On Mon, Jun 11, 2018 at 01:33:07PM -0500, Tom Lendacky wrote: > On 6/10/2018 11:25 PM, Don Bollinger wrote: > > optoe is an i2c based driver that supports read/write access to all > > the pages (tables) of MSA standard SFP and similar devices (conforming > > to the SFF-8472 spec) and MSA standard QSFP and similar devices > > (conforming to the SFF-8436 spec). > > > > These devices provide identification, operational status and control > > registers via an EEPROM model. These devices support one or 3 fixed > > pages (128 bytes) of data, and one page that is selected via a page > > register on the first fixed page. Thus the driver's main task is > > to map these pages onto a simple linear address space for user space > > management applications. See the driver code for a detailed layout. > > > > EEPROM data is accessible via a bin_attribute file called 'eeprom', > > e.g. /sys/bus/i2c/devices/24-0050/eeprom. > > > > Signed-off-by: Don Bollinger <d...@thebollingers.org> > > --- > > > > Why should this driver be in the Linux kernel? SFP and QSFP devices plug > > into switches to convert electrical to optical signals and drive the > > optical signal over fiber optic cables. They provide status and control > > registers through an i2c interface similar to to other EEPROMS. However, > > they have a paging mechanism that is unique, which requires a different > > driver from (for example) at24. Various drivers have been developed for > > this purpose, none of them support both SFP and QSFP, provide both read > > and write access, and access all 256 architected pages. optoe does all > > of these. > > > > optoe has been adopted and is shipping to customers as a base module, > > available to all platforms (switches) and used by multiple vendors and > > platforms on both ONL (Open Network Linux) and SONiC (Microsoft's > > 'Software for Open Networking in the Cloud'). > > > > This patch has been built on the latest staging-testing kernel. It has > > built and tested with SFP and QSFP devices on an ARM platform with a 4.9 > > kernel, and an x86 switch with a 3.16 kernel. This patch should install > > and build clean on any kernel from 3.16 up to the latest (as of 6/10/2018). > > > > > > Documentation/misc-devices/optoe.txt | 56 ++ > > drivers/misc/eeprom/Kconfig | 18 + > > drivers/misc/eeprom/Makefile | 1 + > > drivers/misc/eeprom/optoe.c | 1141 > > ++++++++++++++++++++++++++++++++++ > > 4 files changed, 1216 insertions(+) > > create mode 100644 Documentation/misc-devices/optoe.txt > > create mode 100644 drivers/misc/eeprom/optoe.c > > > > There's an SFP driver under drivers/net/phy. Can that driver be extended > to provide this support? Adding Russel King who developed sfp.c, as well > at the netdev mailing list. > > Thanks, > Tom
I don't think that would work very well. It's software, anything is possible, but... sfp.c appears to be working with mdio, gpio and 'sfp_bus', in addition to i2c. optoe only access the EEPROM, and only via i2c. The linux standard i2c interfaces are the only dependencies for optoe. Also, sfp.c does not support QSFP (best I can tell), and it does not support additional pages beyond the 256 bytes at i2c address 0x50 and 0x51. Best I can tell, sfp.c supports SFP devices on NIC cards. Those cards have a very different hardware architecture from the network switches that optoe is targeting.
