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// I2C functions for rp2040
//
// Copyright (C) 2022 Lasse Dalegaard <dalegaard@gmail.com>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "board/misc.h" // timer_is_before
#include "gpio.h" // i2c_setup, i2c_read, i2c_write
#include "command.h" // shutdown
#include "sched.h" // sched_shutdown
#include "internal.h" // pclock, gpio_peripheral
#include "hardware/regs/resets.h" // RESETS_RESET_I2C*_BITS
#include "hardware/structs/i2c.h"
struct i2c_info {
i2c_hw_t *i2c;
uint8_t sda_pin, scl_pin, pclk;
};
DECL_ENUMERATION("i2c_bus", "i2c0a", 0);
DECL_ENUMERATION("i2c_bus", "i2c0b", 1);
DECL_ENUMERATION("i2c_bus", "i2c0c", 2);
DECL_ENUMERATION("i2c_bus", "i2c0d", 3);
DECL_ENUMERATION("i2c_bus", "i2c0e", 4);
DECL_ENUMERATION("i2c_bus", "i2c0f", 5);
DECL_ENUMERATION("i2c_bus", "i2c0g", 6);
DECL_ENUMERATION("i2c_bus", "i2c0h", 7);
DECL_ENUMERATION("i2c_bus", "i2c1a", 8);
DECL_ENUMERATION("i2c_bus", "i2c1b", 9);
DECL_ENUMERATION("i2c_bus", "i2c1c", 10);
DECL_ENUMERATION("i2c_bus", "i2c1d", 11);
DECL_ENUMERATION("i2c_bus", "i2c1e", 12);
DECL_ENUMERATION("i2c_bus", "i2c1f", 13);
DECL_ENUMERATION("i2c_bus", "i2c1g", 14);
DECL_CONSTANT_STR("BUS_PINS_i2c0a", "gpio0,gpio1");
DECL_CONSTANT_STR("BUS_PINS_i2c0b", "gpio4,gpio5");
DECL_CONSTANT_STR("BUS_PINS_i2c0c", "gpio8,gpio9");
DECL_CONSTANT_STR("BUS_PINS_i2c0d", "gpio12,gpio13");
DECL_CONSTANT_STR("BUS_PINS_i2c0e", "gpio16,gpio17");
DECL_CONSTANT_STR("BUS_PINS_i2c0f", "gpio20,gpio21");
DECL_CONSTANT_STR("BUS_PINS_i2c0g", "gpio24,gpio25");
DECL_CONSTANT_STR("BUS_PINS_i2c0h", "gpio28,gpio29");
DECL_CONSTANT_STR("BUS_PINS_i2c1a", "gpio2,gpio3");
DECL_CONSTANT_STR("BUS_PINS_i2c1b", "gpio6,gpio7");
DECL_CONSTANT_STR("BUS_PINS_i2c1c", "gpio10,gpio11");
DECL_CONSTANT_STR("BUS_PINS_i2c1d", "gpio14,gpio15");
DECL_CONSTANT_STR("BUS_PINS_i2c1e", "gpio18,gpio19");
DECL_CONSTANT_STR("BUS_PINS_i2c1f", "gpio22,gpio23");
DECL_CONSTANT_STR("BUS_PINS_i2c1g", "gpio26,gpio27");
static const struct i2c_info i2c_bus[] = {
{ i2c0_hw, 0, 1, RESETS_RESET_I2C0_BITS },
{ i2c0_hw, 4, 5, RESETS_RESET_I2C0_BITS },
{ i2c0_hw, 8, 9, RESETS_RESET_I2C0_BITS },
{ i2c0_hw, 12, 13, RESETS_RESET_I2C0_BITS },
{ i2c0_hw, 16, 17, RESETS_RESET_I2C0_BITS },
{ i2c0_hw, 20, 21, RESETS_RESET_I2C0_BITS },
{ i2c0_hw, 24, 25, RESETS_RESET_I2C0_BITS },
{ i2c0_hw, 28, 29, RESETS_RESET_I2C0_BITS },
{ i2c1_hw, 2, 3, RESETS_RESET_I2C1_BITS },
{ i2c1_hw, 6, 7, RESETS_RESET_I2C1_BITS },
{ i2c1_hw, 10, 11, RESETS_RESET_I2C1_BITS },
{ i2c1_hw, 14, 15, RESETS_RESET_I2C1_BITS },
{ i2c1_hw, 18, 19, RESETS_RESET_I2C1_BITS },
{ i2c1_hw, 22, 23, RESETS_RESET_I2C1_BITS },
{ i2c1_hw, 26, 27, RESETS_RESET_I2C1_BITS },
};
struct i2c_config
i2c_setup(uint32_t bus, uint32_t rate, uint8_t addr)
{
if (bus > ARRAY_SIZE(i2c_bus))
shutdown("Invalid i2c bus");
const struct i2c_info *info = &i2c_bus[bus];
gpio_peripheral(info->sda_pin, 3, 1);
gpio_peripheral(info->scl_pin, 3, 1);
if (!is_enabled_pclock(info->pclk)) {
enable_pclock(info->pclk);
i2c_hw_t *i2c = info->i2c;
i2c->enable = 0;
// We set up the bus in 400 kHz mode, but then set timings afterwards
// to match either 100k or 400k mode. This simplifies the setup.
i2c->con = I2C_IC_CON_SPEED_VALUE_FAST << I2C_IC_CON_SPEED_LSB
| I2C_IC_CON_MASTER_MODE_BITS
| I2C_IC_CON_IC_SLAVE_DISABLE_BITS
| I2C_IC_CON_IC_RESTART_EN_BITS;
i2c->tx_tl = 0;
i2c->rx_tl = 0;
uint32_t pclk = get_pclock_frequency(info->pclk);
// See `i2c_set_baudrate` in the Pico SDK `hardware_i2c/i2c.c` file
// for details on the calculations here.
if (rate > 1000000)
rate = 1000000; // Clamp the rate to 1Mbps
uint32_t period = (pclk + rate / 2) / rate;
uint32_t lcnt = period * 3 / 5;
uint32_t hcnt = period - lcnt;
uint32_t sda_tx_hold_count = ((pclk * 3) / 10000000) + 1;
i2c->fs_scl_hcnt = hcnt;
i2c->fs_scl_lcnt = lcnt;
i2c->fs_spklen = lcnt < 16 ? 1 : lcnt / 16;
hw_write_masked(&i2c->sda_hold,
sda_tx_hold_count << I2C_IC_SDA_HOLD_IC_SDA_TX_HOLD_LSB,
I2C_IC_SDA_HOLD_IC_SDA_TX_HOLD_BITS);
}
return (struct i2c_config){ .i2c=info->i2c, .addr=addr };
}
static void
i2c_start(i2c_hw_t *i2c, uint8_t addr)
{
i2c->enable = 0;
i2c->tar = addr;
i2c->enable = 1;
}
static void
i2c_stop(i2c_hw_t *i2c)
{
i2c->enable = 0;
}
static void
i2c_do_write(i2c_hw_t *i2c, uint8_t addr, uint8_t write_len, uint8_t *write
, uint8_t send_stop, uint32_t timeout)
{
for (int i = 0; i < write_len; i++) {
int first = i == 0;
int last = send_stop && (i == write_len - 1);
// Wait until there's a spot in the TX FIFO
while (i2c->txflr == 16) {
if (!timer_is_before(timer_read_time(), timeout))
shutdown("i2c timeout");
}
i2c->data_cmd = first << I2C_IC_DATA_CMD_RESTART_LSB
| last << I2C_IC_DATA_CMD_STOP_LSB
| write[i];
}
if (!send_stop)
return;
// Drain the transmit buffer
while (i2c->txflr != 0) {
if (!timer_is_before(timer_read_time(), timeout))
shutdown("i2c timeout");
}
if (i2c->raw_intr_stat & I2C_IC_RAW_INTR_STAT_TX_ABRT_BITS) {
uint32_t abort_source = i2c->tx_abrt_source;
if (abort_source & I2C_IC_TX_ABRT_SOURCE_ABRT_7B_ADDR_NOACK_BITS)
{
i2c->clr_tx_abrt;
shutdown("i2c Start NACK");
}
if (abort_source & I2C_IC_TX_ABRT_SOURCE_ABRT_TXDATA_NOACK_BITS)
{
i2c->clr_tx_abrt;
shutdown("i2c NACK");
}
}
}
static void
i2c_do_read(i2c_hw_t *i2c, uint8_t addr, uint8_t read_len, uint8_t *read
, uint32_t timeout)
{
int have_read = 0;
int to_send = read_len;
while (have_read < read_len) {
if (!timer_is_before(timer_read_time(), timeout))
shutdown("i2c timeout");
if (to_send > 0 && i2c->txflr < 16) {
int first = to_send == read_len;
int last = to_send == 1;
// Put a read command in the TX FIFO
i2c->data_cmd = first << I2C_IC_DATA_CMD_RESTART_LSB
| last << I2C_IC_DATA_CMD_STOP_LSB
| I2C_IC_DATA_CMD_CMD_BITS;
to_send--;
}
if (have_read < read_len && i2c->rxflr > 0) {
*read++ = i2c->data_cmd & 0xFF;
have_read++;
}
if (i2c->raw_intr_stat & I2C_IC_RAW_INTR_STAT_TX_ABRT_BITS) {
uint32_t abort_source = i2c->tx_abrt_source;
if (abort_source & I2C_IC_TX_ABRT_SOURCE_ABRT_7B_ADDR_NOACK_BITS) {
i2c->clr_tx_abrt;
shutdown("i2c Start Read NACK");
}
}
}
}
void
i2c_write(struct i2c_config config, uint8_t write_len, uint8_t *write)
{
i2c_hw_t *i2c = (i2c_hw_t*)config.i2c;
uint32_t timeout = timer_read_time() + timer_from_us(5000);
i2c_start(i2c, config.addr);
i2c_do_write(i2c, config.addr, write_len, write, 1, timeout);
i2c_stop(i2c);
}
void
i2c_read(struct i2c_config config, uint8_t reg_len, uint8_t *reg
, uint8_t read_len, uint8_t *read)
{
i2c_hw_t *i2c = (i2c_hw_t*)config.i2c;
uint32_t timeout = timer_read_time() + timer_from_us(5000);
i2c_start(i2c, config.addr);
if (reg_len != 0)
i2c_do_write(i2c, config.addr, reg_len, reg, 0, timeout);
i2c_do_read(i2c, config.addr, read_len, read, timeout);
i2c_stop(i2c);
}
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