On 2016/4/7 22:55, Mathieu Poirier wrote:
> On 7 April 2016 at 02:23, Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> wrote:
>> This adds the Hisilicon Random Number Generator(RNG) support,
>> which is found in Hip04 and Hip05 soc.
>>
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
>> ---
>> drivers/char/hw_random/Kconfig | 13 ++++
>> drivers/char/hw_random/Makefile | 1 +
>> drivers/char/hw_random/hisi-rng.c | 121 ++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 135 insertions(+)
>> create mode 100644 drivers/char/hw_random/hisi-rng.c
[...]
>> +
>> +#define RNG_SEED 0x0
>> +#define RNG_CTRL 0x4
>> + #define RNG_SEED_SEL BIT(2)
>> + #define RNG_RING_EN BIT(1)
>> + #define RNG_EN BIT(0)
>> +#define RNG_RAN_NUM 0x10
>> +#define RNG_PHY_SEED 0x14
>> +#define RNG_RELOAD_ERR 0x84
>> +
>> +#define to_hisi_rng(p) container_of(p, struct hisi_rng, rng)
>> +
>> +static int seed_sel;
>> +module_param(seed_sel, int, S_IRUGO);
>> +MODULE_PARM_DESC(seed_sel, "Auto reload seed. 0, use LFSR(default); 1, use ring oscillator.");
>> +
>> +struct hisi_rng {
>> + void __iomem *base;
>> + struct hwrng rng;
>> +};
>> +
>> +static int hisi_rng_init(struct hwrng *rng)
>> +{
>> + struct hisi_rng *hrng = to_hisi_rng(rng);
>> + int val = RNG_EN;
>> + u32 seed;
>> +
>> + /* get a random number as initial seed */
>> + get_random_bytes(&seed, sizeof(seed));
>> +
>> + writel_relaxed(seed, hrng->base + RNG_SEED);
>> +
>> + if (seed_sel == 1)
>> + val |= RNG_RING_EN | RNG_SEED_SEL;
>
> Hello Kefeng,
>
> Please explain what this mode does. Otherwise reviewers have to make
> a guess based on the description of the module parameter.
The seed is reload periodically, there are two choice of seeds, default using
the val from LFSR, seed_sel = 1 will use the val generated by ring oscillator.
>
>> +
>> + writel_relaxed(val, hrng->base + RNG_CTRL);
>> + return 0;
>> +}
>> +
>> +static void hisi_rng_cleanup(struct hwrng *rng)
>> +{
>> + struct hisi_rng *hrng = to_hisi_rng(rng);
>> +
>> + writel_relaxed(0, hrng->base + RNG_CTRL);
>> +}
>> +
>> +static int hisi_rng_read(struct hwrng *rng, void *buf, size_t max,
>> + bool wait)
>
> What are variable 'max' and 'wait' used for? As far as I can tell
> they can be removed.
Ok, will use data_read callback in struct hwrng.
>
>> +{
>> + struct hisi_rng *hrng = to_hisi_rng(rng);
>> + u32 *data = buf;
>> +
>> + *data = readl_relaxed(hrng->base + RNG_RAN_NUM);
>> + return 4;
>
> Why not simply doing the readl_relaxed() in the the code rather than
> introducing a new function?
Not clear, your mean introduce the data variable?
Will use following data_read, thanks.
static int hisi_rng_data_read(struct hwrng *rng, u32 *data)
{
struct hisi_rng *hrng = to_hisi_rng(rng);
*data = readl_relaxed(hrng->base + RNG_RAN_NUM);
return 4;
}
Thanks,
Kefeng
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