astbmc: Fail SFC init if SIO is unavailable

[ Upstream commit a43e9a6 ]

If SuperIO is unavailable then the driver cannot perform accesses on
which it currently depends. Test for SuperIO availability during
initialsation and bail out immediately if it is absent.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Stewart Smith <stewart@linux.ibm.com>

hw/ast-bmc/ast-sf-ctrl.c

@@ -948,6 +948,9 @@ int ast_sf_open(uint8_t type, struct spi_flash_ctrl **ctrl)
 	struct ast_sf_ctrl *ct;
 #ifdef __SKIBOOT__
 	uint32_t hicr7;
+
+	if (!ast_sio_is_enabled())
+		return -ENODEV;
 #endif /* __SKIBOOT__ */
 
 	if (type != AST_SF_TYPE_PNOR && type != AST_SF_TYPE_BMC