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 Yrj��<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 33 #include <asm/io.h> 34 35 #define RNG_OUT_REG 0x00 /* Output register */ 36 #define RNG_STAT_REG 0x04 /* Status register 37 [0] = STAT_BUSY */ 38 #define RNG_ALARM_REG 0x24 /* Alarm register 39 [7:0] = ALARM_COUNTER */ 40 #define RNG_CONFIG_REG 0x28 /* Configuration register 41 [11:6] = RESET_COUNT 42 [5:3] = RING2_DELAY 43 [2:0] = RING1_DELAY */ 44 #define RNG_REV_REG 0x3c /* Revision register 45 [7:0] = REV_NB */ 46 #define RNG_MASK_REG 0x40 /* Mask and reset register 47 [2] = IT_EN 48 [1] = SOFTRESET 49 [0] = AUTOIDLE */ 50 #define RNG_SYSSTATUS 0x44 /* System status 51 [0] = RESETDONE */ 52 53 static void __iomem *rng_base; 54 static struct clk *rng_ick; 55 static struct platform_device *rng_dev; 56 57 static u32 omap_rng_read_reg(int reg) 58 { 59 return __raw_readl(rng_base + reg); 60 } 61 62 static void omap_rng_write_reg(int reg, u32 val) 63 { 64 __raw_writel(val, rng_base + reg); 65 } 66 67 /* REVISIT: Does the status bit really work on 16xx? */ 68 static int omap_rng_data_present(struct hwrng *rng) 69 { 70 return omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1; 71 } 72 73 static int omap_rng_data_read(struct hwrng *rng, u32 *data) 74 { 75 *data = omap_rng_read_reg(RNG_OUT_REG); 76 77 return 4; 78 } 79 80 static struct hwrng omap_rng_ops = { 81 .name = "omap", 82 .data_present = omap_rng_data_present, 83 .data_read = omap_rng_data_read, 84 }; 85 86 static int __init omap_rng_probe(struct platform_device *pdev) 87 { 88 struct resource *res, *mem; 89 int ret; 90 91 /* 92 * A bit ugly, and it will never actually happen but there can 93 * be only one RNG and this catches any bork 94 */ 95 BUG_ON(rng_dev); 96 97 if (cpu_is_omap24xx()) { 98 rng_ick = clk_get(NULL, "rng_ick"); 99 if (IS_ERR(rng_ick)) { 100 dev_err(&pdev->dev, "Could not get rng_ick\n"); 101 ret = PTR_ERR(rng_ick); 102 return ret; 103 } else 104 clk_enable(rng_ick); 105 } 106 107 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 108 109 if (!res) 110 return -ENOENT; 111 112 mem = request_mem_region(res->start, res->end - res->start + 1, 113 pdev->name); 114 if (mem == NULL) 115 return -EBUSY; 116 117 dev_set_drvdata(&pdev->dev, mem); 118 rng_base = (u32 __iomem *)io_p2v(res->start); 119 120 ret = hwrng_register(&omap_rng_ops); 121 if (ret) { 122 release_resource(mem); 123 rng_base = NULL; 124 return ret; 125 } 126 127 dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n", 128 omap_rng_read_reg(RNG_REV_REG)); 129 omap_rng_write_reg(RNG_MASK_REG, 0x1); 130 131 rng_dev = pdev; 132 133 return 0; 134 } 135 136 static int __exit omap_rng_remove(struct platform_device *pdev) 137 { 138 struct resource *mem = dev_get_drvdata(&pdev->dev); 139 140 hwrng_unregister(&omap_rng_ops); 141 142 omap_rng_write_reg(RNG_MASK_REG, 0x0); 143 144 if (cpu_is_omap24xx()) { 145 clk_disable(rng_ick); 146 clk_put(rng_ick); 147 } 148 149 release_resource(mem); 150 rng_base = NULL; 151 152 return 0; 153 } 154 155 #ifdef CONFIG_PM 156 157 static int omap_rng_suspend(struct platform_device *pdev, pm_message_t message) 158 { 159 omap_rng_write_reg(RNG_MASK_REG, 0x0); 160 return 0; 161 } 162 163 static int omap_rng_resume(struct platform_device *pdev) 164 { 165 omap_rng_write_reg(RNG_MASK_REG, 0x1); 166 return 0; 167 } 168 169 #else 170 171 #define omap_rng_suspend NULL 172 #define omap_rng_resume NULL 173 174 #endif 175 176 177 static struct platform_driver omap_rng_driver = { 178 .driver = { 179 .name = "omap_rng", 180 .owner = THIS_MODULE, 181 }, 182 .probe = omap_rng_probe, 183 .remove = __exit_p(omap_rng_remove), 184 .suspend = omap_rng_suspend, 185 .resume = omap_rng_resume 186 }; 187 188 static int __init omap_rng_init(void) 189 { 190 if (!cpu_is_omap16xx() && !cpu_is_omap24xx()) 191 return -ENODEV; 192 193 return platform_driver_register(&omap_rng_driver); 194 } 195 196 static void __exit omap_rng_exit(void) 197 { 198 platform_driver_unregister(&omap_rng_driver); 199 } 200 201 module_init(omap_rng_init); 202 module_exit(omap_rng_exit); 203 204 MODULE_AUTHOR("Deepak Saxena (and others)"); 205 MODULE_LICENSE("GPL"); 206