1 files changed, 94 insertions, 0 deletions
diff --git a/drivers/char/hw_random/nomadik-rng.c b/drivers/char/hw_random/nomadik-rng.c
new file mode 100644
index 000000000..3774adf90
--- /dev/null
+++ b/drivers/char/hw_random/nomadik-rng.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Nomadik RNG support
+ *  Copyright 2009 Alessandro Rubini
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/amba/bus.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+
+static int nmk_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+	void __iomem *base = (void __iomem *)rng->priv;
+
+	/*
+	 * The register is 32 bits and gives 16 random bits (low half).
+	 * A subsequent read will delay the core for 400ns, so we just read
+	 * once and accept the very unlikely very small delay, even if wait==0.
+	 */
+	*(u16 *)data = __raw_readl(base + 8) & 0xffff;
+	return 2;
+}
+
+/* we have at most one RNG per machine, granted */
+static struct hwrng nmk_rng = {
+	.name		= "nomadik",
+	.read		= nmk_rng_read,
+};
+
+static int nmk_rng_probe(struct amba_device *dev, const struct amba_id *id)
+{
+	struct clk *rng_clk;
+	void __iomem *base;
+	int ret;
+
+	rng_clk = devm_clk_get_enabled(&dev->dev, NULL);
+	if (IS_ERR(rng_clk)) {
+		dev_err(&dev->dev, "could not get rng clock\n");
+		ret = PTR_ERR(rng_clk);
+		return ret;
+	}
+
+	ret = amba_request_regions(dev, dev->dev.init_name);
+	if (ret)
+		return ret;
+	ret = -ENOMEM;
+	base = devm_ioremap(&dev->dev, dev->res.start,
+			    resource_size(&dev->res));
+	if (!base)
+		goto out_release;
+	nmk_rng.priv = (unsigned long)base;
+	ret = devm_hwrng_register(&dev->dev, &nmk_rng);
+	if (ret)
+		goto out_release;
+	return 0;
+
+out_release:
+	amba_release_regions(dev);
+	return ret;
+}
+
+static void nmk_rng_remove(struct amba_device *dev)
+{
+	amba_release_regions(dev);
+}
+
+static const struct amba_id nmk_rng_ids[] = {
+	{
+		.id	= 0x000805e1,
+		.mask	= 0x000fffff, /* top bits are rev and cfg: accept all */
+	},
+	{0, 0},
+};
+
+MODULE_DEVICE_TABLE(amba, nmk_rng_ids);
+
+static struct amba_driver nmk_rng_driver = {
+	.drv = {
+		.owner = THIS_MODULE,
+		.name = "rng",
+		},
+	.probe = nmk_rng_probe,
+	.remove = nmk_rng_remove,
+	.id_table = nmk_rng_ids,
+};
+
+module_amba_driver(nmk_rng_driver);
+
+MODULE_LICENSE("GPL");