iwlwifi: enable experimental ucode support

ucode firmware may need to be released as experimental for testing or
debugging. released ucode filenames have the API version as the last
component.  experimental ucode files will have that component be "exp"
and the fw_version string reported by ethtool will also contain the
string EXP to clearly identify this ucode from released ucode.
EXP is short for EXPERIMENTAL since fw_version has a max lenght on 32.

this capability is controlled by Kconfig and defaulted to not be used.
Signed-off-by: Jay Sternberg <jay.e.sternberg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>

drivers/net/wireless/iwlwifi/Kconfig

@@ -36,6 +36,12 @@ config IWLWIFI_DEBUGFS
 	  is a low-impact option that allows getting insight into the
 	  driver's state at runtime.
 
+config IWLWIFI_DEBUG_EXPERIMENTAL_UCODE
+        bool "Experimental uCode support"
+        depends on IWLWIFI && IWLWIFI_DEBUG
+        ---help---
+	  Enable use of experimental ucode for testing and debugging.
+
 config IWLWIFI_DEVICE_TRACING
 	bool "iwlwifi device access tracing"
 	depends on IWLWIFI

drivers/net/wireless/iwlwifi/iwl-agn.c

@@ -1659,24 +1659,37 @@ static void iwl_ucode_callback(const struct firmware *ucode_raw, void *context);
 static int iwl_mac_setup_register(struct iwl_priv *priv,
 				  struct iwlagn_ucode_capabilities *capa);
 
+#define UCODE_EXPERIMENTAL_INDEX	100
+#define UCODE_EXPERIMENTAL_TAG		"exp"
+
 static int __must_check iwl_request_firmware(struct iwl_priv *priv, bool first)
 {
 	const char *name_pre = priv->cfg->fw_name_pre;
+	char tag[8];
 
-	if (first)
+	if (first) {
+#ifdef CONFIG_IWLWIFI_DEBUG_EXPERIMENTAL_UCODE
+		priv->fw_index = UCODE_EXPERIMENTAL_INDEX;
+		strcpy(tag, UCODE_EXPERIMENTAL_TAG);
+	} else if (priv->fw_index == UCODE_EXPERIMENTAL_INDEX) {
+#endif
 		priv->fw_index = priv->cfg->ucode_api_max;
-	else
+		sprintf(tag, "%d", priv->fw_index);
+	} else {
 		priv->fw_index--;
+		sprintf(tag, "%d", priv->fw_index);
+	}
 
 	if (priv->fw_index < priv->cfg->ucode_api_min) {
 		IWL_ERR(priv, "no suitable firmware found!\n");
 		return -ENOENT;
 	}
 
-	sprintf(priv->firmware_name, "%s%d%s",
-		name_pre, priv->fw_index, ".ucode");
+	sprintf(priv->firmware_name, "%s%s%s", name_pre, tag, ".ucode");
 
-	IWL_DEBUG_INFO(priv, "attempting to load firmware '%s'\n",
+	IWL_DEBUG_INFO(priv, "attempting to load firmware %s'%s'\n",
+		       (priv->fw_index == UCODE_EXPERIMENTAL_INDEX)
+				? "EXPERIMENTAL " : "",
 		       priv->firmware_name);
 
 	return request_firmware_nowait(THIS_MODULE, 1, priv->firmware_name,
@@ -1971,8 +1984,10 @@ static void iwl_ucode_callback(const struct firmware *ucode_raw, void *context)
 	memset(&pieces, 0, sizeof(pieces));
 
 	if (!ucode_raw) {
-		IWL_ERR(priv, "request for firmware file '%s' failed.\n",
-			priv->firmware_name);
+		if (priv->fw_index <= priv->cfg->ucode_api_max)
+			IWL_ERR(priv,
+				"request for firmware file '%s' failed.\n",
+				priv->firmware_name);
 		goto try_again;
 	}
 
@@ -2019,7 +2034,9 @@ static void iwl_ucode_callback(const struct firmware *ucode_raw, void *context)
 			  api_max, api_ver);
 
 	if (build)
-		sprintf(buildstr, " build %u", build);
+		sprintf(buildstr, " build %u%s", build,
+		       (priv->fw_index == UCODE_EXPERIMENTAL_INDEX)
+				? " (EXP)" : "");
 	else
 		buildstr[0] = '\0';