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path: root/drivers/char/hw_random/powernv-rng.c
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Diffstat (limited to 'drivers/char/hw_random/powernv-rng.c')
-rw-r--r--drivers/char/hw_random/powernv-rng.c81
1 files changed, 81 insertions, 0 deletions
diff --git a/drivers/char/hw_random/powernv-rng.c b/drivers/char/hw_random/powernv-rng.c
new file mode 100644
index 000000000..263a5bb8e
--- /dev/null
+++ b/drivers/char/hw_random/powernv-rng.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2013 Michael Ellerman, Guo Chao, IBM Corp.
+ *
+ * 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/random.h>
+#include <linux/hw_random.h>
+
+static int powernv_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+ unsigned long *buf;
+ int i, len;
+
+ /* We rely on rng_buffer_size() being >= sizeof(unsigned long) */
+ len = max / sizeof(unsigned long);
+
+ buf = (unsigned long *)data;
+
+ for (i = 0; i < len; i++)
+ powernv_get_random_long(buf++);
+
+ return len * sizeof(unsigned long);
+}
+
+static struct hwrng powernv_hwrng = {
+ .name = "powernv-rng",
+ .read = powernv_rng_read,
+};
+
+static int powernv_rng_remove(struct platform_device *pdev)
+{
+ hwrng_unregister(&powernv_hwrng);
+
+ return 0;
+}
+
+static int powernv_rng_probe(struct platform_device *pdev)
+{
+ int rc;
+
+ rc = hwrng_register(&powernv_hwrng);
+ if (rc) {
+ /* We only register one device, ignore any others */
+ if (rc == -EEXIST)
+ rc = -ENODEV;
+
+ return rc;
+ }
+
+ pr_info("Registered powernv hwrng.\n");
+
+ return 0;
+}
+
+static const struct of_device_id powernv_rng_match[] = {
+ { .compatible = "ibm,power-rng",},
+ {},
+};
+MODULE_DEVICE_TABLE(of, powernv_rng_match);
+
+static struct platform_driver powernv_rng_driver = {
+ .driver = {
+ .name = "powernv_rng",
+ .of_match_table = powernv_rng_match,
+ },
+ .probe = powernv_rng_probe,
+ .remove = powernv_rng_remove,
+};
+module_platform_driver(powernv_rng_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Bare metal HWRNG driver for POWER7+ and above");