artiq_flash: add command to erase flash memory (#1197)

artiq/frontend/artiq_flash.py

@@ -28,6 +28,7 @@ Valid actions:
     * storage: write storage image to flash
     * firmware: write firmware to flash
     * load: load gateware bitstream into device (volatile but fast)
+    * erase: erase flash memory
     * start: trigger the target to (re)load its gateware bitstream from flash
 
 Prerequisites:
@@ -132,6 +133,13 @@ class Programmer:
             "flash bank {name} jtagspi 0 0 0 0 {tap}.{name}.proxy {ir:#x}",
             tap=tap, name=name, ir=0x02 + index)
 
+    def erase_flash(self, bankname):
+        self.load_proxy()
+        add_commands(self._script,
+                     "flash probe {bankname}",
+                     "flash erase_sector {bankname} 0 last",
+                     bankname=bankname)
+
     def load(self, bitfile, pld):
         os.stat(bitfile) # check for existence
 
@@ -362,6 +370,12 @@ def main():
                 programmer.load(gateware_bit, 0)
         elif action == "start":
             programmer.start()
+        elif action == "erase":
+            if args.target == "sayma":
+                programmer.erase_flash("spi0")
+                programmer.erase_flash("spi1")
+            else:
+                programmer.erase_flash("spi0")
         else:
             raise ValueError("invalid action", action)