Function i2c_transfer stops execution for I2C_SAM0

[alfonsotames]

Describe the bug

Function i2c_transfer hangs for I2C_SAM0

To Reproduce

Invoking the i2c_transfer stops execution:

	u8_t data[] = {0xAA,0xBB,0xCC};
	msgs[0].buf = data;
	msgs[0].len = 3;
	msgs[0].flags = I2C_MSG_WRITE | I2C_MSG_STOP;
	i2c_transfer(i2c_dev, &msgs[0], 1, 0x00);

Expected behavior

Continue the program execution after invoking the transfer function.

Impact
i2C is not working for SAM0

Screenshots or console output

I am attaching the program, dts, defconfig, and gdb output.

This is the program:

#include <zephyr.h>
#include <device.h>
#include <drivers/i2c.h>

#define I2C_DEV DT_LABEL(DT_ALIAS(i2c_0))

void main(void)
{
	printk("Sending i2c message in:\n");

	for (int x=3; x >0; x--) {
		printk("t - %d\n",x);
		k_msleep(1000);
	}
	struct device * i2c_dev;
	i2c_dev = device_get_binding(I2C_DEV);
	if (!i2c_dev) {
		printk("I2C: Device driver not found.\n");
		return;
	}

	struct i2c_msg msgs[1];
	u8_t data[] = {0xAA,0xBB,0xCC};
	msgs[0].buf = data;
	msgs[0].len = 3;
	msgs[0].flags = I2C_MSG_WRITE | I2C_MSG_STOP;
	i2c_transfer(i2c_dev, &msgs[0], 1, 0x00);
	u32_t cnt = 0;
	while (1) {
		printk("%d Test !\n",cnt);
		k_msleep(500);
		cnt++;
	}
}

This is the GDB output:

Breakpoint 1, main () at /home/mufufu/opt/zephyr/zephyrmaster/proyectos/test_i2c/src/main.c:25
25		msgs[0].buf = data;
26		msgs[0].len = 3;
28		i2c_transfer(i2c_dev, &msgs[0], 1, 0x00);
i2c_transfer (num_msgs=1 '\001', addr=0, msgs=0x2000164c <z_main_stack+980>, dev=0x200001ec <__device_i2c_sam0_0>)
    at /home/mufufu/opt/zephyr/zephyrmaster/proyectos/test_i2c/src/main.c:28
28		i2c_transfer(i2c_dev, &msgs[0], 1, 0x00);
z_impl_i2c_transfer (num_msgs=1 '\001', addr=0, msgs=0x2000164c <z_main_stack+980>, dev=0x200001ec <__device_i2c_sam0_0>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/drivers/i2c.h:255
255		return api->transfer(dev, msgs, num_msgs, addr);
i2c_sam0_transfer (dev=0x200001ec <__device_i2c_sam0_0>, msgs=0x2000164c <z_main_stack+980>, num_msgs=1 '\001', addr=0)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/drivers/i2c/i2c_sam0.c:382
382		if (!num_msgs) {
387			if (!msgs->len) {
393			i2c->INTENCLR.reg = SERCOM_I2CM_INTENCLR_MASK;
394			i2c->INTFLAG.reg = SERCOM_I2CM_INTFLAG_MASK;
396			i2c->STATUS.reg = SERCOM_I2CM_STATUS_ARBLOST |
402			wait_synchronization(i2c);
wait_synchronization (regs=regs@entry=0x42001c00)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/drivers/i2c/i2c_sam0.c:71
71		while ((regs->SYNCBUSY.reg & SERCOM_I2CM_SYNCBUSY_MASK) != 0) {
72		}
i2c_sam0_transfer (dev=<optimized out>, msgs=0x2000164c <z_main_stack+980>, num_msgs=1 '\001', addr=<optimized out>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/drivers/i2c/i2c_sam0.c:404
404			data->msg.buffer = msgs->buf;
405			data->msg.size = msgs->len;
406			data->msg.status = 0;
409			if ((msgs->flags & I2C_MSG_RW_MASK) == I2C_MSG_READ) {
417			if (msgs->flags & I2C_MSG_ADDR_10_BITS) {
425			int key = irq_lock();
arch_irq_lock () at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/arch/arm/aarch32/asm_inline_gcc.h:48
48		__asm__ volatile("mrs %0, PRIMASK;"
i2c_sam0_transfer (dev=<optimized out>, msgs=0x2000164c <z_main_stack+980>, num_msgs=1 '\001', addr=<optimized out>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/drivers/i2c/i2c_sam0.c:438
438			wait_synchronization(i2c);
wait_synchronization (regs=regs@entry=0x42001c00)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/drivers/i2c/i2c_sam0.c:71
71		while ((regs->SYNCBUSY.reg & SERCOM_I2CM_SYNCBUSY_MASK) != 0) {
72		}
i2c_sam0_transfer (dev=<optimized out>, msgs=0x2000164c <z_main_stack+980>, num_msgs=1 '\001', addr=<optimized out>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/drivers/i2c/i2c_sam0.c:441
441			i2c->INTENSET.reg = SERCOM_I2CM_INTENSET_ERROR;
444			if ((msgs->flags & I2C_MSG_RW_MASK) == I2C_MSG_READ) {
463					i2c->INTENSET.reg = SERCOM_I2CM_INTENSET_MB;
455					i2c->INTENSET.reg = SERCOM_I2CM_INTENSET_SB;
467			irq_unlock(key);
arch_irq_unlock (key=<optimized out>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/arch/arm/aarch32/asm_inline_gcc.h:87
87		if (key) {
90		__asm__ volatile(
i2c_sam0_transfer (dev=<optimized out>, msgs=0x2000164c <z_main_stack+980>, num_msgs=1 '\001', addr=<optimized out>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/drivers/i2c/i2c_sam0.c:470
470			k_sem_take(&data->sem, K_FOREVER);
k_sem_take (timeout=..., sem=0x20000898 <i2c_sam0_dev_data_0>) at zephyr/include/generated/syscalls/kernel.h:756
756		return z_impl_k_sem_take(sem, timeout);
z_impl_k_sem_take (sem=sem@entry=0x20000898 <i2c_sam0_dev_data_0>, timeout=...)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/arch/arm/aarch32/asm_inline_gcc.h:48
48		__asm__ volatile("mrs %0, PRIMASK;"
146		if (likely(sem->count > 0U)) {
153		if (K_TIMEOUT_EQ(timeout, K_NO_WAIT)) {
159		ret = z_pend_curr(&lock, key, &sem->wait_q, timeout);
z_pend_curr (lock=lock@entry=0x20001277, key=..., wait_q=wait_q@entry=0x20000898 <i2c_sam0_dev_data_0>, timeout=...)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:675
675		pending_current = _current;
677		pend(_current, wait_q, timeout);
pend (thread=0x20000940 <z_main_thread>, wait_q=wait_q@entry=0x20000898 <i2c_sam0_dev_data_0>, timeout=...)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/arch/arm/aarch32/asm_inline_gcc.h:48
48		__asm__ volatile("mrs %0, PRIMASK;"
600			add_to_waitq_locked(thread, wait_q);
add_to_waitq_locked (thread=thread@entry=0x20000940 <z_main_thread>, wait_q=wait_q@entry=0x20000898 <i2c_sam0_dev_data_0>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:576
576		unready_thread(thread);
unready_thread (thread=thread@entry=0x20000940 <z_main_thread>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/include/ksched.h:143
143		return z_is_thread_state_set(thread, _THREAD_QUEUED);
560			_priq_run_remove(&_kernel.ready_q.runq, thread);
z_priq_dumb_remove (pq=pq@entry=0x200009d0 <_kernel+36>, thread=thread@entry=0x20000940 <z_main_thread>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:869
869		if (pq == &_kernel.ready_q.runq && thread == _current &&
115		return (state & (_THREAD_PENDING | _THREAD_PRESTART | _THREAD_DEAD |
877		sys_dlist_remove(&thread->base.qnode_dlist);
sys_dlist_remove (node=0x20000940 <z_main_thread>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/sys/dlist.h:497
497		node->prev->next = node->next;
498		node->next->prev = node->prev;
499		sys_dnode_init(node);
sys_dnode_init (node=0x20000940 <z_main_thread>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/sys/dlist.h:499
499		sys_dnode_init(node);
211		node->prev = NULL;
unready_thread (thread=thread@entry=0x20000940 <z_main_thread>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:561
561			z_mark_thread_as_not_queued(thread);
z_mark_thread_as_not_queued (thread=0x20000940 <z_main_thread>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:561
561			z_mark_thread_as_not_queued(thread);
z_reset_thread_states (thread=0x20000940 <z_main_thread>, states=128)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/include/ksched.h:191
191		z_reset_thread_states(thread, _THREAD_QUEUED);
unready_thread (thread=thread@entry=0x20000940 <z_main_thread>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:563
563		update_cache(thread == _current);
update_cache (preempt_ok=1) at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:354
354		struct k_thread *thread = next_up();
z_priq_dumb_best (pq=pq@entry=0x200009d0 <_kernel+36>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:883
883		sys_dnode_t *n = sys_dlist_peek_head(pq);
sys_dlist_peek_head (list=list@entry=0x200009d0 <_kernel+36>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:883
883		sys_dnode_t *n = sys_dlist_peek_head(pq);
sys_dlist_is_empty (list=list@entry=0x200009d0 <_kernel+36>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/sys/dlist.h:293
293		return sys_dlist_is_empty(list) ? NULL : list->head;
next_up () at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:203
203		if (_current->base.thread_state & _THREAD_ABORTING) {
217		return thread ? thread : _current_cpu->idle_thread;
update_cache (preempt_ok=1) at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:356
356		if (should_preempt(thread, preempt_ok)) {
should_preempt (preempt_ok=1, thread=0x200008d4 <z_idle_threads>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:356
356		if (should_preempt(thread, preempt_ok)) {
update_cache (preempt_ok=1) at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:358
358			if (thread != _current) {
359				z_reset_time_slice();
z_reset_time_slice () at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:285
285		if (slice_time != 0) {
update_cache (preempt_ok=1) at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:363
363			_kernel.ready_q.cache = thread;
add_to_waitq_locked (thread=thread@entry=0x20000940 <z_main_thread>, wait_q=wait_q@entry=0x20000898 <i2c_sam0_dev_data_0>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:577
577		z_mark_thread_as_pending(thread);
z_mark_thread_as_pending (thread=0x20000940 <z_main_thread>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/include/ksched.h:165
165		thread->base.thread_state |= _THREAD_PENDING;
add_to_waitq_locked (thread=thread@entry=0x20000940 <z_main_thread>, wait_q=wait_q@entry=0x20000898 <i2c_sam0_dev_data_0>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:580
580		if (wait_q != NULL) {
582			z_priq_wait_add(&wait_q->waitq, thread);
z_priq_dumb_add (thread=<optimized out>, pq=<optimized out>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:582
582			z_priq_wait_add(&wait_q->waitq, thread);
sys_dlist_peek_head (list=<optimized out>) at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:582
582			z_priq_wait_add(&wait_q->waitq, thread);
sys_dlist_is_empty (list=<optimized out>) at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:581
581			thread->base.pended_on = wait_q;
add_to_waitq_locked (thread=thread@entry=0x20000940 <z_main_thread>, wait_q=wait_q@entry=0x20000898 <i2c_sam0_dev_data_0>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:582
582			z_priq_wait_add(&wait_q->waitq, thread);
z_priq_dumb_add (thread=0x20000940 <z_main_thread>, pq=0x20000898 <i2c_sam0_dev_data_0>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:582
582			z_priq_wait_add(&wait_q->waitq, thread);
sys_dlist_peek_head (list=0x20000898 <i2c_sam0_dev_data_0>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/sys/dlist.h:293
293		return sys_dlist_is_empty(list) ? NULL : list->head;
add_to_waitq_locked (thread=thread@entry=0x20000940 <z_main_thread>, wait_q=wait_q@entry=0x20000898 <i2c_sam0_dev_data_0>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:582
582			z_priq_wait_add(&wait_q->waitq, thread);
z_priq_dumb_add (thread=0x20000940 <z_main_thread>, pq=0x20000898 <i2c_sam0_dev_data_0>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:582
582			z_priq_wait_add(&wait_q->waitq, thread);
sys_dlist_append (node=0x20000940 <z_main_thread>, list=0x20000898 <i2c_sam0_dev_data_0>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/sys/dlist.h:405
405		node->next = list;
406		node->prev = list->tail;
408		list->tail->next = node;
409		list->tail = node;
pend (thread=0x20000940 <z_main_thread>, wait_q=wait_q@entry=0x20000898 <i2c_sam0_dev_data_0>, timeout=...)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:599
599		LOCKED(&sched_spinlock) {
k_spin_unlock (key=..., l=0x20001277) at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:599
599		LOCKED(&sched_spinlock) {
arch_irq_unlock (key=1) at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/arch/arm/aarch32/asm_inline_gcc.h:87
87		if (key) {
pend (thread=0x20000940 <z_main_thread>, wait_q=wait_q@entry=0x20000898 <i2c_sam0_dev_data_0>, timeout=...)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:603
603		add_thread_timeout(thread, timeout);
add_thread_timeout (timeout=..., thread=0x20000940 <z_main_thread>)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/kernel/sched.c:588
588		if (!K_TIMEOUT_EQ(timeout, K_FOREVER)) {
arch_swap (key=key@entry=0) at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/arch/arm/core/aarch32/swap.c:43
43		_current->arch.basepri = key;
44		_current->arch.swap_return_value = _k_neg_eagain;
48		SCB->ICSR |= SCB_ICSR_PENDSVSET_Msk;
51		irq_unlock(0);
arch_irq_unlock (key=0) at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/arch/arm/aarch32/asm_inline_gcc.h:90
90		__asm__ volatile(

Program stopped.
0x000023c2 in arch_irq_unlock (key=0)
    at /home/mufufu/opt/zephyr/zephyrmaster/zephyrproject/zephyr/include/arch/arm/aarch32/asm_inline_gcc.h:90
90		__asm__ volatile(
target not halted
target at91samd21g18a.cpu was not halted when step was requested

My board defconfig:

CONFIG_SOC_SERIES_SAMD21=y
CONFIG_SOC_PART_NUMBER_SAMD21G18A=y
CONFIG_BOARD_ITSYBITSY_M0=y
CONFIG_SOC_ATMEL_SAMD_OSC8M_AS_MAIN=y
CONFIG_CORTEX_M_SYSTICK=y
CONFIG_CONSOLE=y
CONFIG_UART_CONSOLE=y
CONFIG_SERIAL=y
CONFIG_UART_SAM0=y
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_GPIO=y
CONFIG_GPIO_SAM0=y
CONFIG_WATCHDOG=y
CONFIG_WDT_SAM0=y
CONFIG_SPI=y
CONFIG_SPI_SAM0=y
CONFIG_PINMUX=y
CONFIG_PINMUX_SAM0=y
CONFIG_USB_DEVICE_STACK=y
CONFIG_USB=y
CONFIG_USB_DC_SAM0=y
CONFIG_USE_DT_CODE_PARTITION=y
CONFIG_SERIAL=y
CONFIG_UART_INTERRUPT_DRIVEN=y
CONFIG_USB_CDC_ACM=y
CONFIG_USB_DEVICE_PRODUCT="Serafino"
CONFIG_UART_CONSOLE_ON_DEV_NAME="CDC_ACM_0"
CONFIG_UART_SAM0=y
CONFIG_USB_UART_CONSOLE=y
CONFIG_UART_CONSOLE=y
CONFIG_UART_LINE_CTRL=y
CONFIG_USB_UART_DTR_WAIT=y
CONFIG_PRINTK=y
CONFIG_I2C=y
CONFIG_I2C_SAM0=y
CONFIG_COUNTER=y
CONFIG_COUNTER_SAM0_TC32=y

dts:

/dts-v1/;
#include <atmel/samd21.dtsi>

/ {
	model = "ItsyBitsy M0";
	compatible = "atsamd21,itsybitsy_m0", "atmel,samd21j18a", "atmel,samd21";
	chosen {
		zephyr,console = &sercom3;
		zephyr,shell-uart = &sercom3;
		zephyr,sram = &sram0;
		zephyr,flash = &flash0;
	};
	/* These aliases are provided for compatibility with samples */
	aliases {
		led0 = &led0;
		i2c-0 = &sercom5;
                spi-0 = &sercom4;
	};
	leds {
		compatible = "gpio-leds";
		led0: led_0 {
			gpios = <&porta 17 GPIO_ACTIVE_LOW>;
			label = "Red LED";
		};
	};
};
&cpu0 {
	clock-frequency = <48000000>;
};
&sercom0 {
	status = "okay";
	compatible = "atmel,sam0-uart";
	current-speed = <9600>;
	rxpo = <3>;
	txpo = <2>;
};
&sercom4 {
	status = "okay";
	compatible = "atmel,sam0-spi";
	dipo = <0>;
	dopo = <1>;
	#address-cells = <1>;
	#size-cells = <0>;
};
&sercom3 {
	status = "okay";
	compatible = "atmel,sam0-uart";
	current-speed = <115200>;
	rxpo = <1>;
	txpo = <0>;
};
&sercom5 {
	status = "okay";
	compatible = "atmel,sam0-i2c";
	clock-frequency = <I2C_BITRATE_FAST>;
	#address-cells = <1>;
	#size-cells = <0>;
};
&usb0 {
	status = "okay";
};

pinmux.c

#include <init.h>
#include <drivers/pinmux.h>
#include <soc.h>

static int board_pinmux_init(struct device *dev)
{
	struct device *muxa = device_get_binding(DT_LABEL(DT_NODELABEL(pinmux_a)));
	struct device *muxb = device_get_binding(DT_LABEL(DT_NODELABEL(pinmux_b)));

	ARG_UNUSED(dev);

#if (ATMEL_SAM0_DT_SERCOM_CHECK(0, atmel_sam0_uart) && CONFIG_UART_SAM0)
	/* SERCOM0 on RX=PA11, TX=PA10 */
	pinmux_pin_set(muxa, 11, PINMUX_FUNC_C);
	pinmux_pin_set(muxa, 10, PINMUX_FUNC_C);
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(1, atmel_sam0_uart) && CONFIG_UART_SAM0)
#warning Pin mapping may not be configured
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(2, atmel_sam0_uart) && CONFIG_UART_SAM0)
#warning Pin mapping may not be configured
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(3, atmel_sam0_uart) && CONFIG_UART_SAM0)
pinmux_pin_set(muxa, 25, PINMUX_FUNC_C);
pinmux_pin_set(muxa, 24, PINMUX_FUNC_C);
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(4, atmel_sam0_uart) && CONFIG_UART_SAM0)
#warning Pin mapping may not be configured
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(5, atmel_sam0_uart) && CONFIG_UART_SAM0)
#warning Pin mapping may not be configured
#endif

#if (ATMEL_SAM0_DT_SERCOM_CHECK(0, atmel_sam0_spi) && CONFIG_SPI_SAM0)
#warning Pin mapping may not be configured
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(1, atmel_sam0_spi) && CONFIG_SPI_SAM0)
pinmux_pin_set(muxa, 0, PINMUX_FUNC_D);
pinmux_pin_set(muxa, 1, PINMUX_FUNC_D);
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(2, atmel_sam0_spi) && CONFIG_SPI_SAM0)
#warning Pin mapping may not be configured
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(3, atmel_sam0_spi) && CONFIG_SPI_SAM0)
#warning Pin mapping may not be configured
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(4, atmel_sam0_spi) && CONFIG_SPI_SAM0)
/* SPI SERCOM4 on MISO=PB16/pad 0, MOSI=PB22/pad 2, SCK=PB23/pad 3 */
pinmux_pin_set(muxb, 10, PINMUX_FUNC_D);
pinmux_pin_set(muxb, 11, PINMUX_FUNC_D);
pinmux_pin_set(muxa, 12, PINMUX_FUNC_D);
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(5, atmel_sam0_spi) && CONFIG_SPI_SAM0)
#warning Pin mapping may not be configured
#endif

#if (ATMEL_SAM0_DT_SERCOM_CHECK(0, atmel_sam0_i2c) && CONFIG_I2C_SAM0)
#warning Pin mapping may not be configured
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(1, atmel_sam0_i2c) && CONFIG_I2C_SAM0)
#warning Pin mapping may not be configured
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(2, atmel_sam0_i2c) && CONFIG_I2C_SAM0)
#warning Pin mapping may not be configured
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(3, atmel_sam0_i2c) && CONFIG_I2C_SAM0)
#warning Pin mapping may not be configured
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(4, atmel_sam0_i2c) && CONFIG_I2C_SAM0)
#warning Pin mapping may not be configured
#endif
#if (ATMEL_SAM0_DT_SERCOM_CHECK(5, atmel_sam0_i2c) && CONFIG_I2C_SAM0)
/* SERCOM5 */
pinmux_pin_set(muxa, 23, PINMUX_FUNC_D);
pinmux_pin_set(muxa, 22, PINMUX_FUNC_D);
#endif

#ifdef CONFIG_USB_DC_SAM0
	/* USB DP on PA25, USB DM on PA24 */
	pinmux_pin_set(muxa, 25, PINMUX_FUNC_G);
	pinmux_pin_set(muxa, 24, PINMUX_FUNC_G);
#endif
	return 0;
}
SYS_INIT(board_pinmux_init, PRE_KERNEL_1, CONFIG_PINMUX_INIT_PRIORITY);

Environment (please complete the following information):

• Testing with an Adafruit ItsyBitsy M0 (ATSAMD21G18)
• Ubuntu Linux
• Toolchain Zephyr SDK 0.11.3
• Testing in Zephyr master

Additional context
Add any other context about the problem here.

[alfonsotames]

Ha! Forgot to put the pull up resistors! Two 10K pulling up the SDA and SCL lines where enough.