devmem3

kernel_module/user/uio_read.c

@@ -1,9 +1,15 @@
 /*
 Adapted from: https://yurovsky.github.io/2014/10/10/linux-uio-gpio-interrupt/
 
-    modprobe uio_pdrv_genirq
+    modprobe uio_pci_generic
+    echo '1234 11e9' > /sys/bus/pci/drivers/uio_pci_generic/new_id
+    /uio_read.out &
 
-TODO get working.
+TODO get working. The problem now is how to generate IRQs to test our IRQ handling:
+
+-   a synchronous IRQ needs regwrites to be kicked off, but mmap does not seem to work with this driver
+-   a custom PCI periodic timer device would also need to be initiazed by some regwrite, otherwise
+    early interrupts before the OS is setup would crash everything?
 
 Handle interrupts from userland and print a message to stdout.
 */
@@ -17,17 +23,31 @@ Handle interrupts from userland and print a message to stdout.
 #include <sys/types.h>
 #include <unistd.h> /* write */
 
+#include <assert.h>
+#include <sys/mman.h>
+
 int main(int argc, char **argv)
 {
 
-    char *dev;
-    if (argc < 2) {
+    char *dev = "/dev/uio0";
+    if (argc > 1) {
+        dev = argv[1];
+        exit(EXIT_FAILURE);
     }
-    int fd = open("/dev/uio", O_RDWR);
+    int fd = open(dev, O_RDWR);
     if (fd < 0) {
         perror("open");
         exit(EXIT_FAILURE);
     }
+
+    /* TODO not supported by this kernel module? */
+	/*int *addr = mmap(NULL, sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);*/
+	/*if (addr == MAP_FAILED) {*/
+		/*perror("mmap");*/
+		/*assert(0);*/
+	/*}*/
+	/**addr = 0x12345678;*/
+
     while (1) {
         uint32_t info = 1;
         size_t nb = write(fd, &info, sizeof(info));