1/* 2 * omap-rng.c - RNG driver for TI OMAP CPU family 3 * 4 * Author: Deepak Saxena <dsaxena@plexity.net> 5 * 6 * Copyright 2005 (c) MontaVista Software, Inc. 7 * 8 * Mostly based on original driver: 9 * 10 * Copyright (C) 2005 Nokia Corporation 11 * Author: Juha Yrj��l�� <juha.yrjola@nokia.com> 12 * 13 * This file is licensed under the terms of the GNU General Public 14 * License version 2. This program is licensed "as is" without any 15 * warranty of any kind, whether express or implied. 16 */ 17 18#include <linux/module.h> 19#include <linux/init.h> 20#include <linux/random.h> 21#include <linux/clk.h> 22#include <linux/err.h> 23#include <linux/platform_device.h> 24#include <linux/hw_random.h> 25#include <linux/delay.h> 26 27#include <asm/io.h> 28 29#define RNG_OUT_REG 0x00 /* Output register */ 30#define RNG_STAT_REG 0x04 /* Status register 31 [0] = STAT_BUSY */ 32#define RNG_ALARM_REG 0x24 /* Alarm register 33 [7:0] = ALARM_COUNTER */ 34#define RNG_CONFIG_REG 0x28 /* Configuration register 35 [11:6] = RESET_COUNT 36 [5:3] = RING2_DELAY 37 [2:0] = RING1_DELAY */ 38#define RNG_REV_REG 0x3c /* Revision register 39 [7:0] = REV_NB */ 40#define RNG_MASK_REG 0x40 /* Mask and reset register 41 [2] = IT_EN 42 [1] = SOFTRESET 43 [0] = AUTOIDLE */ 44#define RNG_SYSSTATUS 0x44 /* System status 45 [0] = RESETDONE */ 46 47static void __iomem *rng_base; 48static struct clk *rng_ick; 49static struct platform_device *rng_dev; 50 51static inline u32 omap_rng_read_reg(int reg) 52{ 53 return __raw_readl(rng_base + reg); 54} 55 56static inline void omap_rng_write_reg(int reg, u32 val) 57{ 58 __raw_writel(val, rng_base + reg); 59} 60 61static int omap_rng_data_present(struct hwrng *rng, int wait) 62{ 63 int data, i; 64 65 for (i = 0; i < 20; i++) { 66 data = omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1; 67 if (data || !wait) 68 break; 69 /* RNG produces data fast enough (2+ MBit/sec, even 70 * during "rngtest" loads, that these delays don't 71 * seem to trigger. We *could* use the RNG IRQ, but 72 * that'd be higher overhead ... so why bother? 73 */ 74 udelay(10); 75 } 76 return data; 77} 78 79static int omap_rng_data_read(struct hwrng *rng, u32 *data) 80{ 81 *data = omap_rng_read_reg(RNG_OUT_REG); 82 83 return 4; 84} 85 86static struct hwrng omap_rng_ops = { 87 .name = "omap", 88 .data_present = omap_rng_data_present, 89 .data_read = omap_rng_data_read, 90}; 91 92static int __devinit omap_rng_probe(struct platform_device *pdev) 93{ 94 struct resource *res, *mem; 95 int ret; 96 97 /* 98 * A bit ugly, and it will never actually happen but there can 99 * be only one RNG and this catches any bork 100 */ 101 if (rng_dev) 102 return -EBUSY; 103 104 if (cpu_is_omap24xx()) { 105 rng_ick = clk_get(&pdev->dev, "ick"); 106 if (IS_ERR(rng_ick)) { 107 dev_err(&pdev->dev, "Could not get rng_ick\n"); 108 ret = PTR_ERR(rng_ick); 109 return ret; 110 } else 111 clk_enable(rng_ick); 112 } 113 114 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 115 116 if (!res) 117 return -ENOENT; 118 119 mem = request_mem_region(res->start, resource_size(res), 120 pdev->name); 121 if (mem == NULL) { 122 ret = -EBUSY; 123 goto err_region; 124 } 125 126 dev_set_drvdata(&pdev->dev, mem); 127 rng_base = ioremap(res->start, resource_size(res)); 128 if (!rng_base) { 129 ret = -ENOMEM; 130 goto err_ioremap; 131 } 132 133 ret = hwrng_register(&omap_rng_ops); 134 if (ret) 135 goto err_register; 136 137 dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n", 138 omap_rng_read_reg(RNG_REV_REG)); 139 omap_rng_write_reg(RNG_MASK_REG, 0x1); 140 141 rng_dev = pdev; 142 143 return 0; 144 145err_register: 146 iounmap(rng_base); 147 rng_base = NULL; 148err_ioremap: 149 release_resource(mem); 150err_region: 151 if (cpu_is_omap24xx()) { 152 clk_disable(rng_ick); 153 clk_put(rng_ick); 154 } 155 return ret; 156} 157 158static int __exit omap_rng_remove(struct platform_device *pdev) 159{ 160 struct resource *mem = dev_get_drvdata(&pdev->dev); 161 162 hwrng_unregister(&omap_rng_ops); 163 164 omap_rng_write_reg(RNG_MASK_REG, 0x0); 165 166 iounmap(rng_base); 167 168 if (cpu_is_omap24xx()) { 169 clk_disable(rng_ick); 170 clk_put(rng_ick); 171 } 172 173 release_resource(mem); 174 rng_base = NULL; 175 176 return 0; 177} 178 179#ifdef CONFIG_PM 180 181static int omap_rng_suspend(struct platform_device *pdev, pm_message_t message) 182{ 183 omap_rng_write_reg(RNG_MASK_REG, 0x0); 184 return 0; 185} 186 187static int omap_rng_resume(struct platform_device *pdev) 188{ 189 omap_rng_write_reg(RNG_MASK_REG, 0x1); 190 return 0; 191} 192 193#else 194 195#define omap_rng_suspend NULL 196#define omap_rng_resume NULL 197 198#endif 199 200/* work with hotplug and coldplug */ 201MODULE_ALIAS("platform:omap_rng"); 202 203static struct platform_driver omap_rng_driver = { 204 .driver = { 205 .name = "omap_rng", 206 .owner = THIS_MODULE, 207 }, 208 .probe = omap_rng_probe, 209 .remove = __exit_p(omap_rng_remove), 210 .suspend = omap_rng_suspend, 211 .resume = omap_rng_resume 212}; 213 214static int __init omap_rng_init(void) 215{ 216 if (!cpu_is_omap16xx() && !cpu_is_omap24xx()) 217 return -ENODEV; 218 219 return platform_driver_register(&omap_rng_driver); 220} 221 222static void __exit omap_rng_exit(void) 223{ 224 platform_driver_unregister(&omap_rng_driver); 225} 226 227module_init(omap_rng_init); 228module_exit(omap_rng_exit); 229 230MODULE_AUTHOR("Deepak Saxena (and others)"); 231MODULE_LICENSE("GPL"); 232