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/kernel.h>
26 #include <linux/slab.h>
27 #include <linux/pm_runtime.h>
28 #include <linux/of.h>
29 #include <linux/interrupt.h>
30 #include <linux/clk.h>
31 #include <linux/io.h>
32 
33 #define RNG_REG_STATUS_RDY			(1 << 0)
34 
35 #define RNG_REG_INTACK_RDY_MASK			(1 << 0)
36 #define RNG_REG_INTACK_SHUTDOWN_OFLO_MASK	(1 << 1)
37 #define RNG_SHUTDOWN_OFLO_MASK			(1 << 1)
38 
39 #define RNG_CONTROL_STARTUP_CYCLES_SHIFT	16
40 #define RNG_CONTROL_STARTUP_CYCLES_MASK		(0xffff << 16)
41 #define RNG_CONTROL_ENABLE_TRNG_SHIFT		10
42 #define RNG_CONTROL_ENABLE_TRNG_MASK		(1 << 10)
43 
44 #define RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT	16
45 #define RNG_CONFIG_MAX_REFIL_CYCLES_MASK	(0xffff << 16)
46 #define RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT	0
47 #define RNG_CONFIG_MIN_REFIL_CYCLES_MASK	(0xff << 0)
48 
49 #define RNG_CONTROL_STARTUP_CYCLES		0xff
50 #define RNG_CONFIG_MIN_REFIL_CYCLES		0x21
51 #define RNG_CONFIG_MAX_REFIL_CYCLES		0x22
52 
53 #define RNG_ALARMCNT_ALARM_TH_SHIFT		0x0
54 #define RNG_ALARMCNT_ALARM_TH_MASK		(0xff << 0)
55 #define RNG_ALARMCNT_SHUTDOWN_TH_SHIFT		16
56 #define RNG_ALARMCNT_SHUTDOWN_TH_MASK		(0x1f << 16)
57 #define RNG_ALARM_THRESHOLD			0xff
58 #define RNG_SHUTDOWN_THRESHOLD			0x4
59 
60 #define RNG_REG_FROENABLE_MASK			0xffffff
61 #define RNG_REG_FRODETUNE_MASK			0xffffff
62 
63 #define OMAP2_RNG_OUTPUT_SIZE			0x4
64 #define OMAP4_RNG_OUTPUT_SIZE			0x8
65 #define EIP76_RNG_OUTPUT_SIZE			0x10
66 
67 /*
68  * EIP76 RNG takes approx. 700us to produce 16 bytes of output data
69  * as per testing results. And to account for the lack of udelay()'s
70  * reliability, we keep the timeout as 1000us.
71  */
72 #define RNG_DATA_FILL_TIMEOUT			100
73 
74 enum {
75 	RNG_OUTPUT_0_REG = 0,
76 	RNG_OUTPUT_1_REG,
77 	RNG_OUTPUT_2_REG,
78 	RNG_OUTPUT_3_REG,
79 	RNG_STATUS_REG,
80 	RNG_INTMASK_REG,
81 	RNG_INTACK_REG,
82 	RNG_CONTROL_REG,
83 	RNG_CONFIG_REG,
84 	RNG_ALARMCNT_REG,
85 	RNG_FROENABLE_REG,
86 	RNG_FRODETUNE_REG,
87 	RNG_ALARMMASK_REG,
88 	RNG_ALARMSTOP_REG,
89 	RNG_REV_REG,
90 	RNG_SYSCONFIG_REG,
91 };
92 
93 static const u16 reg_map_omap2[] = {
94 	[RNG_OUTPUT_0_REG]	= 0x0,
95 	[RNG_STATUS_REG]	= 0x4,
96 	[RNG_CONFIG_REG]	= 0x28,
97 	[RNG_REV_REG]		= 0x3c,
98 	[RNG_SYSCONFIG_REG]	= 0x40,
99 };
100 
101 static const u16 reg_map_omap4[] = {
102 	[RNG_OUTPUT_0_REG]	= 0x0,
103 	[RNG_OUTPUT_1_REG]	= 0x4,
104 	[RNG_STATUS_REG]	= 0x8,
105 	[RNG_INTMASK_REG]	= 0xc,
106 	[RNG_INTACK_REG]	= 0x10,
107 	[RNG_CONTROL_REG]	= 0x14,
108 	[RNG_CONFIG_REG]	= 0x18,
109 	[RNG_ALARMCNT_REG]	= 0x1c,
110 	[RNG_FROENABLE_REG]	= 0x20,
111 	[RNG_FRODETUNE_REG]	= 0x24,
112 	[RNG_ALARMMASK_REG]	= 0x28,
113 	[RNG_ALARMSTOP_REG]	= 0x2c,
114 	[RNG_REV_REG]		= 0x1FE0,
115 	[RNG_SYSCONFIG_REG]	= 0x1FE4,
116 };
117 
118 static const u16 reg_map_eip76[] = {
119 	[RNG_OUTPUT_0_REG]	= 0x0,
120 	[RNG_OUTPUT_1_REG]	= 0x4,
121 	[RNG_OUTPUT_2_REG]	= 0x8,
122 	[RNG_OUTPUT_3_REG]	= 0xc,
123 	[RNG_STATUS_REG]	= 0x10,
124 	[RNG_INTACK_REG]	= 0x10,
125 	[RNG_CONTROL_REG]	= 0x14,
126 	[RNG_CONFIG_REG]	= 0x18,
127 	[RNG_ALARMCNT_REG]	= 0x1c,
128 	[RNG_FROENABLE_REG]	= 0x20,
129 	[RNG_FRODETUNE_REG]	= 0x24,
130 	[RNG_ALARMMASK_REG]	= 0x28,
131 	[RNG_ALARMSTOP_REG]	= 0x2c,
132 	[RNG_REV_REG]		= 0x7c,
133 };
134 
135 struct omap_rng_dev;
136 /**
137  * struct omap_rng_pdata - RNG IP block-specific data
138  * @regs: Pointer to the register offsets structure.
139  * @data_size: No. of bytes in RNG output.
140  * @data_present: Callback to determine if data is available.
141  * @init: Callback for IP specific initialization sequence.
142  * @cleanup: Callback for IP specific cleanup sequence.
143  */
144 struct omap_rng_pdata {
145 	u16	*regs;
146 	u32	data_size;
147 	u32	(*data_present)(struct omap_rng_dev *priv);
148 	int	(*init)(struct omap_rng_dev *priv);
149 	void	(*cleanup)(struct omap_rng_dev *priv);
150 };
151 
152 struct omap_rng_dev {
153 	void __iomem			*base;
154 	struct device			*dev;
155 	const struct omap_rng_pdata	*pdata;
156 	struct hwrng rng;
157 	struct clk 			*clk;
158 	struct clk			*clk_reg;
159 };
160 
161 static inline u32 omap_rng_read(struct omap_rng_dev *priv, u16 reg)
162 {
163 	return __raw_readl(priv->base + priv->pdata->regs[reg]);
164 }
165 
166 static inline void omap_rng_write(struct omap_rng_dev *priv, u16 reg,
167 				      u32 val)
168 {
169 	__raw_writel(val, priv->base + priv->pdata->regs[reg]);
170 }
171 
172 
173 static int omap_rng_do_read(struct hwrng *rng, void *data, size_t max,
174 			    bool wait)
175 {
176 	struct omap_rng_dev *priv;
177 	int i, present;
178 
179 	priv = (struct omap_rng_dev *)rng->priv;
180 
181 	if (max < priv->pdata->data_size)
182 		return 0;
183 
184 	for (i = 0; i < RNG_DATA_FILL_TIMEOUT; i++) {
185 		present = priv->pdata->data_present(priv);
186 		if (present || !wait)
187 			break;
188 
189 		udelay(10);
190 	}
191 	if (!present)
192 		return 0;
193 
194 	memcpy_fromio(data, priv->base + priv->pdata->regs[RNG_OUTPUT_0_REG],
195 		      priv->pdata->data_size);
196 
197 	if (priv->pdata->regs[RNG_INTACK_REG])
198 		omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_RDY_MASK);
199 
200 	return priv->pdata->data_size;
201 }
202 
203 static int omap_rng_init(struct hwrng *rng)
204 {
205 	struct omap_rng_dev *priv;
206 
207 	priv = (struct omap_rng_dev *)rng->priv;
208 	return priv->pdata->init(priv);
209 }
210 
211 static void omap_rng_cleanup(struct hwrng *rng)
212 {
213 	struct omap_rng_dev *priv;
214 
215 	priv = (struct omap_rng_dev *)rng->priv;
216 	priv->pdata->cleanup(priv);
217 }
218 
219 
220 static inline u32 omap2_rng_data_present(struct omap_rng_dev *priv)
221 {
222 	return omap_rng_read(priv, RNG_STATUS_REG) ? 0 : 1;
223 }
224 
225 static int omap2_rng_init(struct omap_rng_dev *priv)
226 {
227 	omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x1);
228 	return 0;
229 }
230 
231 static void omap2_rng_cleanup(struct omap_rng_dev *priv)
232 {
233 	omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x0);
234 }
235 
236 static struct omap_rng_pdata omap2_rng_pdata = {
237 	.regs		= (u16 *)reg_map_omap2,
238 	.data_size	= OMAP2_RNG_OUTPUT_SIZE,
239 	.data_present	= omap2_rng_data_present,
240 	.init		= omap2_rng_init,
241 	.cleanup	= omap2_rng_cleanup,
242 };
243 
244 static inline u32 omap4_rng_data_present(struct omap_rng_dev *priv)
245 {
246 	return omap_rng_read(priv, RNG_STATUS_REG) & RNG_REG_STATUS_RDY;
247 }
248 
249 static int eip76_rng_init(struct omap_rng_dev *priv)
250 {
251 	u32 val;
252 
253 	/* Return if RNG is already running. */
254 	if (omap_rng_read(priv, RNG_CONTROL_REG) & RNG_CONTROL_ENABLE_TRNG_MASK)
255 		return 0;
256 
257 	/*  Number of 512 bit blocks of raw Noise Source output data that must
258 	 *  be processed by either the Conditioning Function or the
259 	 *  SP 800-90 DRBG ‘BC_DF’ functionality to yield a ‘full entropy’
260 	 *  output value.
261 	 */
262 	val = 0x5 << RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT;
263 
264 	/* Number of FRO samples that are XOR-ed together into one bit to be
265 	 * shifted into the main shift register
266 	 */
267 	val |= RNG_CONFIG_MAX_REFIL_CYCLES << RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT;
268 	omap_rng_write(priv, RNG_CONFIG_REG, val);
269 
270 	/* Enable all available FROs */
271 	omap_rng_write(priv, RNG_FRODETUNE_REG, 0x0);
272 	omap_rng_write(priv, RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);
273 
274 	/* Enable TRNG */
275 	val = RNG_CONTROL_ENABLE_TRNG_MASK;
276 	omap_rng_write(priv, RNG_CONTROL_REG, val);
277 
278 	return 0;
279 }
280 
281 static int omap4_rng_init(struct omap_rng_dev *priv)
282 {
283 	u32 val;
284 
285 	/* Return if RNG is already running. */
286 	if (omap_rng_read(priv, RNG_CONTROL_REG) & RNG_CONTROL_ENABLE_TRNG_MASK)
287 		return 0;
288 
289 	val = RNG_CONFIG_MIN_REFIL_CYCLES << RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT;
290 	val |= RNG_CONFIG_MAX_REFIL_CYCLES << RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT;
291 	omap_rng_write(priv, RNG_CONFIG_REG, val);
292 
293 	omap_rng_write(priv, RNG_FRODETUNE_REG, 0x0);
294 	omap_rng_write(priv, RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);
295 	val = RNG_ALARM_THRESHOLD << RNG_ALARMCNT_ALARM_TH_SHIFT;
296 	val |= RNG_SHUTDOWN_THRESHOLD << RNG_ALARMCNT_SHUTDOWN_TH_SHIFT;
297 	omap_rng_write(priv, RNG_ALARMCNT_REG, val);
298 
299 	val = RNG_CONTROL_STARTUP_CYCLES << RNG_CONTROL_STARTUP_CYCLES_SHIFT;
300 	val |= RNG_CONTROL_ENABLE_TRNG_MASK;
301 	omap_rng_write(priv, RNG_CONTROL_REG, val);
302 
303 	return 0;
304 }
305 
306 static void omap4_rng_cleanup(struct omap_rng_dev *priv)
307 {
308 	int val;
309 
310 	val = omap_rng_read(priv, RNG_CONTROL_REG);
311 	val &= ~RNG_CONTROL_ENABLE_TRNG_MASK;
312 	omap_rng_write(priv, RNG_CONTROL_REG, val);
313 }
314 
315 static irqreturn_t omap4_rng_irq(int irq, void *dev_id)
316 {
317 	struct omap_rng_dev *priv = dev_id;
318 	u32 fro_detune, fro_enable;
319 
320 	/*
321 	 * Interrupt raised by a fro shutdown threshold, do the following:
322 	 * 1. Clear the alarm events.
323 	 * 2. De tune the FROs which are shutdown.
324 	 * 3. Re enable the shutdown FROs.
325 	 */
326 	omap_rng_write(priv, RNG_ALARMMASK_REG, 0x0);
327 	omap_rng_write(priv, RNG_ALARMSTOP_REG, 0x0);
328 
329 	fro_enable = omap_rng_read(priv, RNG_FROENABLE_REG);
330 	fro_detune = ~fro_enable & RNG_REG_FRODETUNE_MASK;
331 	fro_detune = fro_detune | omap_rng_read(priv, RNG_FRODETUNE_REG);
332 	fro_enable = RNG_REG_FROENABLE_MASK;
333 
334 	omap_rng_write(priv, RNG_FRODETUNE_REG, fro_detune);
335 	omap_rng_write(priv, RNG_FROENABLE_REG, fro_enable);
336 
337 	omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_SHUTDOWN_OFLO_MASK);
338 
339 	return IRQ_HANDLED;
340 }
341 
342 static struct omap_rng_pdata omap4_rng_pdata = {
343 	.regs		= (u16 *)reg_map_omap4,
344 	.data_size	= OMAP4_RNG_OUTPUT_SIZE,
345 	.data_present	= omap4_rng_data_present,
346 	.init		= omap4_rng_init,
347 	.cleanup	= omap4_rng_cleanup,
348 };
349 
350 static struct omap_rng_pdata eip76_rng_pdata = {
351 	.regs		= (u16 *)reg_map_eip76,
352 	.data_size	= EIP76_RNG_OUTPUT_SIZE,
353 	.data_present	= omap4_rng_data_present,
354 	.init		= eip76_rng_init,
355 	.cleanup	= omap4_rng_cleanup,
356 };
357 
358 static const struct of_device_id omap_rng_of_match[] __maybe_unused = {
359 		{
360 			.compatible	= "ti,omap2-rng",
361 			.data		= &omap2_rng_pdata,
362 		},
363 		{
364 			.compatible	= "ti,omap4-rng",
365 			.data		= &omap4_rng_pdata,
366 		},
367 		{
368 			.compatible	= "inside-secure,safexcel-eip76",
369 			.data		= &eip76_rng_pdata,
370 		},
371 		{},
372 };
373 MODULE_DEVICE_TABLE(of, omap_rng_of_match);
374 
375 static int of_get_omap_rng_device_details(struct omap_rng_dev *priv,
376 					  struct platform_device *pdev)
377 {
378 	struct device *dev = &pdev->dev;
379 	int irq, err;
380 
381 	priv->pdata = of_device_get_match_data(dev);
382 	if (!priv->pdata)
383 		return -ENODEV;
384 
385 
386 	if (of_device_is_compatible(dev->of_node, "ti,omap4-rng") ||
387 	    of_device_is_compatible(dev->of_node, "inside-secure,safexcel-eip76")) {
388 		irq = platform_get_irq(pdev, 0);
389 		if (irq < 0)
390 			return irq;
391 
392 		err = devm_request_irq(dev, irq, omap4_rng_irq,
393 				       IRQF_TRIGGER_NONE, dev_name(dev), priv);
394 		if (err) {
395 			dev_err(dev, "unable to request irq %d, err = %d\n",
396 				irq, err);
397 			return err;
398 		}
399 
400 		/*
401 		 * On OMAP4, enabling the shutdown_oflo interrupt is
402 		 * done in the interrupt mask register. There is no
403 		 * such register on EIP76, and it's enabled by the
404 		 * same bit in the control register
405 		 */
406 		if (priv->pdata->regs[RNG_INTMASK_REG])
407 			omap_rng_write(priv, RNG_INTMASK_REG,
408 				       RNG_SHUTDOWN_OFLO_MASK);
409 		else
410 			omap_rng_write(priv, RNG_CONTROL_REG,
411 				       RNG_SHUTDOWN_OFLO_MASK);
412 	}
413 	return 0;
414 }
415 
416 static int get_omap_rng_device_details(struct omap_rng_dev *omap_rng)
417 {
418 	/* Only OMAP2/3 can be non-DT */
419 	omap_rng->pdata = &omap2_rng_pdata;
420 	return 0;
421 }
422 
423 static int omap_rng_probe(struct platform_device *pdev)
424 {
425 	struct omap_rng_dev *priv;
426 	struct device *dev = &pdev->dev;
427 	int ret;
428 
429 	priv = devm_kzalloc(dev, sizeof(struct omap_rng_dev), GFP_KERNEL);
430 	if (!priv)
431 		return -ENOMEM;
432 
433 	priv->rng.read = omap_rng_do_read;
434 	priv->rng.init = omap_rng_init;
435 	priv->rng.cleanup = omap_rng_cleanup;
436 	priv->rng.quality = 900;
437 
438 	priv->rng.priv = (unsigned long)priv;
439 	platform_set_drvdata(pdev, priv);
440 	priv->dev = dev;
441 
442 	priv->base = devm_platform_ioremap_resource(pdev, 0);
443 	if (IS_ERR(priv->base)) {
444 		ret = PTR_ERR(priv->base);
445 		goto err_ioremap;
446 	}
447 
448 	priv->rng.name = devm_kstrdup(dev, dev_name(dev), GFP_KERNEL);
449 	if (!priv->rng.name) {
450 		ret = -ENOMEM;
451 		goto err_ioremap;
452 	}
453 
454 	pm_runtime_enable(&pdev->dev);
455 	ret = pm_runtime_resume_and_get(&pdev->dev);
456 	if (ret < 0) {
457 		dev_err(&pdev->dev, "Failed to runtime_get device: %d\n", ret);
458 		goto err_ioremap;
459 	}
460 
461 	priv->clk = devm_clk_get(&pdev->dev, NULL);
462 	if (PTR_ERR(priv->clk) == -EPROBE_DEFER)
463 		return -EPROBE_DEFER;
464 	if (!IS_ERR(priv->clk)) {
465 		ret = clk_prepare_enable(priv->clk);
466 		if (ret) {
467 			dev_err(&pdev->dev,
468 				"Unable to enable the clk: %d\n", ret);
469 			goto err_register;
470 		}
471 	}
472 
473 	priv->clk_reg = devm_clk_get(&pdev->dev, "reg");
474 	if (PTR_ERR(priv->clk_reg) == -EPROBE_DEFER)
475 		return -EPROBE_DEFER;
476 	if (!IS_ERR(priv->clk_reg)) {
477 		ret = clk_prepare_enable(priv->clk_reg);
478 		if (ret) {
479 			dev_err(&pdev->dev,
480 				"Unable to enable the register clk: %d\n",
481 				ret);
482 			goto err_register;
483 		}
484 	}
485 
486 	ret = (dev->of_node) ? of_get_omap_rng_device_details(priv, pdev) :
487 				get_omap_rng_device_details(priv);
488 	if (ret)
489 		goto err_register;
490 
491 	ret = devm_hwrng_register(&pdev->dev, &priv->rng);
492 	if (ret)
493 		goto err_register;
494 
495 	dev_info(&pdev->dev, "Random Number Generator ver. %02x\n",
496 		 omap_rng_read(priv, RNG_REV_REG));
497 
498 	return 0;
499 
500 err_register:
501 	priv->base = NULL;
502 	pm_runtime_put_sync(&pdev->dev);
503 	pm_runtime_disable(&pdev->dev);
504 
505 	clk_disable_unprepare(priv->clk_reg);
506 	clk_disable_unprepare(priv->clk);
507 err_ioremap:
508 	dev_err(dev, "initialization failed.\n");
509 	return ret;
510 }
511 
512 static int omap_rng_remove(struct platform_device *pdev)
513 {
514 	struct omap_rng_dev *priv = platform_get_drvdata(pdev);
515 
516 
517 	priv->pdata->cleanup(priv);
518 
519 	pm_runtime_put_sync(&pdev->dev);
520 	pm_runtime_disable(&pdev->dev);
521 
522 	clk_disable_unprepare(priv->clk);
523 	clk_disable_unprepare(priv->clk_reg);
524 
525 	return 0;
526 }
527 
528 static int __maybe_unused omap_rng_suspend(struct device *dev)
529 {
530 	struct omap_rng_dev *priv = dev_get_drvdata(dev);
531 
532 	priv->pdata->cleanup(priv);
533 	pm_runtime_put_sync(dev);
534 
535 	return 0;
536 }
537 
538 static int __maybe_unused omap_rng_resume(struct device *dev)
539 {
540 	struct omap_rng_dev *priv = dev_get_drvdata(dev);
541 	int ret;
542 
543 	ret = pm_runtime_resume_and_get(dev);
544 	if (ret < 0) {
545 		dev_err(dev, "Failed to runtime_get device: %d\n", ret);
546 		return ret;
547 	}
548 
549 	priv->pdata->init(priv);
550 
551 	return 0;
552 }
553 
554 static SIMPLE_DEV_PM_OPS(omap_rng_pm, omap_rng_suspend, omap_rng_resume);
555 
556 static struct platform_driver omap_rng_driver = {
557 	.driver = {
558 		.name		= "omap_rng",
559 		.pm		= &omap_rng_pm,
560 		.of_match_table = of_match_ptr(omap_rng_of_match),
561 	},
562 	.probe		= omap_rng_probe,
563 	.remove		= omap_rng_remove,
564 };
565 
566 module_platform_driver(omap_rng_driver);
567 MODULE_ALIAS("platform:omap_rng");
568 MODULE_AUTHOR("Deepak Saxena (and others)");
569 MODULE_LICENSE("GPL");
570