iwlwifi: rely on API version read from firmware

This adds the infrastructure to support older firmware APIs.
The API version number is stored as part of the filename, we first try to
load the most recent firmware and progressively try lower versions.
The API version is also read from the firmware self and stored as part
of the iwl_priv structure. Only firmware that is supported by driver will
be loaded. The version number read from firmware is compared
to supported versions in the driver not the API version used as part of
filename.

An example using this new infrastrucure:
   if (IWL_UCODE_API(priv->ucode_ver) >= 2) {
        Driver interacts with Firmware API version >= 2.
   } else {
        Driver interacts with Firmware API version 1.
   }

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 31 insertions, 1 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-core.h b/drivers/net/wireless/iwlwifi/iwl-core.h
index f68883b3246..81ddca07717 100644
--- a/drivers/net/wireless/iwlwifi/iwl-core.h
+++ b/drivers/net/wireless/iwlwifi/iwl-core.h
@@ -164,9 +164,39 @@ struct iwl_mod_params {
 	int restart_fw;		/* def: 1 = restart firmware */
 };
 
+/**
+ * struct iwl_cfg
+ * @fw_name_pre: Firmware filename prefix. The api version and extension
+ * 	(.ucode) will be added to filename before loading from disk. The
+ * 	filename is constructed as fw_name_pre<api>.ucode.
+ * @ucode_api_max: Highest version of uCode API supported by driver.
+ * @ucode_api_min: Lowest version of uCode API supported by driver.
+ *
+ * We enable the driver to be backward compatible wrt API version. The
+ * driver specifies which APIs it supports (with @ucode_api_max being the
+ * highest and @ucode_api_min the lowest). Firmware will only be loaded if
+ * it has a supported API version. The firmware's API version will be
+ * stored in @iwl_priv, enabling the driver to make runtime changes based
+ * on firmware version used.
+ *
+ * For example,
+ * if (IWL_UCODE_API(priv->ucode_ver) >= 2) {
+ * 	Driver interacts with Firmware API version >= 2.
+ * } else {
+ * 	Driver interacts with Firmware API version 1.
+ * }
+ *
+ * The ideal usage of this infrastructure is to treat a new ucode API
+ * release as a new hardware revision. That is, through utilizing the
+ * iwl_hcmd_utils_ops etc. we accommodate different command structures
+ * and flows between hardware versions (4965/5000) as well as their API
+ * versions.
+ */
 struct iwl_cfg {
 	const char *name;
-	const char *fw_name;
+	const char *fw_name_pre;
+	const unsigned int ucode_api_max;
+	const unsigned int ucode_api_min;
 	unsigned int sku;
 	int eeprom_size;
 	u16  eeprom_ver;