From 66548e40583b1470300341c6784fdc5176f7609f Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Fri, 11 Oct 2013 14:07:58 +1100 Subject: hwrng: Add a driver for the hwrng found in power7+ systems Add a driver for the hwrng found in power7+ systems, based on the existing code for the arch_get_random_long() hook. We only register a single instance of the driver, not one per device, because we use the existing per_cpu array of devices in the arch code. This means we always read from the "closest" device, avoiding inter-chip memory traffic. Signed-off-by: Guo Chao Signed-off-by: Michael Ellerman Signed-off-by: Benjamin Herrenschmidt --- drivers/char/hw_random/powernv-rng.c | 81 ++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 drivers/char/hw_random/powernv-rng.c (limited to 'drivers/char/hw_random/powernv-rng.c') diff --git a/drivers/char/hw_random/powernv-rng.c b/drivers/char/hw_random/powernv-rng.c new file mode 100644 index 000000000000..3f4f63204560 --- /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 +#include +#include +#include +#include + +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 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"); -- cgit