allwinner: add I2C glue driver

Allwinner 64-bit SoCs all use the Mentor Graphics MI2CV I2C controller
core, with inverted clear quirk.

Add a glue driver for this.
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>

drivers/allwinner/sunxi_i2c.c

+/*
+ * Copyright (C) 2018 Icenowy Zheng <icenowy@aosc.io>
+ *
+ * SPDX-License-Identifier:     BSD-3-Clause
+ * https://spdx.org/licenses
+ */
+
+/* This driver provides I2C support for Allwinner sunXi SoCs */
+
+#include <mmio.h>
+
+#define CONFIG_SYS_TCLK			24000000
+#define CONFIG_SYS_I2C_SPEED		100000
+#define CONFIG_SYS_I2C_SLAVE		0
+
+#define I2C_INTERRUPT_CLEAR_INVERTED
+
+struct  mentor_i2c_regs {
+	uint32_t slave_address;
+	uint32_t xtnd_slave_addr;
+	uint32_t data;
+	uint32_t control;
+	uint32_t status;
+	uint32_t baudrate;
+	uint32_t soft_reset;
+};
+
+#include "../mentor/i2c/mi2cv.c"

maintainers.rst

@@ -24,6 +24,7 @@ Allwinner ARMv8 platform port
 :G: `smaeul`_
 :F: docs/plat/allwinner.rst
 :F: plat/allwinner/
+:F: drivers/allwinner/
 
 Armv7-A architecture port
 -------------------------