WIP: bit-banging I2C support for EEPROM access on QMOD

for now, it just continuously reads the EEPROM bytes and dumps them to
the serial console for testing.

firmware/Makefile

@@ -147,7 +147,7 @@ C_CMSIS    = core_cm3.o
 C_LOWLEVEL = board_cstartup_gnu.o board_lowlevel.o syscalls.o exceptions.o
 C_LIBLEVEL = spi.o pio.o pmc.o usart.o pio_it.o pio_capture.o uart_console.o iso7816_4.o wdt.o led.o tc.o unique_id.o
 C_CCID = cciddriver.o USBD.o USBDDriver.o USBD_HAL.o USBRequests.o USBDCallbacks.o USBDescriptors.o USBDDriverCallbacks.o
-C_SIMTRACE = simtrace_iso7816.o usb.o ccid.o sniffer.o mitm.o ringbuffer.o host_communication.o iso7816_fidi.o tc_etu.o req_ctx.o card_emu.o mode_cardemu.o
+C_SIMTRACE = simtrace_iso7816.o usb.o ccid.o sniffer.o mitm.o ringbuffer.o host_communication.o iso7816_fidi.o tc_etu.o req_ctx.o card_emu.o mode_cardemu.o i2c.o
 C_APPLEVEL = main.o
 C_OBJECTS  = $(C_CMSIS) $(C_LOWLEVEL) $(C_LIBLEVEL) $(C_APPLEVEL) $(C_CCID) $(C_SIMTRACE)
 

firmware/src_simtrace/i2c.c

@@ -0,0 +1,206 @@
+#include "board.h"
+#include <stdbool.h>
+
+/* Low-Level I2C Routines */
+
+static const Pin pin_sda = {PIO_PA30, PIOA, ID_PIOA, PIO_OUTPUT_1, PIO_OPENDRAIN };
+static const Pin pin_sda_in = {PIO_PA30, PIOA, ID_PIOA, PIO_INPUT, PIO_DEFAULT };
+static const Pin pin_scl = {PIO_PA31, PIOA, ID_PIOA, PIO_OUTPUT_1, PIO_OPENDRAIN };
+
+void i2c_pin_init(void)
+{
+	PIO_Configure(&pin_scl, PIO_LISTSIZE(pin_scl));
+	PIO_Configure(&pin_sda, PIO_LISTSIZE(pin_sda));
+}
+
+static void set_scl(void)
+{
+	PIO_Set(&pin_scl);
+}
+
+static void set_sda(void)
+{
+	PIO_Set(&pin_sda);
+}
+
+static void clear_scl(void)
+{
+	PIO_Clear(&pin_scl);
+}
+
+static void clear_sda(void)
+{
+	PIO_Clear(&pin_sda);
+}
+
+static bool read_sda(void)
+{
+	bool ret;
+
+	PIO_Configure(&pin_sda_in, PIO_LISTSIZE(pin_sda_in));
+	if (PIO_Get(&pin_sda))
+		ret = true;
+	else
+		ret = false;
+	PIO_Configure(&pin_sda, PIO_LISTSIZE(pin_sda));
+
+	return ret;
+}
+
+/* Core I2C Routines */
+
+static bool i2c_started = false;
+
+static void i2c_delay()
+{
+	volatile int v;
+	int i;
+
+	for (i = 0; i < 100; i++) {
+		v = 0;
+	}
+}
+
+static void i2c_start_cond(void)
+{
+	if (i2c_started) {
+		set_sda();
+		i2c_delay();
+		set_scl();
+		i2c_delay();
+	}
+
+	i2c_delay();
+	clear_sda();
+	i2c_delay();
+	clear_scl();
+	i2c_started = true;
+}
+
+static void i2c_stop_cond(void)
+{
+	clear_sda();
+	i2c_delay();
+	set_scl();
+	i2c_delay();
+	set_sda();
+	i2c_delay();
+	i2c_started = false;
+}
+
+static void i2c_write_bit(bool bit)
+{
+	if (bit)
+		set_sda();
+	else
+		clear_sda();
+	i2c_delay();
+	set_scl();
+	i2c_delay();
+	clear_scl();
+	i2c_delay();
+}
+
+static bool i2c_read_bit(void)
+{
+	bool bit;
+
+	set_sda();
+	i2c_delay();
+	set_scl();
+	i2c_delay();
+	bit = read_sda();
+	clear_scl();
+
+	return bit;
+}
+
+bool i2c_write_byte(bool send_start, bool send_stop, uint8_t byte)
+{
+	uint8_t bit;
+	bool nack;
+
+	if (send_start)
+		i2c_start_cond();
+
+	for (bit = 0; bit < 8; bit++) {
+		i2c_write_bit((byte & 0x80) != 0);
+		byte <<= 1;
+	}
+
+	nack = i2c_read_bit();
+
+	if (send_stop)
+		i2c_stop_cond();
+
+	return nack;
+}
+
+uint8_t i2c_read_byte(bool nack, bool send_stop)
+{
+	uint8_t byte = 0;
+	uint8_t bit;
+
+	for (bit = 0; bit < 8; bit++) {
+		byte = (byte << 1) | i2c_read_bit();
+	}
+
+	i2c_write_bit(nack);
+
+	if (send_stop)
+		i2c_stop_cond();
+
+	return byte;
+}
+
+
+/* EEPROM related code */
+
+int eeprom_write_byte(uint8_t slave, uint8_t addr, uint8_t byte)
+{
+	bool nack;
+
+	/* Write slave address */
+	nack = i2c_write_byte(true, false, slave << 1);
+	if (nack)
+		goto out_stop;
+	nack = i2c_write_byte(false, false, addr);
+	if (nack)
+		goto out_stop;
+	nack = i2c_write_byte(false, true, byte);
+	if (nack)
+		goto out_stop;
+
+out_stop:
+	i2c_stop_cond();
+	if (nack)
+		return -1;
+	else
+		return 0;
+}
+
+int eeprom_read_byte(uint8_t slave, uint8_t addr)
+{
+	bool nack;
+
+	/* dummy write cycle */
+	nack = i2c_write_byte(true, false, slave << 1);
+	if (nack)
+		goto out_stop;
+	nack = i2c_write_byte(false, false, addr);
+	if (nack)
+		goto out_stop;
+	/* Re-start with read */
+	nack = i2c_write_byte(true, false, (slave << 1) | 1);
+	if (nack)
+		goto out_stop;
+
+	return i2c_read_byte(true, true);
+
+out_stop:
+	i2c_stop_cond();
+	if (nack)
+		return -1;
+	else
+		return 0;
+}

firmware/src_simtrace/i2c.h

@@ -0,0 +1,5 @@
+#pragma once
+
+void i2c_pin_init(void);
+int eeprom_write_byte(uint8_t slave, uint8_t addr, uint8_t byte);
+int eeprom_read_byte(uint8_t slave, uint8_t addr);

firmware/src_simtrace/main.c

@@ -97,6 +97,7 @@ void USART0_IrqHandler(void)
 	config_func_ptrs[simtrace_config].usart0_irq();
 }
 
+#include "i2c.h"
 /*------------------------------------------------------------------------------
  *        Main
  *------------------------------------------------------------------------------*/
@@ -131,6 +132,18 @@ extern int main(void)
 		   g_unique_id[0], g_unique_id[1],
 		   g_unique_id[2], g_unique_id[3]);
 
+#if 1
+	static const Pin pin_hub_rst = {PIO_PA13, PIOA, ID_PIOA, PIO_OUTPUT_1, PIO_DEFAULT};
+	PIO_Configure(&pin_hub_rst, 1);
+	i2c_pin_init();
+	while (1) {
+		for (i = 0; i < 256; i ++) {
+			int byte = eeprom_read_byte(0x50, i);
+			TRACE_INFO("0x%02x: %02x\r\n", i, byte);
+		}
+	}
+#endif
+
 	TRACE_INFO("USB init...\r\n");
 	while (USBD_GetState() < USBD_STATE_CONFIGURED) {
 		if (i >= MAX_USB_ITER * 3) {