Re: [PATCH v2 0/3] Add the efuse driver on rockchip platform

On 18/06/15 08:05, Stefan Wahren wrote:

Hi Srinivas,

Am 16.06.2015 um 12:54 schrieb Srinivas Kandagatla:

quoted

On 16/06/15 11:06, Caesar Wang wrote:

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Hi Srinivas,

在 2015年06月16日 17:21, Srinivas Kandagatla 写道:

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Hi Stefan,


On 16/06/15 09:52, Stefan Wahren wrote:

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Hi Caesar,

[add Maxime and Srinivas]

Am 16.06.2015 um 09:27 schrieb Caesar Wang:

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The original driver is uploaded by Jianqun.
Here is his patchs:
      https://patchwork.kernel.org/patch/5410341/
      https://patchwork.kernel.org/patch/5410351/

Jianqun, nevermind!
I check-pick it and re-upload the driver for the upstream.
e.g.:
      Tested by on minnie board.(kernel-4.1-rc8)
      cd /sys/devices/platform/ffb40000.efuse
      localhost ffb40000.efuse # cat cpu_leakage_show
      cpu_version_show
      The results:
              19
              2

Changes in v2:
- Change the document decription.
- Move the efuse driver into driver/soc/vendor.
- update the efuse driver.
- Add the dts node on RK3288.

i want to mention that there is a upcoming new framework suitable for
efuse drivers:

https://lkml.org/lkml/2015/5/21/643

Unfortunately i don't know the current development state.

Currently this framework is used by atleast 3 drivers(qcom-tsens,
qcom-cpr, begel-bone-cape manager) which are still floating in the
mailing list.

I was hoping that these 3 users would getback with tested-by.. which
did not happen for last 3-4 weeks.

I would appreciate, If you could try framework too, and let me know.

yes i work on OCOTP driver for MXS platform and i will try ...

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int rockchip_efuse_reg_read(void *context, unsigned int reg, unsigned
int *val)
{
     /* efuse specific read sequence */
     ...
}

I will need a specific read sequence too.

You can have a look at https://git.linaro.org/people/srinivas.kandagatla/linux.git/blob/b4c3ad253747767511233687436f20144e850d67:/drivers/nvmem/rockchip-efuse.c

I did modify the rockchip driver, which I guess should be very much similar to what OCOTP driver would need.

Sorry for these newbie questions:

What data structure does context points to for this reg_read opteration?

Do we need range checking of reg or is it handled by the framework?

We already have that in place.

Are there any limitation for reg_read regarding sleeping or locking
operations?

There are no limitaions as such from nvmem framework, regmap might have limitations w.r.t to sleeping and fast_io, as fast_io would take spinlocks, AFAIK the providers would not have fast_io, as they not IO devices.

In case of a read only driver, is everything handle by devicetree or do
we need an empty write operation?

Yes, if you pass read-only flag in the provider, the framework would not attempt to even write.

You will find answers to most of your question in the rochip-efuse.c file.


--srini

Best regards
Stefan