/**
* Searched a statically assigned array for a free entry
* Starts with the last given element + 1 for optimisation
* This call is safe from both ISR and task context
* @return poiter to a free csp_packet_t or NULL if out of memory
*/
void * csp_buffer_get(size_t buf_size) {
void * buffer;
CSP_ENTER_CRITICAL(csp_critical_lock);
buffer = csp_buffer_get_isr(buf_size);
CSP_EXIT_CRITICAL(csp_critical_lock);
return buffer;
}
/**
* Interrupt service routine
* Basically handles the entire protocol
*/
void __attribute__((noinline)) pca9665_dsr(portBASE_TYPE * task_woken) {
static int handle, len;
static uint8_t state;
static uint8_t dest;
/* Loop through number of devices */
for (handle = 0; handle < pca9665_device_count; handle++) {
/* Check for interrupt flag in device status register */
if (!(pca9665_read_reg(handle, I2CCON) & CON_SI))
continue;
/* We have an interrupt, read the status register */
state = pca9665_read_reg(handle, I2CSTA);
/* The I2C driver is one _big_ state-machine */
driver_debug(DEBUG_I2C, "I2C ISR %u %x\n\r", handle, state);
switch (state) {
/**
* MASTER IRQ's
*/
/* START: is the first ISR that appears for outgoing frames */
case STA_M_REPEATED_START_SENDT:
case STA_M_START_SENDT:
/* Mark as busy, so start flag is not sent from task context while transmission is active */
device[handle].is_busy = 1;
/* If this is the beginning of a new frame, dequeue */
if (device[handle].tx.frame == NULL && device[handle].rx.frame == NULL) {
/* Try do dequeue element, if it fails, stop transmission */
xQueueReceiveFromISR(device[handle].tx.queue, &device[handle].tx.frame, task_woken);
if (device[handle].tx.frame == NULL) {
pca9665_try_tx_from_isr(handle, task_woken);
break;
}
/* If TX len > 0, go for master transmit */
if (device[handle].tx.frame->len) {
device[handle].mode = DEVICE_MODE_M_T;
device[handle].tx.next_byte = 0;
/* If TX len == 0 and RX len > 0, go for master receive */
} else if (device[handle].tx.frame->len_rx) {
device[handle].mode = DEVICE_MODE_M_R;
device[handle].rx.frame = device[handle].tx.frame;
device[handle].tx.frame = NULL;
device[handle].rx.frame->len = device[handle].rx.frame->len_rx;
device[handle].rx.next_byte = 0;
/* Well, this should not happen */
} else {
csp_buffer_free_isr(device[handle].tx.frame);
device[handle].tx.frame = NULL;
pca9665_try_tx_from_isr(handle, task_woken);
break;
}
}
/* If mode is master receiver then set the read-bit in the address field */
if (device[handle].mode == DEVICE_MODE_M_R) {
dest = (device[handle].rx.frame->dest << 1) | 0x01;
device[handle].rx.next_byte = 0;
/* Do first part of frame here */
if (device[handle].rx.frame->len > PCA9665_MAX_BUF) {
pca9665_write_reg(handle, I2CCOUNT, PCA9665_MAX_BUF);
} else {
pca9665_write_reg(handle, I2CCOUNT, device[handle].rx.frame->len | 0x80);
}
pca9665_write_data(handle, &dest, 1);
} else {
dest = device[handle].tx.frame->dest << 1;
device[handle].tx.next_byte = 0;
/* Do first part of frame here */
if (device[handle].tx.frame->len + 1 > PCA9665_MAX_BUF) {
pca9665_write_reg(handle, I2CCOUNT, PCA9665_MAX_BUF);
pca9665_write_data(handle, &dest, 1);
pca9665_write_data(handle, &device[handle].tx.frame->data[device[handle].tx.next_byte], PCA9665_MAX_BUF - 1);
device[handle].tx.next_byte += PCA9665_MAX_BUF - 1;
} else {
pca9665_write_reg(handle, I2CCOUNT, device[handle].tx.frame->len + 1);
pca9665_write_data(handle, &dest, 1);
pca9665_write_data(handle, &device[handle].tx.frame->data[device[handle].tx.next_byte], device[handle].tx.frame->len);
device[handle].tx.next_byte += device[handle].tx.frame->len;
}
}
/* Let the hardware continue */
pca9665_write_reg(handle, I2CCON, CON_ENSIO | CON_MODE | CON_AA);
break;
/* WRITE ACK: A node is ready to be written to */
case STA_M_SLAW_SENDT_ACKED:
case STA_M_DATA_SENDT_ACKED:
/* Safety first */
if (device[handle].tx.frame == NULL)
goto isr_error;
/* Calculate remaining length */
len = device[handle].tx.frame->len - device[handle].tx.next_byte;
/* Transmit next chunk */
if (len > 0) {
if (len > PCA9665_MAX_BUF) {
pca9665_write_reg(handle, I2CCOUNT, PCA9665_MAX_BUF);
pca9665_write_data(handle, &device[handle].tx.frame->data[device[handle].tx.next_byte], PCA9665_MAX_BUF);
device[handle].tx.next_byte += PCA9665_MAX_BUF;
} else {
pca9665_write_reg(handle, I2CCOUNT, len);
pca9665_write_data(handle, &device[handle].tx.frame->data[device[handle].tx.next_byte], len);
device[handle].tx.next_byte += len;
}
pca9665_write_reg(handle, I2CCON, CON_ENSIO | CON_MODE | CON_AA);
break;
/* Or, Change from master transmit, to master read if wanted */
} else if (device[handle].tx.frame->len_rx) {
device[handle].mode = DEVICE_MODE_M_R;
device[handle].rx.frame = device[handle].tx.frame;
device[handle].tx.frame = NULL;
device[handle].rx.frame->len = device[handle].rx.frame->len_rx;
/* We need to send a repeated start now! */
pca9665_write_reg(handle, I2CCON, CON_ENSIO | CON_MODE | CON_AA | CON_STA);
break;
/* Or, We are done */
} else {
csp_buffer_free_isr(device[handle].tx.frame);
device[handle].tx.frame = NULL;
pca9665_try_tx_from_isr(handle, task_woken);
}
break;
/* WRITE ERROR: A write has failed */
case STA_M_SLAW_SENDT_NACKED:
case STA_M_DATA_SENDT_LAST_NACKED:
if (device[handle].tx.frame != NULL) {
driver_debug(DEBUG_I2C, "I2C SLA+W NACK: 0x%02"PRIx8"\n\r", device[handle].tx.frame->dest);
csp_buffer_free_isr(device[handle].tx.frame);
device[handle].tx.frame = NULL;
}
pca9665_try_tx_from_isr(handle, task_woken);
break;
/* ARBITRATION LOST: Start condition failed */
case STA_M_ARBITRATION_LOST:
/* Restart transmission by resetting next_byte and preserving tx_frame pointer */
device[handle].tx.next_byte = 0;
pca9665_try_tx_from_isr(handle, task_woken);
break;
/* READ ACK: A node is ready to be read from */
case STA_M_SLAR_SENT_ACKED:
case STA_M_DATA_RECEIVED_ACKED:
case STA_M_DATA_RECEIVED_NACKED:
/* Safety first */
if (device[handle].rx.frame == NULL)
goto isr_error;
if (device[handle].rx.queue == NULL)
goto isr_error;
pca9665_read_data_to_buffer(handle);
int remaining = device[handle].rx.frame->len - device[handle].rx.next_byte;
driver_debug(DEBUG_I2C, "RX: Remaining %u\r\n", remaining);
/* If no more to receive */
if (remaining == 0) {
if (xQueueSendToBackFromISR(device[handle].rx.queue, &device[handle].rx.frame, task_woken) == pdFALSE) {
driver_debug(DEBUG_I2C, "I2C rx queue full - freeing\n\r");
csp_buffer_free_isr(device[handle].rx.frame);
}
device[handle].rx.frame = NULL;
pca9665_try_tx_from_isr(handle, task_woken);
break;
}
/* If more than a full PCA9665 buffer remains */
if (remaining > PCA9665_MAX_BUF) {
pca9665_write_reg(handle, I2CCOUNT, PCA9665_MAX_BUF);
/* Otherwise, this is the last bit, set NACK on final slave read */
} else {
pca9665_write_reg(handle, I2CCOUNT, remaining | 0x80);
}
pca9665_write_reg(handle, I2CCON, CON_ENSIO | CON_MODE | CON_AA);
break;
/* READ ERROR: A read has failed */
case STA_M_SLAR_SENT_NACKED:
/* Safety first */
if (device[handle].rx.frame == NULL)
goto isr_error;
driver_debug(DEBUG_I2C, "I2C SLA+R nacked\n\r");
csp_buffer_free_isr(device[handle].rx.frame);
device[handle].rx.frame = NULL;
/* Start up again */
pca9665_try_tx_from_isr(handle, task_woken);
break;
/**
* SLAVE RECEIVER BUFFERED MODE
*/
/* START: Lost the arbitration and is addressed as a slave receiver */
case STA_S_ARB_LOST_SLAW_RECEIVED:
case STA_S_ARB_LOST_GC_RECEIVED:
/* Preserve TX frame active, so the START flag will be re-set when the
* reception is completed
*/
/* Deliberate Fallthrough */
/* START: Addressed as a slave receiver */
case STA_S_SLAW_RECEIVED_ACKED:
case STA_S_GC_RECEIVED:
/* Check if RX frame was started */
if (device[handle].rx.frame != NULL)
goto isr_error;
/* Allocate new frame */
device[handle].rx.frame = csp_buffer_get_isr(I2C_MTU);
if (device[handle].rx.frame == NULL)
goto isr_error;
device[handle].is_busy = 1;
device[handle].rx.next_byte = 0;
device[handle].rx.frame->len = 0;
device[handle].rx.frame->dest = device[handle].slave_addr;
pca9665_write_reg(handle, I2CCOUNT, PCA9665_MAX_BUF);
pca9665_write_reg(handle, I2CCON, CON_ENSIO | CON_MODE | CON_AA);
break;
/* READ: Data received. */
case STA_S_DATA_RECEIVED_SLA_ACKED:
case STA_S_DATA_RECEIVED_GC_ACKED:
/* Safety first */
if (device[handle].rx.frame == NULL)
goto isr_error;
/* Receive data, if any */
pca9665_read_data_to_buffer(handle);
/* Limit incoming bytes */
pca9665_write_reg(handle, I2CCOUNT, (device[handle].rx.next_byte + PCA9665_MAX_BUF > I2C_MTU) ? (I2C_MTU - device[handle].rx.next_byte) | 0x80 : PCA9665_MAX_BUF);
pca9665_write_reg(handle, I2CCON, CON_ENSIO | CON_MODE | CON_AA);
break;
/* STOP or NACK: No more data to receive */
case STA_S_STOP_REP_RECEIVED:
case STA_S_DATA_RECEIVED_SLA_NACKED:
case STA_S_DATA_RECEIVED_GC_NACKED:
/* Safety first */
if (device[handle].rx.frame == NULL)
goto isr_error;
/* Receive data, if any */
pca9665_read_data_to_buffer(handle);
/* Queue up frame */
device[handle].rx.frame->len = device[handle].rx.next_byte;
if (device[handle].rx.queue != NULL) {
if (xQueueSendToBackFromISR(device[handle].rx.queue, &device[handle].rx.frame, task_woken) == pdFALSE) {
driver_debug(DEBUG_I2C, "I2C RX queue full\n\r");
csp_buffer_free_isr(device[handle].rx.frame);
}
} else if (device[handle].callback != NULL) {
device[handle].callback(device[handle].rx.frame, task_woken);
} else {
csp_buffer_free_isr(device[handle].rx.frame);
}
/* The frame has been freed now */
device[handle].rx.frame = NULL;
/* Set back to master mode */
pca9665_try_tx_from_isr(handle, task_woken);
break;
/**
* Other IRQ's, typically indicates a hardware or protcol error
* The IDLE status is considered an error if asserted at the same time as the Serial Interrupt flag
*/
case STA_IDLE:
default:
isr_error:
/* Soft reset the device */
driver_debug(DEBUG_I2C, "I2C ERR 0x%02X\n\r", state);
pca9665_init_registers(handle);
/* Clean up RX */
if (device[handle].rx.frame != NULL) {
csp_buffer_free_isr(device[handle].rx.frame);
device[handle].rx.frame = NULL;
}
/* Clean up TX */
if (device[handle].tx.frame != NULL) {
csp_buffer_free_isr(device[handle].tx.frame);
device[handle].tx.frame = NULL;
}
/* Start up again */
pca9665_try_tx_from_isr(handle, task_woken);
break;
}
} /**< END Switch/Case */
}