drivers/i2c/i2c_sam_twihs_rtio.c

/*
 * Copyright (c) 2017 Piotr Mienkowski
 * Copyright (c) 2023 Gerson Fernando Budke
 * Copyright (c) 2023 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#define DT_DRV_COMPAT atmel_sam_i2c_twihs

/** @file
 * @brief I2C bus (TWIHS) driver for Atmel SAM MCU family.
 *
 * Only I2C Controller Mode with 7 bit addressing is currently supported.
 */

#include <errno.h>
#include <zephyr/sys/__assert.h>
#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/init.h>
#include <soc.h>
#include <zephyr/drivers/i2c.h>
#include <zephyr/drivers/i2c/rtio.h>
#include <zephyr/drivers/pinctrl.h>
#include <zephyr/drivers/clock_control/atmel_sam_pmc.h>

#define LOG_LEVEL CONFIG_I2C_LOG_LEVEL
#include <zephyr/logging/log.h>
#include <zephyr/irq.h>
LOG_MODULE_REGISTER(i2c_sam_twihs_rtio);

#include "i2c-priv.h"

/** I2C bus speed [Hz] in Standard Mode */
#define BUS_SPEED_STANDARD_HZ         100000U
/** I2C bus speed [Hz] in Fast Mode */
#define BUS_SPEED_FAST_HZ             400000U
/** I2C bus speed [Hz] in High Speed Mode */
#define BUS_SPEED_HIGH_HZ            3400000U
/* Maximum value of Clock Divider (CKDIV) */
#define CKDIV_MAX                          7

/* Device constant configuration parameters */
struct i2c_sam_twihs_dev_cfg {
	Twihs *regs;
	void (*irq_config)(void);
	uint32_t bitrate;
	const struct atmel_sam_pmc_config clock_cfg;
	const struct pinctrl_dev_config *pcfg;
	uint8_t irq_id;
};

/* Device run time data */
struct i2c_sam_twihs_dev_data {
	struct i2c_rtio *ctx;
	uint32_t buf_idx;
};

static int i2c_clk_set(Twihs *const twihs, uint32_t speed)
{
	uint32_t ck_div = 0U;
	uint32_t cl_div;
	bool div_completed = false;

	/*  From the datasheet "TWIHS Clock Waveform Generator Register"
	 *  T_low = ( ( CLDIV × 2^CKDIV ) + 3 ) × T_MCK
	 */
	while (!div_completed) {
		cl_div =   ((SOC_ATMEL_SAM_MCK_FREQ_HZ / (speed * 2U)) - 3)
			 / (1 << ck_div);

		if (cl_div <= 255U) {
			div_completed = true;
		} else {
			ck_div++;
		}
	}

	if (ck_div > CKDIV_MAX) {
		LOG_ERR("Failed to configure I2C clock");
		return -EIO;
	}

	/* Set I2C bus clock duty cycle to 50% */
	twihs->TWIHS_CWGR = TWIHS_CWGR_CLDIV(cl_div) | TWIHS_CWGR_CHDIV(cl_div)
			    | TWIHS_CWGR_CKDIV(ck_div);

	return 0;
}

static int i2c_sam_twihs_configure(const struct device *dev, uint32_t config)
{
	const struct i2c_sam_twihs_dev_cfg *const dev_cfg = dev->config;
	Twihs *const twihs = dev_cfg->regs;
	uint32_t bitrate;
	int ret;

	if (!(config & I2C_MODE_CONTROLLER)) {
		LOG_ERR("Master Mode is not enabled");
		return -EIO;
	}

	if (config & I2C_ADDR_10_BITS) {
		LOG_ERR("I2C 10-bit addressing is currently not supported");
		LOG_ERR("Please submit a patch");
		return -EIO;
	}

	/* Configure clock */
	switch (I2C_SPEED_GET(config)) {
	case I2C_SPEED_STANDARD:
		bitrate = BUS_SPEED_STANDARD_HZ;
		break;
	case I2C_SPEED_FAST:
		bitrate = BUS_SPEED_FAST_HZ;
		break;
	default:
		LOG_ERR("Unsupported I2C speed value");
		return -EIO;
	}

	/* Setup clock waveform */
	ret = i2c_clk_set(twihs, bitrate);
	if (ret < 0) {
		return ret;
	}

	/* Disable Target Mode */
	twihs->TWIHS_CR = TWIHS_CR_SVDIS;

	/* Enable Controller Mode */
	twihs->TWIHS_CR = TWIHS_CR_MSEN;

	return 0;
}

static void write_msg_start(Twihs *const twihs, const uint8_t *buf, const uint32_t idx,
			    const uint8_t daddr)
{
	/* Set target address. */
	twihs->TWIHS_MMR = TWIHS_MMR_DADR(daddr);

	/* Write first data byte on I2C bus */
	twihs->TWIHS_THR = buf[idx];

	/* Enable Transmit Ready and Transmission Completed interrupts */
	twihs->TWIHS_IER = TWIHS_IER_TXRDY | TWIHS_IER_TXCOMP | TWIHS_IER_NACK;

}

static void read_msg_start(Twihs *const twihs, const uint32_t len, const uint8_t daddr)
{
	uint32_t twihs_cr_stop;

	/* Set target address and number of internal address bytes */
	twihs->TWIHS_MMR = TWIHS_MMR_MREAD | TWIHS_MMR_DADR(daddr);

	/* In single data byte read the START and STOP must both be set */
	twihs_cr_stop = (len == 1U) ? TWIHS_CR_STOP : 0;

	/* Enable Receive Ready and Transmission Completed interrupts */
	twihs->TWIHS_IER = TWIHS_IER_RXRDY | TWIHS_IER_TXCOMP | TWIHS_IER_NACK;

	/* Start the transfer by sending START condition */
	twihs->TWIHS_CR = TWIHS_CR_START | twihs_cr_stop;
}

static void i2c_sam_twihs_complete(const struct device *dev, int status);

static void i2c_sam_twihs_start(const struct device *dev)
{
	struct i2c_sam_twihs_dev_data *const dev_data = dev->data;
	const struct i2c_sam_twihs_dev_cfg *const dev_cfg = dev->config;
	Twihs *const twihs = dev_cfg->regs;
	struct rtio_sqe *sqe = &dev_data->ctx->txn_curr->sqe;
	struct i2c_dt_spec *dt_spec = sqe->iodev->data;

	/* Clear pending interrupts, such as NACK. */
	(void)twihs->TWIHS_SR;

	/* Set number of internal address bytes to 0, not used. */
	twihs->TWIHS_IADR = 0;

	/* Set the current index to 0 */
	dev_data->buf_idx = 0;

	switch (sqe->op) {
	case RTIO_OP_RX:
		read_msg_start(twihs, sqe->rx.buf_len, dt_spec->addr);
		break;
	case RTIO_OP_TX:
		dev_data->buf_idx = 1;
		write_msg_start(twihs, sqe->tx.buf, 0, dt_spec->addr);
		break;
	default:
		LOG_ERR("Invalid op code %d for submission %p\n", sqe->op, (void *)sqe);
		i2c_sam_twihs_complete(dev, -EINVAL);
	}
}

static void i2c_sam_twihs_complete(const struct device *dev, int status)
{
	const struct i2c_sam_twihs_dev_cfg *const dev_cfg = dev->config;
	Twihs *const twihs = dev_cfg->regs;
	struct i2c_rtio *const ctx = ((struct i2c_sam_twihs_dev_data *)
		dev->data)->ctx;

	/* Disable all enabled interrupts */
	twihs->TWIHS_IDR = twihs->TWIHS_IMR;

	if (i2c_rtio_complete(ctx, status)) {
		i2c_sam_twihs_start(dev);
	}
}

static void i2c_sam_twihs_submit(const struct device *dev, struct rtio_iodev_sqe *iodev_sqe)
{
	struct i2c_rtio *const ctx = ((struct i2c_sam_twihs_dev_data *)
		dev->data)->ctx;

	if (i2c_rtio_submit(ctx, iodev_sqe)) {
		i2c_sam_twihs_start(dev);
	}
}

static void i2c_sam_twihs_isr(const struct device *dev)
{
	const struct i2c_sam_twihs_dev_cfg *const dev_cfg = dev->config;
	struct i2c_sam_twihs_dev_data *const dev_data = dev->data;
	Twihs *const twihs = dev_cfg->regs;
	struct rtio_sqe *sqe = &dev_data->ctx->txn_curr->sqe;
	uint32_t isr_status;

	/* Retrieve interrupt status */
	isr_status = twihs->TWIHS_SR & twihs->TWIHS_IMR;

	/* Not Acknowledged */
	if (isr_status & TWIHS_SR_NACK) {
		i2c_sam_twihs_complete(dev, -EIO);
		return;
	}

	/* Byte received */
	if (isr_status & TWIHS_SR_RXRDY) {
		sqe->rx.buf[dev_data->buf_idx] = twihs->TWIHS_RHR;
		dev_data->buf_idx += 1;

		if (dev_data->buf_idx == sqe->rx.buf_len - 1U) {
			/* Send STOP condition */
			twihs->TWIHS_CR = TWIHS_CR_STOP;
		}
	}

	/* Byte sent */
	if (isr_status & TWIHS_SR_TXRDY) {
		if (dev_data->buf_idx == sqe->tx.buf_len) {
			if (sqe->iodev_flags & RTIO_IODEV_I2C_STOP) {
				/* Send STOP condition */
				twihs->TWIHS_CR = TWIHS_CR_STOP;
				/* Disable Transmit Ready interrupt */
				twihs->TWIHS_IDR = TWIHS_IDR_TXRDY;
			} else {
				/* Transmission completed */
				i2c_sam_twihs_complete(dev, 0);
				return;
			}
		} else {
			twihs->TWIHS_THR = sqe->tx.buf[dev_data->buf_idx++];
		}
	}

	/* Transmission completed */
	if (isr_status & TWIHS_SR_TXCOMP) {
		i2c_sam_twihs_complete(dev, 0);
	}
}

static int i2c_sam_twihs_transfer(const struct device *dev, struct i2c_msg *msgs, uint8_t num_msgs,
				  uint16_t addr)
{
	struct i2c_rtio *const ctx = ((struct i2c_sam_twihs_dev_data *)
		dev->data)->ctx;

	return i2c_rtio_transfer(ctx, msgs, num_msgs, addr);
}

static int i2c_sam_twihs_initialize(const struct device *dev)
{
	const struct i2c_sam_twihs_dev_cfg *const dev_cfg = dev->config;
	struct i2c_sam_twihs_dev_data *const dev_data = dev->data;
	Twihs *const twihs = dev_cfg->regs;
	uint32_t bitrate_cfg;
	int ret;

	/* Configure interrupts */
	dev_cfg->irq_config();

	/* Connect pins to the peripheral */
	ret = pinctrl_apply_state(dev_cfg->pcfg, PINCTRL_STATE_DEFAULT);
	if (ret < 0) {
		return ret;
	}

	/* Enable TWIHS clock in PMC */
	(void)clock_control_on(SAM_DT_PMC_CONTROLLER,
			       (clock_control_subsys_t *)&dev_cfg->clock_cfg);

	/* Reset the module */
	twihs->TWIHS_CR = TWIHS_CR_SWRST;

	bitrate_cfg = i2c_map_dt_bitrate(dev_cfg->bitrate);

	ret = i2c_sam_twihs_configure(dev, I2C_MODE_CONTROLLER | bitrate_cfg);
	if (ret < 0) {
		LOG_ERR("Failed to initialize %s device", dev->name);
		return ret;
	}

	i2c_rtio_init(dev_data->ctx, dev);

	/* Enable module's IRQ */
	irq_enable(dev_cfg->irq_id);

	LOG_INF("Device %s initialized", dev->name);

	return 0;
}

static const struct i2c_driver_api i2c_sam_twihs_driver_api = {
	.configure = i2c_sam_twihs_configure,
	.transfer = i2c_sam_twihs_transfer,
	.iodev_submit = i2c_sam_twihs_submit,
};

#define I2C_TWIHS_SAM_INIT(n)									\
	PINCTRL_DT_INST_DEFINE(n);								\
	static void i2c##n##_sam_irq_config(void)						\
	{											\
		IRQ_CONNECT(DT_INST_IRQN(n), DT_INST_IRQ(n, priority),				\
			    i2c_sam_twihs_isr,							\
			    DEVICE_DT_INST_GET(n), 0);						\
	}											\
												\
	I2C_RTIO_DEFINE(_i2c##n##_sam_rtio,							\
		    DT_INST_PROP_OR(n, sq_size, CONFIG_I2C_RTIO_SQ_SIZE),			\
		    DT_INST_PROP_OR(n, cq_size, CONFIG_I2C_RTIO_CQ_SIZE));			\
												\
	static const struct i2c_sam_twihs_dev_cfg i2c##n##_sam_config = {			\
		.regs = (Twihs *)DT_INST_REG_ADDR(n),						\
		.irq_config = i2c##n##_sam_irq_config,						\
		.clock_cfg = SAM_DT_INST_CLOCK_PMC_CFG(n),					\
		.irq_id = DT_INST_IRQN(n),							\
		.pcfg = PINCTRL_DT_INST_DEV_CONFIG_GET(n),					\
		.bitrate = DT_INST_PROP(n, clock_frequency),					\
	};											\
												\
	static struct i2c_sam_twihs_dev_data i2c##n##_sam_data = {				\
		.ctx = &_i2c##n##_sam_rtio,							\
	};											\
												\
	I2C_DEVICE_DT_INST_DEFINE(n, i2c_sam_twihs_initialize,					\
			    NULL,								\
			    &i2c##n##_sam_data, &i2c##n##_sam_config,				\
			    POST_KERNEL, CONFIG_I2C_INIT_PRIORITY,				\
			    &i2c_sam_twihs_driver_api);

DT_INST_FOREACH_STATUS_OKAY(I2C_TWIHS_SAM_INIT)