ARM: Add generic fiq serial debugger

Change-Id: Ibb536c88f0dbaf4766d0599296907e35e42cbfd6
Signed-off-by: Iliyan Malchev <malchev@google.com>
Signed-off-by: Arve Hjønnevåg <arve@android.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/arch/arm/common/fiq_debugger_ringbuf.h b/arch/arm/common/fiq_debugger_ringbuf.h
new file mode 100644
index 00000000000..2649b558108
--- /dev/null
+++ b/arch/arm/common/fiq_debugger_ringbuf.h
@@ -0,0 +1,94 @@
+/*
+ * arch/arm/common/fiq_debugger_ringbuf.c
+ *
+ * simple lockless ringbuffer
+ *
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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/slab.h>
+
+struct fiq_debugger_ringbuf {
+	int len;
+	int head;
+	int tail;
+	u8 buf[];
+};
+
+
+static inline struct fiq_debugger_ringbuf *fiq_debugger_ringbuf_alloc(int len)
+{
+	struct fiq_debugger_ringbuf *rbuf;
+
+	rbuf = kzalloc(sizeof(*rbuf) + len, GFP_KERNEL);
+	if (rbuf == NULL)
+		return NULL;
+
+	rbuf->len = len;
+	rbuf->head = 0;
+	rbuf->tail = 0;
+	smp_mb();
+
+	return rbuf;
+}
+
+static inline void fiq_debugger_ringbuf_free(struct fiq_debugger_ringbuf *rbuf)
+{
+	kfree(rbuf);
+}
+
+static inline int fiq_debugger_ringbuf_level(struct fiq_debugger_ringbuf *rbuf)
+{
+	int level = rbuf->head - rbuf->tail;
+
+	if (level < 0)
+		level = rbuf->len + level;
+
+	return level;
+}
+
+static inline int fiq_debugger_ringbuf_room(struct fiq_debugger_ringbuf *rbuf)
+{
+	return rbuf->len - fiq_debugger_ringbuf_level(rbuf) - 1;
+}
+
+static inline u8
+fiq_debugger_ringbuf_peek(struct fiq_debugger_ringbuf *rbuf, int i)
+{
+	return rbuf->buf[(rbuf->tail + i) % rbuf->len];
+}
+
+static inline int
+fiq_debugger_ringbuf_consume(struct fiq_debugger_ringbuf *rbuf, int count)
+{
+	count = min(count, fiq_debugger_ringbuf_level(rbuf));
+
+	rbuf->tail = (rbuf->tail + count) % rbuf->len;
+	smp_mb();
+
+	return count;
+}
+
+static inline int
+fiq_debugger_ringbuf_push(struct fiq_debugger_ringbuf *rbuf, u8 datum)
+{
+	if (fiq_debugger_ringbuf_room(rbuf) == 0)
+		return 0;
+
+	rbuf->buf[rbuf->head] = datum;
+	smp_mb();
+	rbuf->head = (rbuf->head + 1) % rbuf->len;
+	smp_mb();
+
+	return 1;
+}