1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright 2013 Michael Ellerman, Guo Chao, IBM Corp. 4 */ 5 6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 7 8 #include <linux/module.h> 9 #include <linux/mod_devicetable.h> 10 #include <linux/kernel.h> 11 #include <linux/platform_device.h> 12 #include <linux/random.h> 13 #include <linux/hw_random.h> 14 #include <asm/archrandom.h> 15 16 static int powernv_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) 17 { 18 unsigned long *buf; 19 int i, len; 20 21 /* We rely on rng_buffer_size() being >= sizeof(unsigned long) */ 22 len = max / sizeof(unsigned long); 23 24 buf = (unsigned long *)data; 25 26 for (i = 0; i < len; i++) 27 pnv_get_random_long(buf++); 28 29 return len * sizeof(unsigned long); 30 } 31 32 static struct hwrng powernv_hwrng = { 33 .name = "powernv-rng", 34 .read = powernv_rng_read, 35 }; 36 37 static int powernv_rng_probe(struct platform_device *pdev) 38 { 39 int rc; 40 41 rc = devm_hwrng_register(&pdev->dev, &powernv_hwrng); 42 if (rc) { 43 /* We only register one device, ignore any others */ 44 if (rc == -EEXIST) 45 rc = -ENODEV; 46 47 return rc; 48 } 49 50 pr_info("Registered powernv hwrng.\n"); 51 52 return 0; 53 } 54 55 static const struct of_device_id powernv_rng_match[] = { 56 { .compatible = "ibm,power-rng",}, 57 {}, 58 }; 59 MODULE_DEVICE_TABLE(of, powernv_rng_match); 60 61 static struct platform_driver powernv_rng_driver = { 62 .driver = { 63 .name = "powernv_rng", 64 .of_match_table = powernv_rng_match, 65 }, 66 .probe = powernv_rng_probe, 67 }; 68 module_platform_driver(powernv_rng_driver); 69 70 MODULE_LICENSE("GPL"); 71 MODULE_DESCRIPTION("Bare metal HWRNG driver for POWER7+ and above"); 72