[RFC Patch v2 0/3] I2C statistics as sysfs attributes

[Sui Chen]

Add I2C statistics such as Bus Error counts and NACK counts as sysfs
attributes so they don't need to live in debugfs.

There are a few I2C statistics that are implemented in many I2C
controllers, such as bus error counts and NACK counts. Having those
statistics in sysfs will 1) allow for a unified definition across
various I2C drivers, and 2) make the statistics more ABI-stable and
available on devices with the debugfs disabled.

Overall the patch works as the following way:
1) An I2C statistics sysfs directory is created.
2) Each specific I2C driver is responsible for instantiating the
statistics available.

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      tx_complete_cnt
root at gsj:/sys/class/i2c-adapter/i2c-1/stats# cat *
0
100000
0
0
0
0
53

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

Tali Perry (1):
  i2c: npcm7xx: add tx_complete counter

 drivers/i2c/busses/i2c-npcm7xx.c |  13 ++++
 drivers/i2c/i2c-core-base.c      |   2 +
 drivers/i2c/i2c-dev.c            | 103 +++++++++++++++++++++++++++++++
 include/linux/i2c.h              |  27 ++++++++
 4 files changed, 145 insertions(+)

-- 
2.34.0.384.gca35af8252-goog