wimax/i2400m: add the ability to fallback to other firmware files if the default is not there

In order to support backwards compatibility with older firmwares when
a driver is updated by a new kernel release, the i2400m bus drivers
can declare a list of firmware files they can work with (in general
these will be each a different version). The firmware loader will try
them in sequence until one loads.

Thus, if a user doesn't have the latest and greatest firmware that a
newly installed kernel would require, the driver would fall back to
the firmware from a previous release.

To support this, the i2400m->bus_fw_name is changed to be a NULL
terminated array firmware file names (and renamed to bus_fw_names) and
we add a new entry (i2400m->fw_name) that points to the name of the
firmware being currently used. All code that needs to print the
firmware file name uses i2400m->fw_name instead of the old
i2400m->bus_fw_name.

The code in i2400m_dev_bootstrap() that loads the firmware is changed
with an iterator over the firmware file name list that tries to load
each form user space, using the first one that succeeds in
request_firmware() (and thus stopping the iteration).

The USB and SDIO bus drivers are updated to take advantage of this and
reflect which firmwares they support.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 9 deletions

diff --git a/drivers/net/wimax/i2400m/i2400m.h b/drivers/net/wimax/i2400m/i2400m.h
index f9e55397ee88..ad71ad1086ea 100644
--- a/drivers/net/wimax/i2400m/i2400m.h
+++ b/drivers/net/wimax/i2400m/i2400m.h
@@ -156,10 +156,6 @@ enum {
 };
 
 
-/* Firmware version we request when pulling the fw image file */
-#define I2400M_FW_VERSION "1.4"
-
-
 /**
  * i2400m_reset_type - methods to reset a device
  *
@@ -242,10 +238,14 @@ struct i2400m_reset_ctx;
  *     The caller to this function will check if the response is a
  *     barker that indicates the device going into reset mode.
  *
- * @bus_fw_name: [fill] name of the firmware image (in most cases,
- *     they are all the same for a single release, except that they
- *     have the type of the bus embedded in the name (eg:
- *     i2400m-fw-X-VERSION.sbcf, where X is the bus name).
+ * @bus_fw_names: [fill] a NULL-terminated array with the names of the
+ *     firmware images to try loading. This is made a list so we can
+ *     support backward compatibility of firmware releases (eg: if we
+ *     can't find the default v1.4, we try v1.3). In general, the name
+ *     should be i2400m-fw-X-VERSION.sbcf, where X is the bus name.
+ *     The list is tried in order and the first one that loads is
+ *     used. The fw loader will set i2400m->fw_name to point to the
+ *     active firmware image.
  *
  * @bus_bm_mac_addr_impaired: [fill] Set to true if the device's MAC
  *     address provided in boot mode is kind of broken and needs to
@@ -364,6 +364,8 @@ struct i2400m_reset_ctx;
  *     These have to be in a separate directory, a child of
  *     (wimax_dev->debugfs_dentry) so they can be removed when the
  *     module unloads, as we don't keep each dentry.
+ *
+ * @fw_name: name of the firmware image that is currently being used.
  */
 struct i2400m {
 	struct wimax_dev wimax_dev;	/* FIRST! See doc */
@@ -388,7 +390,7 @@ struct i2400m {
 				   size_t, int flags);
 	ssize_t (*bus_bm_wait_for_ack)(struct i2400m *,
 				       struct i2400m_bootrom_header *, size_t);
-	const char *bus_fw_name;
+	const char **bus_fw_names;
 	unsigned bus_bm_mac_addr_impaired:1;
 
 	spinlock_t tx_lock;		/* protect TX state */
@@ -421,6 +423,7 @@ struct i2400m {
 	struct sk_buff *wake_tx_skb;
 
 	struct dentry *debugfs_dentry;
+	const char *fw_name;		/* name of the current firmware image */
 };