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nrf52/i2c: Use mutex and IRQ for blocking

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This commit enhances the I2C code of the nRF52 family to block on a
mutex while the I2C transfer is busy. The mutex is unlocked in the ISR
when it is trigger by either a stop condition or an error condition.
This commit is contained in:
Koen Zandberg 2020-05-29 09:37:42 +02:00
parent e7abd8805c
commit 83a6ad182d
No known key found for this signature in database
GPG Key ID: 0895A893E6D2985B
1 changed files with 26 additions and 3 deletions
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29
cpu/nrf52/periph/i2c.c
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@ -45,6 +45,14 @@
*/
static mutex_t locks[I2C_NUMOF];
/**
* @brief array with a busy mutex for each I2C device, used to block the
* thread until the transfer is done
*/
static mutex_t busy[I2C_NUMOF];
void i2c_isr_handler(void *arg);
static inline NRF_TWIM_Type *bus(i2c_t dev)
{
return i2c_config[dev].dev;
@ -53,9 +61,9 @@ static inline NRF_TWIM_Type *bus(i2c_t dev)
static int finish(i2c_t dev)
{
DEBUG("[i2c] waiting for STOPPED or ERROR event\n");
while ((!(bus(dev)->EVENTS_STOPPED)) && (!(bus(dev)->EVENTS_ERROR))) {
nrf52_sleep();
}
/* Unmask interrupts */
bus(dev)->INTENSET = TWIM_INTEN_STOPPED_Msk | TWIM_INTEN_ERROR_Msk;
mutex_lock(&busy[dev]);
if ((bus(dev)->EVENTS_STOPPED)) {
bus(dev)->EVENTS_STOPPED = 0;
@ -85,6 +93,9 @@ void i2c_init(i2c_t dev)
/* Initialize mutex */
mutex_init(&locks[dev]);
mutex_init(&busy[dev]);
mutex_lock(&busy[dev]);
/* disable device during initialization, will be enabled when acquire is
* called */
bus(dev)->ENABLE = TWIM_ENABLE_ENABLE_Disabled;
@ -96,6 +107,8 @@ void i2c_init(i2c_t dev)
/* configure dev clock speed */
bus(dev)->FREQUENCY = i2c_config[dev].speed;
spi_twi_irq_register_i2c(bus(dev), i2c_isr_handler, (void *)dev);
/* re-enable the device. We expect that the device was being acquired before
* the i2c_init_master() function is called, so it should be enabled when
* exiting this function. */
@ -211,3 +224,13 @@ int i2c_write_bytes(i2c_t dev, uint16_t addr, const void *data, size_t len,
return finish(dev);
}
void i2c_isr_handler(void *arg)
{
i2c_t dev = (i2c_t)arg;
/* Mask interrupts to ensure that they only trigger once */
bus(dev)->INTENCLR = TWIM_INTEN_STOPPED_Msk | TWIM_INTEN_ERROR_Msk;
mutex_unlock(&busy[dev]);
}