@@ -7,6 +7,13 @@ if TTY
menu "Serial drivers"
depends on HAS_IOMEM
+config SERIAL_EARLYCON
+ bool
+ help
+ Support for early consoles with the earlycon parameter. This enables
+ the console before standard serial driver is probed. The console is
+ enabled when early_param is processed.
+
source "drivers/tty/serial/8250/Kconfig"
comment "Non-8250 serial port support"
@@ -5,6 +5,8 @@
obj-$(CONFIG_SERIAL_CORE) += serial_core.o
obj-$(CONFIG_SERIAL_21285) += 21285.o
+obj-$(CONFIG_SERIAL_EARLYCON) += earlycon.o
+
# These Sparc drivers have to appear before others such as 8250
# which share ttySx minor node space. Otherwise console device
# names change and other unplesantries.
new file mode 100644
@@ -0,0 +1,152 @@
+/*
+ * 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>
+
+#ifdef CONFIG_FIX_EARLYCON_MEM
+#include <asm/fixmap.h>
+#endif
+
+#include <asm/serial.h>
+
+static struct console early_con = {
+ .name = "earlycon",
+ .flags = CON_PRINTBUFFER | CON_BOOT,
+ .index = -1,
+};
+
+static struct earlycon_device early_console_dev = {
+ .con = &early_con,
+};
+
+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, ret;
+ 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;
+ ret = kstrtoul(options, 0, &addr);
+ if (ret)
+ return ret;
+ port->mapbase = addr;
+ if (mmio32)
+ port->regshift = 2;
+ } else if (!strncmp(options, "io,", 3)) {
+ port->iotype = UPIO_PORT;
+ options += 3;
+ ret = kstrtoul(options, 0, &addr);
+ if (ret)
+ return ret;
+ port->iobase = addr;
+ mmio = 0;
+ } else if (!strncmp(options, "0x", 2)) {
+ port->iotype = UPIO_MEM;
+ ret = kstrtoul(options, 0, &addr);
+ if (ret)
+ return ret;
+ port->mapbase = addr;
+ } else {
+ return -EINVAL;
+ }
+
+ port->uartclk = BASE_BAUD * 16;
+
+ options = strchr(options, ',');
+ if (options) {
+ options++;
+ ret = kstrtouint(options, 0, &device->baud);
+ if (ret)
+ return ret;
+ 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;
+}
@@ -285,6 +285,22 @@ static inline int uart_poll_timeout(struct uart_port *port)
/*
* Console helpers.
*/
+struct earlycon_device {
+ struct console *con;
+ struct uart_port port;
+ char options[16]; /* e.g., 115200n8 */
+ unsigned int baud;
+};
+int setup_earlycon(char *buf, const char *match,
+ int (*setup)(struct earlycon_device *, const char *));
+
+#define EARLYCON_DECLARE(name, func) \
+static int __init name ## _setup_earlycon(char *buf) \
+{ \
+ return setup_earlycon(buf, __stringify(name), func); \
+} \
+early_param("earlycon", name ## _setup_earlycon);
+
struct uart_port *uart_get_console(struct uart_port *ports, int nr,
struct console *c);
void uart_parse_options(char *options, int *baud, int *parity, int *bits,