platform/x86: ISST: Add IOCTL default callback

The common IOCTL handler has a predefined list of IOCTLs it can
handle. There is no default handler, if there is no match.

Allow a client driver to define their own version of default IOCTL
callback. In this way the default handling is passed to the client
drivers to handle.

With the introduction of TPMI target, IOCTL list is extended. The
additional TPMI specific IOCTLs will be passed to the TPMI client
driver default IOCTL handler.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://lore.kernel.org/r/20230211063257.311746-4-srinivas.pandruvada@linux.intel.comSigned-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/intel/speed_select_if/isst_if_common.c

@@ -588,6 +588,7 @@ static long isst_if_def_ioctl(struct file *file, unsigned int cmd,
 	struct isst_if_cmd_cb cmd_cb;
 	struct isst_if_cmd_cb *cb;
 	long ret = -ENOTTY;
+	int i;
 
 	switch (cmd) {
 	case ISST_IF_GET_PLATFORM_INFO:
@@ -616,6 +617,16 @@ static long isst_if_def_ioctl(struct file *file, unsigned int cmd,
 		ret = isst_if_exec_multi_cmd(argp, &cmd_cb);
 		break;
 	default:
+		for (i = 0; i < ISST_IF_DEV_MAX; ++i) {
+			struct isst_if_cmd_cb *cb = &punit_callbacks[i];
+			int ret;
+
+			if (cb->def_ioctl) {
+				ret = cb->def_ioctl(file, cmd, arg);
+				if (!ret)
+					return ret;
+			}
+		}
 		break;
 	}
 

drivers/platform/x86/intel/speed_select_if/isst_if_common.h

@@ -48,6 +48,8 @@
  *		response to user ioctl buffer. The "resume" argument
  *		can be used to avoid storing the command for replay
  *		during system resume
+ * @def_ioctl:	Default IOCTL handler callback, if there is no match in
+ *		the existing list of IOCTL handled by the common handler.
  *
  * This structure is used to register an handler for IOCTL. To avoid
  * code duplication common code handles all the IOCTL command read/write
@@ -58,8 +60,10 @@ struct isst_if_cmd_cb {
 	int registered;
 	int cmd_size;
 	int offset;
+
 	struct module *owner;
 	long (*cmd_callback)(u8 *ptr, int *write_only, int resume);
+	long (*def_ioctl)(struct file *file, unsigned int cmd, unsigned long arg);
 };
 
 /* Internal interface functions */