spi: add runtime support

artiq/runtime/Makefile

@@ -7,7 +7,7 @@ OBJECTS := isr.o clock.o rtiocrg.o flash_storage.o mailbox.o \
 	session.o log.o analyzer.o moninj.o net_server.o bridge_ctl.o \
 	ksupport_data.o kloader.o test_mode.o main.o
 OBJECTS_KSUPPORT := ksupport.o artiq_personality.o mailbox.o \
-	bridge.o rtio.o ttl.o dds.o
+	bridge.o rtio.o ttl.o dds.o spi.o
 
 CFLAGS += -I$(LIBALLOC_DIRECTORY) \
 	-I$(MISOC_DIRECTORY)/software/include/dyld \

artiq/runtime/ksupport.c

@@ -15,6 +15,7 @@
 #include "artiq_personality.h"
 #include "ttl.h"
 #include "dds.h"
+#include "spi.h"
 #include "rtio.h"
 
 double round(double x);
@@ -121,6 +122,9 @@ static const struct symbol runtime_exports[] = {
     {"dds_batch_exit", &dds_batch_exit},
     {"dds_set", &dds_set},
 
+    {"spi_write", &spi_write},
+    {"spi_read", &spi_read},
+
     {"cache_get", &cache_get},
     {"cache_put", &cache_put},
 

artiq/runtime/spi.c

@@ -0,0 +1,50 @@
+#include <generated/csr.h>
+#include <stdio.h>
+
+#include "artiq_personality.h"
+#include "rtio.h"
+#include "log.h"
+#include "spi.h"
+
+
+#define DURATION_WRITE (1 << CONFIG_RTIO_FINE_TS_WIDTH)
+
+void spi_write(long long int timestamp, int channel, int addr,
+        unsigned int data)
+{
+    rtio_chan_sel_write(CONFIG_RTIO_SPI_CHANNEL + channel);
+    rtio_o_address_write(addr);
+    rtio_o_data_write(data);
+    rtio_o_timestamp_write(timestamp);
+    rtio_write_and_process_status(timestamp, channel);
+}
+
+
+unsigned int spi_read(long long int timestamp, int channel, int addr)
+{
+    int status;
+    long long int time_limit = timestamp + DURATION_WRITE;
+    unsigned int r;
+
+    spi_write(timestamp, channel, addr | SPI_WB_READ, 0);
+
+    while((status = rtio_i_status_read())) {
+        if(rtio_i_status_read() & RTIO_I_STATUS_OVERFLOW) {
+            rtio_i_overflow_reset_write(1);
+            artiq_raise_from_c("RTIOOverflow",
+                "RTIO overflow at channel {0}",
+                channel, 0, 0);
+        }
+        if(rtio_get_counter() >= time_limit) {
+            /* check empty flag again to prevent race condition.
+             * now we are sure that the time limit has been exceeded.
+             */
+            if(rtio_i_status_read() & RTIO_I_STATUS_EMPTY)
+                return -1;
+        }
+        /* input FIFO is empty - keep waiting */
+    }
+    r = rtio_i_data_read();
+    rtio_i_re_write(1);
+    return r;
+}

artiq/runtime/spi.h

@@ -0,0 +1,20 @@
+#ifndef __SPI_H
+#define __SPI_H
+
+#include <hw/common.h>
+#include <generated/csr.h>
+#include <generated/mem.h>
+
+#define SPI_ADDR_DATA 0
+#define SPI_ADDR_XFER 1
+#define SPI_ADDR_CONFIG 2
+#define SPI_WB_READ (1 << 2)
+
+#define SPI_XFER_CS(x) (x)
+#define SPI_XFER_WRITE_LENGTH(x) ((x) << 16)
+#define SPI_XFER_READ_LENGTH(x) ((x) << 24)
+
+void spi_write(long long int timestamp, int channel, int address, unsigned int data);
+unsigned int spi_read(long long int timestamp, int channel, int address);
+
+#endif /* __SPI_H */