diff --git a/src/isp.c b/src/isp.c
index 0eb710c2..1b4f29fb 100644
--- a/src/isp.c
+++ b/src/isp.c
@@ -2,9 +2,23 @@
 
 #include "adt.h"
 #include "dart.h"
+#include "firmware.h"
 #include "pmgr.h"
+#include "soc.h"
 #include "utils.h"
 
+#define ISP_ASC_VERSION 0x1800000
+
+#define ISP_VER_T8103 0xb0090
+#define ISP_VER_T6000 0xb3091
+#define ISP_VER_T8112 0xc1090
+#define ISP_VER_T6020 0xc3091
+
+// PMGR offset to enable to get the version info to work
+#define ISP_PMGR_T8103 0x4018
+#define ISP_PMGR_T6000 0x8
+#define ISP_PMGR_T6020 0x4008
+
 /* ISP DART has some quirks we must work around */
 
 #define DART_T8020_ENABLED_STREAMS 0xfc
@@ -66,6 +80,20 @@ static void isp_ctrr_init_t6000(u64 base, const struct dart_tunables *config, u3
     write32(base + 0x13c, val);
 }
 
+static bool isp_initialized = false;
+static u64 heap_phys, heap_iova, heap_size, heap_top;
+
+int isp_get_heap(u64 *phys, u64 *iova, u64 *size)
+{
+    if (!isp_initialized)
+        return -1;
+
+    *phys = heap_phys;
+    *iova = heap_iova;
+    *size = heap_size;
+    return 0;
+}
+
 int isp_init(void)
 {
     int err = 0;
@@ -73,11 +101,13 @@ int isp_init(void)
     const char *isp_path = "/arm-io/isp";
     const char *dart_path = "/arm-io/dart-isp";
 
-    int adt_path[8];
+    int adt_path[8], adt_isp_path[8];
+    int isp_node = adt_path_offset_trace(adt, isp_path, adt_isp_path);
     int node = adt_path_offset_trace(adt, dart_path, adt_path);
-    if (node < 0) {
+    if (node < 0 || isp_node < 0) {
         isp_path = "/arm-io/isp0";
         dart_path = "/arm-io/dart-isp0";
+        isp_node = adt_path_offset_trace(adt, isp_path, adt_isp_path);
         node = adt_path_offset_trace(adt, dart_path, adt_path);
     }
     if (node < 0)
@@ -86,6 +116,100 @@ int isp_init(void)
     if (pmgr_adt_power_enable(isp_path) < 0)
         return -1;
 
+    u64 isp_base;
+    u64 pmgr_base;
+    err = adt_get_reg(adt, adt_isp_path, "reg", 0, &isp_base, NULL);
+    if (err)
+        return err;
+
+    err = adt_get_reg(adt, adt_isp_path, "reg", 1, &pmgr_base, NULL);
+    if (err)
+        return err;
+
+    u32 pmgr_off;
+    switch (chip_id) {
+        case T8103:
+        case T8112:
+            pmgr_off = ISP_PMGR_T8103;
+            break;
+        case T6000 ... T6002:
+            pmgr_off = ISP_PMGR_T6000;
+            break;
+        case T6020 ... T6022:
+            pmgr_off = ISP_PMGR_T6020;
+            break;
+        default:
+            printf("isp: Unsupported SoC\n");
+            return -1;
+    }
+
+    err = pmgr_set_mode(pmgr_base + pmgr_off, PMGR_PS_ACTIVE);
+    if (err) {
+        printf("isp: Failed to power on\n");
+        return err;
+    }
+
+    u32 ver_rev = read32(isp_base + ISP_ASC_VERSION);
+    printf("isp: Version 0x%x\n", ver_rev);
+
+    pmgr_set_mode(pmgr_base + pmgr_off, PMGR_PS_PWRGATE);
+
+    /* TODO: confirm versions */
+    switch (ver_rev) {
+        case ISP_VER_T8103:
+        case ISP_VER_T8112:
+            switch (os_firmware.version) {
+                case V12_3 ... V12_4:
+                    heap_top = 0x1800000;
+                    break;
+                case V13_5:
+                    heap_top = 0x1000000;
+                    break;
+                default:
+                    printf("isp: unsupported firmware\n");
+                    return -1;
+            }
+            break;
+        case ISP_VER_T6000:
+            switch (os_firmware.version) {
+                case V12_3:
+                    heap_top = 0xe00000;
+                    break;
+                case V13_5:
+                    heap_top = 0xf00000;
+                    break;
+                default:
+                    printf("isp: unsupported firmware\n");
+                    return -1;
+            }
+            break;
+        case ISP_VER_T6020:
+            switch (os_firmware.version) {
+                case V13_5:
+                    heap_top = 0xf00000;
+                    break;
+                default:
+                    printf("isp: unsupported firmware\n");
+                    return -1;
+            }
+            break;
+        default:
+            printf("isp: unknown revision 0x%x\n", ver_rev);
+            return -1;
+    }
+
+    const struct adt_segment_ranges *seg;
+    u32 segments_len;
+
+    seg = adt_getprop(adt, isp_node, "segment-ranges", &segments_len);
+    unsigned int count = segments_len / sizeof(*seg);
+
+    heap_iova = seg[count - 1].iova + seg[count - 1].size;
+    heap_size = heap_top - heap_iova;
+    heap_phys = top_of_memory_alloc(heap_size);
+
+    printf("isp: Heap: 0x%lx..0x%lx (0x%lx @ 0x%lx)\n", heap_iova, heap_top, heap_size, heap_phys);
+
     enum dart_type_t type;
     const char *type_s;
     if (adt_is_compatible(adt, node, "dart,t8020")) {
@@ -137,6 +261,8 @@ int isp_init(void)
         }
     }
 
+    isp_initialized = true;
+
 out:
     pmgr_adt_power_disable(isp_path);
     return err;
diff --git a/src/isp.h b/src/isp.h
index af83b344..08e0e7f3 100644
--- a/src/isp.h
+++ b/src/isp.h
@@ -6,5 +6,6 @@
 #include "types.h"
 
 int isp_init(void);
+int isp_get_heap(u64 *phys, u64 *iova, u64 *size);
 
 #endif