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Message-Id: <1214483429-32360-21-git-send-email-monstr@seznam.cz>
Date: Thu, 26 Jun 2008 14:29:49 +0200
From: monstr@...nam.cz
To: linux-kernel@...r.kernel.org
Cc: arnd@...db.de, linux-arch@...r.kernel.org,
stephen.neuendorffer@...inx.com, John.Linn@...inx.com,
john.williams@...alogix.com, matthew@....cx, will.newton@...il.com,
drepper@...hat.com, microblaze-uclinux@...e.uq.edu.au,
grant.likely@...retlab.ca, linuxppc-dev@...abs.org,
vapier.adi@...il.com, alan@...rguk.ukuu.org.uk, hpa@...or.com,
Michal Simek <monstr@...str.eu>
Subject: [PATCH 20/60] microblaze_v4: early_printk support
From: Michal Simek <monstr@...str.eu>
Signed-off-by: Michal Simek <monstr@...str.eu>
---
arch/microblaze/kernel/early_printk.c | 130 +++++++++++++++++++++++++++++++++
1 files changed, 130 insertions(+), 0 deletions(-)
create mode 100644 arch/microblaze/kernel/early_printk.c
diff --git a/arch/microblaze/kernel/early_printk.c b/arch/microblaze/kernel/early_printk.c
new file mode 100644
index 0000000..6da0fd9
--- /dev/null
+++ b/arch/microblaze/kernel/early_printk.c
@@ -0,0 +1,130 @@
+/*
+ * Early printk support for Microblaze.
+ *
+ * Copyright (C) 2007-2008 Michal Simek <monstr@...str.eu>
+ * Copyright (C) 2003-2006 Yasushi SHOJI <yashi@...ark-techno.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+/* FIXME Once we got some system without uart light, we need to refactor */
+
+#include <linux/console.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/tty.h>
+#include <asm/io.h>
+#include <asm/processor.h>
+#include <asm/fcntl.h>
+#include <asm/setup.h>
+
+#ifdef CONFIG_EARLY_PRINTK
+#define BASE_ADDR ((unsigned char *)CONFIG_EARLY_PRINTK_UARTLITE_ADDRESS)
+
+#define RX_FIFO BASE_ADDR
+#define TX_FIFO ((unsigned long *)(BASE_ADDR + 4))
+#define STATUS ((unsigned long *)(BASE_ADDR + 8))
+#define CONTROL ((unsigned long *)(BASE_ADDR + 12))
+
+static void early_printk_putc(char c)
+{
+ /*
+ * Limit how many times we'll spin waiting for TX FIFO status.
+ * This will prevent lockups if the base address is incorrectly
+ * set, or any other issue on the UARTLITE.
+ * This limit is pretty arbitrary, unless we are at about 10 baud
+ * we'll never timeout on a working UART.
+ */
+
+ unsigned retries = 10000;
+ while (retries-- && (ioread32(STATUS) & (1<<3)))
+ ;
+
+ /* Only attempt the iowrite if we didn't timeout */
+ if (retries)
+ iowrite32((c & 0xff), TX_FIFO);
+}
+
+static void early_printk_write(struct console *unused,
+ const char *s, unsigned n)
+{
+ while (*s && n-- > 0) {
+ early_printk_putc(*s);
+ if (*s == '\n')
+ early_printk_putc('\r');
+ s++;
+ }
+}
+
+static struct console early_serial_console = {
+ .name = "earlyser",
+ .write = early_printk_write,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+};
+
+/* Direct interface for emergencies */
+static struct console *early_console = &early_serial_console;
+static int early_console_initialized;
+
+void early_printk(const char *fmt, ...)
+{
+ char buf[512];
+ int n;
+ va_list ap;
+
+ if (early_console_initialized) {
+ va_start(ap, fmt);
+ n = vscnprintf(buf, 512, fmt, ap);
+ early_console->write(early_console, buf, n);
+ va_end(ap);
+ }
+}
+
+static int __initdata keep_early;
+
+int __init setup_early_printk(char *opt)
+{
+ char *space;
+ char buf[256];
+
+ if (early_console_initialized)
+ return 1;
+
+ strlcpy(buf, opt, sizeof(buf));
+ space = strchr(buf, ' ');
+ if (space)
+ *space = 0;
+
+ if (strstr(buf, "keep"))
+ keep_early = 1;
+
+ early_console = &early_serial_console;
+ early_console_initialized = 1;
+ register_console(early_console);
+ return 0;
+}
+#if 0
+static void __init disable_early_printk(void)
+{
+ if (!early_console_initialized || !early_console)
+ return;
+ if (!keep_early) {
+ printk(KERN_INFO "disabling early console\n");
+ unregister_console(early_console);
+ early_console_initialized = 0;
+ } else
+ printk(KERN_INFO "keeping early console\n");
+}
+#endif
+
+__setup("earlyprintk=", setup_early_printk);
+
+#else
+void early_printk(const char *fmt, ...)
+{
+}
+#endif
--
1.5.4.GIT
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