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/err.h>
22 #include <linux/platform_device.h>
23 #include <linux/hw_random.h>
24 #include <linux/delay.h>
25 #include <linux/slab.h>
26 #include <linux/pm_runtime.h>
27 #include <linux/of.h>
28 #include <linux/of_device.h>
29 #include <linux/of_address.h>
30 #include <linux/interrupt.h>
31 
32 #include <asm/io.h>
33 
34 #define RNG_REG_STATUS_RDY			(1 << 0)
35 
36 #define RNG_REG_INTACK_RDY_MASK			(1 << 0)
37 #define RNG_REG_INTACK_SHUTDOWN_OFLO_MASK	(1 << 1)
38 #define RNG_SHUTDOWN_OFLO_MASK			(1 << 1)
39 
40 #define RNG_CONTROL_STARTUP_CYCLES_SHIFT	16
41 #define RNG_CONTROL_STARTUP_CYCLES_MASK		(0xffff << 16)
42 #define RNG_CONTROL_ENABLE_TRNG_SHIFT		10
43 #define RNG_CONTROL_ENABLE_TRNG_MASK		(1 << 10)
44 
45 #define RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT	16
46 #define RNG_CONFIG_MAX_REFIL_CYCLES_MASK	(0xffff << 16)
47 #define RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT	0
48 #define RNG_CONFIG_MIN_REFIL_CYCLES_MASK	(0xff << 0)
49 
50 #define RNG_CONTROL_STARTUP_CYCLES		0xff
51 #define RNG_CONFIG_MIN_REFIL_CYCLES		0x21
52 #define RNG_CONFIG_MAX_REFIL_CYCLES		0x22
53 
54 #define RNG_ALARMCNT_ALARM_TH_SHIFT		0x0
55 #define RNG_ALARMCNT_ALARM_TH_MASK		(0xff << 0)
56 #define RNG_ALARMCNT_SHUTDOWN_TH_SHIFT		16
57 #define RNG_ALARMCNT_SHUTDOWN_TH_MASK		(0x1f << 16)
58 #define RNG_ALARM_THRESHOLD			0xff
59 #define RNG_SHUTDOWN_THRESHOLD			0x4
60 
61 #define RNG_REG_FROENABLE_MASK			0xffffff
62 #define RNG_REG_FRODETUNE_MASK			0xffffff
63 
64 #define OMAP2_RNG_OUTPUT_SIZE			0x4
65 #define OMAP4_RNG_OUTPUT_SIZE			0x8
66 
67 enum {
68 	RNG_OUTPUT_L_REG = 0,
69 	RNG_OUTPUT_H_REG,
70 	RNG_STATUS_REG,
71 	RNG_INTMASK_REG,
72 	RNG_INTACK_REG,
73 	RNG_CONTROL_REG,
74 	RNG_CONFIG_REG,
75 	RNG_ALARMCNT_REG,
76 	RNG_FROENABLE_REG,
77 	RNG_FRODETUNE_REG,
78 	RNG_ALARMMASK_REG,
79 	RNG_ALARMSTOP_REG,
80 	RNG_REV_REG,
81 	RNG_SYSCONFIG_REG,
82 };
83 
84 static const u16 reg_map_omap2[] = {
85 	[RNG_OUTPUT_L_REG]	= 0x0,
86 	[RNG_STATUS_REG]	= 0x4,
87 	[RNG_CONFIG_REG]	= 0x28,
88 	[RNG_REV_REG]		= 0x3c,
89 	[RNG_SYSCONFIG_REG]	= 0x40,
90 };
91 
92 static const u16 reg_map_omap4[] = {
93 	[RNG_OUTPUT_L_REG]	= 0x0,
94 	[RNG_OUTPUT_H_REG]	= 0x4,
95 	[RNG_STATUS_REG]	= 0x8,
96 	[RNG_INTMASK_REG]	= 0xc,
97 	[RNG_INTACK_REG]	= 0x10,
98 	[RNG_CONTROL_REG]	= 0x14,
99 	[RNG_CONFIG_REG]	= 0x18,
100 	[RNG_ALARMCNT_REG]	= 0x1c,
101 	[RNG_FROENABLE_REG]	= 0x20,
102 	[RNG_FRODETUNE_REG]	= 0x24,
103 	[RNG_ALARMMASK_REG]	= 0x28,
104 	[RNG_ALARMSTOP_REG]	= 0x2c,
105 	[RNG_REV_REG]		= 0x1FE0,
106 	[RNG_SYSCONFIG_REG]	= 0x1FE4,
107 };
108 
109 struct omap_rng_dev;
110 /**
111  * struct omap_rng_pdata - RNG IP block-specific data
112  * @regs: Pointer to the register offsets structure.
113  * @data_size: No. of bytes in RNG output.
114  * @data_present: Callback to determine if data is available.
115  * @init: Callback for IP specific initialization sequence.
116  * @cleanup: Callback for IP specific cleanup sequence.
117  */
118 struct omap_rng_pdata {
119 	u16	*regs;
120 	u32	data_size;
121 	u32	(*data_present)(struct omap_rng_dev *priv);
122 	int	(*init)(struct omap_rng_dev *priv);
123 	void	(*cleanup)(struct omap_rng_dev *priv);
124 };
125 
126 struct omap_rng_dev {
127 	void __iomem			*base;
128 	struct device			*dev;
129 	const struct omap_rng_pdata	*pdata;
130 };
131 
132 static inline u32 omap_rng_read(struct omap_rng_dev *priv, u16 reg)
133 {
134 	return __raw_readl(priv->base + priv->pdata->regs[reg]);
135 }
136 
137 static inline void omap_rng_write(struct omap_rng_dev *priv, u16 reg,
138 				      u32 val)
139 {
140 	__raw_writel(val, priv->base + priv->pdata->regs[reg]);
141 }
142 
143 static int omap_rng_data_present(struct hwrng *rng, int wait)
144 {
145 	struct omap_rng_dev *priv;
146 	int data, i;
147 
148 	priv = (struct omap_rng_dev *)rng->priv;
149 
150 	for (i = 0; i < 20; i++) {
151 		data = priv->pdata->data_present(priv);
152 		if (data || !wait)
153 			break;
154 		/* RNG produces data fast enough (2+ MBit/sec, even
155 		 * during "rngtest" loads, that these delays don't
156 		 * seem to trigger.  We *could* use the RNG IRQ, but
157 		 * that'd be higher overhead ... so why bother?
158 		 */
159 		udelay(10);
160 	}
161 	return data;
162 }
163 
164 static int omap_rng_data_read(struct hwrng *rng, u32 *data)
165 {
166 	struct omap_rng_dev *priv;
167 	u32 data_size, i;
168 
169 	priv = (struct omap_rng_dev *)rng->priv;
170 	data_size = priv->pdata->data_size;
171 
172 	for (i = 0; i < data_size / sizeof(u32); i++)
173 		data[i] = omap_rng_read(priv, RNG_OUTPUT_L_REG + i);
174 
175 	if (priv->pdata->regs[RNG_INTACK_REG])
176 		omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_RDY_MASK);
177 	return data_size;
178 }
179 
180 static int omap_rng_init(struct hwrng *rng)
181 {
182 	struct omap_rng_dev *priv;
183 
184 	priv = (struct omap_rng_dev *)rng->priv;
185 	return priv->pdata->init(priv);
186 }
187 
188 static void omap_rng_cleanup(struct hwrng *rng)
189 {
190 	struct omap_rng_dev *priv;
191 
192 	priv = (struct omap_rng_dev *)rng->priv;
193 	priv->pdata->cleanup(priv);
194 }
195 
196 static struct hwrng omap_rng_ops = {
197 	.name		= "omap",
198 	.data_present	= omap_rng_data_present,
199 	.data_read	= omap_rng_data_read,
200 	.init		= omap_rng_init,
201 	.cleanup	= omap_rng_cleanup,
202 };
203 
204 static inline u32 omap2_rng_data_present(struct omap_rng_dev *priv)
205 {
206 	return omap_rng_read(priv, RNG_STATUS_REG) ? 0 : 1;
207 }
208 
209 static int omap2_rng_init(struct omap_rng_dev *priv)
210 {
211 	omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x1);
212 	return 0;
213 }
214 
215 static void omap2_rng_cleanup(struct omap_rng_dev *priv)
216 {
217 	omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x0);
218 }
219 
220 static struct omap_rng_pdata omap2_rng_pdata = {
221 	.regs		= (u16 *)reg_map_omap2,
222 	.data_size	= OMAP2_RNG_OUTPUT_SIZE,
223 	.data_present	= omap2_rng_data_present,
224 	.init		= omap2_rng_init,
225 	.cleanup	= omap2_rng_cleanup,
226 };
227 
228 #if defined(CONFIG_OF)
229 static inline u32 omap4_rng_data_present(struct omap_rng_dev *priv)
230 {
231 	return omap_rng_read(priv, RNG_STATUS_REG) & RNG_REG_STATUS_RDY;
232 }
233 
234 static int omap4_rng_init(struct omap_rng_dev *priv)
235 {
236 	u32 val;
237 
238 	/* Return if RNG is already running. */
239 	if (omap_rng_read(priv, RNG_CONFIG_REG) & RNG_CONTROL_ENABLE_TRNG_MASK)
240 		return 0;
241 
242 	val = RNG_CONFIG_MIN_REFIL_CYCLES << RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT;
243 	val |= RNG_CONFIG_MAX_REFIL_CYCLES << RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT;
244 	omap_rng_write(priv, RNG_CONFIG_REG, val);
245 
246 	omap_rng_write(priv, RNG_FRODETUNE_REG, 0x0);
247 	omap_rng_write(priv, RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);
248 	val = RNG_ALARM_THRESHOLD << RNG_ALARMCNT_ALARM_TH_SHIFT;
249 	val |= RNG_SHUTDOWN_THRESHOLD << RNG_ALARMCNT_SHUTDOWN_TH_SHIFT;
250 	omap_rng_write(priv, RNG_ALARMCNT_REG, val);
251 
252 	val = RNG_CONTROL_STARTUP_CYCLES << RNG_CONTROL_STARTUP_CYCLES_SHIFT;
253 	val |= RNG_CONTROL_ENABLE_TRNG_MASK;
254 	omap_rng_write(priv, RNG_CONTROL_REG, val);
255 
256 	return 0;
257 }
258 
259 static void omap4_rng_cleanup(struct omap_rng_dev *priv)
260 {
261 	int val;
262 
263 	val = omap_rng_read(priv, RNG_CONTROL_REG);
264 	val &= ~RNG_CONTROL_ENABLE_TRNG_MASK;
265 	omap_rng_write(priv, RNG_CONFIG_REG, val);
266 }
267 
268 static irqreturn_t omap4_rng_irq(int irq, void *dev_id)
269 {
270 	struct omap_rng_dev *priv = dev_id;
271 	u32 fro_detune, fro_enable;
272 
273 	/*
274 	 * Interrupt raised by a fro shutdown threshold, do the following:
275 	 * 1. Clear the alarm events.
276 	 * 2. De tune the FROs which are shutdown.
277 	 * 3. Re enable the shutdown FROs.
278 	 */
279 	omap_rng_write(priv, RNG_ALARMMASK_REG, 0x0);
280 	omap_rng_write(priv, RNG_ALARMSTOP_REG, 0x0);
281 
282 	fro_enable = omap_rng_read(priv, RNG_FROENABLE_REG);
283 	fro_detune = ~fro_enable & RNG_REG_FRODETUNE_MASK;
284 	fro_detune = fro_detune | omap_rng_read(priv, RNG_FRODETUNE_REG);
285 	fro_enable = RNG_REG_FROENABLE_MASK;
286 
287 	omap_rng_write(priv, RNG_FRODETUNE_REG, fro_detune);
288 	omap_rng_write(priv, RNG_FROENABLE_REG, fro_enable);
289 
290 	omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_SHUTDOWN_OFLO_MASK);
291 
292 	return IRQ_HANDLED;
293 }
294 
295 static struct omap_rng_pdata omap4_rng_pdata = {
296 	.regs		= (u16 *)reg_map_omap4,
297 	.data_size	= OMAP4_RNG_OUTPUT_SIZE,
298 	.data_present	= omap4_rng_data_present,
299 	.init		= omap4_rng_init,
300 	.cleanup	= omap4_rng_cleanup,
301 };
302 
303 static const struct of_device_id omap_rng_of_match[] = {
304 		{
305 			.compatible	= "ti,omap2-rng",
306 			.data		= &omap2_rng_pdata,
307 		},
308 		{
309 			.compatible	= "ti,omap4-rng",
310 			.data		= &omap4_rng_pdata,
311 		},
312 		{},
313 };
314 MODULE_DEVICE_TABLE(of, omap_rng_of_match);
315 
316 static int of_get_omap_rng_device_details(struct omap_rng_dev *priv,
317 					  struct platform_device *pdev)
318 {
319 	const struct of_device_id *match;
320 	struct device *dev = &pdev->dev;
321 	int irq, err;
322 
323 	match = of_match_device(of_match_ptr(omap_rng_of_match), dev);
324 	if (!match) {
325 		dev_err(dev, "no compatible OF match\n");
326 		return -EINVAL;
327 	}
328 	priv->pdata = match->data;
329 
330 	if (of_device_is_compatible(dev->of_node, "ti,omap4-rng")) {
331 		irq = platform_get_irq(pdev, 0);
332 		if (irq < 0) {
333 			dev_err(dev, "%s: error getting IRQ resource - %d\n",
334 				__func__, irq);
335 			return irq;
336 		}
337 
338 		err = devm_request_irq(dev, irq, omap4_rng_irq,
339 				       IRQF_TRIGGER_NONE, dev_name(dev), priv);
340 		if (err) {
341 			dev_err(dev, "unable to request irq %d, err = %d\n",
342 				irq, err);
343 			return err;
344 		}
345 		omap_rng_write(priv, RNG_INTMASK_REG, RNG_SHUTDOWN_OFLO_MASK);
346 	}
347 	return 0;
348 }
349 #else
350 static int of_get_omap_rng_device_details(struct omap_rng_dev *omap_rng,
351 					  struct platform_device *pdev)
352 {
353 	return -EINVAL;
354 }
355 #endif
356 
357 static int get_omap_rng_device_details(struct omap_rng_dev *omap_rng)
358 {
359 	/* Only OMAP2/3 can be non-DT */
360 	omap_rng->pdata = &omap2_rng_pdata;
361 	return 0;
362 }
363 
364 static int omap_rng_probe(struct platform_device *pdev)
365 {
366 	struct omap_rng_dev *priv;
367 	struct resource *res;
368 	struct device *dev = &pdev->dev;
369 	int ret;
370 
371 	priv = devm_kzalloc(dev, sizeof(struct omap_rng_dev), GFP_KERNEL);
372 	if (!priv)
373 		return -ENOMEM;
374 
375 	omap_rng_ops.priv = (unsigned long)priv;
376 	platform_set_drvdata(pdev, priv);
377 	priv->dev = dev;
378 
379 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
380 	priv->base = devm_ioremap_resource(dev, res);
381 	if (IS_ERR(priv->base)) {
382 		ret = PTR_ERR(priv->base);
383 		goto err_ioremap;
384 	}
385 
386 	pm_runtime_enable(&pdev->dev);
387 	pm_runtime_get_sync(&pdev->dev);
388 
389 	ret = (dev->of_node) ? of_get_omap_rng_device_details(priv, pdev) :
390 				get_omap_rng_device_details(priv);
391 	if (ret)
392 		goto err_ioremap;
393 
394 	ret = hwrng_register(&omap_rng_ops);
395 	if (ret)
396 		goto err_register;
397 
398 	dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n",
399 		 omap_rng_read(priv, RNG_REV_REG));
400 
401 	return 0;
402 
403 err_register:
404 	priv->base = NULL;
405 	pm_runtime_disable(&pdev->dev);
406 err_ioremap:
407 	dev_err(dev, "initialization failed.\n");
408 	return ret;
409 }
410 
411 static int __exit omap_rng_remove(struct platform_device *pdev)
412 {
413 	struct omap_rng_dev *priv = platform_get_drvdata(pdev);
414 
415 	hwrng_unregister(&omap_rng_ops);
416 
417 	priv->pdata->cleanup(priv);
418 
419 	pm_runtime_put_sync(&pdev->dev);
420 	pm_runtime_disable(&pdev->dev);
421 
422 	return 0;
423 }
424 
425 #ifdef CONFIG_PM_SLEEP
426 
427 static int omap_rng_suspend(struct device *dev)
428 {
429 	struct omap_rng_dev *priv = dev_get_drvdata(dev);
430 
431 	priv->pdata->cleanup(priv);
432 	pm_runtime_put_sync(dev);
433 
434 	return 0;
435 }
436 
437 static int omap_rng_resume(struct device *dev)
438 {
439 	struct omap_rng_dev *priv = dev_get_drvdata(dev);
440 
441 	pm_runtime_get_sync(dev);
442 	priv->pdata->init(priv);
443 
444 	return 0;
445 }
446 
447 static SIMPLE_DEV_PM_OPS(omap_rng_pm, omap_rng_suspend, omap_rng_resume);
448 #define	OMAP_RNG_PM	(&omap_rng_pm)
449 
450 #else
451 
452 #define	OMAP_RNG_PM	NULL
453 
454 #endif
455 
456 static struct platform_driver omap_rng_driver = {
457 	.driver = {
458 		.name		= "omap_rng",
459 		.pm		= OMAP_RNG_PM,
460 		.of_match_table = of_match_ptr(omap_rng_of_match),
461 	},
462 	.probe		= omap_rng_probe,
463 	.remove		= __exit_p(omap_rng_remove),
464 };
465 
466 module_platform_driver(omap_rng_driver);
467 MODULE_ALIAS("platform:omap_rng");
468 MODULE_AUTHOR("Deepak Saxena (and others)");
469 MODULE_LICENSE("GPL");
470