I2c reset functionality (espressif#678)

* Addition of a i2cReset method and timeout handling for the case where the i2c hardware FSM (state machine) gets stuck in a busy state.

* Use newly added i2cReset function within the wire library.

Author: lonerzzz

Diff for: cores/esp32/esp32-hal-i2c.c

@@ -18,6 +18,7 @@
 #include "freertos/task.h"
 #include "freertos/semphr.h"
 #include "rom/ets_sys.h"
+#include "driver/periph_ctrl.h"
 #include "soc/i2c_reg.h"
 #include "soc/i2c_struct.h"
 #include "soc/dport_reg.h"
@@ -154,6 +155,13 @@ i2c_err_t i2cWrite(i2c_t * i2c, uint16_t address, bool addr_10bit, uint8_t * dat
 
     I2C_MUTEX_LOCK();
 
+    if (i2c->dev->status_reg.bus_busy == 1)
+    {
+	//log_w( "Busy Timeout! Addr: %x", address >> 1 );
+        I2C_MUTEX_UNLOCK();
+        return I2C_ERROR_BUSY;
+    }
+
     while(dataLen) {
         uint8_t willSend = (dataLen > 32)?32:dataLen;
         uint8_t dataSend = willSend;
@@ -221,7 +229,7 @@ i2c_err_t i2cWrite(i2c_t * i2c, uint16_t address, bool addr_10bit, uint8_t * dat
             //Transmission did not finish and ACK_ERR is set
             if(i2c->dev->int_raw.ack_err) {
                 //log_w("Ack Error! Addr: %x", address >> 1);
-                while(i2c->dev->status_reg.bus_busy);
+                while((i2c->dev->status_reg.bus_busy) && ((millis() - startAt)>50));
                 I2C_MUTEX_UNLOCK();
                 return I2C_ERROR_ACK;
             }
@@ -250,6 +258,13 @@ i2c_err_t i2cRead(i2c_t * i2c, uint16_t address, bool addr_10bit, uint8_t * data
 
     I2C_MUTEX_LOCK();
 
+    if (i2c->dev->status_reg.bus_busy == 1)
+    {
+	//log_w( "Busy Timeout! Addr: %x", address >> 1 );
+        I2C_MUTEX_UNLOCK();
+        return I2C_ERROR_BUSY;
+    }
+
     i2cResetFiFo(i2c);
     i2cResetCmd(i2c);
 
@@ -445,7 +460,25 @@ void i2cInitFix(i2c_t * i2c){
     i2c->dev->fifo_data.data = 0;
     i2cSetCmd(i2c, 1, I2C_CMD_WRITE, 1, false, false, false);
     i2cSetCmd(i2c, 2, I2C_CMD_STOP, 0, false, false, false);
+    if (i2c->dev->status_reg.bus_busy) // If this condition is true, the while loop will timeout as done will not be set
+    {
+        //log_e("Busy at initialization!");
+    }
     i2c->dev->ctr.trans_start = 1;
-    while(!i2c->dev->command[2].done);
+    uint16_t count = 50000;
+    while ((!i2c->dev->command[2].done) && (--count > 0));
     I2C_MUTEX_UNLOCK();
 }
+
+void i2cReset(i2c_t* i2c){
+    if(i2c == NULL){
+        return;
+    }
+    I2C_MUTEX_LOCK();
+    periph_module_t moduleId = (i2c == &_i2c_bus_array[0])?PERIPH_I2C0_MODULE:PERIPH_I2C1_MODULE;
+    periph_module_disable( moduleId );
+    delay( 20 ); // Seems long but delay was chosen to ensure system teardown and setup without core generation
+    periph_module_enable( moduleId );
+    I2C_MUTEX_UNLOCK();
+}
+

Diff for: cores/esp32/esp32-hal-i2c.h

@@ -27,7 +27,8 @@ typedef enum {
     I2C_ERROR_DEV,
     I2C_ERROR_ACK,
     I2C_ERROR_TIMEOUT,
-    I2C_ERROR_BUS
+    I2C_ERROR_BUS,
+    I2C_ERROR_BUSY
 } i2c_err_t;
 
 struct i2c_struct_t;
@@ -50,6 +51,7 @@ i2c_err_t i2cDetachSDA(i2c_t * i2c, int8_t sda);
 i2c_err_t i2cWrite(i2c_t * i2c, uint16_t address, bool addr_10bit, uint8_t * data, uint8_t len, bool sendStop);
 i2c_err_t i2cRead(i2c_t * i2c, uint16_t address, bool addr_10bit, uint8_t * data, uint8_t len, bool sendStop);
 
+void i2cReset(i2c_t* i2c);
 
 #ifdef __cplusplus
 }

Diff for: libraries/Wire/src/Wire.cpp

@@ -211,4 +211,11 @@ void TwoWire::flush(void)
     txLength = 0;
 }
 
+void TwoWire::reset(void)
+{
+    i2cReset( i2c );
+    i2c = NULL;
+    begin( sda, scl );
+}
+
 TwoWire Wire = TwoWire(0);

Diff for: libraries/Wire/src/Wire.h

@@ -72,6 +72,8 @@ class TwoWire: public Stream
     int peek(void);
     void flush(void);
 
+    void reset(void);
+
     inline size_t write(const char * s)
     {
         return write((uint8_t*) s, strlen(s));