1 files changed, 180 insertions, 5 deletions

diff --git a/firmware/microblaze/lib/i2c.c b/firmware/microblaze/lib/i2c.c
index 3f738733b..177341267 100644
--- a/firmware/microblaze/lib/i2c.c
+++ b/firmware/microblaze/lib/i2c.c
@@ -19,12 +19,15 @@
 #include "i2c.h"
 #include "memory_map.h"
 #include "stdint.h"
+#include <string.h>
+#include "pic.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 * 100000)) - 1)
+#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
@@ -34,6 +37,18 @@ static uint16_t prescaler_values[MAX_WB_DIV+1] = {
   PRESCALER(4), // 4:  25 MHz
 };
 
+//asynchronous (interrupt-driven) i2c state variables
+volatile uint8_t i2c_buf[17]; //tx/rx data transfer buffer
+volatile uint8_t *volatile i2c_bufptr = i2c_buf; //ptr to current position
+volatile uint8_t i2c_len = 0; //length remaining in current transfer
+volatile i2c_state_t i2c_state = I2C_STATE_IDLE; //current I2C transfer state
+i2c_dir_t i2c_dir; //I2C transfer direction
+
+void  (*volatile i2c_callback)(void); //function pointer to i2c callback to be called when transaction is complete
+
+static void i2c_irq_handler(unsigned irq);
+inline void i2c_async_err(void);
+
 void
 i2c_init(void)
 {
@@ -47,9 +62,10 @@ i2c_init(void)
   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;	// enable core
+  i2c_regs->ctrl = I2C_CTRL_EN; //| I2C_CTRL_IE;	// enable core
 
-  // FIXME interrupt driven?
+  // FIXME interrupt driven?  
+  pic_register_handler(IRQ_I2C, i2c_irq_handler);
 }
 
 static inline void
@@ -107,7 +123,7 @@ i2c_write(unsigned char i2c_addr, const unsigned char *buf, unsigned int len)
   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);  
+  i2c_regs->cmd_status = I2C_CMD_WR | I2C_CMD_START | (len == 0 ? I2C_CMD_STOP : 0);
   if (!wait_chk_ack())
     goto fail;
 
@@ -124,4 +140,163 @@ i2c_write(unsigned char i2c_addr, const unsigned char *buf, unsigned int len)
   return false;
 }
 
-  
+static void i2c_irq_handler(unsigned irq) {
+//i2c state machine.
+
+  //printf("I2C irq handler\n");
+  //first let's make sure nothing is f'ed up
+  //TODO: uncomment this error checking when we have some way to handle errors
+//  if(((i2c_regs->cmd_status & I2C_ST_RXACK) != 0) && i2c_dir == I2C_DIR_WRITE) { //we got a NACK and we didn't send it
+//    printf("\tNACK received\n");
+//    i2c_async_err();
+//    return;
+//  }// else printf("\tACK received, proceeding\n");
+
+  if(i2c_regs->cmd_status & I2C_ST_AL) { 
+    printf("\tArbitration lost!\n");
+    i2c_async_err();
+    return;
+  }
+
+  if(i2c_regs->cmd_status & I2C_ST_TIP) {
+    //printf("\tI2C still busy in interrupt\n");
+    return;
+  }
+
+  //now decide what to do
+  switch(i2c_state) {
+
+  case I2C_STATE_IDLE:
+    //this is an error. in idle state, we shouldn't be transferring data, and the fact that the IRQ fired is terrible bad.
+    printf("AAAAAHHHHH INTERRUPT IN THE IDLE STATE AAAHHHHHHHHH\n");
+    i2c_async_err();
+    break;
+
+  case I2C_STATE_CONTROL_BYTE_SENT: //here we've sent the control byte, and we're either clocking data in or out now, but we haven't received a byte yet.
+  case I2C_STATE_DATA:      //here we're sending/receiving data and if we're receiving there's data in the data reg
+
+    //if(i2c_state == I2C_STATE_DATA) printf("\tI2C in state DATA with dir=%d and len=%d\n", i2c_dir, i2c_len);
+    //else printf("\tI2C in state CONTROL_BYTE_SENT with dir=%d and len=%d\n", i2c_dir, i2c_len);
+
+    if(i2c_dir == I2C_DIR_READ) {
+      if(i2c_state == I2C_STATE_DATA) *(i2c_bufptr++) = i2c_regs->data;
+      //printf("\tRead %x\n", *(i2c_bufptr-1));
+      //set up another data byte
+      if(i2c_len > 1) //only one more byte to transfer
+        i2c_regs->cmd_status = I2C_CMD_RD;
+      else
+        i2c_regs->cmd_status = I2C_CMD_RD | I2C_CMD_NACK | I2C_CMD_STOP;
+    }
+    else if(i2c_dir == I2C_DIR_WRITE) {
+      //write a byte
+      //printf("\tWriting %x\n", *i2c_bufptr);
+      i2c_regs->data = *(i2c_bufptr++);
+      if(i2c_len > 1)
+        i2c_regs->cmd_status = I2C_CMD_WR;
+      else {
+        //printf("\tGenerating STOP\n");
+        i2c_regs->cmd_status = I2C_CMD_WR | I2C_CMD_STOP;
+      }
+    };
+    i2c_len--;
+    if(i2c_len == 0) i2c_state = I2C_STATE_LAST_BYTE;
+    else i2c_state = I2C_STATE_DATA; //takes care of the addr_sent->data transition
+    break;
+
+
+  case I2C_STATE_LAST_BYTE: //here we've already sent the last read request and the last data is waiting for us.
+    //printf("\tI2C in state LAST BYTE\n");
+
+    if(i2c_dir == I2C_DIR_READ) {
+      *(i2c_bufptr++) = i2c_regs->data;
+      //printf("\tRead %x\n", *(i2c_bufptr-1));
+      i2c_state = I2C_STATE_DATA_READY;
+    } else {
+      i2c_state = I2C_STATE_IDLE;
+    }
+    i2c_regs->ctrl &= ~I2C_CTRL_IE; //disable interrupts until next time
+
+    if(i2c_callback) {
+      i2c_callback(); //if we registered a callback, call it!
+    }
+
+    break;
+
+
+  default: //terrible things have happened.
+    break;
+  }
+
+}
+
+void i2c_register_callback(void (*volatile callback)(void)) {
+  i2c_callback = callback;
+}
+
+inline void i2c_async_err(void) {
+  i2c_state = I2C_STATE_IDLE;
+  i2c_regs->ctrl &= ~I2C_CTRL_IE;
+  printf("I2C error\n");
+//TODO: set an error flag instead of just dropping things on the floor
+  i2c_regs->cmd_status = I2C_CMD_STOP;
+}
+
+bool i2c_async_read(uint8_t addr, unsigned int len) {
+  //printf("Starting async read\n");
+  if(i2c_state != I2C_STATE_IDLE) return false; //sorry mario but your i2c is in another castle
+  if(len == 0) return true; //just idiot-proofing
+  if(len > sizeof(i2c_buf)) return false;
+
+  //disable I2C interrupts and clear pending interrupts on the I2C device
+  i2c_regs->ctrl &= ~I2C_CTRL_IE;
+  i2c_regs->cmd_status |= I2C_CMD_IACK;
+
+  i2c_len = len;
+  i2c_dir = I2C_DIR_READ;
+  i2c_bufptr = i2c_buf;
+  //then set up the transfer by issuing the control byte
+  i2c_regs->ctrl |= I2C_CTRL_IE;
+  i2c_regs->data = (addr << 1) | 0x01; //7 bit addr and read bit
+  i2c_regs->cmd_status = I2C_CMD_WR | I2C_CMD_START; //generate start & start writing addr
+  //update the state so the irq handler knows what's going on
+  i2c_state = I2C_STATE_CONTROL_BYTE_SENT;
+  return true;
+}
+
+bool i2c_async_write(uint8_t addr, const uint8_t *buf, unsigned int len) {
+  //printf("Starting async write\n");
+  if(i2c_state != I2C_STATE_IDLE) return false; //sorry mario but your i2c is in another castle
+  if(len > sizeof(i2c_buf)) return false;
+
+  //disable I2C interrupts and clear pending interrupts on the I2C device
+  i2c_regs->ctrl &= ~I2C_CTRL_IE;
+  i2c_regs->cmd_status |= I2C_CMD_IACK;
+
+  //copy the buffer into our own if writing
+  memcpy((void *)i2c_buf, buf, len);
+
+  i2c_len = len;
+  i2c_dir = I2C_DIR_WRITE;
+  i2c_bufptr = i2c_buf;
+  //then set up the transfer by issuing the control byte
+  i2c_regs->ctrl |= I2C_CTRL_IE;
+  i2c_regs->data = (addr << 1) | 0x00; //7 bit addr and read bit
+  i2c_regs->cmd_status = I2C_CMD_WR | I2C_CMD_START; //generate start & start writing addr
+  //update the state so the irq handler knows what's going on
+  i2c_state = I2C_STATE_CONTROL_BYTE_SENT;
+
+  return true;
+}
+
+//TODO: determine if it's better to read sequentially into the user's buffer, copy on transfer complete, or copy on request (shown below). probably best to copy on request.
+bool i2c_async_data_ready(void *buf) {
+  if(i2c_state == I2C_STATE_DATA_READY) {
+    i2c_state = I2C_STATE_IDLE;
+    memcpy(buf, (void *)i2c_buf, (i2c_bufptr - i2c_buf)); //TODO: not really comfortable with this
+    //printf("Copying %d bytes to user buffer\n", i2c_bufptr-i2c_buf);
+    return true;
+  }
+  return false;
+}
+
+