i2cslave: Support uselect.poll

This adds MP_STREAM_POLL support to i2cslave.

Author: notro

ports/atmel-samd/common-hal/i2cslave/I2CSlave.c

@@ -143,13 +143,22 @@ int common_hal_i2cslave_i2c_slave_is_addressed(i2cslave_i2c_slave_obj_t *self, u
 
     self->writing = false;
 
-    *address = self->sercom->I2CS.DATA.reg >> 1;
-    *is_read = self->sercom->I2CS.STATUS.bit.DIR;
-    *is_restart = self->sercom->I2CS.STATUS.bit.SR;
+    uint8_t addr = self->sercom->I2CS.DATA.reg >> 1;
+    if (address) {
+        *address = addr;
+    }
+    if (is_read) {
+        *is_read = self->sercom->I2CS.STATUS.bit.DIR;
+    }
+    if (is_restart) {
+        *is_restart = self->sercom->I2CS.STATUS.bit.SR;
+    }
 
     for (unsigned int i = 0; i < self->num_addresses; i++) {
-        if (*address == self->addresses[i]) {
-            common_hal_i2cslave_i2c_slave_ack(self, true);
+        if (addr == self->addresses[i]) {
+            if (address) {
+                common_hal_i2cslave_i2c_slave_ack(self, true);
+            }
             return 1;
         }
     }

shared-bindings/i2cslave/I2CSlave.c

@@ -38,6 +38,7 @@
 #include "py/obj.h"
 #include "py/objproperty.h"
 #include "py/runtime.h"
+#include "py/stream.h"
 
 STATIC mp_obj_t mp_obj_new_i2cslave_i2c_slave_request(i2cslave_i2c_slave_obj_t *slave, uint8_t address, bool is_read, bool is_restart) {
     i2cslave_i2c_slave_request_obj_t *self = m_new_obj(i2cslave_i2c_slave_request_obj_t);
@@ -226,10 +227,28 @@ STATIC const mp_rom_map_elem_t i2cslave_i2c_slave_locals_dict_table[] = {
 
 STATIC MP_DEFINE_CONST_DICT(i2cslave_i2c_slave_locals_dict, i2cslave_i2c_slave_locals_dict_table);
 
+STATIC mp_uint_t i2cslave_ioctl(mp_obj_t obj, mp_uint_t request, uintptr_t arg, int *errcode) {
+    i2cslave_i2c_slave_obj_t *self = MP_OBJ_TO_PTR(obj);
+    int status = -MP_EINVAL;
+    if (request == MP_STREAM_POLL) {
+        status = common_hal_i2cslave_i2c_slave_is_addressed(self, NULL, NULL, NULL);
+    }
+    if (status < 0) {
+        *errcode = -status;
+        return MP_STREAM_ERROR;
+    }
+    return status;
+}
+
+STATIC const mp_stream_p_t i2cslave_p = {
+    .ioctl = i2cslave_ioctl,
+};
+
 const mp_obj_type_t i2cslave_i2c_slave_type = {
    { &mp_type_type },
    .name = MP_QSTR_I2CSlave,
    .make_new = i2cslave_i2c_slave_make_new,
+   .protocol = &i2cslave_p,
    .locals_dict = (mp_obj_dict_t*)&i2cslave_i2c_slave_locals_dict,
 };