mambo: Add persistent memory disk support

This adds support to for mapping disks images using persistent
memory. Disks can be added by setting this ENV variable:

  PMEM_DISK="/mydisks/disk1.img,/mydisks/disk2.img"

These will show up in Linux as /dev/pmem0 and /dev/pmem1.

This uses a new feature in mambo "mysim memory mmap .." which is only
available since mambo commit 0131f0fc08 (from 24/4/2018).

This also needs the of_pmem.c driver in Linux which is only available
since v4.17. It works with powernv_defconfig + CONFIG_OF_PMEM. ie

  --- a/arch/powerpc/configs/powernv_defconfig
  +++ b/arch/powerpc/configs/powernv_defconfig
  @@ -238,6 +238,8 @@ CONFIG_RTC_CLASS=y
   CONFIG_RTC_DRV_GENERIC=y
   CONFIG_VIRTIO_PCI=m
   CONFIG_VIRTIO_BALLOON=m
  +CONFIG_LIBNVDIMM=y
  +# CONFIG_ND_BLK is not set
   CONFIG_EXT2_FS=y
   CONFIG_EXT2_FS_XATTR=y
   CONFIG_EXT2_FS_POSIX_ACL=y

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Stewart Smith <stewart@linux.ibm.com>

external/mambo/skiboot.tcl

@@ -227,6 +227,35 @@ if { [info exists env(SKIBOOT_INITRD)] } {
     mysim of addprop $chosen_node int "linux,initrd-end"   $cpio_end
 }
 
+# Map persistent memory disks
+if { [info exists env(PMEM_DISK)] } {
+
+    set pmem_files [split $env(PMEM_DISK) ","]
+
+    set pmem_root [mysim of addchild $root_node "pmem" ""]
+    mysim of addprop $pmem_root int "#address-cells" 2
+    mysim of addprop $pmem_root int "#size-cells" 2
+    mysim of addprop $pmem_root empty "ranges" ""
+
+    # Start above where XICS normally is at 0x1A0000000000
+    set pmem_start [expr 0x20000000000]
+    foreach pmem_file $pmem_files {
+	set pmem_file [string trim $pmem_file]
+	set pmem_size [file size $pmem_file]
+	set pmem_start_hex [format %x $pmem_start]
+	set pmem_node [mysim of addchild $pmem_root "pmem@$pmem_start_hex" ""]
+	set reg [list [expr $pmem_start >> 32] [expr $pmem_start & 0xffffffff] [expr $pmem_size >> 32] [expr $pmem_size & 0xffffffff] ]
+	mysim of addprop $pmem_node array "reg" reg
+	mysim of addprop $pmem_node string "compatible" "pmem-region"
+	mysim of addprop $pmem_root empty "volatile" ""
+	if {[catch {mysim memory mmap $pmem_start $pmem_size $pmem_file rw}]} {
+	    puts "ERROR: pmem: 'mysim mmap' command needs newer mambo"
+	    exit
+	}
+	set pmem_start [expr $pmem_start + $pmem_size]
+    }
+}
+
 # Default NVRAM is blank and will be formatted by Skiboot if no file is provided
 set fake_nvram_start $cpio_end
 set fake_nvram_size 0x40000