%llx\n", __func__, + (unsigned long long)paddr); + + return base; +} + +static int __init parse_options(struct earlycon_device *device, + char *options) +{ + struct uart_port *port = &device->port; + int mmio, mmio32, length; + unsigned long addr; + + if (!options) + return -ENODEV; + + mmio = !strncmp(options, "mmio,", 5); + mmio32 = !strncmp(options, "mmio32,", 7); + if (mmio || mmio32) { + port->iotype = (mmio ? UPIO_MEM : UPIO_MEM32); + options += mmio ? 5 : 7; + addr = simple_strtoul(options, NULL, 0); + port->mapbase = addr; + if (mmio32) + port->regshift = 2; + } else if (!strncmp(options, "io,", 3)) { + port->iotype = UPIO_PORT; + options += 3; + addr = simple_strtoul(options, NULL, 0); + port->iobase = addr; + mmio = 0; + } else if (!strncmp(options, "0x", 2)) { + port->iotype = UPIO_MEM; + addr = simple_strtoul(options, NULL, 0); + port->mapbase = addr; + } else { + return -EINVAL; + } + + port->uartclk = BASE_BAUD * 16; + + options = strchr(options, ','); + if (options) { + options++; + device->baud = simple_strtoul(options, NULL, 0); + length = min(strcspn(options, " ") + 1, + (size_t)(sizeof(device->options))); + strlcpy(device->options, options, length); + } + + if (mmio || mmio32) + pr_info("Early serial console at MMIO%s 0x%llx (options '%s')\n", + mmio32 ? "32" : "", + (unsigned long long)port->mapbase, + device->options); + else + pr_info("Early serial console at I/O port 0x%lx (options '%s')\n", + port->iobase, + device->options); + + return 0; +} + +int __init setup_earlycon(char *buf, const char *match, + int (*setup)(struct earlycon_device *, const char *)) +{ + int err; + size_t len; + struct uart_port *port = &early_console_dev.port; + + if (!buf || !match || !setup) + return 0; + + len = strlen(match); + if (strncmp(buf, match, len)) + return 0; + if (buf[len] && (buf[len] != ',')) + return 0; + + buf += len + 1; + + err = parse_options(&early_console_dev, buf); + /* On parsing error, pass the options buf to the setup function */ + if (!err) + buf = NULL; + + if (port->mapbase) + port->membase = earlycon_map(port->mapbase, 64); + + early_console_dev.con->data = &early_console_dev; + err = setup(&early_console_dev, buf); + if (err < 0) + return err; + if (!early_console_dev.con->write) + return -ENODEV; + + register_console(early_console_dev.con); + return 0; +} + +int __init of_setup_earlycon(unsigned long addr, + int (*setup)(struct earlycon_device *, const char *)) +{ + int err; + struct uart_port *port = &early_console_dev.port; + + port->iotype = UPIO_MEM; + port->mapbase = addr; + port->uartclk = BASE_BAUD * 16; + port->membase = earlycon_map(addr, SZ_4K); + + early_console_dev.con->data = &early_console_dev; + err = setup(&early_console_dev, NULL); + if (err < 0) + return err; + if (!early_console_dev.con->write) + return -ENODEV; + + + register_console(early_console_dev.con); + return 0; +} |