[phantom] Allow for PXE boot to be enabled/disabled on a per-port basis

This is something of an ugly hack to accommodate an OEM requirement.
The NIC has only one expansion ROM BAR, rather than one per port.  To
allow individual ports to be selectively enabled/disabled for PXE boot
(as required), we must therefore leave the expansion ROM always
enabled, and place the per-port enable/disable logic within the gPXE
driver.

src/drivers/net/phantom/phantom.c

 	       phantom, eth_ntoa ( ll_addr ) );
 }
 
+/**
+ * Check Phantom is enabled for boot
+ *
+ * @v phanton_port	Phantom NIC
+ * @ret rc		Return status code
+ *
+ * This is something of an ugly hack to accommodate an OEM
+ * requirement.  The NIC has only one expansion ROM BAR, rather than
+ * one per port.  To allow individual ports to be selectively
+ * enabled/disabled for PXE boot (as required), we must therefore
+ * leave the expansion ROM always enabled, and place the per-port
+ * enable/disable logic within the gPXE driver.
+ */
+static int phantom_check_boot_enable ( struct phantom_nic *phantom ) {
+	unsigned long boot_enable;
+
+	boot_enable = phantom_readl ( phantom, UNM_CAM_RAM_BOOT_ENABLE );
+	if ( ! ( boot_enable & ( 1 << phantom->port ) ) ) {
+		DBGC ( phantom, "Phantom %p PXE boot is disabled\n",
+		       phantom );
+		return -ENOTSUP;
+	}
+
+	return 0;
+}
+
 /**
  * Initialise Phantom receive PEG
  *
 	/* Read MAC addresses */
 	phantom_get_macaddr ( phantom, netdev->ll_addr );
 
+	/* Skip if boot disabled on NIC */
+	if ( ( rc = phantom_check_boot_enable ( phantom ) ) != 0 )
+		goto err_check_boot_enable;
+
 	/* Register network devices */
 	if ( ( rc = register_netdev ( netdev ) ) != 0 ) {
 		DBGC ( phantom, "Phantom %p could not register net device: "
  err_register_settings:
 	unregister_netdev ( netdev );
  err_register_netdev:
+ err_check_boot_enable:
  err_init_rcvpeg:
  err_init_cmdpeg:
 	phantom_halt_pegs ( phantom );

src/drivers/net/phantom/phantom.h

 #define UNM_CAM_RAM_CLP_STATUS_DONE		0x00000002UL
 #define UNM_CAM_RAM_CLP_STATUS_ERROR		0x0000ff00UL
 #define UNM_CAM_RAM_CLP_STATUS_UNINITIALISED	0xffffffffUL
+#define UNM_CAM_RAM_BOOT_ENABLE		( UNM_CAM_RAM + 0x000fc )
 #define UNM_CAM_RAM_WOL_PORT_MODE	( UNM_CAM_RAM + 0x00198 )
 #define UNM_CAM_RAM_MAC_ADDRS		( UNM_CAM_RAM + 0x001c0 )
 #define UNM_CAM_RAM_COLD_BOOT		( UNM_CAM_RAM + 0x001fc )