[PATCH] libertas: add sysfs hooks to update boot2 and persistent firmware

[Dan Williams]

On Mon, 2008-06-02 at 17:12 -0700, Brian Cavagnolo wrote:
> To update boot2, copy the boot2 and firmware images to /lib/firmware and:
> 
> echo <boot2_image_name> > /sys/class/net/eth2/lbs_boot2
> echo <firmware_image_name> > /sys/class/net/eth2/lbs_fw

So by this point the driver has already sent BOOT_CMD_FW_BY_USB and
there's already a runtime firmware loaded on the device.

Am I correct in assuming that the runtime firmware implements _all_ the
same boot commands that the boot2 firmware does, including UPDATE_BOOT2
(flash new boot2 to EEPROM), FW_BY_USB (execute uploaded firmware but do
not flash), and UPDATE_FW (flash new runtime firmware to EEPROM)?  Or
does the runtime firmware only support flashing, not re-executing itself
with FW_BY_USB?

Are there _any_ side effects of sending the boot command to a running
firmware?  We didn't have to care about these before because the module
wasn't loaded, and when you were done flashing you were supposed to load
the module which would reset the card.

You'll need to grab priv->driver_lock before calling if_usb_prog_fw().
If you don't, anyone can issue WEXT commands or call 'ifconfig eth0 up'
and start inserting random commands into the command queue.  I'm not
even sure grabbing priv->driver_lock will help you here, because the
firmware upload code was always executed _before_ there was a network
interface registered with the system, and thus doesn't need to do _any_
locking at all.  So just grabbing priv->driver_lock doesn't necessarily
stop other USB commands from getting issued, though in practice since
you have to have priv->driver_lock held before grabbing a free cmd_node
from the driver core, this would stop the driver core from sending
commands during a firmware upload.  So the behavior you'd get would be
that an iwconfig call would block until the firmware upload was
complete, then immediately send the pending command to the firmware.
Hence my question about side-effects above.

Does the loaded runtime firmware just write the new firmware to EEPROM
and then continue as normal?  If so, I assume that the new firmware is
not expected to be active until (a) reboot, (b) USB port reset, (c) OLPC
EC-triggered reset, (d) CMD_802_11_RESET, or (e) hotplug of the active
antenna.

The code probably shouldn't allow updating the firmware if the battery
is low.  Unfortunately, this isn't something that can or should be
stuffed into the driver, which is one great benefit of doing the update
in userspace.  Second, you probably want to make sure that the system is
prohibited from entering the suspend state during a firmware update.
This is also probably better done via userspace.  Obviously neither of
these two is implemented in the current userspace tool but they would be
nice, and not something that can be done from the kernel side in any
upstream-able manner.

Dan

> Signed-off-by: Brian Cavagnolo <brian at cozybit.com>
> ---
>  drivers/net/wireless/libertas/if_usb.c |   65 ++++++++++++++++++++++++++++++++
>  1 files changed, 65 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/net/wireless/libertas/if_usb.c b/drivers/net/wireless/libertas/if_usb.c
> index 91413a6..6a32f37 100644
> --- a/drivers/net/wireless/libertas/if_usb.c
> +++ b/drivers/net/wireless/libertas/if_usb.c
> @@ -46,6 +46,62 @@ static void if_usb_free(struct if_usb_card *cardp);
>  static int if_usb_submit_rx_urb(struct if_usb_card *cardp);
>  static int if_usb_reset_device(struct if_usb_card *cardp);
>  
> +/* sysfs hooks */
> +
> +/**
> + *  Set function to write firmware to device's persistent memory
> + */
> +static ssize_t if_usb_firmware_set(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t count)
> +{
> +	struct lbs_private *priv = to_net_dev(dev)->priv;
> +	struct if_usb_card *cardp = priv->card;
> +	char fwname[FIRMWARE_NAME_MAX];
> +	int ret;
> +
> +	sscanf(buf, "%29s", fwname); /* FIRMWARE_NAME_MAX - 1 = 29 */
> +	ret = if_usb_prog_firmware(cardp, fwname, BOOT_CMD_UPDATE_FW);
> +	if (ret == 0)
> +		return count;
> +
> +	return ret;
> +}
> +
> +/**
> + * lbs_fw attribute to be exported per ethX interface through sysfs
> + * (/sys/class/net/ethX/lbs_fw).  Use this like so to write firmware to the
> + * device's persistent memory:
> + * echo usb8388-5.126.0.p5.bin > /sys/class/net/ethX/lbs_fw
> + */
> +static DEVICE_ATTR(lbs_fw, 0200, NULL, if_usb_firmware_set);
> +
> +/**
> + *  Set function to write firmware to device's persistent memory
> + */
> +static ssize_t if_usb_boot2_set(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t count)
> +{
> +	struct lbs_private *priv = to_net_dev(dev)->priv;
> +	struct if_usb_card *cardp = priv->card;
> +	char fwname[FIRMWARE_NAME_MAX];
> +	int ret;
> +
> +	sscanf(buf, "%29s", fwname); /* FIRMWARE_NAME_MAX - 1 = 29 */
> +	ret = if_usb_prog_firmware(cardp, fwname, BOOT_CMD_UPDATE_BOOT2);
> +	if (ret == 0)
> +		return count;
> +
> +	return ret;
> +}
> +
> +/**
> + * lbs_boot2 attribute to be exported per ethX interface through sysfs
> + * (/sys/class/net/ethX/lbs_boot2).  Use this like so to write firmware to the
> + * device's persistent memory:
> + * echo usb8388-5.126.0.p5.bin > /sys/class/net/ethX/lbs_boot2
> + */
> +static DEVICE_ATTR(lbs_boot2, 0200, NULL, if_usb_boot2_set);
> +
>  /**
>   *  @brief  call back function to handle the status of the URB
>   *  @param urb 		pointer to urb structure
> @@ -246,6 +302,12 @@ static int if_usb_probe(struct usb_interface *intf,
>  	usb_get_dev(udev);
>  	usb_set_intfdata(intf, cardp);
>  
> +	if (device_create_file(&priv->dev->dev, &dev_attr_lbs_fw))
> +		lbs_pr_err("cannot register lbs_fw attribute\n");
> +
> +	if (device_create_file(&priv->dev->dev, &dev_attr_lbs_boot2))
> +		lbs_pr_err("cannot register lbs_boot2 attribute\n");
> +
>  	return 0;
>  
>  err_start_card:
> @@ -271,6 +333,9 @@ static void if_usb_disconnect(struct usb_interface *intf)
>  
>  	lbs_deb_enter(LBS_DEB_MAIN);
>  
> +	device_remove_file(&priv->dev->dev, &dev_attr_lbs_boot2);
> +	device_remove_file(&priv->dev->dev, &dev_attr_lbs_fw);
> +
>  	cardp->surprise_removed = 1;
>  
>  	if (priv) {