Add initial set of I2C functions.

Thomas Otto has tested the code by successfully talking to a temperature
sensor from ST in master tranciever mode.

Thanks Thomas Otto <tommi@viadmin.org> for the patch!

include/libopenstm32/i2c.h

@@ -308,4 +308,25 @@
  * TRISE[5:0]: Maximum rise time in Fast/Standard mode (master mode)
  */
 
+/* --- I2C const definitions ----------------------------------------------- */
+
+#define I2C_WRITE			0
+#define I2C_READ			1
+
+/* --- I2C funtion prototypes----------------------------------------------- */
+
+void i2c_peripheral_enable(u32 i2c);
+void i2c_peripheral_disable(u32 i2c);
+void i2c_send_start(u32 i2c);
+void i2c_send_stop(u32 i2c);
+void i2c_set_own_7bit_slave_address(u32 i2c, u8 slave);
+void i2c_set_own_10bit_slave_address(u32 i2c, u16 slave);
+void i2c_set_fast_mode(u32 i2c);
+void i2c_set_standard_mode(u32 i2c);
+void i2c_set_clock_frequency(u32 i2c, u8 freq);
+void i2c_set_ccr(u32 i2c, u16 freq);
+void i2c_set_trise(u32 i2c, u16 trise);
+void i2c_send_7bit_address(u32 i2c, u8 slave, u8 readwrite);
+void i2c_send_data(u32 i2c, u8 data);
+
 #endif

lib/Makefile

@@ -27,7 +27,8 @@ CFLAGS		= -Os -g -Wall -Wextra -I../include -fno-common \
 		  -mcpu=cortex-m3 -mthumb -Wstrict-prototypes
 # ARFLAGS	= rcsv
 ARFLAGS		= rcs
-OBJS		= vector.o rcc.o gpio.o usart.o adc.o spi.o flash.o nvic.o rtc.o
+OBJS		= vector.o rcc.o gpio.o usart.o adc.o spi.o flash.o nvic.o \
+		  rtc.o i2c.o
 
 # Be silent per default, but 'make V=1' will show all compiler calls.
 ifneq ($(V),1)

lib/i2c.c

@@ -0,0 +1,93 @@
+/*
+ * This file is part of the libopenstm32 project.
+ *
+ * Copyright (C) 2010 Thomas Otto <tommi@viadmin.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 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/>.
+ */
+
+#include <libopenstm32.h>
+
+void i2c_peripheral_enable(u32 i2c)
+{
+	I2C_CR1(i2c) |= I2C_CR1_PE;
+}
+
+void i2c_peripheral_disable(u32 i2c)
+{
+	I2C_CR1(i2c) &= ~I2C_CR1_PE;
+}
+
+void i2c_send_start(u32 i2c)
+{
+	I2C_CR1(i2c) |= I2C_CR1_START;
+}
+
+void i2c_send_stop(u32 i2c)
+{
+	I2C_CR1(i2c) |= I2C_CR1_STOP;
+}
+
+void i2c_set_own_7bit_slave_address(u32 i2c, u8 slave)
+{
+	I2C_OAR1(i2c) = (u16)(slave << 1);
+	I2C_OAR1(i2c) &= ~I2C_OAR1_ADDMODE;
+	I2C_OAR1(i2c) |= (1 << 14); /* Datasheet: always keep 1 by software. */
+}
+
+void i2c_set_own_10bit_slave_address(u32 i2c, u16 slave)
+{
+	I2C_OAR1(i2c) = (u16)(I2C_OAR1_ADDMODE | slave);
+}
+
+void i2c_set_fast_mode(u32 i2c)
+{
+	I2C_CCR(i2c) |= I2C_CCR_FS;
+}
+
+void i2c_set_standard_mode(u32 i2c)
+{
+	I2C_CCR(i2c) &= ~I2C_CCR_FS;
+}
+
+void i2c_set_clock_frequency(u32 i2c, u8 freq)
+{
+	u16 reg16;
+	reg16 = I2C_CR2(i2c) & 0xffc0; /* Clear bits [5:0]. */
+	reg16 |= freq;
+	I2C_CR2(i2c) = reg16;
+}
+
+void i2c_set_ccr(u32 i2c, u16 freq)
+{
+	u16 reg16;
+	reg16 = I2C_CCR(i2c) & 0xf000; /* Clear bits [11:0]. */
+	reg16 |= freq;
+	I2C_CCR(i2c) = reg16;
+}
+
+void i2c_set_trise(u32 i2c, u16 trise)
+{
+	I2C_TRISE(i2c) = trise;
+}
+
+void i2c_send_7bit_address(u32 i2c, u8 slave, u8 readwrite)
+{
+	I2C_DR(i2c) = (u8)((slave << 1) | readwrite);
+}
+
+void i2c_send_data(u32 i2c, u8 data)
+{
+	I2C_DR(i2c) = data;
+}