samd/machine_i2c: Add the machine.I2C class.

Using the common API.  Tested with SAMD21 and SAMD51 boards.

6 files changed, 277 insertions, 2 deletions

diff --git a/ports/samd/Makefile b/ports/samd/Makefile
index ca0309fa6..c5d36adda 100644
--- a/ports/samd/Makefile
+++ b/ports/samd/Makefile
@@ -91,6 +91,7 @@ SRC_C = \
 	clock_config.c \
 	help.c \
 	machine_adc.c \
+	machine_i2c.c \
 	machine_led.c \
 	machine_pin.c \
 	machine_spi.c \
@@ -143,6 +144,7 @@ endif
 # List of sources for qstr extraction
 SRC_QSTR += \
 	machine_adc.c \
+	machine_i2c.c \
 	machine_led.c \
 	machine_pin.c \
 	machine_pwm.c \
diff --git a/ports/samd/machine_i2c.c b/ports/samd/machine_i2c.c
new file mode 100644
index 000000000..4d1b03f7d
--- /dev/null
+++ b/ports/samd/machine_i2c.c
@@ -0,0 +1,270 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020-2021 Damien P. George
+ * Copyright (c) 2022 Robert Hammelrath
+ *
+ * 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 "py/runtime.h"
+#include "py/mphal.h"
+#include "py/mperrno.h"
+#include "extmod/machine_i2c.h"
+#include "modmachine.h"
+#include "samd_soc.h"
+#include "pin_af.h"
+#include "clock_config.h"
+
+#define DEFAULT_I2C_FREQ  (400000)
+#define RISETIME_NS       (300)
+#define I2C_TIMEOUT       (100)
+
+#define IS_BUS_BUSY       (i2c->I2CM.STATUS.bit.BUSSTATE == 3)
+#define NACK_RECVD        (i2c->I2CM.STATUS.bit.RXNACK == 1)
+#define IRQ_DATA_SENT     (i2c->I2CM.INTFLAG.bit.MB == 1)
+#define IRQ_DATA_RECVD    (i2c->I2CM.INTFLAG.bit.SB == 1)
+#define READ_MODE         ((flags & MP_MACHINE_I2C_FLAG_READ) != 0)
+
+#define PREPARE_ACK       i2c->I2CM.CTRLB.bit.ACKACT = 0
+#define PREPARE_NACK      i2c->I2CM.CTRLB.bit.ACKACT = 1
+#define SET_STOP_STATE    i2c_send_command(i2c, 0x03)
+
+enum state_t {
+    state_done = 0,
+    state_busy,
+    state_buserr,
+    state_nack
+};
+
+typedef struct _machine_i2c_obj_t {
+    mp_obj_base_t base;
+    Sercom *instance;
+    uint8_t id;
+    uint8_t scl;
+    uint8_t sda;
+    uint8_t state;
+    uint32_t freq;
+    uint32_t timeout;
+    size_t len;
+    uint8_t *buf;
+} machine_i2c_obj_t;
+
+extern Sercom *sercom_instance[];
+extern void *sercom_table[SERCOM_INST_NUM];
+
+STATIC void i2c_send_command(Sercom *i2c, uint8_t command) {
+    i2c->I2CM.CTRLB.bit.CMD = command;
+    while (i2c->I2CM.SYNCBUSY.bit.SYSOP) {
+    }
+}
+
+void common_i2c_irq_handler(int i2c_id) {
+    // handle Sercom I2C IRQ
+    machine_i2c_obj_t *self = sercom_table[i2c_id];
+    // Handle IRQ
+    if (self != NULL) {
+        Sercom *i2c = self->instance;
+        // For now, clear all interrupts
+        if (IRQ_DATA_RECVD) {
+            if (self->len > 0) {
+                *(self->buf)++ = i2c->I2CM.DATA.reg;
+                self->len--;
+                self->timeout = I2C_TIMEOUT;
+            }
+            if (self->len > 0) { // no ACK at the last byte
+                PREPARE_ACK; // Send ACK
+                i2c_send_command(i2c, 0x02);
+            } else {
+                PREPARE_NACK; // Send NACK after the last byte
+                self->state = state_done;
+                i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_SB;
+            }
+        } else if (IRQ_DATA_SENT) {
+            if (NACK_RECVD) { // e.g. NACK after adress for both read and write.
+                self->state = state_nack; // force stop of transmission
+                i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_MB;
+            } else if (self->len > 0) { // data to be sent
+                i2c->I2CM.DATA.bit.DATA = *(self->buf)++;
+                self->len--;
+                self->timeout = I2C_TIMEOUT;
+            } else { // No data left, if there was any.
+                self->state = state_done;
+                i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_MB;
+            }
+        } else { // On any error, e.g. ARBLOST or BUSERROR, stop the transmission
+            self->len = 0;
+            self->state = state_buserr;
+            i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_ERROR;
+        }
+    }
+}
+
+STATIC void machine_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_printf(print, "I2C(%u, freq=%u, scl=%u, sda=%u)",
+        self->id, self->freq, self->scl, self->sda);
+}
+
+mp_obj_t machine_i2c_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
+    enum { ARG_id, ARG_freq, ARG_scl, ARG_sda };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_freq, MP_ARG_INT, {.u_int = DEFAULT_I2C_FREQ} },
+        { MP_QSTR_scl, MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+        { MP_QSTR_sda, MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
+    };
+
+    // Parse args.
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    // Get I2C bus.
+    int id = mp_obj_get_int(args[ARG_id].u_obj);
+    if (id < 0 || id >= SERCOM_INST_NUM) {
+        mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("I2C(%d) doesn't exist"), id);
+    }
+
+    // Get the peripheral object.
+    machine_i2c_obj_t *self = mp_obj_malloc(machine_i2c_obj_t, &machine_hw_i2c_type);
+    self->id = id;
+    self->instance = sercom_instance[self->id];
+
+    // Set SCL/SDA pins.
+    sercom_pad_config_t scl_pad_config;
+    self->scl = mp_hal_get_pin_obj(args[ARG_scl].u_obj);
+    scl_pad_config = get_sercom_config(self->scl, self->id);
+
+    sercom_pad_config_t sda_pad_config;
+    self->sda = mp_hal_get_pin_obj(args[ARG_sda].u_obj);
+    sda_pad_config = get_sercom_config(self->sda, self->id);
+    if (sda_pad_config.pad_nr != 0 || scl_pad_config.pad_nr != 1) {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid pin for sda or scl"));
+    }
+    sercom_table[self->id] = self;
+    self->freq = args[ARG_freq].u_int;
+
+    // Configure the Pin mux.
+    mp_hal_set_pin_mux(self->scl, scl_pad_config.alt_fct);
+    mp_hal_set_pin_mux(self->sda, sda_pad_config.alt_fct);
+
+    // Set up the clocks
+    enable_sercom_clock(self->id);
+
+    // Initialise the I2C peripheral
+    Sercom *i2c = self->instance;
+
+    // Reset the device
+    i2c->I2CM.CTRLA.reg = SERCOM_I2CM_CTRLA_SWRST;
+    while (i2c->I2CM.SYNCBUSY.bit.SWRST == 1) {
+    }
+    // Set to master mode, inactivity timeout of 20 SCL cycles and speed.
+    i2c->I2CM.CTRLA.reg = SERCOM_I2CM_CTRLA_MODE(0x05)
+        | SERCOM_I2CM_CTRLA_INACTOUT(3)
+        | SERCOM_I2CM_CTRLA_SPEED(self->freq > 400000 ? 1 : 0);
+
+    // I2C is driven by the clock of GCLK Generator 2, with it's freq in variable bus_freq
+    // baud = peripheral_freq / (2 * baudrate) - 5 - (rise_time * peripheral_freq) / 2
+    // Just set the minimal configuration for standard and fast mode.
+    // Set Baud. Assume ~300ns rise time. Maybe set later by a keyword argument.
+    i2c->I2CM.BAUD.reg = get_apb_freq() / (2 * self->freq) - 5 - (get_apb_freq() / 1000000) * RISETIME_NS / 2000;
+
+    // Enable interrupts
+    sercom_register_irq(self->id, SERCOM_IRQ_TYPE_SPI);
+    #if defined(MCU_SAMD21)
+    NVIC_EnableIRQ(SERCOM0_IRQn + self->id);
+    #elif defined(MCU_SAMD51)
+    NVIC_EnableIRQ(SERCOM0_0_IRQn + 4 * self->id); // MB interrupt
+    NVIC_EnableIRQ(SERCOM0_0_IRQn + 4 * self->id + 1); // SB interrupt
+    NVIC_EnableIRQ(SERCOM0_0_IRQn + 4 * self->id + 3); // ERRROR interrupt
+    #endif
+
+    // Now enable I2C.
+    sercom_enable(i2c, 1);
+
+    // Force the bus state to idle
+    i2c->I2CM.STATUS.bit.BUSSTATE = 1;
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC int machine_i2c_transfer_single(mp_obj_base_t *self_in, uint16_t addr, size_t len, uint8_t *buf, unsigned int flags) {
+    machine_i2c_obj_t *self = (machine_i2c_obj_t *)self_in;
+    Sercom *i2c = self->instance;
+
+    self->timeout = I2C_TIMEOUT;
+    self->len = len;
+    self->buf = buf;
+    // Wait a while if the bus is busy
+    while (IS_BUS_BUSY && self->timeout) {
+        MICROPY_EVENT_POLL_HOOK
+        if (--self->timeout == 0) {
+            return -MP_ETIMEDOUT;
+        }
+    }
+    // Enable interrupts and set the state
+    i2c->I2CM.INTENSET.reg = SERCOM_I2CM_INTENSET_MB | SERCOM_I2CM_INTENSET_SB | SERCOM_I2CM_INTENSET_ERROR;
+    self->state = state_busy;
+
+    // Send the adress, which kicks off the transfer
+    i2c->I2CM.ADDR.bit.ADDR = (addr << 1) | READ_MODE;
+
+    // Transfer the data
+    self->timeout = I2C_TIMEOUT;
+    while (self->state == state_busy && self->timeout) {
+        self->timeout--;
+        MICROPY_EVENT_POLL_HOOK
+    }
+    i2c->I2CM.INTENCLR.reg = SERCOM_I2CM_INTENSET_MB | SERCOM_I2CM_INTENSET_SB | SERCOM_I2CM_INTENSET_ERROR;
+
+    // Check the error states after the transfer is stopped
+    if (self->state == state_nack) {
+        SET_STOP_STATE;
+        return self->len == len ? -MP_ENODEV : -MP_EIO;
+    } else if (self->state == state_buserr) {
+        SET_STOP_STATE;
+        return -MP_EIO;
+    } else if (self->timeout == 0) {
+        SET_STOP_STATE;
+        return -MP_ETIMEDOUT;
+    }
+
+    if (flags & MP_MACHINE_I2C_FLAG_STOP) {
+        SET_STOP_STATE;
+    }
+
+    return len;
+}
+
+STATIC const mp_machine_i2c_p_t machine_i2c_p = {
+    .transfer = mp_machine_i2c_transfer_adaptor,
+    .transfer_single = machine_i2c_transfer_single,
+};
+
+MP_DEFINE_CONST_OBJ_TYPE(
+    machine_hw_i2c_type,
+    MP_QSTR_I2C,
+    MP_TYPE_FLAG_NONE,
+    make_new, machine_i2c_make_new,
+    print, machine_i2c_print,
+    protocol, &machine_i2c_p,
+    locals_dict, &mp_machine_i2c_locals_dict
+    );
diff --git a/ports/samd/modmachine.c b/ports/samd/modmachine.c
index 712b520f5..acd672faf 100644
--- a/ports/samd/modmachine.c
+++ b/ports/samd/modmachine.c
@@ -154,6 +154,7 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_Pin),                 MP_ROM_PTR(&machine_pin_type) },
     { MP_ROM_QSTR(MP_QSTR_PWM),                 MP_ROM_PTR(&machine_pwm_type) },
     { MP_ROM_QSTR(MP_QSTR_SoftI2C),             MP_ROM_PTR(&mp_machine_soft_i2c_type) },
+    { MP_ROM_QSTR(MP_QSTR_I2C),                 MP_ROM_PTR(&machine_hw_i2c_type) },
     { MP_ROM_QSTR(MP_QSTR_SoftSPI),             MP_ROM_PTR(&mp_machine_soft_spi_type) },
     { MP_ROM_QSTR(MP_QSTR_SPI),                 MP_ROM_PTR(&machine_spi_type) },
     { MP_ROM_QSTR(MP_QSTR_UART),                MP_ROM_PTR(&machine_uart_type) },
diff --git a/ports/samd/modmachine.h b/ports/samd/modmachine.h
index 143e3488f..431986719 100644
--- a/ports/samd/modmachine.h
+++ b/ports/samd/modmachine.h
@@ -29,6 +29,7 @@
 #include "py/obj.h"
 
 extern const mp_obj_type_t machine_adc_type;
+extern const mp_obj_type_t machine_hw_i2c_type;
 extern const mp_obj_type_t machine_led_type;
 extern const mp_obj_type_t machine_pin_type;
 extern const mp_obj_type_t machine_pwm_type;
diff --git a/ports/samd/mpconfigport.h b/ports/samd/mpconfigport.h
index 22fed00b2..425ecc597 100644
--- a/ports/samd/mpconfigport.h
+++ b/ports/samd/mpconfigport.h
@@ -98,6 +98,7 @@
 #define MICROPY_PY_URANDOM                  (1)
 #define MICROPY_PY_UZLIB                    (1)
 #define MICROPY_PY_UASYNCIO                 (1)
+#define MICROPY_PY_MACHINE_I2C              (1)
 #define MICROPY_PY_MACHINE_SOFTI2C          (1)
 #define MICROPY_PY_MACHINE_SPI              (1)
 #define MICROPY_PY_MACHINE_SOFTSPI          (1)
diff --git a/ports/samd/samd_isr.c b/ports/samd/samd_isr.c
index 2a5a3e042..5cb0668c2 100644
--- a/ports/samd/samd_isr.c
+++ b/ports/samd/samd_isr.c
@@ -109,11 +109,11 @@ void PendSV_Handler(void) {
 
 
 static uint8_t sercom_irq_type[SERCOM_INST_NUM] = {};
-// Temporarily commented until the module is added
+
 void (*sercom_irq_handler_table[])(int num) = {
     common_uart_irq_handler,
     common_spi_irq_handler,
-    NULL  // common_i2c_irq_handler
+    common_i2c_irq_handler
 };
 
 void sercom_register_irq(int sercom_id, int mode) {