Merge pull request #10017 from gschorcht/esp8266_i2c_fix

cpu/esp8266: periph/i2c fix

cpu/esp8266/periph/i2c.c

@@ -53,8 +53,8 @@
 extern uint8_t system_get_cpu_freq(void);
 extern bool system_update_cpu_freq(uint8_t freq);
 
-/* max clock stretching counter */
-#define I2C_CLOCK_STRETCH 400
+/* max clock stretching counter (ca. 10 ms) */
+#define I2C_CLOCK_STRETCH 40000
 
 typedef struct
 {
@@ -128,9 +128,9 @@ static int _i2c_read_bit (_i2c_bus_t* bus, bool* bit);
 static int _i2c_write_byte (_i2c_bus_t* bus, uint8_t byte);
 static int _i2c_read_byte (_i2c_bus_t* bus, uint8_t* byte, bool ack);
 static int _i2c_arbitration_lost (_i2c_bus_t* bus, const char* func);
+static void _i2c_abort (_i2c_bus_t* bus, const char* func);
 
 /* implementation of i2c interface */
-
 void i2c_init(i2c_t dev)
 {
     if (I2C_NUMOF != sizeof(_i2c_bus)/sizeof(_i2c_bus_t)) {
@@ -217,12 +217,16 @@ int /* IRAM */ i2c_read_bytes(i2c_t dev, uint16_t addr, void *data, size_t len,
             /* send address bytes wit read flag */
             if ((res = _i2c_write_byte (bus, addr1)) != 0 ||
                 (res = _i2c_write_byte (bus, addr2)) != 0) {
+                /* abort transfer */
+                _i2c_abort (bus, __func__);
                 return res;
             }
         }
         else {
             /* send address byte with read flag */
             if ((res = _i2c_write_byte (bus, (addr << 1 | I2C_READ))) != 0) {
+                /* abort transfer */
+                _i2c_abort (bus, __func__);
                 return res;
             }
         }
@@ -231,7 +235,9 @@ int /* IRAM */ i2c_read_bytes(i2c_t dev, uint16_t addr, void *data, size_t len,
     /* receive bytes if send address was successful */
     for (unsigned int i = 0; i < len; i++) {
         if ((res = _i2c_read_byte (bus, &(((uint8_t*)data)[i]), i < len-1)) != 0) {
-            break;
+            /* abort transfer */
+            _i2c_abort (bus, __func__);
+            return res;
         }
     }
 
@@ -272,12 +278,16 @@ int /* IRAM */ i2c_write_bytes(i2c_t dev, uint16_t addr, const void *data, size_
             /* send address bytes without read flag */
             if ((res = _i2c_write_byte (bus, addr1)) != 0 ||
                 (res = _i2c_write_byte (bus, addr2)) != 0) {
+                /* abort transfer */
+                _i2c_abort (bus, __func__);
                 return res;
             }
         }
         else {
             /* send address byte without read flag */
             if ((res = _i2c_write_byte (bus, addr << 1)) != 0) {
+                /* abort transfer */
+                _i2c_abort (bus, __func__);
                 return res;
             }
         }
@@ -286,7 +296,9 @@ int /* IRAM */ i2c_write_bytes(i2c_t dev, uint16_t addr, const void *data, size_
     /* send bytes if send address was successful */
     for (unsigned int i = 0; i < len; i++) {
         if ((res = _i2c_write_byte (bus, ((uint8_t*)data)[i])) != 0) {
-            break;
+            /* abort transfer */
+            _i2c_abort (bus, __func__);
+            return res;
         }
     }
 
@@ -372,6 +384,18 @@ static inline void _i2c_clear_sda(_i2c_bus_t* bus)
     GPIO.OUT_CLEAR = bus->sda_bit;
 }
 
+static void _i2c_abort(_i2c_bus_t* bus, const char* func)
+{
+    DEBUG("%s: dev=%u\n", func, bus->dev);
+
+    /* reset SCL and SDA to passive HIGH (floating and pulled-up) */
+    _i2c_set_sda (bus);
+    _i2c_set_scl (bus);
+
+    /* reset repeated start indicator */
+    bus->started = false;
+}
+
 static /* IRAM */ int _i2c_arbitration_lost (_i2c_bus_t* bus, const char* func)
 {
     DEBUG("%s: arbitration lost dev=%u\n", func, bus->dev);
@@ -471,7 +495,7 @@ static /* IRAM */ int _i2c_stop_cond(_i2c_bus_t* bus)
         res = -ETIMEDOUT;
     }
 
-    /* wait t_SU;STO - hold time (repeated) START condition, */
+    /* wait t_SU;STO - hold time STOP condition, */
     /* min. in us: 4.0 (SM), 0.6 (FM), 0.26 (FPM), 0.16 (HSM); no max. */
     _i2c_delay (bus);
 
@@ -484,6 +508,8 @@ static /* IRAM */ int _i2c_stop_cond(_i2c_bus_t* bus)
     /* wait t_BUF - bus free time between a STOP and a START condition */
     /* min. in us: 4.7 (SM), 1.3 (FM), 0.5 (FPM), 0.16 (HSM); no max. */
     _i2c_delay (bus);
+    /* one additional delay */
+    _i2c_delay (bus);
 
     /* if SDA is low, arbitration is lost and someone else is driving the bus */
     if (_i2c_read_sda (bus) == 0) {