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 Yrjölä <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 47 static void __iomem *rng_base; 48 static struct clk *rng_ick; 49 static struct platform_device *rng_dev; 50 51 static inline u32 omap_rng_read_reg(int reg) 52 { 53 return __raw_readl(rng_base + reg); 54 } 55 56 static inline void omap_rng_write_reg(int reg, u32 val) 57 { 58 __raw_writel(val, rng_base + reg); 59 } 60 61 static 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 79 static 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 86 static struct hwrng omap_rng_ops = { 87 .name = "omap", 88 .data_present = omap_rng_data_present, 89 .data_read = omap_rng_data_read, 90 }; 91 92 static int __init 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(NULL, "rng_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, res->end - res->start + 1, 120 pdev->name); 121 if (mem == NULL) 122 return -EBUSY; 123 124 dev_set_drvdata(&pdev->dev, mem); 125 rng_base = (u32 __force __iomem *)io_p2v(res->start); 126 127 ret = hwrng_register(&omap_rng_ops); 128 if (ret) { 129 release_resource(mem); 130 rng_base = NULL; 131 return ret; 132 } 133 134 dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n", 135 omap_rng_read_reg(RNG_REV_REG)); 136 omap_rng_write_reg(RNG_MASK_REG, 0x1); 137 138 rng_dev = pdev; 139 140 return 0; 141 } 142 143 static int __exit omap_rng_remove(struct platform_device *pdev) 144 { 145 struct resource *mem = dev_get_drvdata(&pdev->dev); 146 147 hwrng_unregister(&omap_rng_ops); 148 149 omap_rng_write_reg(RNG_MASK_REG, 0x0); 150 151 if (cpu_is_omap24xx()) { 152 clk_disable(rng_ick); 153 clk_put(rng_ick); 154 } 155 156 release_resource(mem); 157 rng_base = NULL; 158 159 return 0; 160 } 161 162 #ifdef CONFIG_PM 163 164 static int omap_rng_suspend(struct platform_device *pdev, pm_message_t message) 165 { 166 omap_rng_write_reg(RNG_MASK_REG, 0x0); 167 return 0; 168 } 169 170 static int omap_rng_resume(struct platform_device *pdev) 171 { 172 omap_rng_write_reg(RNG_MASK_REG, 0x1); 173 return 0; 174 } 175 176 #else 177 178 #define omap_rng_suspend NULL 179 #define omap_rng_resume NULL 180 181 #endif 182 183 /* work with hotplug and coldplug */ 184 MODULE_ALIAS("platform:omap_rng"); 185 186 static struct platform_driver omap_rng_driver = { 187 .driver = { 188 .name = "omap_rng", 189 .owner = THIS_MODULE, 190 }, 191 .probe = omap_rng_probe, 192 .remove = __exit_p(omap_rng_remove), 193 .suspend = omap_rng_suspend, 194 .resume = omap_rng_resume 195 }; 196 197 static int __init omap_rng_init(void) 198 { 199 if (!cpu_is_omap16xx() && !cpu_is_omap24xx()) 200 return -ENODEV; 201 202 return platform_driver_register(&omap_rng_driver); 203 } 204 205 static void __exit omap_rng_exit(void) 206 { 207 platform_driver_unregister(&omap_rng_driver); 208 } 209 210 module_init(omap_rng_init); 211 module_exit(omap_rng_exit); 212 213 MODULE_AUTHOR("Deepak Saxena (and others)"); 214 MODULE_LICENSE("GPL"); 215