Two I2C fixes:

1) Bus error will be thrown on read/write errors with errno set. (Read didn't used to fail at all.)
2) try_lock correctly returns boolean whether lock was grabbed.

Fixes #87

7 files changed, 81 insertions, 47 deletions

diff --git a/atmel-samd/common-hal/nativeio/I2C.c b/atmel-samd/common-hal/nativeio/I2C.c
index fb1080268..00b2a43e5 100644
--- a/atmel-samd/common-hal/nativeio/I2C.c
+++ b/atmel-samd/common-hal/nativeio/I2C.c
@@ -28,6 +28,7 @@
  // module.
 
 #include "shared-bindings/nativeio/I2C.h"
+#include "py/mperrno.h"
 #include "py/nlr.h"
 
 #include "asf/sam0/drivers/sercom/i2c/i2c_master.h"
@@ -135,7 +136,7 @@ void common_hal_nativeio_i2c_unlock(nativeio_i2c_obj_t *self) {
     i2c_master_unlock(&self->i2c_master_instance);
 }
 
-bool common_hal_nativeio_i2c_write(nativeio_i2c_obj_t *self, uint16_t addr,
+uint8_t common_hal_nativeio_i2c_write(nativeio_i2c_obj_t *self, uint16_t addr,
         const uint8_t *data, size_t len, bool transmit_stop_bit) {
     struct i2c_master_packet packet = {
         .address     = addr,
@@ -161,10 +162,15 @@ bool common_hal_nativeio_i2c_write(nativeio_i2c_obj_t *self, uint16_t addr,
             break;
         }
     }
-    return status == STATUS_OK;
+    if (status == STATUS_OK) {
+        return 0;
+    } else if (status == STATUS_ERR_BAD_ADDRESS) {
+        return MP_ENODEV;
+    }
+    return MP_EIO;
 }
 
-bool common_hal_nativeio_i2c_read(nativeio_i2c_obj_t *self, uint16_t addr,
+uint8_t common_hal_nativeio_i2c_read(nativeio_i2c_obj_t *self, uint16_t addr,
         uint8_t *data, size_t len) {
     struct i2c_master_packet packet = {
         .address     = addr,
@@ -185,5 +191,10 @@ bool common_hal_nativeio_i2c_read(nativeio_i2c_obj_t *self, uint16_t addr,
             break;
         }
     }
-    return status == STATUS_OK;
+    if (status == STATUS_OK) {
+        return 0;
+    } else if (status == STATUS_ERR_BAD_ADDRESS) {
+        return MP_ENODEV;
+    }
+    return MP_EIO;
 }
diff --git a/esp8266/common-hal/nativeio/I2C.c b/esp8266/common-hal/nativeio/I2C.c
index 4fb05ba29..8addb92cd 100644
--- a/esp8266/common-hal/nativeio/I2C.c
+++ b/esp8266/common-hal/nativeio/I2C.c
@@ -25,6 +25,7 @@
  */
 
 #include "shared-bindings/nativeio/I2C.h"
+#include "py/mperrno.h"
 #include "py/nlr.h"
 
 void common_hal_nativeio_i2c_construct(nativeio_i2c_obj_t *self,
@@ -51,12 +52,12 @@ bool common_hal_nativeio_i2c_has_lock(nativeio_i2c_obj_t *self) {
 void common_hal_nativeio_i2c_unlock(nativeio_i2c_obj_t *self) {
 }
 
-bool common_hal_nativeio_i2c_write(nativeio_i2c_obj_t *self, uint16_t addr,
+uint8_t common_hal_nativeio_i2c_write(nativeio_i2c_obj_t *self, uint16_t addr,
         const uint8_t * data, size_t len, bool transmit_stop_bit) {
-    return false;
+    return MP_EIO;
 }
 
-bool common_hal_nativeio_i2c_read(nativeio_i2c_obj_t *self, uint16_t addr,
+uint8_t common_hal_nativeio_i2c_read(nativeio_i2c_obj_t *self, uint16_t addr,
         uint8_t * data, size_t len) {
-    return false;
+    return MP_EIO;
 }
diff --git a/shared-bindings/bitbangio/I2C.c b/shared-bindings/bitbangio/I2C.c
index 2b547d65c..5b772c9bf 100644
--- a/shared-bindings/bitbangio/I2C.c
+++ b/shared-bindings/bitbangio/I2C.c
@@ -31,6 +31,7 @@
 #include "shared-bindings/microcontroller/Pin.h"
 
 #include "lib/utils/context_manager_helpers.h"
+#include "py/mperrno.h"
 #include "py/runtime.h"
 //| .. currentmodule:: bitbangio
 //|
@@ -129,8 +130,7 @@ MP_DEFINE_CONST_FUN_OBJ_1(bitbangio_i2c_scan_obj, bitbangio_i2c_scan);
 //|     Attempts to grab the I2C lock. Returns True on success.
 //|
 STATIC mp_obj_t bitbangio_i2c_obj_try_lock(mp_obj_t self_in) {
-    shared_module_bitbangio_i2c_try_lock(MP_OBJ_TO_PTR(self_in));
-    return self_in;
+    return mp_obj_new_bool(shared_module_bitbangio_i2c_try_lock(MP_OBJ_TO_PTR(self_in)));
 }
 MP_DEFINE_CONST_FUN_OBJ_1(bitbangio_i2c_try_lock_obj, bitbangio_i2c_obj_try_lock);
 
@@ -183,7 +183,13 @@ STATIC mp_obj_t bitbangio_i2c_readfrom_into(size_t n_args, const mp_obj_t *pos_a
     } else if (len > bufinfo.len) {
         len = bufinfo.len;
     }
-    shared_module_bitbangio_i2c_read(self, args[ARG_address].u_int, ((uint8_t*)bufinfo.buf) + start, len);
+    uint8_t status = shared_module_bitbangio_i2c_read(self,
+                                                      args[ARG_address].u_int,
+                                                      ((uint8_t*)bufinfo.buf) + start,
+                                                      len);
+    if (status != 0) {
+        mp_raise_OSError(status);
+    }
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_KW(bitbangio_i2c_readfrom_into_obj, 3, bitbangio_i2c_readfrom_into);
@@ -235,10 +241,10 @@ STATIC mp_obj_t bitbangio_i2c_writeto(size_t n_args, const mp_obj_t *pos_args, m
     }
 
     // do the transfer
-    bool ok = shared_module_bitbangio_i2c_write(self, args[ARG_address].u_int,
+    uint8_t status = shared_module_bitbangio_i2c_write(self, args[ARG_address].u_int,
         ((uint8_t*) bufinfo.buf) + start, len, args[ARG_stop].u_bool);
-    if (!ok) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
+    if (status != 0) {
+        mp_raise_OSError(status);
     }
     return mp_const_none;
 }
diff --git a/shared-bindings/bitbangio/I2C.h b/shared-bindings/bitbangio/I2C.h
index 451fa4d94..4d01230af 100644
--- a/shared-bindings/bitbangio/I2C.h
+++ b/shared-bindings/bitbangio/I2C.h
@@ -50,14 +50,14 @@ extern void shared_module_bitbangio_i2c_unlock(bitbangio_i2c_obj_t *self);
 // Probe the bus to see if a device acknowledges the given address.
 extern bool shared_module_bitbangio_i2c_probe(bitbangio_i2c_obj_t *self, uint8_t addr);
 
-extern bool shared_module_bitbangio_i2c_write(bitbangio_i2c_obj_t *self,
-                                              uint16_t address,
-                                              const uint8_t * data, size_t len,
-                                              bool stop);
+extern uint8_t shared_module_bitbangio_i2c_write(bitbangio_i2c_obj_t *self,
+                                                 uint16_t address,
+                                                 const uint8_t * data, size_t len,
+                                                 bool stop);
 
 // Reads memory of the i2c device picking up where it left off.
-extern bool shared_module_bitbangio_i2c_read(bitbangio_i2c_obj_t *self,
-                                             uint16_t address,
-                                             uint8_t * data, size_t len);
+extern uint8_t shared_module_bitbangio_i2c_read(bitbangio_i2c_obj_t *self,
+                                                uint16_t address,
+                                                uint8_t * data, size_t len);
 
 #endif // __MICROPY_INCLUDED_SHARED_BINDINGS_BITBANGIO_I2C_H__
diff --git a/shared-bindings/nativeio/I2C.c b/shared-bindings/nativeio/I2C.c
index bb827a95d..43cf7b63d 100644
--- a/shared-bindings/nativeio/I2C.c
+++ b/shared-bindings/nativeio/I2C.c
@@ -141,8 +141,7 @@ MP_DEFINE_CONST_FUN_OBJ_1(nativeio_i2c_scan_obj, nativeio_i2c_scan);
 //|     Attempts to grab the I2C lock. Returns True on success.
 //|
 STATIC mp_obj_t nativeio_i2c_obj_try_lock(mp_obj_t self_in) {
-    common_hal_nativeio_i2c_try_lock(MP_OBJ_TO_PTR(self_in));
-    return self_in;
+    return mp_obj_new_bool(common_hal_nativeio_i2c_try_lock(MP_OBJ_TO_PTR(self_in)));
 }
 MP_DEFINE_CONST_FUN_OBJ_1(nativeio_i2c_try_lock_obj, nativeio_i2c_obj_try_lock);
 
@@ -196,7 +195,11 @@ STATIC mp_obj_t nativeio_i2c_readfrom_into(size_t n_args, const mp_obj_t *pos_ar
     } else if (len > bufinfo.len) {
         len = bufinfo.len;
     }
-    common_hal_nativeio_i2c_read(self, args[ARG_address].u_int, ((uint8_t*)bufinfo.buf) + start, len);
+    uint8_t status = common_hal_nativeio_i2c_read(self, args[ARG_address].u_int, ((uint8_t*)bufinfo.buf) + start, len);
+    if (status != 0) {
+        mp_raise_OSError(status);
+    }
+
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_KW(nativeio_i2c_readfrom_into_obj, 3, nativeio_i2c_readfrom_into);
@@ -248,10 +251,10 @@ STATIC mp_obj_t nativeio_i2c_writeto(size_t n_args, const mp_obj_t *pos_args, mp
     }
 
     // do the transfer
-    bool ok = common_hal_nativeio_i2c_write(self, args[ARG_address].u_int,
+    uint8_t status = common_hal_nativeio_i2c_write(self, args[ARG_address].u_int,
         ((uint8_t*) bufinfo.buf) + start, len, args[ARG_stop].u_bool);
-    if (!ok) {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
+    if (status != 0) {
+        mp_raise_OSError(status);
     }
     return mp_const_none;
 }
diff --git a/shared-bindings/nativeio/I2C.h b/shared-bindings/nativeio/I2C.h
index cf7a9fa60..5f3c89a77 100644
--- a/shared-bindings/nativeio/I2C.h
+++ b/shared-bindings/nativeio/I2C.h
@@ -57,12 +57,14 @@ extern void common_hal_nativeio_i2c_unlock(nativeio_i2c_obj_t *self);
 // Probe the bus to see if a device acknowledges the given address.
 extern bool common_hal_nativeio_i2c_probe(nativeio_i2c_obj_t *self, uint8_t addr);
 
-extern bool common_hal_nativeio_i2c_write(nativeio_i2c_obj_t *self, uint16_t address,
-                                          const uint8_t * data, size_t len,
-                                          bool stop);
+// Write to the device and return 0 on success or an appropriate error code from mperrno.h
+extern uint8_t common_hal_nativeio_i2c_write(nativeio_i2c_obj_t *self, uint16_t address,
+                                             const uint8_t * data, size_t len,
+                                             bool stop);
 
-// Reads memory of the i2c device picking up where it left off.
-extern bool common_hal_nativeio_i2c_read(nativeio_i2c_obj_t *self, uint16_t address,
-                                         uint8_t * data, size_t len);
+// Reads memory of the i2c device picking up where it left off and return 0 on
+// success or an appropriate error code from mperrno.h
+extern uint8_t common_hal_nativeio_i2c_read(nativeio_i2c_obj_t *self, uint16_t address,
+                                            uint8_t * data, size_t len);
 
 #endif // __MICROPY_INCLUDED_SHARED_BINDINGS_NATIVEIO_I2C_H__
diff --git a/shared-module/bitbangio/I2C.c b/shared-module/bitbangio/I2C.c
index 9ba68262f..422f7778d 100644
--- a/shared-module/bitbangio/I2C.c
+++ b/shared-module/bitbangio/I2C.c
@@ -26,6 +26,7 @@
 
 #include "shared-bindings/bitbangio/I2C.h"
 
+#include "py/mperrno.h"
 #include "py/obj.h"
 
 #include "common-hal/microcontroller/types.h"
@@ -192,38 +193,48 @@ bool shared_module_bitbangio_i2c_probe(bitbangio_i2c_obj_t *self, uint8_t addr)
     return ok;
 }
 
-bool shared_module_bitbangio_i2c_write(bitbangio_i2c_obj_t *self, uint16_t addr,
+uint8_t shared_module_bitbangio_i2c_write(bitbangio_i2c_obj_t *self, uint16_t addr,
                                        const uint8_t *data, size_t len, bool transmit_stop_bit) {
     // start the I2C transaction
     start(self);
-    bool ok = write_byte(self, addr << 1);
+    uint8_t status = 0;
+    if (!write_byte(self, addr << 1)) {
+        status = MP_ENODEV;
+    }
 
-    for (uint32_t i = 0; i < len; i++) {
-        ok = ok && write_byte(self, data[i]);
-        if (!ok) {
-            break;
+    if (status == 0) {
+        for (uint32_t i = 0; i < len; i++) {
+            if (!write_byte(self, data[i])) {
+                status = MP_EIO;
+                break;
+            }
         }
     }
 
     if (transmit_stop_bit) {
         stop(self);
     }
-    return ok;
+    return status;
 }
 
-bool shared_module_bitbangio_i2c_read(bitbangio_i2c_obj_t *self, uint16_t addr,
+uint8_t shared_module_bitbangio_i2c_read(bitbangio_i2c_obj_t *self, uint16_t addr,
                                       uint8_t * data, size_t len) {
     // start the I2C transaction
     start(self);
-    bool ok = write_byte(self, (addr << 1) | 1);
+    uint8_t status = 0;
+    if (!write_byte(self, (addr << 1) | 1)) {
+        status = MP_ENODEV;
+    }
 
-    for (uint32_t i = 0; i < len; i++) {
-        ok = ok && read_byte(self, data + i, i < len - 1);
-        if (!ok) {
-            break;
+    if (status == 0) {
+        for (uint32_t i = 0; i < len; i++) {
+            if (!read_byte(self, data + i, i < len - 1)) {
+                status = MP_EIO;
+                break;
+            }
         }
     }
 
     stop(self);
-    return ok;
+    return status;
 }