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// i2c support on samd
//
// Copyright (C) 2019 Florian Heilmann <Florian.Heilmann@gmx.net>
// Copyright (C) 2018-2019 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "internal.h" // enable_pclock
#include "command.h" // shutdown
#include "gpio.h" // i2c_setup
#include "sched.h" // sched_shutdown
#define TIME_RISE 125ULL // 125 nanoseconds
#define I2C_FREQ 100000
static void
i2c_init(uint32_t bus, SercomI2cm *si)
{
static int have_run_init[8];
if (have_run_init[bus])
return;
have_run_init[bus] = 1;
// Configure i2c
si->CTRLA.reg = 0;
uint32_t areg = (SERCOM_I2CM_CTRLA_LOWTOUTEN
| SERCOM_I2CM_CTRLA_INACTOUT(3)
| SERCOM_I2CM_STATUS_SEXTTOUT
| SERCOM_I2CM_STATUS_MEXTTOUT
| SERCOM_I2CM_CTRLA_MODE(5));
si->CTRLA.reg = areg;
uint32_t freq = sercom_get_pclock_frequency(bus);
uint32_t baud = (freq/I2C_FREQ - 10 - freq*TIME_RISE/1000000000) / 2;
si->BAUD.reg = baud;
si->CTRLA.reg = areg | SERCOM_I2CM_CTRLA_ENABLE;
while (si->SYNCBUSY.reg & SERCOM_I2CM_SYNCBUSY_ENABLE)
;
// Go into idle mode
si->STATUS.reg = SERCOM_I2CM_STATUS_BUSSTATE(1);
while (si->SYNCBUSY.reg & SERCOM_I2CM_SYNCBUSY_SYSOP)
;
}
struct i2c_config
i2c_setup(uint32_t bus, uint32_t rate, uint8_t addr)
{
#ifdef SERCOM7
if (bus > 7)
#else
if (bus > 5)
#endif
shutdown("Unsupported i2c bus");
Sercom *sercom = sercom_enable_pclock(bus);
sercom_i2c_pins(bus);
SercomI2cm *si = &sercom->I2CM;
i2c_init(bus, si);
return (struct i2c_config){ .si=si, .addr=addr<<1 };
}
static void
i2c_wait(SercomI2cm *si)
{
for (;;) {
uint32_t intflag = si->INTFLAG.reg;
if (!(intflag & SERCOM_I2CM_INTFLAG_MB)) {
if (si->STATUS.reg & SERCOM_I2CM_STATUS_BUSERR)
shutdown("i2c buserror");
continue;
}
if (intflag & SERCOM_I2CM_INTFLAG_ERROR)
shutdown("i2c error");
break;
}
}
static void
i2c_start(SercomI2cm *si, uint8_t addr)
{
si->ADDR.reg = addr;
i2c_wait(si);
}
static void
i2c_send_byte(SercomI2cm *si, uint8_t b)
{
si->DATA.reg = b;
i2c_wait(si);
}
static void
i2c_stop(SercomI2cm *si)
{
si->CTRLB.reg = SERCOM_I2CM_CTRLB_CMD(3);
}
void
i2c_write(struct i2c_config config, uint8_t write_len, uint8_t *write)
{
SercomI2cm *si = (SercomI2cm *)config.si;
i2c_start(si, config.addr);
while (write_len--)
i2c_send_byte(si, *write++);
i2c_stop(si);
}
void
i2c_read(struct i2c_config config, uint8_t reg_len, uint8_t *reg
, uint8_t read_len, uint8_t *read)
{
shutdown("i2c_read not supported on samd21");
}
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