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[PATCH 2/4] hwrng: bcm2835: Support Broadcom NSP SoC rng

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  [PATCH 2/4] hwrng: bcm2835: Support Broadcom NSP SoC rng Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com> - 2016-05-23 18:30 +0200
    Re: [PATCH 2/4] hwrng: bcm2835: Support Broadcom NSP SoC rng Eric Anholt <eric@anholt.net> - 2016-05-24 04:20 +0200

#1405496 — [PATCH 2/4] 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>
---
 drivers/char/hw_random/Kconfig       |  2 +-
 drivers/char/hw_random/bcm2835-rng.c | 34 ++++++++++++++++++++++++++++++----
 2 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index 67ee8b0..f8d1a2b 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/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
diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c
index 7192ec2..b1e8b78 100644
--- a/drivers/char/hw_random/bcm2835-rng.c
+++ b/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 = {
-- 
2.1.0

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#1405777

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Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
writes:

> This supports the random number generator available in NSP SoC.
> Masks the rng interrupt for NSP.

The interrupt reg is also present on the 2835.  I would prefer for
simplicity if you also initialized the register to the same value on the
Pi, even though the firmware has presumably been setting it for us
already.

However, this patch is still correct and I'm fine with it, so it's:

Acked-by: Eric Anholt <eric@anholt.net>

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