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
74enum {
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
93static 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
101static 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
118static 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
135struct 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 */
144struct 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
152struct 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
161static inline u32 omap_rng_read(struct omap_rng_dev *priv, u16 reg)
162{
163 return __raw_readl(addr: priv->base + priv->pdata->regs[reg]);
164}
165
166static inline void omap_rng_write(struct omap_rng_dev *priv, u16 reg,
167 u32 val)
168{
169 __raw_writel(val, addr: priv->base + priv->pdata->regs[reg]);
170}
171
172
173static 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, reg: RNG_INTACK_REG, RNG_REG_INTACK_RDY_MASK);
199
200 return priv->pdata->data_size;
201}
202
203static 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
211static 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
220static inline u32 omap2_rng_data_present(struct omap_rng_dev *priv)
221{
222 return omap_rng_read(priv, reg: RNG_STATUS_REG) ? 0 : 1;
223}
224
225static int omap2_rng_init(struct omap_rng_dev *priv)
226{
227 omap_rng_write(priv, reg: RNG_SYSCONFIG_REG, val: 0x1);
228 return 0;
229}
230
231static void omap2_rng_cleanup(struct omap_rng_dev *priv)
232{
233 omap_rng_write(priv, reg: RNG_SYSCONFIG_REG, val: 0x0);
234}
235
236static 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
244static inline u32 omap4_rng_data_present(struct omap_rng_dev *priv)
245{
246 return omap_rng_read(priv, reg: RNG_STATUS_REG) & RNG_REG_STATUS_RDY;
247}
248
249static 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, reg: 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, reg: RNG_CONFIG_REG, val);
269
270 /* Enable all available FROs */
271 omap_rng_write(priv, reg: RNG_FRODETUNE_REG, val: 0x0);
272 omap_rng_write(priv, reg: RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);
273
274 /* Enable TRNG */
275 val = RNG_CONTROL_ENABLE_TRNG_MASK;
276 omap_rng_write(priv, reg: RNG_CONTROL_REG, val);
277
278 return 0;
279}
280
281static 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, reg: 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, reg: RNG_CONFIG_REG, val);
292
293 omap_rng_write(priv, reg: RNG_FRODETUNE_REG, val: 0x0);
294 omap_rng_write(priv, reg: 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, reg: 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, reg: RNG_CONTROL_REG, val);
302
303 return 0;
304}
305
306static void omap4_rng_cleanup(struct omap_rng_dev *priv)
307{
308 int val;
309
310 val = omap_rng_read(priv, reg: RNG_CONTROL_REG);
311 val &= ~RNG_CONTROL_ENABLE_TRNG_MASK;
312 omap_rng_write(priv, reg: RNG_CONTROL_REG, val);
313}
314
315static 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, reg: RNG_ALARMMASK_REG, val: 0x0);
327 omap_rng_write(priv, reg: RNG_ALARMSTOP_REG, val: 0x0);
328
329 fro_enable = omap_rng_read(priv, reg: RNG_FROENABLE_REG);
330 fro_detune = ~fro_enable & RNG_REG_FRODETUNE_MASK;
331 fro_detune = fro_detune | omap_rng_read(priv, reg: RNG_FRODETUNE_REG);
332 fro_enable = RNG_REG_FROENABLE_MASK;
333
334 omap_rng_write(priv, reg: RNG_FRODETUNE_REG, val: fro_detune);
335 omap_rng_write(priv, reg: RNG_FROENABLE_REG, val: fro_enable);
336
337 omap_rng_write(priv, reg: RNG_INTACK_REG, RNG_REG_INTACK_SHUTDOWN_OFLO_MASK);
338
339 return IRQ_HANDLED;
340}
341
342static 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
350static 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
358static 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};
373MODULE_DEVICE_TABLE(of, omap_rng_of_match);
374
375static 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(device: dev->of_node, "ti,omap4-rng") ||
387 of_device_is_compatible(device: 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, handler: omap4_rng_irq,
393 IRQF_TRIGGER_NONE, devname: dev_name(dev), dev_id: 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, reg: RNG_INTMASK_REG,
408 RNG_SHUTDOWN_OFLO_MASK);
409 else
410 omap_rng_write(priv, reg: RNG_CONTROL_REG,
411 RNG_SHUTDOWN_OFLO_MASK);
412 }
413 return 0;
414}
415
416static 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
423static 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, size: 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, data: priv);
440 priv->dev = dev;
441
442 priv->base = devm_platform_ioremap_resource(pdev, index: 0);
443 if (IS_ERR(ptr: priv->base)) {
444 ret = PTR_ERR(ptr: priv->base);
445 goto err_ioremap;
446 }
447
448 priv->rng.name = devm_kstrdup(dev, s: dev_name(dev), GFP_KERNEL);
449 if (!priv->rng.name) {
450 ret = -ENOMEM;
451 goto err_ioremap;
452 }
453
454 pm_runtime_enable(dev: &pdev->dev);
455 ret = pm_runtime_resume_and_get(dev: &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(dev: &pdev->dev, NULL);
462 if (PTR_ERR(ptr: priv->clk) == -EPROBE_DEFER)
463 return -EPROBE_DEFER;
464 if (!IS_ERR(ptr: priv->clk)) {
465 ret = clk_prepare_enable(clk: 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(dev: &pdev->dev, id: "reg");
474 if (PTR_ERR(ptr: priv->clk_reg) == -EPROBE_DEFER)
475 return -EPROBE_DEFER;
476 if (!IS_ERR(ptr: priv->clk_reg)) {
477 ret = clk_prepare_enable(clk: 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(omap_rng: priv);
488 if (ret)
489 goto err_register;
490
491 ret = devm_hwrng_register(dev: &pdev->dev, rng: &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
500err_register:
501 priv->base = NULL;
502 pm_runtime_put_sync(dev: &pdev->dev);
503 pm_runtime_disable(dev: &pdev->dev);
504
505 clk_disable_unprepare(clk: priv->clk_reg);
506 clk_disable_unprepare(clk: priv->clk);
507err_ioremap:
508 dev_err(dev, "initialization failed.\n");
509 return ret;
510}
511
512static 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(dev: &pdev->dev);
520 pm_runtime_disable(dev: &pdev->dev);
521
522 clk_disable_unprepare(clk: priv->clk);
523 clk_disable_unprepare(clk: priv->clk_reg);
524
525 return 0;
526}
527
528static 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
538static 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
554static SIMPLE_DEV_PM_OPS(omap_rng_pm, omap_rng_suspend, omap_rng_resume);
555
556static 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
566module_platform_driver(omap_rng_driver);
567MODULE_ALIAS("platform:omap_rng");
568MODULE_AUTHOR("Deepak Saxena (and others)");
569MODULE_LICENSE("GPL");
570

source code of linux/drivers/char/hw_random/omap-rng.c