drivers/char/hw_random/iproc-rng200.c

Source file repositories/reference/linux-study-clean/drivers/char/hw_random/iproc-rng200.c

File Facts

System
Linux kernel
Corpus path
drivers/char/hw_random/iproc-rng200.c
Extension
.c
Size
6204 bytes
Lines
247
Domain
Driver Families
Bucket
drivers/char
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct iproc_rng200_dev {
	struct hwrng rng;
	void __iomem *base;
};

#define to_rng_priv(rng)	container_of(rng, struct iproc_rng200_dev, rng)

static void iproc_rng200_enable_set(void __iomem *rng_base, bool enable)
{
	u32 val;

	val = ioread32(rng_base + RNG_CTRL_OFFSET);
	val &= ~RNG_CTRL_RNG_RBGEN_MASK;

	if (enable)
		val |= RNG_CTRL_RNG_RBGEN_ENABLE;

	iowrite32(val, rng_base + RNG_CTRL_OFFSET);
}

static void iproc_rng200_restart(void __iomem *rng_base)
{
	uint32_t val;

	iproc_rng200_enable_set(rng_base, false);

	/* Clear all interrupt status */
	iowrite32(0xFFFFFFFFUL, rng_base + RNG_INT_STATUS_OFFSET);

	/* Reset RNG and RBG */
	val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);
	val |= RBG_SOFT_RESET;
	iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);

	val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);
	val |= RNG_SOFT_RESET;
	iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);

	val = ioread32(rng_base + RNG_SOFT_RESET_OFFSET);
	val &= ~RNG_SOFT_RESET;
	iowrite32(val, rng_base + RNG_SOFT_RESET_OFFSET);

	val = ioread32(rng_base + RBG_SOFT_RESET_OFFSET);
	val &= ~RBG_SOFT_RESET;
	iowrite32(val, rng_base + RBG_SOFT_RESET_OFFSET);

	iproc_rng200_enable_set(rng_base, true);
}

static int iproc_rng200_read(struct hwrng *rng, void *buf, size_t max,
			     bool wait)
{
	struct iproc_rng200_dev *priv = to_rng_priv(rng);
	uint32_t num_remaining = max;
	uint32_t status;

	#define MAX_RESETS_PER_READ	1
	uint32_t num_resets = 0;

	#define MAX_IDLE_TIME	(1 * HZ)
	unsigned long idle_endtime = jiffies + MAX_IDLE_TIME;

	while ((num_remaining > 0) && time_before(jiffies, idle_endtime)) {

		/* Is RNG sane? If not, reset it. */
		status = ioread32(priv->base + RNG_INT_STATUS_OFFSET);
		if ((status & (RNG_INT_STATUS_MASTER_FAIL_LOCKOUT_IRQ_MASK |
			RNG_INT_STATUS_NIST_FAIL_IRQ_MASK)) != 0) {

			if (num_resets >= MAX_RESETS_PER_READ)
				return max - num_remaining;

			iproc_rng200_restart(priv->base);
			num_resets++;
		}

		/* Are there any random numbers available? */
		if ((ioread32(priv->base + RNG_FIFO_COUNT_OFFSET) &
				RNG_FIFO_COUNT_RNG_FIFO_COUNT_MASK) > 0) {

			if (num_remaining >= sizeof(uint32_t)) {
				/* Buffer has room to store entire word */
				*(uint32_t *)buf = ioread32(priv->base +
							RNG_FIFO_DATA_OFFSET);
				buf += sizeof(uint32_t);
				num_remaining -= sizeof(uint32_t);
			} else {
				/* Buffer can only store partial word */
				uint32_t rnd_number = ioread32(priv->base +
							RNG_FIFO_DATA_OFFSET);

Annotation

Implementation Notes