[PATCH v2 05/14] rockchip: rk3308: Enable random generator

[Jonas Karlman]

Hi Quentin,

On 2024-04-09 17:45, Quentin Schulz wrote:
> Hi Jonas,
> 
> On 4/8/24 20:14, Jonas Karlman wrote:
>> The RK3308 SoC contain a crypto engine block that can generate random
>> numbers.
>>
>> Add rng node to soc u-boot.dtsi and enable Kconfig options to take
>> advantage of the random generator.
>>
>> Signed-off-by: Jonas Karlman <jonas at kwiboo.se>
>> ---
>> v2: No change
>> ---
>>   arch/arm/dts/rk3308-u-boot.dtsi | 5 +++++
>>   arch/arm/mach-rockchip/Kconfig  | 2 ++
>>   2 files changed, 7 insertions(+)
>>
>> diff --git a/arch/arm/dts/rk3308-u-boot.dtsi b/arch/arm/dts/rk3308-u-boot.dtsi
>> index 436f66d1b87d..fa31c838d34d 100644
>> --- a/arch/arm/dts/rk3308-u-boot.dtsi
>> +++ b/arch/arm/dts/rk3308-u-boot.dtsi
>> @@ -26,6 +26,11 @@
>>   			reg = <0x07 0x10>;
>>   		};
>>   	};
>> +
>> +	rng: rng at ff2f0000 {
>> +		compatible = "rockchip,cryptov2-rng";
>> +		reg = <0x0 0xff2f0000 0x0 0x4000>;
> 
> Downstream says something different:
> 
> https://github.com/rockchip-linux/kernel/blob/develop-5.10/arch/arm64/boot/dts/rockchip/rk3308.dtsi#L1007-L1020
> 
> I couldn't quickly find the TRM for the RK3308 so cannot check myself :/

RK3308TRM Part1 mention following under address mapping:

ff2f0000 CRYPTO 64K

And RK3308TRM Part2 mention following under crypto regs:

CRYPTO_CLK_CTL  0x0000  W  0x00000001  Clock Control Register
[...]
CRYPTO_RNG_CTL  0x0400  W  0x0000000c  RNG Control Register
[...]
CRYPTO_SRAM_ADDR  0x1000  W  0x00000000  SRAM Base Address

And the U-Boot driver:

/* start of CRYPTO V2 register define */
#define CRYPTO_V2_RNG_CTL			0x0400

So 0xff2f0000 should be correct for the crypto block on RK3308. And the
rng cmd also gives me proper random numbers on my Rock Pi S board.

> 
> Also seems to be missing clocks and resets?

Yeah, this is just a minimal node to get the rng driver in U-Boot
working and like most other clocks they are enabled and running at an
acceptable rate by default.

Regards,
Jonas

> 
> Cheers,
> Quentin