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