2 * omap-rng.c - RNG driver for TI OMAP CPU family
4 * Author: Deepak Saxena <dsaxena@plexity.net>
6 * Copyright 2005 (c) MontaVista Software, Inc.
8 * Mostly based on original driver:
10 * Copyright (C) 2005 Nokia Corporation
11 * Author: Juha Yrjölä <juha.yrjola@nokia.com>
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.
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>
31 #define RNG_OUT_REG 0x00 /* Output register */
32 #define RNG_STAT_REG 0x04 /* Status register
34 #define RNG_ALARM_REG 0x24 /* Alarm register
35 [7:0] = ALARM_COUNTER */
36 #define RNG_CONFIG_REG 0x28 /* Configuration register
39 [2:0] = RING1_DELAY */
40 #define RNG_REV_REG 0x3c /* Revision register
42 #define RNG_MASK_REG 0x40 /* Mask and reset register
46 #define RNG_SYSSTATUS 0x44 /* System status
49 static void __iomem *rng_base;
50 static struct clk *rng_ick;
51 static struct platform_device *rng_dev;
53 static inline u32 omap_rng_read_reg(int reg)
55 return __raw_readl(rng_base + reg);
58 static inline void omap_rng_write_reg(int reg, u32 val)
60 __raw_writel(val, rng_base + reg);
63 static int omap_rng_data_present(struct hwrng *rng, int wait)
67 for (i = 0; i < 20; i++) {
68 data = omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1;
71 /* RNG produces data fast enough (2+ MBit/sec, even
72 * during "rngtest" loads, that these delays don't
73 * seem to trigger. We *could* use the RNG IRQ, but
74 * that'd be higher overhead ... so why bother?
81 static int omap_rng_data_read(struct hwrng *rng, u32 *data)
83 *data = omap_rng_read_reg(RNG_OUT_REG);
88 static struct hwrng omap_rng_ops = {
90 .data_present = omap_rng_data_present,
91 .data_read = omap_rng_data_read,
94 static int __devinit omap_rng_probe(struct platform_device *pdev)
100 * A bit ugly, and it will never actually happen but there can
101 * be only one RNG and this catches any bork
106 if (cpu_is_omap24xx()) {
107 rng_ick = clk_get(&pdev->dev, "ick");
108 if (IS_ERR(rng_ick)) {
109 dev_err(&pdev->dev, "Could not get rng_ick\n");
110 ret = PTR_ERR(rng_ick);
116 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
123 if (!request_mem_region(res->start, resource_size(res), pdev->name)) {
128 dev_set_drvdata(&pdev->dev, res);
129 rng_base = ioremap(res->start, resource_size(res));
135 ret = hwrng_register(&omap_rng_ops);
139 dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n",
140 omap_rng_read_reg(RNG_REV_REG));
141 omap_rng_write_reg(RNG_MASK_REG, 0x1);
151 release_mem_region(res->start, resource_size(res));
153 if (cpu_is_omap24xx()) {
154 clk_disable(rng_ick);
160 static int __exit omap_rng_remove(struct platform_device *pdev)
162 struct resource *res = dev_get_drvdata(&pdev->dev);
164 hwrng_unregister(&omap_rng_ops);
166 omap_rng_write_reg(RNG_MASK_REG, 0x0);
170 if (cpu_is_omap24xx()) {
171 clk_disable(rng_ick);
175 release_mem_region(res->start, resource_size(res));
183 static int omap_rng_suspend(struct platform_device *pdev, pm_message_t message)
185 omap_rng_write_reg(RNG_MASK_REG, 0x0);
189 static int omap_rng_resume(struct platform_device *pdev)
191 omap_rng_write_reg(RNG_MASK_REG, 0x1);
197 #define omap_rng_suspend NULL
198 #define omap_rng_resume NULL
202 /* work with hotplug and coldplug */
203 MODULE_ALIAS("platform:omap_rng");
205 static struct platform_driver omap_rng_driver = {
208 .owner = THIS_MODULE,
210 .probe = omap_rng_probe,
211 .remove = __exit_p(omap_rng_remove),
212 .suspend = omap_rng_suspend,
213 .resume = omap_rng_resume
216 static int __init omap_rng_init(void)
218 if (!cpu_is_omap16xx() && !cpu_is_omap24xx())
221 return platform_driver_register(&omap_rng_driver);
224 static void __exit omap_rng_exit(void)
226 platform_driver_unregister(&omap_rng_driver);
229 module_init(omap_rng_init);
230 module_exit(omap_rng_exit);
232 MODULE_AUTHOR("Deepak Saxena (and others)");
233 MODULE_LICENSE("GPL");