tx4939-rng.c revision 5a0e3ad6af8660be21ca98a971cd00f331318c05
1049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto/* 2049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * RNG driver for TX4939 Random Number Generators (RNG) 3049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * 4049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * Copyright (C) 2009 Atsushi Nemoto <anemo@mba.ocn.ne.jp> 5049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * 6049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * This file is subject to the terms and conditions of the GNU General Public 7049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * License. See the file "COPYING" in the main directory of this archive 8049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * for more details. 9049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto */ 10049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#include <linux/module.h> 11049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#include <linux/kernel.h> 12049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#include <linux/init.h> 13049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#include <linux/delay.h> 14049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#include <linux/io.h> 15049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#include <linux/platform_device.h> 16049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#include <linux/hw_random.h> 175a0e3ad6af8660be21ca98a971cd00f331318c05Tejun Heo#include <linux/gfp.h> 18049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 19049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#define TX4939_RNG_RCSR 0x00000000 20049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#define TX4939_RNG_ROR(n) (0x00000018 + (n) * 8) 21049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 22049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#define TX4939_RNG_RCSR_INTE 0x00000008 23049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#define TX4939_RNG_RCSR_RST 0x00000004 24049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#define TX4939_RNG_RCSR_FIN 0x00000002 25049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#define TX4939_RNG_RCSR_ST 0x00000001 26049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 27049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostruct tx4939_rng { 28049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto struct hwrng rng; 29049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto void __iomem *base; 30049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto u64 databuf[3]; 31049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto unsigned int data_avail; 32049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto}; 33049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 34049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostatic void rng_io_start(void) 35049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto{ 36049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#ifndef CONFIG_64BIT 37049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto /* 38049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * readq is reading a 64-bit register using a 64-bit load. On 39049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * a 32-bit kernel however interrupts or any other processor 40049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * exception would clobber the upper 32-bit of the processor 41049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * register so interrupts need to be disabled. 42049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto */ 43049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto local_irq_disable(); 44049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#endif 45049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto} 46049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 47049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostatic void rng_io_end(void) 48049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto{ 49049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#ifndef CONFIG_64BIT 50049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto local_irq_enable(); 51049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto#endif 52049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto} 53049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 54049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostatic u64 read_rng(void __iomem *base, unsigned int offset) 55049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto{ 56049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return ____raw_readq(base + offset); 57049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto} 58049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 59049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostatic void write_rng(u64 val, void __iomem *base, unsigned int offset) 60049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto{ 61049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return ____raw_writeq(val, base + offset); 62049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto} 63049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 64049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostatic int tx4939_rng_data_present(struct hwrng *rng, int wait) 65049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto{ 66049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng); 67049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto int i; 68049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 69049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto if (rngdev->data_avail) 70049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return rngdev->data_avail; 71049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto for (i = 0; i < 20; i++) { 72049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rng_io_start(); 73049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto if (!(read_rng(rngdev->base, TX4939_RNG_RCSR) 74049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto & TX4939_RNG_RCSR_ST)) { 75049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev->databuf[0] = 76049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto read_rng(rngdev->base, TX4939_RNG_ROR(0)); 77049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev->databuf[1] = 78049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto read_rng(rngdev->base, TX4939_RNG_ROR(1)); 79049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev->databuf[2] = 80049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto read_rng(rngdev->base, TX4939_RNG_ROR(2)); 81049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev->data_avail = 82049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto sizeof(rngdev->databuf) / sizeof(u32); 83049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto /* Start RNG */ 84049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto write_rng(TX4939_RNG_RCSR_ST, 85049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev->base, TX4939_RNG_RCSR); 86049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto wait = 0; 87049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto } 88049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rng_io_end(); 89049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto if (!wait) 90049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto break; 91049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto /* 90 bus clock cycles by default for generation */ 92049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto ndelay(90 * 5); 93049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto } 94049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return rngdev->data_avail; 95049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto} 96049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 97049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostatic int tx4939_rng_data_read(struct hwrng *rng, u32 *buffer) 98049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto{ 99049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto struct tx4939_rng *rngdev = container_of(rng, struct tx4939_rng, rng); 100049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 101049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev->data_avail--; 102049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto *buffer = *((u32 *)&rngdev->databuf + rngdev->data_avail); 103049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return sizeof(u32); 104049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto} 105049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 106049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostatic int __init tx4939_rng_probe(struct platform_device *dev) 107049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto{ 108049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto struct tx4939_rng *rngdev; 109049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto struct resource *r; 110049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto int i; 111049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 112049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto r = platform_get_resource(dev, IORESOURCE_MEM, 0); 113049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto if (!r) 114049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return -EBUSY; 115049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev = devm_kzalloc(&dev->dev, sizeof(*rngdev), GFP_KERNEL); 116049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto if (!rngdev) 117049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return -ENOMEM; 118049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto if (!devm_request_mem_region(&dev->dev, r->start, resource_size(r), 119049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto dev_name(&dev->dev))) 120049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return -EBUSY; 121049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev->base = devm_ioremap(&dev->dev, r->start, resource_size(r)); 122049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto if (!rngdev->base) 123049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return -EBUSY; 124049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 125049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev->rng.name = dev_name(&dev->dev); 126049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev->rng.data_present = tx4939_rng_data_present; 127049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev->rng.data_read = tx4939_rng_data_read; 128049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 129049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rng_io_start(); 130049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto /* Reset RNG */ 131049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto write_rng(TX4939_RNG_RCSR_RST, rngdev->base, TX4939_RNG_RCSR); 132049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto write_rng(0, rngdev->base, TX4939_RNG_RCSR); 133049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto /* Start RNG */ 134049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto write_rng(TX4939_RNG_RCSR_ST, rngdev->base, TX4939_RNG_RCSR); 135049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rng_io_end(); 136049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto /* 137049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * Drop first two results. From the datasheet: 138049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * The quality of the random numbers generated immediately 139049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * after reset can be insufficient. Therefore, do not use 140049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * random numbers obtained from the first and second 141049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * generations; use the ones from the third or subsequent 142049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto * generation. 143049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto */ 144049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto for (i = 0; i < 2; i++) { 145049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto rngdev->data_avail = 0; 146049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto if (!tx4939_rng_data_present(&rngdev->rng, 1)) 147049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return -EIO; 148049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto } 149049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 150049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto platform_set_drvdata(dev, rngdev); 151049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return hwrng_register(&rngdev->rng); 152049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto} 153049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 154049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostatic int __exit tx4939_rng_remove(struct platform_device *dev) 155049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto{ 156049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto struct tx4939_rng *rngdev = platform_get_drvdata(dev); 157049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 158049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto hwrng_unregister(&rngdev->rng); 159049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto platform_set_drvdata(dev, NULL); 160049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return 0; 161049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto} 162049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 163049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostatic struct platform_driver tx4939_rng_driver = { 164049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto .driver = { 165049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto .name = "tx4939-rng", 166049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto .owner = THIS_MODULE, 167049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto }, 168049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto .remove = tx4939_rng_remove, 169049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto}; 170049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 171049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostatic int __init tx4939rng_init(void) 172049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto{ 173049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto return platform_driver_probe(&tx4939_rng_driver, tx4939_rng_probe); 174049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto} 175049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 176049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotostatic void __exit tx4939rng_exit(void) 177049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto{ 178049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto platform_driver_unregister(&tx4939_rng_driver); 179049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto} 180049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 181049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotomodule_init(tx4939rng_init); 182049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemotomodule_exit(tx4939rng_exit); 183049a947c611a19523eaaf193f698b897a62d0593Atsushi Nemoto 184049a947c611a19523eaaf193f698b897a62d0593Atsushi NemotoMODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver for TX4939"); 185049a947c611a19523eaaf193f698b897a62d0593Atsushi NemotoMODULE_LICENSE("GPL"); 186