mfd: Add HI6421 PMIC Core driver

This adds driver to support HiSilicon Hi6421 PMIC. Hi6421 includes multi-
functions, such as regulators, codec, ADCs, Coulomb counter, etc.
This driver includes core APIs _only_.

Drivers for individul components, like voltage regulators, are
implemented in corresponding driver directories and files.

Registers in Hi6421 are memory mapped, so using regmap-mmio API.

Signed-off-by: Guodong Xu <guodong.xu@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

include/linux/mfd/hi6421-pmic.h

@@ -0,0 +1,41 @@
+/*
+ * Header file for device driver Hi6421 PMIC
+ *
+ * Copyright (c) <2011-2014> HiSilicon Technologies Co., Ltd.
+ *              http://www.hisilicon.com
+ * Copyright (c) <2013-2014> Linaro Ltd.
+ *              http://www.linaro.org
+ *
+ * Author: Guodong Xu <guodong.xu@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef	__HI6421_PMIC_H
+#define	__HI6421_PMIC_H
+
+/* Hi6421 registers are mapped to memory bus in 4 bytes stride */
+#define HI6421_REG_TO_BUS_ADDR(x)	(x << 2)
+
+/* Hi6421 maximum register number */
+#define HI6421_REG_MAX			0xFF
+
+/* Hi6421 OCP (over current protection) and DEB (debounce) control register */
+#define	HI6421_OCP_DEB_CTRL_REG		HI6421_REG_TO_BUS_ADDR(0x51)
+#define	HI6421_OCP_DEB_SEL_MASK		0x0C
+#define HI6421_OCP_DEB_SEL_8MS		0x00
+#define HI6421_OCP_DEB_SEL_16MS		0x04
+#define HI6421_OCP_DEB_SEL_32MS		0x08
+#define HI6421_OCP_DEB_SEL_64MS		0x0C
+#define HI6421_OCP_EN_DEBOUNCE_MASK	0x02
+#define HI6421_OCP_EN_DEBOUNCE_ENABLE	0x02
+#define HI6421_OCP_AUTO_STOP_MASK	0x01
+#define HI6421_OCP_AUTO_STOP_ENABLE	0x01
+
+struct hi6421_pmic {
+	struct regmap		*regmap;
+};
+
+#endif		/* __HI6421_PMIC_H */