using the same regmap by multiple device drivers

using the same regmap by multiple device drivers

[Vitaly Andrianov]

Hello,

I'm working on two drivers "crypto" and "hwrng", which use the same 
hardware module and the same block of registers. Actually the drivers 
don't need to access the same registers except several common ones.

Here is fragment of dts.

sa_subsys: subsys@1234000 {
	compatible	= "syscon";
	reg		= <0x1234000 0x1000>;
};

crypto@1234000 {
	compatible = "ti,netcp-sa-crypto";
	syscon-subsys = <&sa_subsys>;
	clocks = <&clksa>;
	.....
};

rng@1234000 {
	compatible = "ti,keystone-rng";
	syscon-subsys = <&sa_subsys>;
	clocks = <&clksa>;
};

The both drivers use

regmap = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
				  	"syscon-subsys");

to get pointers to "struct regmap".

Unfortunately I can get the first driver working only. When the second 
driver tries to call regmap_read() kernel gives "Division by zero in 
kernel" error.

Here is my question. Is that actually possible to use in regmap 
framework the same registers in multiple different drivers?

Thank you,
-Vitaly

Re: using the same regmap by multiple device drivers

[Mark Brown]

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On Wed, Jun 29, 2016 at 01:19:37PM -0400, Vitaly Andrianov wrote:

> Here is my question. Is that actually possible to use in regmap framework
> the same registers in multiple different drivers?

Of course, this is how the vast majority of MFDs work.  The regmap has
no idea what's calling it, it can't tell if a call comes from one driver
or another.

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Re: using the same regmap by multiple device drivers

[Vitaly Andrianov]

On 06/29/2016 02:31 PM, Mark Brown wrote:
> On Wed, Jun 29, 2016 at 01:19:37PM -0400, Vitaly Andrianov wrote:
>
>> Here is my question. Is that actually possible to use in regmap framework
>> the same registers in multiple different drivers?
>
> Of course, this is how the vast majority of MFDs work.  The regmap has
> no idea what's calling it, it can't tell if a call comes from one driver
> or another.
>
Thank you.