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-rw-r--r--stm-fmc.h58
1 files changed, 56 insertions, 2 deletions
diff --git a/stm-fmc.h b/stm-fmc.h
index d0f8bb4..eab053d 100644
--- a/stm-fmc.h
+++ b/stm-fmc.h
@@ -57,7 +57,61 @@
extern void fmc_init(void);
-extern HAL_StatusTypeDef fmc_write_32(uint32_t addr, uint32_t *data);
-extern HAL_StatusTypeDef fmc_read_32(uint32_t addr, uint32_t *data);
+
+static inline HAL_StatusTypeDef _fmc_nwait_idle(void)
+{
+ int cnt;
+
+ // poll NWAIT (number of iterations is limited)
+ for (cnt=0; cnt<FMC_FPGA_NWAIT_MAX_POLL_TICKS; cnt++)
+ {
+ // read pin state
+ if (HAL_GPIO_ReadPin(FMC_GPIO_PORT_NWAIT, FMC_GPIO_PIN_NWAIT) == FMC_NWAIT_IDLE)
+ return HAL_OK;
+ }
+
+ return HAL_ERROR;
+}
+
+static inline HAL_StatusTypeDef fmc_write_32(const uint32_t addr, const uint32_t data)
+{
+ // calculate target fpga address
+ uint32_t *ptr = (uint32_t *) (FMC_FPGA_BASE_ADDR + (addr & FMC_FPGA_ADDR_MASK));
+
+ // write data to fpga
+ *ptr = data;
+
+ // wait for transaction to complete
+ return _fmc_nwait_idle();
+}
+
+static inline HAL_StatusTypeDef fmc_read_32(const uint32_t addr, uint32_t * const data)
+{
+ // calculate target fpga address
+ uint32_t *ptr = (uint32_t *) (FMC_FPGA_BASE_ADDR + (addr & FMC_FPGA_ADDR_MASK));
+
+ /* Pavel says:
+ * The short story is like, on one hand STM32 has a dedicated FMC_NWAIT
+ * pin, that can be used in variable-latency data transfer mode. On the
+ * other hand STM32 also has a very nasty hardware bug associated with
+ * FMC_WAIT, that causes processor to freeze under certain conditions.
+ * Because of this FMC_NWAIT cannot be used and FPGA can't properly signal
+ * to STM32, when data transfer is done. Because of that we have to read
+ * two times.
+ */
+
+ HAL_StatusTypeDef status;
+
+ *data = *ptr;
+ status = _fmc_nwait_idle();
+
+ if (status != HAL_OK)
+ return status;
+
+ *data = *ptr;
+ status = _fmc_nwait_idle();
+
+ return status;
+}
#endif /* __STM_FMC_H */