1 /* 2 * drivers/char/hw_random/omap-rng.c 3 * 4 * RNG driver for TI OMAP CPU family 5 * 6 * Author: Deepak Saxena <dsaxena@plexity.net> 7 * 8 * Copyright 2005 (c) MontaVista Software, Inc. 9 * 10 * Mostly based on original driver: 11 * 12 * Copyright (C) 2005 Nokia Corporation 13 * Author: Juha Yrjölä <juha.yrjola@nokia.com> 14 * 15 * This file is licensed under the terms of the GNU General Public 16 * License version 2. This program is licensed "as is" without any 17 * warranty of any kind, whether express or implied. 18 * 19 * TODO: 20 * 21 * - Make status updated be interrupt driven so we don't poll 22 * 23 */ 24 25 #include <linux/module.h> 26 #include <linux/init.h> 27 #include <linux/random.h> 28 #include <linux/clk.h> 29 #include <linux/err.h> 30 #include <linux/platform_device.h> 31 #include <linux/hw_random.h> 32 #include <linux/delay.h> 33 34 #include <asm/io.h> 35 36 #define RNG_OUT_REG 0x00 /* Output register */ 37 #define RNG_STAT_REG 0x04 /* Status register 38 [0] = STAT_BUSY */ 39 #define RNG_ALARM_REG 0x24 /* Alarm register 40 [7:0] = ALARM_COUNTER */ 41 #define RNG_CONFIG_REG 0x28 /* Configuration register 42 [11:6] = RESET_COUNT 43 [5:3] = RING2_DELAY 44 [2:0] = RING1_DELAY */ 45 #define RNG_REV_REG 0x3c /* Revision register 46 [7:0] = REV_NB */ 47 #define RNG_MASK_REG 0x40 /* Mask and reset register 48 [2] = IT_EN 49 [1] = SOFTRESET 50 [0] = AUTOIDLE */ 51 #define RNG_SYSSTATUS 0x44 /* System status 52 [0] = RESETDONE */ 53 54 static void __iomem *rng_base; 55 static struct clk *rng_ick; 56 static struct platform_device *rng_dev; 57 58 static u32 omap_rng_read_reg(int reg) 59 { 60 return __raw_readl(rng_base + reg); 61 } 62 63 static void omap_rng_write_reg(int reg, u32 val) 64 { 65 __raw_writel(val, rng_base + reg); 66 } 67 68 /* REVISIT: Does the status bit really work on 16xx? */ 69 static int omap_rng_data_present(struct hwrng *rng, int wait) 70 { 71 int data, i; 72 73 for (i = 0; i < 20; i++) { 74 data = omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1; 75 if (data || !wait) 76 break; 77 udelay(10); 78 } 79 return data; 80 } 81 82 static int omap_rng_data_read(struct hwrng *rng, u32 *data) 83 { 84 *data = omap_rng_read_reg(RNG_OUT_REG); 85 86 return 4; 87 } 88 89 static struct hwrng omap_rng_ops = { 90 .name = "omap", 91 .data_present = omap_rng_data_present, 92 .data_read = omap_rng_data_read, 93 }; 94 95 static int __init omap_rng_probe(struct platform_device *pdev) 96 { 97 struct resource *res, *mem; 98 int ret; 99 100 /* 101 * A bit ugly, and it will never actually happen but there can 102 * be only one RNG and this catches any bork 103 */ 104 BUG_ON(rng_dev); 105 106 if (cpu_is_omap24xx()) { 107 rng_ick = clk_get(NULL, "rng_ick"); 108 if (IS_ERR(rng_ick)) { 109 dev_err(&pdev->dev, "Could not get rng_ick\n"); 110 ret = PTR_ERR(rng_ick); 111 return ret; 112 } else 113 clk_enable(rng_ick); 114 } 115 116 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 117 118 if (!res) 119 return -ENOENT; 120 121 mem = request_mem_region(res->start, res->end - res->start + 1, 122 pdev->name); 123 if (mem == NULL) 124 return -EBUSY; 125 126 dev_set_drvdata(&pdev->dev, mem); 127 rng_base = (u32 __iomem *)io_p2v(res->start); 128 129 ret = hwrng_register(&omap_rng_ops); 130 if (ret) { 131 release_resource(mem); 132 rng_base = NULL; 133 return ret; 134 } 135 136 dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n", 137 omap_rng_read_reg(RNG_REV_REG)); 138 omap_rng_write_reg(RNG_MASK_REG, 0x1); 139 140 rng_dev = pdev; 141 142 return 0; 143 } 144 145 static int __exit omap_rng_remove(struct platform_device *pdev) 146 { 147 struct resource *mem = dev_get_drvdata(&pdev->dev); 148 149 hwrng_unregister(&omap_rng_ops); 150 151 omap_rng_write_reg(RNG_MASK_REG, 0x0); 152 153 if (cpu_is_omap24xx()) { 154 clk_disable(rng_ick); 155 clk_put(rng_ick); 156 } 157 158 release_resource(mem); 159 rng_base = NULL; 160 161 return 0; 162 } 163 164 #ifdef CONFIG_PM 165 166 static int omap_rng_suspend(struct platform_device *pdev, pm_message_t message) 167 { 168 omap_rng_write_reg(RNG_MASK_REG, 0x0); 169 return 0; 170 } 171 172 static int omap_rng_resume(struct platform_device *pdev) 173 { 174 omap_rng_write_reg(RNG_MASK_REG, 0x1); 175 return 0; 176 } 177 178 #else 179 180 #define omap_rng_suspend NULL 181 #define omap_rng_resume NULL 182 183 #endif 184 185 186 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