Rgb matrix arm (#3648)

* Addition of I2C master driver for STM32, Generalization of ISSI3731 driver

- Addition of an i2c_master driver for STM32 to replicate expectations of AVR driver.
- Moved ISSI3731 driver one level up to make it accesible by both architectures.
- Renamed ISSI3731 functions to a more general name for preparation of other ISSI drivers.
- Added compiler directives where necessary to differenciate each architecture.

* converted tabs to spaces

drivers/arm/i2c_master.h

@@ -0,0 +1,39 @@
+/* Copyright 2018 Jack Humbert
+ * Copyright 2018 Yiancar
+ *
+ * This program is free sofare: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Sofare Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* This library follows the convention of the AVR i2c_master library.
+ * As a result addresses are expected to be already shifted (addr << 1).
+ * I2CD1 is the default driver which corresponds to pins B6 and B7. This
+ * can be changed.
+ * Please ensure that HAL_USE_I2C is TRUE in the halconf.h file and that
+ * STM32_I2C_USE_I2C1 is TRUE in the mcuconf.h file.
+ */
+
+#include "ch.h"
+#include <hal.h>
+
+#ifndef I2C_DRIVER
+  #define I2C_DRIVER I2CD1
+#endif
+
+void i2c_init(void);
+uint8_t i2c_start(uint8_t address);
+uint8_t i2c_transmit(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout);
+uint8_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout);
+uint8_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
+uint8_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
+void i2c_stop(void);