Blackfin arch: Initial patch to add earlyprintk support

This allows debugging of problems which happen eary in the kernel
boot process (after bootargs are parsed, but before serial subsystem
is fully initialized)

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

Documentation/kernel-parameters.txt

@@ -35,6 +35,7 @@ parameter is applicable:
 	APIC	APIC support is enabled.
 	APM	Advanced Power Management support is enabled.
 	AX25	Appropriate AX.25 support is enabled.
+	BLACKFIN Blackfin architecture is enabled.
 	DRM	Direct Rendering Management support is enabled.
 	EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled
 	EFI	EFI Partitioning (GPT) is enabled
@@ -550,7 +551,7 @@ and is between 256 and 4096 characters. It is defined in the file
 
 	dtc3181e=	[HW,SCSI]
 
-	earlyprintk=	[X86-32,X86-64,SH]
+	earlyprintk=	[X86-32,X86-64,SH,BLACKFIN]
 			earlyprintk=vga
 			earlyprintk=serial[,ttySn[,baudrate]]
 

arch/blackfin/Kconfig

@@ -1164,6 +1164,20 @@ config DEBUG_BFIN_NO_KERN_HWTRACE
 	  Say Y here to disable hardware tracing in some known "jumpy" pieces
 	  of code so that the trace buffer will extend further back.
 
+config EARLY_PRINTK
+	bool "Early printk" 
+	default n
+	help
+	  This option enables special console drivers which allow the kernel
+	  to print messages very early in the bootup process.
+
+	  This is useful for kernel debugging when your machine crashes very
+	  early before the console code is initialized. After enabling this
+	  feature, you must add "earlyprintk=serial,uart0,57600" to the
+	  command line (bootargs). It is safe to say Y here in all cases, as
+	  all of this lives in the init section and is thrown away after the
+	  kernel boots completely.
+
 config DUAL_CORE_TEST_MODULE
 	tristate "Dual Core Test Module"
 	depends on (BF561)

arch/blackfin/kernel/Makefile

@@ -13,3 +13,4 @@ obj-$(CONFIG_MODULES)                += module.o
 obj-$(CONFIG_BFIN_DMA_5XX)           += bfin_dma_5xx.o
 obj-$(CONFIG_DUAL_CORE_TEST_MODULE)  += dualcore_test.o
 obj-$(CONFIG_KGDB)                   += kgdb.o
+obj-$(CONFIG_EARLY_PRINTK)           += early_printk.o

arch/blackfin/kernel/early_printk.c

@@ -0,0 +1,161 @@
+/*
+ * File:         arch/blackfin/kernel/early_printk.c
+ * Based on:     arch/x86_64/kernel/early_printk.c
+ * Author:       Robin Getz <rgetz@blackfin.uclinux.org
+ *
+ * Created:      14Aug2007
+ * Description:  allow a console to be used for early printk
+ *
+ * Modified:
+ *               Copyright 2004-2007 Analog Devices Inc.
+ *
+ * Bugs:         Enter bugs at http://blackfin.uclinux.org/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/serial_core.h>
+#include <linux/console.h>
+#include <linux/string.h>
+#include <asm/blackfin.h>
+#include <asm/irq_handler.h>
+#include <asm/early_printk.h>
+
+#ifdef CONFIG_SERIAL_BFIN
+extern struct console *bfin_earlyserial_init(unsigned int port,
+						unsigned int cflag);
+#endif
+
+static struct console *early_console;
+
+/* Default console
+ * Port n == ttyBFn
+ * cflags == UART output modes
+ */
+#define DEFAULT_PORT 0
+#define DEFAULT_CFLAG CS8|B57600
+
+#ifdef CONFIG_SERIAL_CORE
+/* What should get here is "0,57600" */
+static struct console * __init earlyserial_init(char *buf)
+{
+	int baud, bit;
+	char parity;
+	unsigned int serial_port = DEFAULT_PORT;
+	unsigned int cflag = DEFAULT_CFLAG;
+
+	serial_port = simple_strtoul(buf, &buf, 10);
+	buf++;
+
+	cflag = 0;
+	baud = simple_strtoul(buf, &buf, 10);
+	switch (baud) {
+	case 1200:
+		cflag |= B1200;
+		break;
+	case 2400:
+		cflag |= B2400;
+		break;
+	case 4800:
+		cflag |= B4800;
+		break;
+	case 9600:
+		cflag |= B9600;
+		break;
+	case 19200:
+		cflag |= B19200;
+		break;
+	case 38400:
+		cflag |= B38400;
+		break;
+	case 115200:
+		cflag |= B115200;
+		break;
+	default:
+		cflag |= B57600;
+	}
+
+	parity = buf[0];
+	buf++;
+	switch (parity) {
+	case 'e':
+		cflag |= PARENB;
+		break;
+	case 'o':
+		cflag |= PARODD;
+		break;
+	}
+
+	bit = simple_strtoul(buf, &buf, 10);
+	switch (bit) {
+	case 5:
+		cflag |= CS5;
+		break;
+	case 6:
+		cflag |= CS5;
+		break;
+	case 7:
+		cflag |= CS5;
+		break;
+	default:
+		cflag |= CS8;
+	}
+
+#ifdef CONFIG_SERIAL_BFIN
+	return bfin_earlyserial_init(serial_port, cflag);
+#else
+	return NULL;
+#endif
+
+}
+#endif
+
+int __init setup_early_printk(char *buf)
+{
+
+	/* Crashing in here would be really bad, so check both the var
+	   and the pointer before we start using it
+	 */
+	if (!buf)
+		return 0;
+
+	if (!*buf)
+		return 0;
+
+	if (early_console != NULL)
+		return 0;
+
+#ifdef CONFIG_SERIAL_BFIN
+	/* Check for Blackfin Serial */
+	if (!strncmp(buf, "serial,uart", 11)) {
+		buf += 11;
+		early_console = earlyserial_init(buf);
+	}
+#endif
+#ifdef CONFIG_FB
+		/* TODO: add framebuffer console support */
+#endif
+
+	if (likely(early_console)) {
+		early_console->flags |= CON_BOOT;
+
+		register_console(early_console);
+		printk(KERN_INFO "early printk enabled on %s%d\n",
+			early_console->name,
+			early_console->index);
+	}
+
+	return 0;
+}
+
+early_param("earlyprintk", setup_early_printk);

drivers/serial/bfin_5xx.c

@@ -962,30 +962,6 @@ static void __init bfin_serial_init_ports(void)
 }
 
 #ifdef CONFIG_SERIAL_BFIN_CONSOLE
-static void bfin_serial_console_putchar(struct uart_port *port, int ch)
-{
-	struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
-	while (!(UART_GET_LSR(uart) & THRE))
-		barrier();
-	UART_PUT_CHAR(uart, ch);
-	SSYNC();
-}
-
-/*
- * Interrupts are disabled on entering
- */
-static void
-bfin_serial_console_write(struct console *co, const char *s, unsigned int count)
-{
-	struct bfin_serial_port *uart = &bfin_serial_ports[co->index];
-	int flags = 0;
-
-	spin_lock_irqsave(&uart->port.lock, flags);
-	uart_console_write(&uart->port, s, count, bfin_serial_console_putchar);
-	spin_unlock_irqrestore(&uart->port.lock, flags);
-
-}
-
 /*
  * If the port was already initialised (eg, by a boot loader),
  * try to determine the current setup.
@@ -1038,19 +1014,25 @@ bfin_serial_console_get_options(struct bfin_serial_port *uart, int *baud,
 	}
 	pr_debug("%s:baud = %d, parity = %c, bits= %d\n", __FUNCTION__, *baud, *parity, *bits);
 }
+#endif
+
+#if defined(CONFIG_SERIAL_BFIN_CONSOLE) || defined(CONFIG_EARLY_PRINTK)
+static struct uart_driver bfin_serial_reg;
 
 static int __init
 bfin_serial_console_setup(struct console *co, char *options)
 {
 	struct bfin_serial_port *uart;
+# ifdef CONFIG_SERIAL_BFIN_CONSOLE
 	int baud = 57600;
 	int bits = 8;
 	int parity = 'n';
-#ifdef CONFIG_SERIAL_BFIN_CTSRTS
+#  ifdef CONFIG_SERIAL_BFIN_CTSRTS
 	int flow = 'r';
-#else
+#  else
 	int flow = 'n';
-#endif
+#  endif
+# endif
 
 	/*
 	 * Check whether an invalid uart number has been specified, and
@@ -1061,15 +1043,45 @@ bfin_serial_console_setup(struct console *co, char *options)
 		co->index = 0;
 	uart = &bfin_serial_ports[co->index];
 
+# ifdef CONFIG_SERIAL_BFIN_CONSOLE
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
 	else
 		bfin_serial_console_get_options(uart, &baud, &parity, &bits);
 
 	return uart_set_options(&uart->port, co, baud, parity, bits, flow);
+# else
+	return 0;
+# endif
+}
+#endif /* defined (CONFIG_SERIAL_BFIN_CONSOLE) ||
+				 defined (CONFIG_EARLY_PRINTK) */
+
+#ifdef CONFIG_SERIAL_BFIN_CONSOLE
+static void bfin_serial_console_putchar(struct uart_port *port, int ch)
+{
+	struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
+	while (!(UART_GET_LSR(uart) & THRE))
+		barrier();
+	UART_PUT_CHAR(uart, ch);
+	SSYNC();
+}
+
+/*
+ * Interrupts are disabled on entering
+ */
+static void
+bfin_serial_console_write(struct console *co, const char *s, unsigned int count)
+{
+	struct bfin_serial_port *uart = &bfin_serial_ports[co->index];
+	int flags = 0;
+
+	spin_lock_irqsave(&uart->port.lock, flags);
+	uart_console_write(&uart->port, s, count, bfin_serial_console_putchar);
+	spin_unlock_irqrestore(&uart->port.lock, flags);
+
 }
 
-static struct uart_driver bfin_serial_reg;
 static struct console bfin_serial_console = {
 	.name		= BFIN_SERIAL_NAME,
 	.write		= bfin_serial_console_write,
@@ -1095,7 +1107,68 @@ console_initcall(bfin_serial_rs_console_init);
 #define BFIN_SERIAL_CONSOLE	&bfin_serial_console
 #else
 #define BFIN_SERIAL_CONSOLE	NULL
+#endif /* CONFIG_SERIAL_BFIN_CONSOLE */
+
+
+#ifdef CONFIG_EARLY_PRINTK
+static __init void early_serial_putc(struct uart_port *port, int ch)
+{
+	unsigned timeout = 0xffff;
+	struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
+
+	while ((!(UART_GET_LSR(uart) & THRE)) && --timeout)
+		cpu_relax();
+	UART_PUT_CHAR(uart, ch);
+}
+
+static __init void early_serial_write(struct console *con, const char *s,
+					unsigned int n)
+{
+	struct bfin_serial_port *uart = &bfin_serial_ports[con->index];
+	unsigned int i;
+
+	for (i = 0; i < n; i++, s++) {
+		if (*s == '\n')
+			early_serial_putc(&uart->port, '\r');
+		early_serial_putc(&uart->port, *s);
+	}
+}
+
+static struct __init console bfin_early_serial_console = {
+	.name = "early_BFuart",
+	.write = early_serial_write,
+	.device = uart_console_device,
+	.flags = CON_PRINTBUFFER,
+	.setup = bfin_serial_console_setup,
+	.index = -1,
+	.data  = &bfin_serial_reg,
+};
+
+struct console __init *bfin_earlyserial_init(unsigned int port,
+						unsigned int cflag)
+{
+	struct bfin_serial_port *uart;
+	struct ktermios t;
+
+	if (port == -1 || port >= nr_ports)
+		port = 0;
+	bfin_serial_init_ports();
+	bfin_early_serial_console.index = port;
+#ifdef CONFIG_KGDB_UART
+	kgdb_entry_state = 0;
+	init_kgdb_uart();
 #endif
+	uart = &bfin_serial_ports[port];
+	t.c_cflag = cflag;
+	t.c_iflag = 0;
+	t.c_oflag = 0;
+	t.c_lflag = ICANON;
+	t.c_line = port;
+	bfin_serial_set_termios(&uart->port, &t, &t);
+	return &bfin_early_serial_console;
+}
+
+#endif /* CONFIG_SERIAL_BFIN_CONSOLE */
 
 static struct uart_driver bfin_serial_reg = {
 	.owner			= THIS_MODULE,

include/asm-blackfin/early_printk.h

@@ -0,0 +1,28 @@
+/*
+ * File:         include/asm-blackfin/early_printk.h
+ * Author:       Robin Getz <rgetz@blackfin.uclinux.org
+ *
+ * Created:      14Aug2007
+ * Description:  function prototpyes for early printk
+ *
+ * Modified:
+ *               Copyright 2004-2007 Analog Devices Inc.
+ *
+ * Bugs:         Enter bugs at http://blackfin.uclinux.org/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifdef CONFIG_EARLY_PRINTK
+extern int setup_early_printk(char *);
+#else
+#define setup_early_printk(fmt) do { } while (0)
+#endif /* CONFIG_EARLY_PRINTK */