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authorRob Herring <robh@kernel.org>2014-04-18 17:19:55 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-04-24 16:32:27 -0700
commit9aac5887595b765b6f64b2af08b785e82e095b57 (patch)
tree9c3cfe69823dbd0d79f8cf9f757e4fe4589c8711 /drivers/tty/serial
parentd20642f0a32575605f152a1cb7753bdfca5fc94b (diff)
tty/serial: add generic serial earlycon
This introduces generic earlycon infrastructure for serial devices based on the 8250 earlycon. This allows for supporting earlycon option with other serial devices. The earlycon output is enabled at the time early_params are processed. Only architectures that have fixmap support or have functional ioremap when early_params are processed are supported. This is the same restriction that the 8250 driver had. Signed-off-by: Rob Herring <robh@kernel.org> Cc: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial')
-rw-r--r--drivers/tty/serial/Kconfig7
-rw-r--r--drivers/tty/serial/Makefile2
-rw-r--r--drivers/tty/serial/earlycon.c152
3 files changed, 161 insertions, 0 deletions
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 30530e47cdf0..9fb6028ad900 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -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"
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 5f2a3f493ab9..28048178f308 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -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.
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
new file mode 100644
index 000000000000..73bf1e21aae0
--- /dev/null
+++ b/drivers/tty/serial/earlycon.c
@@ -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;
+}