On Tue, Feb 24, 2015 at 04:48:08PM +0000, Stathis Voukelatos wrote: > This patch adds support for the Ethernet Packet Sniffer H/W module > developed by Linn Products Ltd and found in the IMG Pistachio SoC. > The module allows Ethernet packets to be parsed, matched against > a user-defined pattern and timestamped. It sits between a 100M > Ethernet MAC and PHY and is completely passive with respect to > Ethernet frames. First off, please stop calling this device a "sniffer". Real sniffers are able to deliver whole frames. Real sniffers are most commonly used to inspect traffic between two or more nodes, but from a third host. Instead, this device really is a time stamping unit with a programmable frame matching engine. So, the approach of this driver is totally wrong. It runs contrary to how time stamping is handled in the kernel. - This driver delivers time stamps "out of band" from a separate interface. The other kernel drivers deliver time stamps "in band", using the same socket from the requesting process. - This driver requires user space to match time stamps with packets. The other kernel drivers perform the matching automatically. - This driver requires user space to program a vendor specific matching engine. The other kernel drivers program their matching engines automatically. Let me suggest another approach that stays in line with the existing frame work. Based on the device's limitations and your own example, it seems clear that the intended use case is synchronization for AVB applications using gPTP. Your time stamping unit is conceptually the same a PHY with hardware time stamping, and you should treat it as such. This means using the CONFIG_NETWORK_PHY_TIMESTAMPING kernel option. There is one mainline PHY driver as an example, dp83640.c. You will have to hard code command strings in the driver, one for each of the SIOCSHWTSTAMP filter types that you want to support. I would recommend supporting just HWTSTAMP_FILTER_PTP_V2_EVENT. You will probably need different filters for L2, IPv4, and IPv6, with and without VLAN. For the transmit case, you can limit the match to PTP events as well. Your filters should at least return the sequenceId and the messageType back to the driver. The only (small) difficulty I can see would be how to arrange for your driver to be called back just like a PHY driver would be. We might need to adapt or expand the internal PHY timestamping framework within the kernel, but if you are willing to rework your driver, then I can help with that part. Thanks, Richard -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
