Some progress on i2c control.

i2c.c

@@ -0,0 +1,104 @@
+
+#include "i2c.h"
+
+#define I2CBASE  0xE001C000
+
+#define I2CONSET 0x00
+#define I2STAT   0x04
+#define I2DAT    0x08
+#define I2ADR    0x0c
+#define I2SCLH   0x10
+#define I2SCLL   0x14
+#define I2CONCLR 0x18
+
+#define IREG(x) (((volatile unsigned char *)I2CBASE)[x])
+#define IWREG(x) (((volatile unsigned int *)I2CBASE)[(x)/sizeof(unsigned int)])
+
+#define AAFLAG (1<<2)
+#define SIFLAG (1<<3)
+#define STOFLAG (1<<4)
+#define STAFLAG (1<<5)
+
+#define SI (IREG(I2CONSET) & SIFLAG)
+
+void init_i2c(void)
+{
+	IREG(I2CONSET) = 0x40; /* Enable I2C ready for Master Tx */
+	/* Set up for just under 400kHz */
+#if 0
+	IWREG(I2SCLL) = (25 * 100);
+	IWREG(I2SCLH) = (12 * 100);
+#else
+	IWREG(I2SCLL) = 1475; /* ~5kHz */
+	IWREG(I2SCLH) = 1475;
+#endif
+}
+
+int i2cstat;
+
+int i2c_wait(void)
+{
+	int stat;
+	while (!SI);
+	stat = IREG(I2STAT);
+	i2cstat = stat;
+	return stat;
+}
+
+void i2c_go(void)
+{
+	IREG(I2CONCLR) = SIFLAG;
+}
+
+int i2c_conreg(void)
+{
+	return IREG(I2CONSET);
+}
+
+int i2c_statreg(void)
+{
+	return IREG(I2STAT);
+}
+
+bool i2c_send_start(void)
+{
+	IREG(I2CONCLR) = STOFLAG | STAFLAG;
+	IREG(I2CONSET) = STAFLAG;
+/*	i2c_go(); */
+	switch (i2c_wait()) {
+	case 0x08:
+	case 0x10:
+/*		IREG(I2CONCLR) = STAFLAG; */
+		return TRUE;
+	default:
+/*		IREG(I2CONCLR) = STAFLAG; */
+		return FALSE;
+	}
+}
+
+bool i2c_send_address(int addr, bool write)
+{
+	return i2c_send_data((addr<<1) + (write?0:1));
+}
+
+bool i2c_send_data(int data)
+{
+	IREG(I2DAT) = data;
+	IREG(I2CONCLR) = STAFLAG | SIFLAG;
+	switch (i2c_wait()) {
+	case 0x18:
+	case 0x28:
+		return TRUE;
+	default:
+		return FALSE;
+	}
+}
+
+void i2c_send_stop(void)
+{
+	IREG(I2CONCLR) = STAFLAG | AAFLAG;
+	IREG(I2CONSET) = STOFLAG;
+	i2c_go();
+	/* Don't think we need to wait here. Could be wrong. */
+}
+