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_0_REG = 0,
69 	RNG_OUTPUT_1_REG,
70 	RNG_OUTPUT_2_REG,
71 	RNG_OUTPUT_3_REG,
72 	RNG_STATUS_REG,
73 	RNG_INTMASK_REG,
74 	RNG_INTACK_REG,
75 	RNG_CONTROL_REG,
76 	RNG_CONFIG_REG,
77 	RNG_ALARMCNT_REG,
78 	RNG_FROENABLE_REG,
79 	RNG_FRODETUNE_REG,
80 	RNG_ALARMMASK_REG,
81 	RNG_ALARMSTOP_REG,
82 	RNG_REV_REG,
83 	RNG_SYSCONFIG_REG,
84 };
85 
86 static const u16 reg_map_omap2[] = {
87 	[RNG_OUTPUT_0_REG]	= 0x0,
88 	[RNG_STATUS_REG]	= 0x4,
89 	[RNG_CONFIG_REG]	= 0x28,
90 	[RNG_REV_REG]		= 0x3c,
91 	[RNG_SYSCONFIG_REG]	= 0x40,
92 };
93 
94 static const u16 reg_map_omap4[] = {
95 	[RNG_OUTPUT_0_REG]	= 0x0,
96 	[RNG_OUTPUT_1_REG]	= 0x4,
97 	[RNG_STATUS_REG]	= 0x8,
98 	[RNG_INTMASK_REG]	= 0xc,
99 	[RNG_INTACK_REG]	= 0x10,
100 	[RNG_CONTROL_REG]	= 0x14,
101 	[RNG_CONFIG_REG]	= 0x18,
102 	[RNG_ALARMCNT_REG]	= 0x1c,
103 	[RNG_FROENABLE_REG]	= 0x20,
104 	[RNG_FRODETUNE_REG]	= 0x24,
105 	[RNG_ALARMMASK_REG]	= 0x28,
106 	[RNG_ALARMSTOP_REG]	= 0x2c,
107 	[RNG_REV_REG]		= 0x1FE0,
108 	[RNG_SYSCONFIG_REG]	= 0x1FE4,
109 };
110 
111 struct omap_rng_dev;
112 /**
113  * struct omap_rng_pdata - RNG IP block-specific data
114  * @regs: Pointer to the register offsets structure.
115  * @data_size: No. of bytes in RNG output.
116  * @data_present: Callback to determine if data is available.
117  * @init: Callback for IP specific initialization sequence.
118  * @cleanup: Callback for IP specific cleanup sequence.
119  */
120 struct omap_rng_pdata {
121 	u16	*regs;
122 	u32	data_size;
123 	u32	(*data_present)(struct omap_rng_dev *priv);
124 	int	(*init)(struct omap_rng_dev *priv);
125 	void	(*cleanup)(struct omap_rng_dev *priv);
126 };
127 
128 struct omap_rng_dev {
129 	void __iomem			*base;
130 	struct device			*dev;
131 	const struct omap_rng_pdata	*pdata;
132 	struct hwrng rng;
133 };
134 
135 static inline u32 omap_rng_read(struct omap_rng_dev *priv, u16 reg)
136 {
137 	return __raw_readl(priv->base + priv->pdata->regs[reg]);
138 }
139 
140 static inline void omap_rng_write(struct omap_rng_dev *priv, u16 reg,
141 				      u32 val)
142 {
143 	__raw_writel(val, priv->base + priv->pdata->regs[reg]);
144 }
145 
146 
147 static int omap_rng_do_read(struct hwrng *rng, void *data, size_t max,
148 			    bool wait)
149 {
150 	struct omap_rng_dev *priv;
151 	int i, present;
152 
153 	priv = (struct omap_rng_dev *)rng->priv;
154 
155 	if (max < priv->pdata->data_size)
156 		return 0;
157 
158 	for (i = 0; i < 20; i++) {
159 		present = priv->pdata->data_present(priv);
160 		if (present || !wait)
161 			break;
162 
163 		udelay(10);
164 	}
165 	if (!present)
166 		return 0;
167 
168 	memcpy_fromio(data, priv->base + priv->pdata->regs[RNG_OUTPUT_0_REG],
169 		      priv->pdata->data_size);
170 
171 	if (priv->pdata->regs[RNG_INTACK_REG])
172 		omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_RDY_MASK);
173 
174 	return priv->pdata->data_size;
175 }
176 
177 static int omap_rng_init(struct hwrng *rng)
178 {
179 	struct omap_rng_dev *priv;
180 
181 	priv = (struct omap_rng_dev *)rng->priv;
182 	return priv->pdata->init(priv);
183 }
184 
185 static void omap_rng_cleanup(struct hwrng *rng)
186 {
187 	struct omap_rng_dev *priv;
188 
189 	priv = (struct omap_rng_dev *)rng->priv;
190 	priv->pdata->cleanup(priv);
191 }
192 
193 
194 static inline u32 omap2_rng_data_present(struct omap_rng_dev *priv)
195 {
196 	return omap_rng_read(priv, RNG_STATUS_REG) ? 0 : 1;
197 }
198 
199 static int omap2_rng_init(struct omap_rng_dev *priv)
200 {
201 	omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x1);
202 	return 0;
203 }
204 
205 static void omap2_rng_cleanup(struct omap_rng_dev *priv)
206 {
207 	omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x0);
208 }
209 
210 static struct omap_rng_pdata omap2_rng_pdata = {
211 	.regs		= (u16 *)reg_map_omap2,
212 	.data_size	= OMAP2_RNG_OUTPUT_SIZE,
213 	.data_present	= omap2_rng_data_present,
214 	.init		= omap2_rng_init,
215 	.cleanup	= omap2_rng_cleanup,
216 };
217 
218 #if defined(CONFIG_OF)
219 static inline u32 omap4_rng_data_present(struct omap_rng_dev *priv)
220 {
221 	return omap_rng_read(priv, RNG_STATUS_REG) & RNG_REG_STATUS_RDY;
222 }
223 
224 static int omap4_rng_init(struct omap_rng_dev *priv)
225 {
226 	u32 val;
227 
228 	/* Return if RNG is already running. */
229 	if (omap_rng_read(priv, RNG_CONTROL_REG) & RNG_CONTROL_ENABLE_TRNG_MASK)
230 		return 0;
231 
232 	val = RNG_CONFIG_MIN_REFIL_CYCLES << RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT;
233 	val |= RNG_CONFIG_MAX_REFIL_CYCLES << RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT;
234 	omap_rng_write(priv, RNG_CONFIG_REG, val);
235 
236 	omap_rng_write(priv, RNG_FRODETUNE_REG, 0x0);
237 	omap_rng_write(priv, RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);
238 	val = RNG_ALARM_THRESHOLD << RNG_ALARMCNT_ALARM_TH_SHIFT;
239 	val |= RNG_SHUTDOWN_THRESHOLD << RNG_ALARMCNT_SHUTDOWN_TH_SHIFT;
240 	omap_rng_write(priv, RNG_ALARMCNT_REG, val);
241 
242 	val = RNG_CONTROL_STARTUP_CYCLES << RNG_CONTROL_STARTUP_CYCLES_SHIFT;
243 	val |= RNG_CONTROL_ENABLE_TRNG_MASK;
244 	omap_rng_write(priv, RNG_CONTROL_REG, val);
245 
246 	return 0;
247 }
248 
249 static void omap4_rng_cleanup(struct omap_rng_dev *priv)
250 {
251 	int val;
252 
253 	val = omap_rng_read(priv, RNG_CONTROL_REG);
254 	val &= ~RNG_CONTROL_ENABLE_TRNG_MASK;
255 	omap_rng_write(priv, RNG_CONTROL_REG, val);
256 }
257 
258 static irqreturn_t omap4_rng_irq(int irq, void *dev_id)
259 {
260 	struct omap_rng_dev *priv = dev_id;
261 	u32 fro_detune, fro_enable;
262 
263 	/*
264 	 * Interrupt raised by a fro shutdown threshold, do the following:
265 	 * 1. Clear the alarm events.
266 	 * 2. De tune the FROs which are shutdown.
267 	 * 3. Re enable the shutdown FROs.
268 	 */
269 	omap_rng_write(priv, RNG_ALARMMASK_REG, 0x0);
270 	omap_rng_write(priv, RNG_ALARMSTOP_REG, 0x0);
271 
272 	fro_enable = omap_rng_read(priv, RNG_FROENABLE_REG);
273 	fro_detune = ~fro_enable & RNG_REG_FRODETUNE_MASK;
274 	fro_detune = fro_detune | omap_rng_read(priv, RNG_FRODETUNE_REG);
275 	fro_enable = RNG_REG_FROENABLE_MASK;
276 
277 	omap_rng_write(priv, RNG_FRODETUNE_REG, fro_detune);
278 	omap_rng_write(priv, RNG_FROENABLE_REG, fro_enable);
279 
280 	omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_SHUTDOWN_OFLO_MASK);
281 
282 	return IRQ_HANDLED;
283 }
284 
285 static struct omap_rng_pdata omap4_rng_pdata = {
286 	.regs		= (u16 *)reg_map_omap4,
287 	.data_size	= OMAP4_RNG_OUTPUT_SIZE,
288 	.data_present	= omap4_rng_data_present,
289 	.init		= omap4_rng_init,
290 	.cleanup	= omap4_rng_cleanup,
291 };
292 
293 static const struct of_device_id omap_rng_of_match[] = {
294 		{
295 			.compatible	= "ti,omap2-rng",
296 			.data		= &omap2_rng_pdata,
297 		},
298 		{
299 			.compatible	= "ti,omap4-rng",
300 			.data		= &omap4_rng_pdata,
301 		},
302 		{},
303 };
304 MODULE_DEVICE_TABLE(of, omap_rng_of_match);
305 
306 static int of_get_omap_rng_device_details(struct omap_rng_dev *priv,
307 					  struct platform_device *pdev)
308 {
309 	const struct of_device_id *match;
310 	struct device *dev = &pdev->dev;
311 	int irq, err;
312 
313 	match = of_match_device(of_match_ptr(omap_rng_of_match), dev);
314 	if (!match) {
315 		dev_err(dev, "no compatible OF match\n");
316 		return -EINVAL;
317 	}
318 	priv->pdata = match->data;
319 
320 	if (of_device_is_compatible(dev->of_node, "ti,omap4-rng")) {
321 		irq = platform_get_irq(pdev, 0);
322 		if (irq < 0) {
323 			dev_err(dev, "%s: error getting IRQ resource - %d\n",
324 				__func__, irq);
325 			return irq;
326 		}
327 
328 		err = devm_request_irq(dev, irq, omap4_rng_irq,
329 				       IRQF_TRIGGER_NONE, dev_name(dev), priv);
330 		if (err) {
331 			dev_err(dev, "unable to request irq %d, err = %d\n",
332 				irq, err);
333 			return err;
334 		}
335 		omap_rng_write(priv, RNG_INTMASK_REG, RNG_SHUTDOWN_OFLO_MASK);
336 	}
337 	return 0;
338 }
339 #else
340 static int of_get_omap_rng_device_details(struct omap_rng_dev *omap_rng,
341 					  struct platform_device *pdev)
342 {
343 	return -EINVAL;
344 }
345 #endif
346 
347 static int get_omap_rng_device_details(struct omap_rng_dev *omap_rng)
348 {
349 	/* Only OMAP2/3 can be non-DT */
350 	omap_rng->pdata = &omap2_rng_pdata;
351 	return 0;
352 }
353 
354 static int omap_rng_probe(struct platform_device *pdev)
355 {
356 	struct omap_rng_dev *priv;
357 	struct resource *res;
358 	struct device *dev = &pdev->dev;
359 	int ret;
360 
361 	priv = devm_kzalloc(dev, sizeof(struct omap_rng_dev), GFP_KERNEL);
362 	if (!priv)
363 		return -ENOMEM;
364 
365 	priv->rng.read = omap_rng_do_read;
366 	priv->rng.init = omap_rng_init;
367 	priv->rng.cleanup = omap_rng_cleanup;
368 
369 	priv->rng.priv = (unsigned long)priv;
370 	platform_set_drvdata(pdev, priv);
371 	priv->dev = dev;
372 
373 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
374 	priv->base = devm_ioremap_resource(dev, res);
375 	if (IS_ERR(priv->base)) {
376 		ret = PTR_ERR(priv->base);
377 		goto err_ioremap;
378 	}
379 
380 	priv->rng.name = devm_kstrdup(dev, dev_name(dev), GFP_KERNEL);
381 	if (!priv->rng.name) {
382 		ret = -ENOMEM;
383 		goto err_ioremap;
384 	}
385 
386 	pm_runtime_enable(&pdev->dev);
387 	ret = pm_runtime_get_sync(&pdev->dev);
388 	if (ret < 0) {
389 		dev_err(&pdev->dev, "Failed to runtime_get device: %d\n", ret);
390 		pm_runtime_put_noidle(&pdev->dev);
391 		goto err_ioremap;
392 	}
393 
394 	ret = (dev->of_node) ? of_get_omap_rng_device_details(priv, pdev) :
395 				get_omap_rng_device_details(priv);
396 	if (ret)
397 		goto err_ioremap;
398 
399 	ret = hwrng_register(&priv->rng);
400 	if (ret)
401 		goto err_register;
402 
403 	dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n",
404 		 omap_rng_read(priv, RNG_REV_REG));
405 
406 	return 0;
407 
408 err_register:
409 	priv->base = NULL;
410 	pm_runtime_disable(&pdev->dev);
411 err_ioremap:
412 	dev_err(dev, "initialization failed.\n");
413 	return ret;
414 }
415 
416 static int omap_rng_remove(struct platform_device *pdev)
417 {
418 	struct omap_rng_dev *priv = platform_get_drvdata(pdev);
419 
420 	hwrng_unregister(&priv->rng);
421 
422 	priv->pdata->cleanup(priv);
423 
424 	pm_runtime_put_sync(&pdev->dev);
425 	pm_runtime_disable(&pdev->dev);
426 
427 	return 0;
428 }
429 
430 static int __maybe_unused omap_rng_suspend(struct device *dev)
431 {
432 	struct omap_rng_dev *priv = dev_get_drvdata(dev);
433 
434 	priv->pdata->cleanup(priv);
435 	pm_runtime_put_sync(dev);
436 
437 	return 0;
438 }
439 
440 static int __maybe_unused omap_rng_resume(struct device *dev)
441 {
442 	struct omap_rng_dev *priv = dev_get_drvdata(dev);
443 	int ret;
444 
445 	ret = pm_runtime_get_sync(dev);
446 	if (ret < 0) {
447 		dev_err(dev, "Failed to runtime_get device: %d\n", ret);
448 		pm_runtime_put_noidle(dev);
449 		return ret;
450 	}
451 
452 	priv->pdata->init(priv);
453 
454 	return 0;
455 }
456 
457 static SIMPLE_DEV_PM_OPS(omap_rng_pm, omap_rng_suspend, omap_rng_resume);
458 
459 static struct platform_driver omap_rng_driver = {
460 	.driver = {
461 		.name		= "omap_rng",
462 		.pm		= &omap_rng_pm,
463 		.of_match_table = of_match_ptr(omap_rng_of_match),
464 	},
465 	.probe		= omap_rng_probe,
466 	.remove		= omap_rng_remove,
467 };
468 
469 module_platform_driver(omap_rng_driver);
470 MODULE_ALIAS("platform:omap_rng");
471 MODULE_AUTHOR("Deepak Saxena (and others)");
472 MODULE_LICENSE("GPL");
473