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authorMichal Simek <monstr@monstr.eu>2009-03-27 14:25:22 +0100
committerMichal Simek <monstr@monstr.eu>2009-03-27 14:25:22 +0100
commit89272a51b322aa14332d58896b9d377ea9b4e551 (patch)
tree800e6ca040bb16062b4600e5bdfa765e2765089a /arch/microblaze/kernel
parentf11e044b449c0534cd2de3465f68925f68190866 (diff)
microblaze_v8: early_printk support
Reviewed-by: Ingo Molnar <mingo@elte.hu> Acked-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com> Acked-by: John Linn <john.linn@xilinx.com> Acked-by: John Williams <john.williams@petalogix.com> Signed-off-by: Michal Simek <monstr@monstr.eu>
Diffstat (limited to 'arch/microblaze/kernel')
-rw-r--r--arch/microblaze/kernel/early_printk.c107
1 files changed, 107 insertions, 0 deletions
diff --git a/arch/microblaze/kernel/early_printk.c b/arch/microblaze/kernel/early_printk.c
new file mode 100644
index 00000000000..62cc78993f4
--- /dev/null
+++ b/arch/microblaze/kernel/early_printk.c
@@ -0,0 +1,107 @@
+/*
+ * Early printk support for Microblaze.
+ *
+ * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2007-2009 PetaLogix
+ * Copyright (C) 2003-2006 Yasushi SHOJI <yashi@atmark-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.
+ */
+
+#include <linux/console.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/tty.h>
+#include <linux/io.h>
+#include <asm/processor.h>
+#include <linux/fcntl.h>
+#include <asm/setup.h>
+#include <asm/prom.h>
+
+static u32 early_console_initialized;
+static u32 base_addr;
+
+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;
+ /* read status bit - 0x8 offset */
+ while (retries-- && (in_be32(base_addr + 8) & (1 << 3)))
+ ;
+
+ /* Only attempt the iowrite if we didn't timeout */
+ /* write to TX_FIFO - 0x4 offset */
+ if (retries)
+ out_be32(base_addr + 4, c & 0xff);
+}
+
+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,
+};
+
+static struct console *early_console = &early_serial_console;
+
+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);
+ }
+}
+
+int __init setup_early_printk(char *opt)
+{
+ if (early_console_initialized)
+ return 1;
+
+ base_addr = early_uartlite_console();
+ if (base_addr) {
+ early_console_initialized = 1;
+ early_printk("early_printk_console is enabled at 0x%08x\n",
+ base_addr);
+
+ /* register_console(early_console); */
+
+ return 0;
+ } else
+ return 1;
+}
+
+void __init disable_early_printk(void)
+{
+ if (!early_console_initialized || !early_console)
+ return;
+ printk(KERN_WARNING "disabling early console\n");
+ unregister_console(early_console);
+ early_console_initialized = 0;
+}