1 files changed, 92 insertions, 0 deletions
diff --git a/drivers/char/hw_random/pseries-rng.c b/drivers/char/hw_random/pseries-rng.c
new file mode 100644
index 000000000..62bdd5af1
--- /dev/null
+++ b/drivers/char/hw_random/pseries-rng.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2010 Michael Neuling IBM Corporation
+ *
+ * Driver for the pseries hardware RNG for POWER7+ and above
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/hw_random.h>
+#include <asm/vio.h>
+
+
+static int pseries_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+	u64 buffer[PLPAR_HCALL_BUFSIZE];
+	int rc;
+
+	rc = plpar_hcall(H_RANDOM, (unsigned long *)buffer);
+	if (rc != H_SUCCESS) {
+		pr_err_ratelimited("H_RANDOM call failed %d\n", rc);
+		return -EIO;
+	}
+	memcpy(data, buffer, 8);
+
+	/* The hypervisor interface returns 64 bits */
+	return 8;
+}
+
+/*
+ * pseries_rng_get_desired_dma - Return desired DMA allocate for CMO operations
+ *
+ * This is a required function for a driver to operate in a CMO environment
+ * but this device does not make use of DMA allocations, return 0.
+ *
+ * Return value:
+ *	Number of bytes of IO data the driver will need to perform well -> 0
+ */
+static unsigned long pseries_rng_get_desired_dma(struct vio_dev *vdev)
+{
+	return 0;
+};
+
+static struct hwrng pseries_rng = {
+	.name		= KBUILD_MODNAME,
+	.read		= pseries_rng_read,
+};
+
+static int pseries_rng_probe(struct vio_dev *dev,
+		const struct vio_device_id *id)
+{
+	return hwrng_register(&pseries_rng);
+}
+
+static void pseries_rng_remove(struct vio_dev *dev)
+{
+	hwrng_unregister(&pseries_rng);
+}
+
+static const struct vio_device_id pseries_rng_driver_ids[] = {
+	{ "ibm,random-v1", "ibm,random"},
+	{ "", "" }
+};
+MODULE_DEVICE_TABLE(vio, pseries_rng_driver_ids);
+
+static struct vio_driver pseries_rng_driver = {
+	.name = KBUILD_MODNAME,
+	.probe = pseries_rng_probe,
+	.remove = pseries_rng_remove,
+	.get_desired_dma = pseries_rng_get_desired_dma,
+	.id_table = pseries_rng_driver_ids
+};
+
+static int __init rng_init(void)
+{
+	pr_info("Registering IBM pSeries RNG driver\n");
+	return vio_register_driver(&pseries_rng_driver);
+}
+
+module_init(rng_init);
+
+static void __exit rng_exit(void)
+{
+	vio_unregister_driver(&pseries_rng_driver);
+}
+module_exit(rng_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Michael Neuling <mikey@neuling.org>");
+MODULE_DESCRIPTION("H/W RNG driver for IBM pSeries processors");