sw: add dram scrubber test

sw/sf2-test/main.c

@@ -20,6 +20,7 @@ static enum t_test
   {
    TEST_DRAM_DE,
    TEST_DRAM_SE,
+   TEST_DRAM_SCRUB,
    TEST_IRAM_DE,
    TEST_IRAM_SE,
    TEST_IRAM_SCRUB,
@@ -182,16 +183,20 @@ main (void)
 
   switch (next_test) {
   case TEST_DRAM_DE:
+    /* Add double-errors  */
     SUPERVISOR->dram_ecc_mask = 0x03;
     ecc[0] = 12;
     ecc[2] = 23;
+    /* Add single-errors */
     SUPERVISOR->dram_ecc_mask = 0x01;
     ecc[1] = 56;
     ecc[3] = 78;
+    /* Do not add errors anymore! */
     SUPERVISOR->dram_ecc_mask = 0x00;
     next_test = TEST_DRAM_SE;
     /* Order is important! */
     asm volatile ("");
+    /* Trigger a single error */
     v = ecc[0];
     unreachable();
     break;
@@ -199,6 +204,7 @@ main (void)
   case TEST_DRAM_SE:
     if (SUPERVISOR->dram_ecc_se != 0)
       unreachable();
+    /* Trigger a single error */
     v = ecc[1];
     if (SUPERVISOR->dram_ecc_se != 1)
       unreachable();
@@ -206,12 +212,38 @@ main (void)
     /* Fallthrough */
 
   case TEST_IRAM_DE:
-    next_test = TEST_IRAM_SE;
+    next_test = TEST_DRAM_SCRUB;
     /* Generate a fatal error */
     v = *(volatile unsigned *)0xfffc;
     unreachable();
     break;
 
+  case TEST_DRAM_SCRUB:
+    if (SUPERVISOR->dram_scrub_se != 0
+        || SUPERVISOR->dram_scrub_de != 0)
+      unreachable();
+    uart_puts("Start DRAM scrubber");
+    SUPERVISOR->scrub_cfg = HYDRA_SUPERVISOR_REGS_SCRUB_CFG_DRAM_EN;
+    next_test = TEST_IRAM_SE;
+    do {
+      v = SUPERVISOR->dram_scrub_de;
+      SUPERVISOR->wd_key = WD_KEY;
+    } while (v == 0);
+    /* Because the scrubber is always running, the counter is always
+       incrementing.  So the original value is kept. */
+    uart_putc('\n');
+    if (SUPERVISOR->dram_scrub_se != 1 || v > 2) {
+      uart_puts ("se:");
+      uart_put_hex8 (SUPERVISOR->dram_scrub_se);
+      uart_puts (", de:");
+      uart_put_hex8 (v);
+      unreachable();
+    }
+    /* Remove the errors */
+    ecc[0] = 0;
+    ecc[2] = 0;
+    /* Fallthrough */
+
   case TEST_IRAM_SE:
     /* Generate a single error */
     v = *(volatile unsigned *)0xfff8;