Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / char / hw_random / nomadik-rng.c

diff --git a/kernel/drivers/char/hw_random/nomadik-rng.c b/kernel/drivers/char/hw_random/nomadik-rng.c
new file mode 100644 (file)
index 0000000..9c85815
--- /dev/null
+++ b/kernel/drivers/char/hw_random/nomadik-rng.c
@@ -0,0 +1,106 @@
+/*
+ * Nomadik RNG support
+ *  Copyright 2009 Alessandro Rubini
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ */
+
+#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 struct clk *rng_clk;
+
+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)
+{
+       void __iomem *base;
+       int ret;
+
+       rng_clk = devm_clk_get(&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;
+       }
+
+       clk_prepare_enable(rng_clk);
+
+       ret = amba_request_regions(dev, dev->dev.init_name);
+       if (ret)
+               goto out_clk;
+       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 = hwrng_register(&nmk_rng);
+       if (ret)
+               goto out_release;
+       return 0;
+
+out_release:
+       amba_release_regions(dev);
+out_clk:
+       clk_disable(rng_clk);
+       return ret;
+}
+
+static int nmk_rng_remove(struct amba_device *dev)
+{
+       hwrng_unregister(&nmk_rng);
+       amba_release_regions(dev);
+       clk_disable(rng_clk);
+       return 0;
+}
+
+static 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");