1 /* Copyright (C) 2005 - 2008 Jeff Dike <jdike@{linux.intel,addtoit}.com> */ 2 3 /* Much of this ripped from drivers/char/hw_random.c, see there for other 4 * copyright. 5 * 6 * This software may be used and distributed according to the terms 7 * of the GNU General Public License, incorporated herein by reference. 8 */ 9 #include <linux/sched/signal.h> 10 #include <linux/module.h> 11 #include <linux/fs.h> 12 #include <linux/interrupt.h> 13 #include <linux/miscdevice.h> 14 #include <linux/hw_random.h> 15 #include <linux/delay.h> 16 #include <linux/uaccess.h> 17 #include <init.h> 18 #include <irq_kern.h> 19 #include <os.h> 20 21 /* 22 * core module information 23 */ 24 #define RNG_MODULE_NAME "hw_random" 25 26 /* Changed at init time, in the non-modular case, and at module load 27 * time, in the module case. Presumably, the module subsystem 28 * protects against a module being loaded twice at the same time. 29 */ 30 static int random_fd = -1; 31 static struct hwrng hwrng; 32 static DECLARE_COMPLETION(have_data); 33 34 static int rng_dev_read(struct hwrng *rng, void *buf, size_t max, bool block) 35 { 36 int ret; 37 38 for (;;) { 39 ret = os_read_file(random_fd, buf, max); 40 if (block && ret == -EAGAIN) { 41 add_sigio_fd(random_fd); 42 43 ret = wait_for_completion_killable(&have_data); 44 45 ignore_sigio_fd(random_fd); 46 deactivate_fd(random_fd, RANDOM_IRQ); 47 48 if (ret < 0) 49 break; 50 } else { 51 break; 52 } 53 } 54 55 return ret != -EAGAIN ? ret : 0; 56 } 57 58 static irqreturn_t random_interrupt(int irq, void *data) 59 { 60 complete(&have_data); 61 62 return IRQ_HANDLED; 63 } 64 65 /* 66 * rng_init - initialize RNG module 67 */ 68 static int __init rng_init (void) 69 { 70 int err; 71 72 err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0); 73 if (err < 0) 74 goto out; 75 76 random_fd = err; 77 err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt, 78 0, "random", NULL); 79 if (err < 0) 80 goto err_out_cleanup_hw; 81 82 sigio_broken(random_fd); 83 hwrng.name = RNG_MODULE_NAME; 84 hwrng.read = rng_dev_read; 85 86 err = hwrng_register(&hwrng); 87 if (err) { 88 pr_err(RNG_MODULE_NAME " registering failed (%d)\n", err); 89 goto err_out_cleanup_hw; 90 } 91 out: 92 return err; 93 94 err_out_cleanup_hw: 95 os_close_file(random_fd); 96 random_fd = -1; 97 goto out; 98 } 99 100 /* 101 * rng_cleanup - shutdown RNG module 102 */ 103 104 static void cleanup(void) 105 { 106 free_irq_by_fd(random_fd); 107 os_close_file(random_fd); 108 } 109 110 static void __exit rng_cleanup(void) 111 { 112 hwrng_unregister(&hwrng); 113 os_close_file(random_fd); 114 } 115 116 module_init (rng_init); 117 module_exit (rng_cleanup); 118 __uml_exitcall(cleanup); 119 120 MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver"); 121 MODULE_LICENSE("GPL"); 122