[RFC Patch Resend 0/2] I2C statistics as sysfs attributes

[Sui Chen]

Add I2C statistics such as Bus Error counts and NACK counts as sysfs
attributes.

I2C statistics such as bus error counts and NACK counts, are
implemented in many I2C controllers.

Some drivers already populate the counters in debugfs. Having those
statistics in sysfs can enable for a unified definition across various
I2C drivers, make the statistics more ABI-stable.

Overall the patch works in the following way:
1) A sysfs directory for I2C statistics is created for an i2c_adapter.
2) Each specific I2C driver can optionally instantiate each of the
statistics individually.

Test Process:
1. Clone the OpenBMC repository
2. `devtool modify`and apply patch to the linux-nuvoton recipe
3. Build image for quanta-gsj
4. Build QEMU
5. Run the image-bmc image in QEMU

Results:
root at gsj:/sys/class/i2c-adapter/i2c-1/stats# ls
ber_cnt       i2c_speed     nack_cnt      rec_fail_cnt  rec_succ_cnt
timeout_cnt
root at gsj:/sys/class/i2c-adapter/i2c-1/stats# cat *
0
100000
0
0
0
0

Sui Chen (2):
  i2c debug counters as sysfs attributes
  add npcm7xx debug counters as sysfs attributes

 drivers/i2c/busses/i2c-npcm7xx.c |  8 +++
 drivers/i2c/i2c-core-base.c      |  2 +
 drivers/i2c/i2c-dev.c            | 98 ++++++++++++++++++++++++++++++++
 include/linux/i2c.h              | 26 +++++++++
 4 files changed, 134 insertions(+)

(Previously sent to linux-i2c, resending to linux-kernel with
CCed correspondents)

CC: OpenBMC Mailing List <openbmc at lists.ozlabs.org>
CC: linux-i2c <linux-i2c at vger.kernel.org>
CC: linux-kernel <linux-kernel at vger.kernel.org>
CC: Joel Stanley <joel at jms.id.au>
CC: Andrew Jeffery <andrew at aj.id.au>
CC: Tali Perry <tali.perry1 at gmail.com>
CC: Benjamin Fair <benjaminfair at google.com>
CC: Josh Lehan <krellan at google.com>


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2.34.0.rc0.344.g81b53c2807-goog