1 /* 2 * omap3-rom-rng.c - RNG driver for TI OMAP3 CPU family 3 * 4 * Copyright (C) 2009 Nokia Corporation 5 * Author: Juha Yrjola <juha.yrjola@solidboot.com> 6 * 7 * Copyright (C) 2013 Pali Rohár <pali.rohar@gmail.com> 8 * 9 * This file is licensed under the terms of the GNU General Public 10 * License version 2. This program is licensed "as is" without any 11 * warranty of any kind, whether express or implied. 12 */ 13 14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 15 16 #include <linux/module.h> 17 #include <linux/init.h> 18 #include <linux/random.h> 19 #include <linux/hw_random.h> 20 #include <linux/timer.h> 21 #include <linux/clk.h> 22 #include <linux/err.h> 23 #include <linux/platform_device.h> 24 25 #define RNG_RESET 0x01 26 #define RNG_GEN_PRNG_HW_INIT 0x02 27 #define RNG_GEN_HW 0x08 28 29 /* param1: ptr, param2: count, param3: flag */ 30 static u32 (*omap3_rom_rng_call)(u32, u32, u32); 31 32 static struct timer_list idle_timer; 33 static int rng_idle; 34 static struct clk *rng_clk; 35 36 static void omap3_rom_rng_idle(unsigned long data) 37 { 38 int r; 39 40 r = omap3_rom_rng_call(0, 0, RNG_RESET); 41 if (r != 0) { 42 pr_err("reset failed: %d\n", r); 43 return; 44 } 45 clk_disable_unprepare(rng_clk); 46 rng_idle = 1; 47 } 48 49 static int omap3_rom_rng_get_random(void *buf, unsigned int count) 50 { 51 u32 r; 52 u32 ptr; 53 54 del_timer_sync(&idle_timer); 55 if (rng_idle) { 56 clk_prepare_enable(rng_clk); 57 r = omap3_rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT); 58 if (r != 0) { 59 clk_disable_unprepare(rng_clk); 60 pr_err("HW init failed: %d\n", r); 61 return -EIO; 62 } 63 rng_idle = 0; 64 } 65 66 ptr = virt_to_phys(buf); 67 r = omap3_rom_rng_call(ptr, count, RNG_GEN_HW); 68 mod_timer(&idle_timer, jiffies + msecs_to_jiffies(500)); 69 if (r != 0) 70 return -EINVAL; 71 return 0; 72 } 73 74 static int omap3_rom_rng_data_present(struct hwrng *rng, int wait) 75 { 76 return 1; 77 } 78 79 static int omap3_rom_rng_data_read(struct hwrng *rng, u32 *data) 80 { 81 int r; 82 83 r = omap3_rom_rng_get_random(data, 4); 84 if (r < 0) 85 return r; 86 return 4; 87 } 88 89 static struct hwrng omap3_rom_rng_ops = { 90 .name = "omap3-rom", 91 .data_present = omap3_rom_rng_data_present, 92 .data_read = omap3_rom_rng_data_read, 93 }; 94 95 static int omap3_rom_rng_probe(struct platform_device *pdev) 96 { 97 pr_info("initializing\n"); 98 99 omap3_rom_rng_call = pdev->dev.platform_data; 100 if (!omap3_rom_rng_call) { 101 pr_err("omap3_rom_rng_call is NULL\n"); 102 return -EINVAL; 103 } 104 105 setup_timer(&idle_timer, omap3_rom_rng_idle, 0); 106 rng_clk = clk_get(&pdev->dev, "ick"); 107 if (IS_ERR(rng_clk)) { 108 pr_err("unable to get RNG clock\n"); 109 return PTR_ERR(rng_clk); 110 } 111 112 /* Leave the RNG in reset state. */ 113 clk_prepare_enable(rng_clk); 114 omap3_rom_rng_idle(0); 115 116 return hwrng_register(&omap3_rom_rng_ops); 117 } 118 119 static int omap3_rom_rng_remove(struct platform_device *pdev) 120 { 121 hwrng_unregister(&omap3_rom_rng_ops); 122 clk_disable_unprepare(rng_clk); 123 clk_put(rng_clk); 124 return 0; 125 } 126 127 static struct platform_driver omap3_rom_rng_driver = { 128 .driver = { 129 .name = "omap3-rom-rng", 130 .owner = THIS_MODULE, 131 }, 132 .probe = omap3_rom_rng_probe, 133 .remove = omap3_rom_rng_remove, 134 }; 135 136 module_platform_driver(omap3_rom_rng_driver); 137 138 MODULE_ALIAS("platform:omap3-rom-rng"); 139 MODULE_AUTHOR("Juha Yrjola"); 140 MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>"); 141 MODULE_LICENSE("GPL"); 142