ports/atmel-samd: Implement i2cslave.I2CSlave

This adds support for SAMD acting as a I2C slave in polled mode.

ports/atmel-samd/Makefile

@@ -308,6 +308,8 @@ SRC_COMMON_HAL = \
 	busio/UART.c \
 	digitalio/__init__.c \
 	digitalio/DigitalInOut.c \
+	i2cslave/__init__.c \
+	i2cslave/I2CSlave.c \
 	microcontroller/__init__.c \
 	microcontroller/Pin.c \
 	microcontroller/Processor.c \

ports/atmel-samd/boards/feather_m0_express/mpconfigboard.h

@@ -62,3 +62,5 @@
 // USB is always used internally so skip the pin objects for it.
 #define IGNORE_PIN_PA24     1
 #define IGNORE_PIN_PA25     1
+
+#define CIRCUITPY_I2CSLAVE

ports/atmel-samd/boards/feather_m4_express/mpconfigboard.h

@@ -47,3 +47,5 @@
 // USB is always used internally so skip the pin objects for it.
 #define IGNORE_PIN_PA24     1
 #define IGNORE_PIN_PA25     1
+
+#define CIRCUITPY_I2CSLAVE

ports/atmel-samd/boards/metro_m0_express/mpconfigboard.h

@@ -63,3 +63,5 @@
 // USB is always used internally so skip the pin objects for it.
 #define IGNORE_PIN_PA24     1
 #define IGNORE_PIN_PA25     1
+
+#define CIRCUITPY_I2CSLAVE

ports/atmel-samd/boards/metro_m4_express/mpconfigboard.h

@@ -48,3 +48,5 @@
 // USB is always used internally so skip the pin objects for it.
 #define IGNORE_PIN_PA24     1
 #define IGNORE_PIN_PA25     1
+
+#define CIRCUITPY_I2CSLAVE

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

@@ -0,0 +1,252 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Noralf Trønnes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "shared-bindings/i2cslave/I2CSlave.h"
+#include "common-hal/busio/I2C.h"
+
+#include "lib/utils/interrupt_char.h"
+#include "py/mperrno.h"
+#include "py/mphal.h"
+#include "py/runtime.h"
+
+#include "hal/include/hal_gpio.h"
+#include "peripherals/samd/sercom.h"
+
+void common_hal_i2cslave_i2c_slave_construct(i2cslave_i2c_slave_obj_t *self,
+        const mcu_pin_obj_t *scl, const mcu_pin_obj_t *sda,
+        uint8_t *addresses, unsigned int num_addresses, bool smbus) {
+    uint8_t sercom_index;
+    uint32_t sda_pinmux, scl_pinmux;
+    Sercom *sercom = samd_i2c_get_sercom(scl, sda, &sercom_index, &sda_pinmux, &scl_pinmux);
+    if (sercom == NULL) {
+        mp_raise_ValueError("Invalid pins");
+    }
+    self->sercom = sercom;
+
+    gpio_set_pin_function(sda->number, GPIO_PIN_FUNCTION_OFF);
+    gpio_set_pin_function(scl->number, GPIO_PIN_FUNCTION_OFF);
+    gpio_set_pin_function(sda->number, sda_pinmux);
+    gpio_set_pin_function(scl->number, scl_pinmux);
+
+    self->sda_pin = sda->number;
+    self->scl_pin = scl->number;
+    claim_pin(sda);
+    claim_pin(scl);
+
+    samd_peripherals_sercom_clock_init(sercom, sercom_index);
+
+    sercom->I2CS.CTRLA.bit.SWRST = 1;
+    while (sercom->I2CS.CTRLA.bit.SWRST || sercom->I2CS.SYNCBUSY.bit.SWRST) {}
+
+    sercom->I2CS.CTRLB.bit.AACKEN = 0; //  Automatic acknowledge is disabled.
+
+    if (num_addresses == 1) {
+        sercom->I2CS.CTRLB.bit.AMODE = 0x0; // MASK
+        sercom->I2CS.ADDR.bit.ADDR = addresses[0];
+        sercom->I2CS.ADDR.bit.ADDRMASK = 0x00; // Match exact address
+    } else if (num_addresses == 2) {
+        sercom->I2CS.CTRLB.bit.AMODE = 0x1; // 2_ADDRS
+        sercom->I2CS.ADDR.bit.ADDR = addresses[0];
+        sercom->I2CS.ADDR.bit.ADDRMASK = addresses[1];
+    } else {
+        uint32_t combined = 0; // all addresses OR'ed
+        uint32_t differ = 0; // bits that differ between addresses
+        for (unsigned int i = 0; i < num_addresses; i++) {
+            combined |= addresses[i];
+            differ |= addresses[0] ^ addresses[i];
+        }
+        sercom->I2CS.CTRLB.bit.AMODE = 0x0; // MASK
+        sercom->I2CS.ADDR.bit.ADDR = combined;
+        sercom->I2CS.ADDR.bit.ADDRMASK = differ;
+    }
+    self->addresses = addresses;
+    self->num_addresses = num_addresses;
+
+    if (smbus) {
+        sercom->I2CS.CTRLA.bit.LOWTOUTEN = 1; // Errata 12003
+        sercom->I2CS.CTRLA.bit.SEXTTOEN = 1; // Slave SCL Low Extend/Cumulative Time-Out 25ms
+    }
+    sercom->I2CS.CTRLA.bit.SCLSM = 0; // Clock stretch before ack
+    sercom->I2CS.CTRLA.bit.MODE = 0x04; // Slave mode
+    sercom->I2CS.CTRLA.bit.ENABLE = 1;
+}
+
+bool common_hal_i2cslave_i2c_slave_deinited(i2cslave_i2c_slave_obj_t *self) {
+    return self->sda_pin == NO_PIN;
+}
+
+void common_hal_i2cslave_i2c_slave_deinit(i2cslave_i2c_slave_obj_t *self) {
+    if (common_hal_i2cslave_i2c_slave_deinited(self)) {
+        return;
+    }
+
+    self->sercom->I2CS.CTRLA.bit.ENABLE = 0;
+
+    reset_pin(self->sda_pin);
+    reset_pin(self->scl_pin);
+    self->sda_pin = NO_PIN;
+    self->scl_pin = NO_PIN;
+}
+
+static int i2c_slave_check_error(i2cslave_i2c_slave_obj_t *self, bool raise) {
+    if (!self->sercom->I2CS.INTFLAG.bit.ERROR) {
+        return 0;
+    }
+
+    int err = MP_EIO;
+
+    if (self->sercom->I2CS.STATUS.bit.LOWTOUT || self->sercom->I2CS.STATUS.bit.SEXTTOUT) {
+        err = MP_ETIMEDOUT;
+    }
+
+    self->sercom->I2CS.INTFLAG.reg = SERCOM_I2CS_INTFLAG_ERROR; // Clear flag
+
+    if (raise) {
+        mp_raise_OSError(err);
+    }
+    return -err;
+}
+
+int common_hal_i2cslave_i2c_slave_is_addressed(i2cslave_i2c_slave_obj_t *self, uint8_t *address, bool *is_read, bool *is_restart)
+{
+    int err = i2c_slave_check_error(self, false);
+    if (err) {
+        return err;
+    }
+
+    if (!self->sercom->I2CS.INTFLAG.bit.AMATCH) {
+        return 0;
+    }
+
+    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;
+
+    for (unsigned int i = 0; i < self->num_addresses; i++) {
+        if (*address == self->addresses[i]) {
+            common_hal_i2cslave_i2c_slave_ack(self, true);
+            return 1;
+        }
+    }
+
+    // This should clear AMATCH, but it doesn't...
+    common_hal_i2cslave_i2c_slave_ack(self, false);
+    return 0;
+}
+
+int common_hal_i2cslave_i2c_slave_read_byte(i2cslave_i2c_slave_obj_t *self, uint8_t *data) {
+    for (int t = 0; t < 100 && !self->sercom->I2CS.INTFLAG.reg; t++) {
+        mp_hal_delay_us(10);
+    }
+
+    i2c_slave_check_error(self, true);
+
+    if (!self->sercom->I2CS.INTFLAG.bit.DRDY ||
+        self->sercom->I2CS.INTFLAG.bit.PREC ||
+        self->sercom->I2CS.INTFLAG.bit.AMATCH) {
+        return 0;
+    }
+
+    *data = self->sercom->I2CS.DATA.reg;
+    return 1;
+}
+
+int common_hal_i2cslave_i2c_slave_write_byte(i2cslave_i2c_slave_obj_t *self, uint8_t data) {
+    for (int t = 0; !self->sercom->I2CS.INTFLAG.reg && t < 100; t++) {
+        mp_hal_delay_us(10);
+    }
+
+    i2c_slave_check_error(self, true);
+
+    if (self->sercom->I2CS.INTFLAG.bit.PREC) {
+        return 0;
+    }
+
+    // RXNACK can carry over from the previous transfer
+    if (self->writing && self->sercom->I2CS.STATUS.bit.RXNACK) {
+        return 0;
+    }
+
+    self->writing = true;
+
+    if (!self->sercom->I2CS.INTFLAG.bit.DRDY) {
+        return 0;
+    }
+
+    self->sercom->I2CS.DATA.bit.DATA = data; // Send data
+
+    return 1;
+}
+
+void common_hal_i2cslave_i2c_slave_ack(i2cslave_i2c_slave_obj_t *self, bool ack) {
+    self->sercom->I2CS.CTRLB.bit.ACKACT = !ack;
+    self->sercom->I2CS.CTRLB.bit.CMD = 0x03;
+}
+
+void common_hal_i2cslave_i2c_slave_close(i2cslave_i2c_slave_obj_t *self) {
+    for (int t = 0; !self->sercom->I2CS.INTFLAG.reg && t < 100; t++) {
+        mp_hal_delay_us(10);
+    }
+
+    if (self->sercom->I2CS.INTFLAG.bit.AMATCH || !self->sercom->I2CS.STATUS.bit.CLKHOLD) {
+        return;
+    }
+
+    if (!self->sercom->I2CS.STATUS.bit.DIR) {
+        common_hal_i2cslave_i2c_slave_ack(self, false);
+    } else {
+        int i = 0;
+        while (self->sercom->I2CS.INTFLAG.reg == SERCOM_I2CS_INTFLAG_DRDY) {
+            if (mp_hal_is_interrupted()) {
+                return;
+            }
+
+            self->sercom->I2CS.DATA.bit.DATA = 0xff;  // Send dummy byte
+
+            // Wait for a result (if any).
+            // test_byte_word.py::TestWord::test_write_seq leaves us with no INTFLAGs set in some of the tests
+            for (int t = 0; !self->sercom->I2CS.INTFLAG.reg && t < 100; t++) {
+                mp_hal_delay_us(10);
+            }
+
+            if (++i > 1000) { // Avoid getting stuck "forever"
+                mp_raise_OSError(MP_EIO);
+            }
+        }
+    }
+
+    if (self->sercom->I2CS.INTFLAG.bit.AMATCH) {
+        return;
+    }
+
+    if (self->sercom->I2CS.STATUS.bit.CLKHOLD) {
+        // Unable to release the clock.
+        // The slave might have to be re-initialized to get unstuck.
+        mp_raise_OSError(MP_EIO);
+    }
+}

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

@@ -0,0 +1,45 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Noralf Trønnes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_BUSIO_I2C_SLAVE_H
+#define MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_BUSIO_I2C_SLAVE_H
+
+#include "common-hal/microcontroller/Pin.h"
+#include "py/obj.h"
+
+typedef struct {
+    mp_obj_base_t base;
+
+    uint8_t *addresses;
+    unsigned int num_addresses;
+
+    Sercom *sercom;
+    uint8_t scl_pin;
+    uint8_t sda_pin;
+    bool writing;
+} i2cslave_i2c_slave_obj_t;
+
+#endif // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_BUSIO_I2C_SLAVE_H

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

@@ -0,0 +1 @@
+// No i2cslave module functions.

ports/atmel-samd/mpconfigport.h

@@ -174,6 +174,7 @@ extern const struct _mp_obj_module_t digitalio_module;
 extern const struct _mp_obj_module_t pulseio_module;
 extern const struct _mp_obj_module_t busio_module;
 extern const struct _mp_obj_module_t board_module;
+extern const struct _mp_obj_module_t i2cslave_module;
 extern const struct _mp_obj_module_t math_module;
 extern const struct _mp_obj_module_t os_module;
 extern const struct _mp_obj_module_t random_module;
@@ -225,11 +226,18 @@ extern const struct _mp_obj_module_t usb_hid_module;
         #define AUDIOIO_MODULE { MP_OBJ_NEW_QSTR(MP_QSTR_audioio), (mp_obj_t)&audioio_module },
     #endif
 
+    #ifdef CIRCUITPY_I2CSLAVE
+        #define I2CSLAVE_MODULE { MP_OBJ_NEW_QSTR(MP_QSTR_i2cslave), (mp_obj_t)&i2cslave_module },
+    #else
+        #define I2CSLAVE_MODULE
+    #endif
+
     #ifndef EXTRA_BUILTIN_MODULES
     #define EXTRA_BUILTIN_MODULES \
         AUDIOIO_MODULE \
         AUDIOBUSIO_MODULE \
         { MP_OBJ_NEW_QSTR(MP_QSTR_bitbangio), (mp_obj_t)&bitbangio_module }, \
+        I2CSLAVE_MODULE \
         { MP_OBJ_NEW_QSTR(MP_QSTR_rotaryio), (mp_obj_t)&rotaryio_module }, \
         { MP_OBJ_NEW_QSTR(MP_QSTR_gamepad),(mp_obj_t)&gamepad_module }
     #endif

shared-bindings/index.rst

@@ -34,6 +34,7 @@ Module             Supported Ports
 `digitalio`        **All Supported**
 `gamepad`          **SAMD Express, nRF**
 `hashlib`          **ESP8266**
+`i2cslave`         **SAMD Express**
 `math`             **All Supported**
 `microcontroller`  **All Supported**
 `multiterminal`    **ESP8266**