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I2C. Added note about different API classes usage. 

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/branches/i2c_dev@3569 35acf78f-673a-0410-8e92-d51de3d6d3f4
This commit is contained in:
barthess 2011-12-07 14:13:57 +00:00
parent d0b7c28f9a
commit ac8123d2da
1 changed files with 38 additions and 9 deletions
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47
os/hal/platforms/STM32/i2c_lld.c
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@ -43,6 +43,30 @@
* Otherwise there is a risk of setting a second STOP, START or PEC request.
*/
/*===========================================================================*/
/* Knowledge base. */
/*===========================================================================*/
/*
Not all system functions are usable in a given context.
The most restrictive type are the i-class, an I-class function is a function that must:
- Not access the "current" thread in any way (from an ISR the current thread
is random so it is meaningless).
- Not reschedule internally (from an ISR the reschedule is done at the end of
the ISR chain, rescheduling from within an ISR is forbidden because would
leave the IRQ stack not empty with all kind of funny consequences.
- Not try to change state for the current thread.
- Must be invoked between a lock() and an unlock() but never lock/unlock internally.
A bit less restrictive are the S-class that must simply:
- Be invoked between a lock() and an unlock() but never lock/unlock internally.
S-class can reschedule internally, access the current thread implicitly and
also change state so are not eligible for ISR context.
Normal functions can be invoked from thread context only but have no internal
restrictions.
*/
/*===========================================================================*/
/* Driver local definitions. */
/*===========================================================================*/
@ -155,12 +179,12 @@ static void i2c_serve_event_interrupt(I2CDriver *i2cp) {
/* catch BTF event after the end of trasmission */
if (i2cp->rxbytes > 1){
/* start "read after write" operation */
i2c_lld_master_receive(i2cp, (i2cp->slave_addr >> 1), i2cp->rxbuf, i2cp->rxbytes);
i2c_lld_master_receive(i2cp, (i2cp->slave_addr >> 1),
i2cp->rxbuf, i2cp->rxbytes);
return;
}
else
i2cp->id_i2c->CR1 |= I2C_CR1_STOP;
// FIXME: change this polling to something else
while(i2cp->id_i2c->CR1 & I2C_CR1_STOP)
;
_i2c_isr_code(i2cp, i2cp->id_slave_config);
@ -181,7 +205,6 @@ static void i2c_lld_serve_rx_end_irq(I2CDriver *i2cp){
dmaStreamDisable(i2cp->dmarx);
i2cp->id_i2c->CR1 |= I2C_CR1_STOP;
// FIXME: change this polling to something else
while(i2cp->id_i2c->CR1 & I2C_CR1_STOP)
;
_i2c_isr_code(i2cp, i2cp->id_slave_config);
@ -209,10 +232,10 @@ static void i2c_serve_error_interrupt(I2CDriver *i2cp) {
chSysLockFromIsr();
/* clear interrupt falgs just to be safe */
dmaStreamClearInterrupt(i2cp->dmatx);
dmaStreamClearInterrupt(i2cp->dmarx);
dmaStreamDisable(i2cp->dmatx);
dmaStreamDisable(i2cp->dmarx);
dmaStreamClearInterrupt(i2cp->dmatx);
dmaStreamClearInterrupt(i2cp->dmarx);
chSysUnlockFromIsr();
reg = i2cp->id_i2c;
@ -344,13 +367,13 @@ void i2c_lld_init(void) {
#endif /* STM32_I2C_USE_I2C3 */
}
/**
* @brief Configures and activates the I2C peripheral.
*
* @param[in] i2cp pointer to the @p I2CDriver object
*/
void i2c_lld_start(I2CDriver *i2cp) {
i2cp->dmamode = STM32_DMA_CR_DMEIE | STM32_DMA_CR_TEIE;
if (i2cp->id_state == I2C_STOP) { /* If in stopped state then enables the I2C clock.*/
@ -641,15 +664,21 @@ void i2c_lld_set_opmode(I2CDriver *i2cp) {
}
/**
* @brief Deactivates the I2C peripheral.
*
* @param[in] i2cp pointer to the @p I2CDriver object
*/
void i2c_lld_stop(I2CDriver *i2cp) {
if (i2cp->id_state == I2C_READY) { /* If in ready state then disables the I2C clock.*/
if (i2cp->id_state != I2C_STOP) { /* If in ready state then disables the I2C clock.*/
dmaStreamDisable(i2cp->dmatx);
dmaStreamDisable(i2cp->dmarx);
dmaStreamClearInterrupt(i2cp->dmatx);
dmaStreamClearInterrupt(i2cp->dmarx);
dmaStreamRelease(i2cp->dmatx);
dmaStreamRelease(i2cp->dmarx);
#if STM32_I2C_USE_I2C1
if (&I2CD1 == i2cp) {