1 files changed, 129 insertions, 0 deletions
diff --git a/firmware/zpu/lib/i2c.c b/firmware/zpu/lib/i2c.c
new file mode 100644
index 000000000..d230f462c
--- /dev/null
+++ b/firmware/zpu/lib/i2c.c
@@ -0,0 +1,129 @@
+/* -*- c -*- */
+/*
+ * Copyright 2007 Free Software Foundation, Inc.
+ *
+ * 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 "i2c.h"
+#include "memory_map.h"
+#include "stdint.h"
+#include <string.h>
+#include "nonstdio.h"
+
+#define MAX_WB_DIV 4	// maximum wishbone divisor (from 100 MHz MASTER_CLK)
+
+// prescaler divisor values for 100 kHz I2C [uses 5 * SCLK internally]
+
+#define PRESCALER(wb_div) (((MASTER_CLK_RATE/(wb_div)) / (5 * 400000)) - 1)
+
+static uint16_t prescaler_values[MAX_WB_DIV+1] = {
+  0xffff,	// 0: can't happen
+  PRESCALER(1),	// 1: 100 MHz
+  PRESCALER(2), // 2:  50 MHz
+  PRESCALER(3), // 3:  33.333 MHz
+  PRESCALER(4), // 4:  25 MHz
+};
+
+void
+i2c_init(void)
+{
+  i2c_regs->ctrl = 0;		// disable core
+  
+  // setup prescaler depending on wishbone divisor
+  int wb_div = hwconfig_wishbone_divisor();
+  if (wb_div > MAX_WB_DIV)
+    wb_div = MAX_WB_DIV;
+
+  i2c_regs->prescaler_lo = prescaler_values[wb_div] & 0xff;
+  i2c_regs->prescaler_hi = (prescaler_values[wb_div] >> 8) & 0xff;
+
+  i2c_regs->ctrl = I2C_CTRL_EN; //| I2C_CTRL_IE;	// enable core
+
+  //now this is done separately to maintain common code for async and sync
+  //pic_register_handler(IRQ_I2C, i2c_irq_handler);
+}
+
+static inline void
+wait_for_xfer(void)
+{
+  while (i2c_regs->cmd_status & I2C_ST_TIP)	// wait for xfer to complete
+    ;
+}
+
+static inline bool
+wait_chk_ack(void)
+{
+  wait_for_xfer();
+
+  if ((i2c_regs->cmd_status & I2C_ST_RXACK) != 0){	// target NAK'd
+    return false;
+  }
+  return true;
+}
+
+bool 
+i2c_read (unsigned char i2c_addr, unsigned char *buf, unsigned int len)
+{
+  if (len == 0)			// reading zero bytes always works
+    return true;
+
+  while (i2c_regs->cmd_status & I2C_ST_BUSY)
+    ;
+
+  i2c_regs->data = (i2c_addr << 1) | 1;	 // 7 bit address and read bit (1)
+  // generate START and write addr
+  i2c_regs->cmd_status = I2C_CMD_WR | I2C_CMD_START;
+  if (!wait_chk_ack())
+    goto fail;
+
+  for (; len > 0; buf++, len--){
+    i2c_regs->cmd_status = I2C_CMD_RD | (len == 1 ? (I2C_CMD_NACK | I2C_CMD_STOP) : 0);
+    wait_for_xfer();
+    *buf = i2c_regs->data;
+  }
+  return true;
+
+ fail:
+  i2c_regs->cmd_status = I2C_CMD_STOP;  // generate STOP
+  return false;
+}
+
+
+bool 
+i2c_write(unsigned char i2c_addr, const unsigned char *buf, unsigned int len)
+{
+  while (i2c_regs->cmd_status & I2C_ST_BUSY)
+    ;
+
+  i2c_regs->data = (i2c_addr << 1) | 0;	 // 7 bit address and write bit (0)
+
+  // generate START and write addr (and maybe STOP)
+  i2c_regs->cmd_status = I2C_CMD_WR | I2C_CMD_START | (len == 0 ? I2C_CMD_STOP : 0);
+  if (!wait_chk_ack())
+    goto fail;
+
+  for (; len > 0; buf++, len--){
+    i2c_regs->data = *buf;
+    i2c_regs->cmd_status = I2C_CMD_WR | (len == 1 ? I2C_CMD_STOP : 0);
+    if (!wait_chk_ack())
+      goto fail;
+  }
+  return true;
+
+ fail:
+  i2c_regs->cmd_status = I2C_CMD_STOP;  // generate STOP
+  return false;
+}
+