aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorRob Herring <robh@kernel.org>2014-04-18 17:19:55 -0500
committerAlex Shi <alex.shi@linaro.org>2014-06-06 17:06:48 +0800
commit9d7451bf0207967c5a65fbd02b13822a52c0512e (patch)
tree81bc2e386573c20e6fde1950a38129c9ace08fc3
parent455c6fdbd219161bd09b1165f11699d6d73de11c (diff)
downloadlinux-linaro-stable-9d7451bf0207967c5a65fbd02b13822a52c0512e.tar.gz
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> (cherry picked from commit 9aac5887595b765b6f64b2af08b785e82e095b57) Signed-off-by: Mark Brown <broonie@linaro.org> (cherry picked from commit b523950dbf9b2cc73f66145bd6f0c00b21a73a90) Signed-off-by: Alex Shi <alex.shi@linaro.org>
-rw-r--r--drivers/tty/serial/Kconfig7
-rw-r--r--drivers/tty/serial/Makefile2
-rw-r--r--drivers/tty/serial/earlycon.c152
-rw-r--r--include/linux/serial_core.h16
4 files changed, 177 insertions, 0 deletions
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index a3815eaed421..108bd797ab44 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 3680854fef41..8af1415a6366 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;
+}
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index f729be981da0..7a15b5b24c0b 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -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,