arch: bcm281xx: Initial commit of bcm281xx architecture code

Add bcm281xx architecture support code including a clock framework and
chip reset.  Define register block base addresses for the bcm281xx
architecture and create an empty gpio header file required when
CONFIG_CMD_GPIO is set.

Signed-off-by: Darwin Rambo <drambo@broadcom.com>
Reviewed-by: Steve Rae <srae@broadcom.com>
Reviewed-by: Tim Kryger <tkryger@linaro.org>

include/bitfield.h

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2013 Broadcom Corporation.
+ *
+ * SPDX-License-Identifier:      GPL-2.0+
+ */
+
+/*
+ * Bitfield operations
+ *
+ * These are generic bitfield operations which allow manipulation of variable
+ * width bitfields within a word. One use of this would be to use data tables
+ * to determine how to reprogram fields within R/W hardware registers.
+ *
+ * Example:
+ *
+ *            old_reg_val
+ * +--------+----+---+--+-----+----------+
+ * |        |    |   |  | old |          |
+ * +--------+----+---+--+-----+----------+
+ *
+ *            new_reg_val
+ * +--------+----+---+--+-----+----------+
+ * |        |    |   |  | new |          |
+ * +--------+----+---+--+-----+----------+
+ *
+ * mask = bitfield_mask(10, 5);
+ * old = bitfield_extract(old_reg_val, 10, 5);
+ * new_reg_val = bitfield_replace(old_reg_val, 10, 5, new);
+ *
+ * The numbers 10 and 5 could for example come from data
+ * tables which describe all bitfields in all registers.
+ */
+
+#include <linux/types.h>
+
+/* Produces a mask of set bits covering a range of a uint value */
+static inline uint bitfield_mask(uint shift, uint width)
+{
+	return ((1 << width) - 1) << shift;
+}
+
+/* Extract the value of a bitfield found within a given register value */
+static inline uint bitfield_extract(uint reg_val, uint shift, uint width)
+{
+	return (reg_val & bitfield_mask(shift, width)) >> shift;
+}
+
+/*
+ * Replace the value of a bitfield found within a given register value
+ * Returns the newly modified uint value with the replaced field.
+ */
+static inline uint bitfield_replace(uint reg_val, uint shift, uint width,
+				    uint bitfield_val)
+{
+	uint mask = bitfield_mask(shift, width);
+
+	return (reg_val & ~mask) | (bitfield_val << shift);
+}