+/*
+ * The advansys chip/microcode contains a 32-bit identifier for each command
+ * known as the 'srb'. I don't know what it stands for. The driver used
+ * to encode the scsi_cmnd pointer by calling virt_to_bus and retrieve it
+ * with bus_to_virt. Now the driver keeps a per-host map of integers to
+ * pointers. It auto-expands when full, unless it can't allocate memory.
+ * Note that an srb of 0 is treated specially by the chip/firmware, hence
+ * the return of i+1 in this routine, and the corresponding subtraction in
+ * the inverse routine.
+ */
+#define BAD_SRB 0
+static u32 advansys_ptr_to_srb(struct asc_dvc_var *asc_dvc, void *ptr)
+{
+ int i;
+ void **new_ptr;
+
+ for (i = 0; i < asc_dvc->ptr_map_count; i++) {
+ if (!asc_dvc->ptr_map[i])
+ goto out;
+ }
+
+ if (asc_dvc->ptr_map_count == 0)
+ asc_dvc->ptr_map_count = 1;
+ else
+ asc_dvc->ptr_map_count *= 2;
+
+ new_ptr = krealloc(asc_dvc->ptr_map,
+ asc_dvc->ptr_map_count * sizeof(void *), GFP_ATOMIC);
+ if (!new_ptr)
+ return BAD_SRB;
+ asc_dvc->ptr_map = new_ptr;
+ out:
+ ASC_DBG(3, "Putting ptr %p into array offset %d\n", ptr, i);
+ asc_dvc->ptr_map[i] = ptr;
+ return i + 1;
+}
+
+static void * advansys_srb_to_ptr(struct asc_dvc_var *asc_dvc, u32 srb)
+{
+ void *ptr;
+
+ srb--;
+ if (srb >= asc_dvc->ptr_map_count) {
+ printk("advansys: bad SRB %u, max %u\n", srb,
+ asc_dvc->ptr_map_count);
+ return NULL;
+ }
+ ptr = asc_dvc->ptr_map[srb];
+ asc_dvc->ptr_map[srb] = NULL;
+ ASC_DBG(3, "Returning ptr %p from array offset %d\n", ptr, srb);
+ return ptr;
+}
+