sun6i: Add basic axp221 driver

The A31 uses the AXP221 pmic for various voltages.

Signed-off-by: Oliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
--
Changes in v2:
-Rebase
Changes in v3:
-Add support for all dldo and aldo-s
-Add Kconfig option to select building AXP221 and to select voltage of
 dldo and aldo-s
Changes in v4:
-Add axp221_setbits helper function
-Use symbolic names for enabled bits in CTRL1 - CTRL3 registers
diff --git a/include/axp221.h b/include/axp221.h
new file mode 100644
index 0000000..e3b4409
--- /dev/null
+++ b/include/axp221.h
@@ -0,0 +1,50 @@
+/*
+ * (C) Copyright 2013 Oliver Schinagl <oliver@schinagl.nl>
+ *
+ * X-Powers AXP221 Power Management IC driver
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#define AXP221_CHIP_ADDR 0x68
+#define AXP221_CTRL_ADDR 0x3e
+#define AXP221_INIT_DATA 0x3e
+
+#define AXP221_CHIP_ID		0x03
+#define AXP221_OUTPUT_CTRL1	0x10
+#define AXP221_OUTPUT_CTRL1_ALDO1_EN	(1 << 6)
+#define AXP221_OUTPUT_CTRL1_ALDO2_EN	(1 << 7)
+#define AXP221_OUTPUT_CTRL2	0x12
+#define AXP221_OUTPUT_CTRL2_DLDO1_EN	(1 << 3)
+#define AXP221_OUTPUT_CTRL2_DLDO2_EN	(1 << 4)
+#define AXP221_OUTPUT_CTRL2_DLDO3_EN	(1 << 5)
+#define AXP221_OUTPUT_CTRL2_DLDO4_EN	(1 << 6)
+#define AXP221_OUTPUT_CTRL2_DCDC1_EN	(1 << 7)
+#define AXP221_OUTPUT_CTRL3	0x13
+#define AXP221_OUTPUT_CTRL3_ALDO3_EN	(1 << 7)
+#define AXP221_DLDO1_CTRL	0x15
+#define AXP221_DLDO2_CTRL	0x16
+#define AXP221_DLDO3_CTRL	0x17
+#define AXP221_DLDO4_CTRL	0x18
+#define AXP221_DCDC1_CTRL	0x21
+#define AXP221_DCDC2_CTRL	0x22
+#define AXP221_DCDC3_CTRL	0x23
+#define AXP221_DCDC4_CTRL	0x24
+#define AXP221_DCDC5_CTRL	0x25
+#define AXP221_ALDO1_CTRL	0x28
+#define AXP221_ALDO2_CTRL	0x28
+#define AXP221_ALDO3_CTRL	0x2a
+
+int axp221_set_dcdc1(unsigned int mvolt);
+int axp221_set_dcdc2(unsigned int mvolt);
+int axp221_set_dcdc3(unsigned int mvolt);
+int axp221_set_dcdc4(unsigned int mvolt);
+int axp221_set_dcdc5(unsigned int mvolt);
+int axp221_set_dldo1(unsigned int mvolt);
+int axp221_set_dldo2(unsigned int mvolt);
+int axp221_set_dldo3(unsigned int mvolt);
+int axp221_set_dldo4(unsigned int mvolt);
+int axp221_set_aldo1(unsigned int mvolt);
+int axp221_set_aldo2(unsigned int mvolt);
+int axp221_set_aldo3(unsigned int mvolt);
+int axp221_init(void);