hwrng: bcm2835 - Support Broadcom NSP SoC rng

This supports the random number generator available in NSP SoC.
Masks the rng interrupt for NSP.
Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
Acked-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/Kconfig

@@ -90,7 +90,7 @@ config HW_RANDOM_BCM63XX
 
 config HW_RANDOM_BCM2835
 	tristate "Broadcom BCM2835 Random Number Generator support"
-	depends on ARCH_BCM2835
+	depends on ARCH_BCM2835 || ARCH_BCM_NSP
 	default HW_RANDOM
 	---help---
 	  This driver provides kernel-side support for the Random Number

drivers/char/hw_random/bcm2835-rng.c

@@ -19,6 +19,7 @@
 #define RNG_CTRL	0x0
 #define RNG_STATUS	0x4
 #define RNG_DATA	0x8
+#define RNG_INT_MASK	0x10
 
 /* enable rng */
 #define RNG_RBGEN	0x1
@@ -26,6 +27,18 @@
 /* the initial numbers generated are "less random" so will be discarded */
 #define RNG_WARMUP_COUNT 0x40000
 
+#define RNG_INT_OFF	0x1
+
+static void __init nsp_rng_init(void __iomem *base)
+{
+	u32 val;
+
+	/* mask the interrupt */
+	val = readl(base + RNG_INT_MASK);
+	val |= RNG_INT_OFF;
+	writel(val, base + RNG_INT_MASK);
+}
+
 static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
 			       bool wait)
 {
@@ -46,10 +59,18 @@ static struct hwrng bcm2835_rng_ops = {
 	.read	= bcm2835_rng_read,
 };
 
+static const struct of_device_id bcm2835_rng_of_match[] = {
+	{ .compatible = "brcm,bcm2835-rng"},
+	{ .compatible = "brcm,bcm-nsp-rng", .data = nsp_rng_init},
+	{},
+};
+
 static int bcm2835_rng_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
+	void (*rng_setup)(void __iomem *base);
+	const struct of_device_id *rng_id;
 	void __iomem *rng_base;
 	int err;
 
@@ -61,6 +82,15 @@ static int bcm2835_rng_probe(struct platform_device *pdev)
 	}
 	bcm2835_rng_ops.priv = (unsigned long)rng_base;
 
+	rng_id = of_match_node(bcm2835_rng_of_match, np);
+	if (!rng_id)
+		return -EINVAL;
+
+	/* Check for rng init function, execute it */
+	rng_setup = rng_id->data;
+	if (rng_setup)
+		rng_setup(rng_base);
+
 	/* set warm-up count & enable */
 	__raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS);
 	__raw_writel(RNG_RBGEN, rng_base + RNG_CTRL);
@@ -90,10 +120,6 @@ static int bcm2835_rng_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static const struct of_device_id bcm2835_rng_of_match[] = {
-	{ .compatible = "brcm,bcm2835-rng", },
-	{},
-};
 MODULE_DEVICE_TABLE(of, bcm2835_rng_of_match);
 
 static struct platform_driver bcm2835_rng_driver = {