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

From: Caesar Wang
Date: Thu Jun 18 2015 - 05:08:38 EST

å 2015å06æ18æ 16:29, Srinivas Kandagatla åé:

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

Am 16.06.2015 um 12:54 schrieb Srinivas Kandagatla:

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

å 2015å06æ16æ 17:21, Srinivas Kandagatla åé:
Hi Stefan,

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

[add Maxime and Srinivas]

Am 16.06.2015 um 09:27 schrieb Caesar Wang:
The original driver is uploaded by Jianqun.
Here is his patchs:

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

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:

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 ...

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

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

That rockchip-efuse.c driver shouldn't be work.

An entire 8-bit word of data can be read in one read operation with STROBE being high and a proper address
selected (address signals A5~A7 are âdonât caresâ).

That's great if we can get the content from the .reg_read when the consumer driver
callback the nvmem_cell_read().

static struct regmap_config rockchip_efuse_regmap_config = {
.reg_bits = 32,
.val_bits = 8,
.reg_stride = 1,
.reg_read = rockchip_efuse_reg_read,
/ * consumer driver */

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
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.


Best regards

- Caesar

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at