i2c_puppet-Linux/app/puppet_i2c.c

#include "puppet_i2c.h"

#include "reg.h"

#include <hardware/i2c.h>
#include <hardware/irq.h>
#include <pico/stdlib.h>

#define REG_ID_INVALID		0x00

static i2c_inst_t *i2c_instances[2] = { i2c0, i2c1 };

static struct
{
	i2c_inst_t *i2c;

	struct
	{
		uint8_t reg;
		uint8_t data;
	} read_buffer;

	uint8_t write_buffer[2];
	uint8_t write_len;
} self;

static void irq_handler(void)
{
	// the controller sent data
	if (self.i2c->hw->intr_stat & I2C_IC_INTR_MASK_M_RX_FULL_BITS) {
		if (self.read_buffer.reg == REG_ID_INVALID) {
			self.read_buffer.reg = self.i2c->hw->data_cmd & 0xff;

			if (self.read_buffer.reg & PACKET_WRITE_MASK) {
				// it'sq a reg write, we need to wait for the second byte before we process
				return;
			}
		} else {
			self.read_buffer.data = self.i2c->hw->data_cmd & 0xff;
		}

		reg_process_packet(self.read_buffer.reg, self.read_buffer.data, self.write_buffer, &self.write_len);

		// ready for the next operation
		self.read_buffer.reg = REG_ID_INVALID;

		return;
	}

	// the controller requested a read
	if (self.i2c->hw->intr_stat & I2C_IC_INTR_MASK_M_RD_REQ_BITS) {
		i2c_write_raw_blocking(self.i2c, self.write_buffer, self.write_len);

		self.i2c->hw->clr_rd_req;
		return;
	}
}

void puppet_i2c_sync_address(void)
{
	i2c_set_slave_mode(self.i2c, true, reg_get_value(REG_ID_ADR));
}

void puppet_i2c_init(void)
{
	// determine the instance based on SCL pin, hope you didn't screw up the SDA pin!
	self.i2c = i2c_instances[(PIN_PUPPET_SCL / 2) % 2];

	i2c_init(self.i2c, 100 * 1000);
	puppet_i2c_sync_address();

	gpio_set_function(PIN_PUPPET_SDA, GPIO_FUNC_I2C);
	gpio_pull_up(PIN_PUPPET_SDA);

	gpio_set_function(PIN_PUPPET_SCL, GPIO_FUNC_I2C);
	gpio_pull_up(PIN_PUPPET_SCL);

	// irq when the controller sends data, and when it requests a read
	self.i2c->hw->intr_mask = I2C_IC_INTR_MASK_M_RD_REQ_BITS | I2C_IC_INTR_MASK_M_RX_FULL_BITS;

	const int irq = I2C0_IRQ + i2c_hw_index(self.i2c);
	irq_set_exclusive_handler(irq, irq_handler);
	irq_set_enabled(irq, true);
}