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Feng Kana91ae4e2014-08-22 16:26:38 -07001/*
2 * APM X-Gene SoC RNG Driver
3 *
4 * Copyright (c) 2014, Applied Micro Circuits Corporation
5 * Author: Rameshwar Prasad Sahu <rsahu@apm.com>
6 * Shamal Winchurkar <swinchurkar@apm.com>
7 * Feng Kan <fkan@apm.com>
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the
11 * Free Software Foundation; either version 2 of the License, or (at your
12 * option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program. If not, see <http://www.gnu.org/licenses/>.
21 *
22 */
23
Feng Kana5084122015-03-06 14:53:15 -080024#include <linux/acpi.h>
Feng Kana91ae4e2014-08-22 16:26:38 -070025#include <linux/clk.h>
26#include <linux/delay.h>
27#include <linux/hw_random.h>
28#include <linux/init.h>
29#include <linux/interrupt.h>
30#include <linux/module.h>
31#include <linux/of_platform.h>
32#include <linux/of_irq.h>
33#include <linux/of_address.h>
34#include <linux/timer.h>
35
36#define RNG_MAX_DATUM 4
37#define MAX_TRY 100
38#define XGENE_RNG_RETRY_COUNT 20
39#define XGENE_RNG_RETRY_INTERVAL 10
40
41/* RNG Registers */
42#define RNG_INOUT_0 0x00
43#define RNG_INTR_STS_ACK 0x10
44#define RNG_CONTROL 0x14
45#define RNG_CONFIG 0x18
46#define RNG_ALARMCNT 0x1c
47#define RNG_FROENABLE 0x20
48#define RNG_FRODETUNE 0x24
49#define RNG_ALARMMASK 0x28
50#define RNG_ALARMSTOP 0x2c
51#define RNG_OPTIONS 0x78
52#define RNG_EIP_REV 0x7c
53
54#define MONOBIT_FAIL_MASK BIT(7)
55#define POKER_FAIL_MASK BIT(6)
56#define LONG_RUN_FAIL_MASK BIT(5)
57#define RUN_FAIL_MASK BIT(4)
58#define NOISE_FAIL_MASK BIT(3)
59#define STUCK_OUT_MASK BIT(2)
60#define SHUTDOWN_OFLO_MASK BIT(1)
61#define READY_MASK BIT(0)
62
63#define MAJOR_HW_REV_RD(src) (((src) & 0x0f000000) >> 24)
64#define MINOR_HW_REV_RD(src) (((src) & 0x00f00000) >> 20)
65#define HW_PATCH_LEVEL_RD(src) (((src) & 0x000f0000) >> 16)
66#define MAX_REFILL_CYCLES_SET(dst, src) \
67 ((dst & ~0xffff0000) | (((u32)src << 16) & 0xffff0000))
68#define MIN_REFILL_CYCLES_SET(dst, src) \
69 ((dst & ~0x000000ff) | (((u32)src) & 0x000000ff))
70#define ALARM_THRESHOLD_SET(dst, src) \
71 ((dst & ~0x000000ff) | (((u32)src) & 0x000000ff))
72#define ENABLE_RNG_SET(dst, src) \
73 ((dst & ~BIT(10)) | (((u32)src << 10) & BIT(10)))
74#define REGSPEC_TEST_MODE_SET(dst, src) \
75 ((dst & ~BIT(8)) | (((u32)src << 8) & BIT(8)))
76#define MONOBIT_FAIL_MASK_SET(dst, src) \
77 ((dst & ~BIT(7)) | (((u32)src << 7) & BIT(7)))
78#define POKER_FAIL_MASK_SET(dst, src) \
79 ((dst & ~BIT(6)) | (((u32)src << 6) & BIT(6)))
80#define LONG_RUN_FAIL_MASK_SET(dst, src) \
81 ((dst & ~BIT(5)) | (((u32)src << 5) & BIT(5)))
82#define RUN_FAIL_MASK_SET(dst, src) \
83 ((dst & ~BIT(4)) | (((u32)src << 4) & BIT(4)))
84#define NOISE_FAIL_MASK_SET(dst, src) \
85 ((dst & ~BIT(3)) | (((u32)src << 3) & BIT(3)))
86#define STUCK_OUT_MASK_SET(dst, src) \
87 ((dst & ~BIT(2)) | (((u32)src << 2) & BIT(2)))
88#define SHUTDOWN_OFLO_MASK_SET(dst, src) \
89 ((dst & ~BIT(1)) | (((u32)src << 1) & BIT(1)))
90
91struct xgene_rng_dev {
92 u32 irq;
93 void __iomem *csr_base;
94 u32 revision;
95 u32 datum_size;
96 u32 failure_cnt; /* Failure count last minute */
97 unsigned long failure_ts;/* First failure timestamp */
98 struct timer_list failure_timer;
99 struct device *dev;
100 struct clk *clk;
101};
102
Kees Cook200d24d2017-10-11 15:55:48 -0700103static void xgene_rng_expired_timer(struct timer_list *t)
Feng Kana91ae4e2014-08-22 16:26:38 -0700104{
Kees Cook200d24d2017-10-11 15:55:48 -0700105 struct xgene_rng_dev *ctx = from_timer(ctx, t, failure_timer);
Feng Kana91ae4e2014-08-22 16:26:38 -0700106
107 /* Clear failure counter as timer expired */
108 disable_irq(ctx->irq);
109 ctx->failure_cnt = 0;
110 del_timer(&ctx->failure_timer);
111 enable_irq(ctx->irq);
112}
113
114static void xgene_rng_start_timer(struct xgene_rng_dev *ctx)
115{
Feng Kana91ae4e2014-08-22 16:26:38 -0700116 ctx->failure_timer.expires = jiffies + 120 * HZ;
117 add_timer(&ctx->failure_timer);
118}
119
120/*
121 * Initialize or reinit free running oscillators (FROs)
122 */
123static void xgene_rng_init_fro(struct xgene_rng_dev *ctx, u32 fro_val)
124{
125 writel(fro_val, ctx->csr_base + RNG_FRODETUNE);
126 writel(0x00000000, ctx->csr_base + RNG_ALARMMASK);
127 writel(0x00000000, ctx->csr_base + RNG_ALARMSTOP);
128 writel(0xFFFFFFFF, ctx->csr_base + RNG_FROENABLE);
129}
130
131static void xgene_rng_chk_overflow(struct xgene_rng_dev *ctx)
132{
133 u32 val;
134
135 val = readl(ctx->csr_base + RNG_INTR_STS_ACK);
136 if (val & MONOBIT_FAIL_MASK)
137 /*
138 * LFSR detected an out-of-bounds number of 1s after
139 * checking 20,000 bits (test T1 as specified in the
140 * AIS-31 standard)
141 */
142 dev_err(ctx->dev, "test monobit failure error 0x%08X\n", val);
143 if (val & POKER_FAIL_MASK)
144 /*
145 * LFSR detected an out-of-bounds value in at least one
146 * of the 16 poker_count_X counters or an out of bounds sum
147 * of squares value after checking 20,000 bits (test T2 as
148 * specified in the AIS-31 standard)
149 */
150 dev_err(ctx->dev, "test poker failure error 0x%08X\n", val);
151 if (val & LONG_RUN_FAIL_MASK)
152 /*
153 * LFSR detected a sequence of 34 identical bits
154 * (test T4 as specified in the AIS-31 standard)
155 */
156 dev_err(ctx->dev, "test long run failure error 0x%08X\n", val);
157 if (val & RUN_FAIL_MASK)
158 /*
159 * LFSR detected an outof-bounds value for at least one
160 * of the running counters after checking 20,000 bits
161 * (test T3 as specified in the AIS-31 standard)
162 */
163 dev_err(ctx->dev, "test run failure error 0x%08X\n", val);
164 if (val & NOISE_FAIL_MASK)
165 /* LFSR detected a sequence of 48 identical bits */
166 dev_err(ctx->dev, "noise failure error 0x%08X\n", val);
167 if (val & STUCK_OUT_MASK)
168 /*
169 * Detected output data registers generated same value twice
170 * in a row
171 */
172 dev_err(ctx->dev, "stuck out failure error 0x%08X\n", val);
173
174 if (val & SHUTDOWN_OFLO_MASK) {
175 u32 frostopped;
176
177 /* FROs shut down after a second error event. Try recover. */
178 if (++ctx->failure_cnt == 1) {
179 /* 1st time, just recover */
180 ctx->failure_ts = jiffies;
181 frostopped = readl(ctx->csr_base + RNG_ALARMSTOP);
182 xgene_rng_init_fro(ctx, frostopped);
183
184 /*
185 * We must start a timer to clear out this error
186 * in case the system timer wrap around
187 */
188 xgene_rng_start_timer(ctx);
189 } else {
190 /* 2nd time failure in lesser than 1 minute? */
191 if (time_after(ctx->failure_ts + 60 * HZ, jiffies)) {
192 dev_err(ctx->dev,
193 "FRO shutdown failure error 0x%08X\n",
194 val);
195 } else {
196 /* 2nd time failure after 1 minutes, recover */
197 ctx->failure_ts = jiffies;
198 ctx->failure_cnt = 1;
199 /*
200 * We must start a timer to clear out this
201 * error in case the system timer wrap
202 * around
203 */
204 xgene_rng_start_timer(ctx);
205 }
206 frostopped = readl(ctx->csr_base + RNG_ALARMSTOP);
207 xgene_rng_init_fro(ctx, frostopped);
208 }
209 }
210 /* Clear them all */
211 writel(val, ctx->csr_base + RNG_INTR_STS_ACK);
212}
213
214static irqreturn_t xgene_rng_irq_handler(int irq, void *id)
215{
216 struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) id;
217
218 /* RNG Alarm Counter overflow */
219 xgene_rng_chk_overflow(ctx);
220
221 return IRQ_HANDLED;
222}
223
224static int xgene_rng_data_present(struct hwrng *rng, int wait)
225{
226 struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
227 u32 i, val = 0;
228
229 for (i = 0; i < XGENE_RNG_RETRY_COUNT; i++) {
230 val = readl(ctx->csr_base + RNG_INTR_STS_ACK);
231 if ((val & READY_MASK) || !wait)
232 break;
233 udelay(XGENE_RNG_RETRY_INTERVAL);
234 }
235
236 return (val & READY_MASK);
237}
238
239static int xgene_rng_data_read(struct hwrng *rng, u32 *data)
240{
241 struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
242 int i;
243
244 for (i = 0; i < ctx->datum_size; i++)
245 data[i] = readl(ctx->csr_base + RNG_INOUT_0 + i * 4);
246
247 /* Clear ready bit to start next transaction */
248 writel(READY_MASK, ctx->csr_base + RNG_INTR_STS_ACK);
249
250 return ctx->datum_size << 2;
251}
252
253static void xgene_rng_init_internal(struct xgene_rng_dev *ctx)
254{
255 u32 val;
256
257 writel(0x00000000, ctx->csr_base + RNG_CONTROL);
258
259 val = MAX_REFILL_CYCLES_SET(0, 10);
260 val = MIN_REFILL_CYCLES_SET(val, 10);
261 writel(val, ctx->csr_base + RNG_CONFIG);
262
263 val = ALARM_THRESHOLD_SET(0, 0xFF);
264 writel(val, ctx->csr_base + RNG_ALARMCNT);
265
266 xgene_rng_init_fro(ctx, 0);
267
268 writel(MONOBIT_FAIL_MASK |
269 POKER_FAIL_MASK |
270 LONG_RUN_FAIL_MASK |
271 RUN_FAIL_MASK |
272 NOISE_FAIL_MASK |
273 STUCK_OUT_MASK |
274 SHUTDOWN_OFLO_MASK |
275 READY_MASK, ctx->csr_base + RNG_INTR_STS_ACK);
276
277 val = ENABLE_RNG_SET(0, 1);
278 val = MONOBIT_FAIL_MASK_SET(val, 1);
279 val = POKER_FAIL_MASK_SET(val, 1);
280 val = LONG_RUN_FAIL_MASK_SET(val, 1);
281 val = RUN_FAIL_MASK_SET(val, 1);
282 val = NOISE_FAIL_MASK_SET(val, 1);
283 val = STUCK_OUT_MASK_SET(val, 1);
284 val = SHUTDOWN_OFLO_MASK_SET(val, 1);
285 writel(val, ctx->csr_base + RNG_CONTROL);
286}
287
288static int xgene_rng_init(struct hwrng *rng)
289{
290 struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
291
292 ctx->failure_cnt = 0;
Kees Cook200d24d2017-10-11 15:55:48 -0700293 timer_setup(&ctx->failure_timer, xgene_rng_expired_timer, 0);
Feng Kana91ae4e2014-08-22 16:26:38 -0700294
295 ctx->revision = readl(ctx->csr_base + RNG_EIP_REV);
296
297 dev_dbg(ctx->dev, "Rev %d.%d.%d\n",
298 MAJOR_HW_REV_RD(ctx->revision),
299 MINOR_HW_REV_RD(ctx->revision),
300 HW_PATCH_LEVEL_RD(ctx->revision));
301
302 dev_dbg(ctx->dev, "Options 0x%08X",
303 readl(ctx->csr_base + RNG_OPTIONS));
304
305 xgene_rng_init_internal(ctx);
306
307 ctx->datum_size = RNG_MAX_DATUM;
308
309 return 0;
310}
311
Feng Kana5084122015-03-06 14:53:15 -0800312#ifdef CONFIG_ACPI
313static const struct acpi_device_id xgene_rng_acpi_match[] = {
314 { "APMC0D18", },
315 { }
316};
317MODULE_DEVICE_TABLE(acpi, xgene_rng_acpi_match);
318#endif
319
Feng Kana91ae4e2014-08-22 16:26:38 -0700320static struct hwrng xgene_rng_func = {
321 .name = "xgene-rng",
322 .init = xgene_rng_init,
323 .data_present = xgene_rng_data_present,
324 .data_read = xgene_rng_data_read,
325};
326
327static int xgene_rng_probe(struct platform_device *pdev)
328{
329 struct resource *res;
330 struct xgene_rng_dev *ctx;
331 int rc = 0;
332
333 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
334 if (!ctx)
335 return -ENOMEM;
336
337 ctx->dev = &pdev->dev;
338 platform_set_drvdata(pdev, ctx);
339
340 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
341 ctx->csr_base = devm_ioremap_resource(&pdev->dev, res);
342 if (IS_ERR(ctx->csr_base))
343 return PTR_ERR(ctx->csr_base);
344
Andrzej Hajda09185e22015-09-21 15:33:42 +0200345 rc = platform_get_irq(pdev, 0);
346 if (rc < 0) {
Feng Kana91ae4e2014-08-22 16:26:38 -0700347 dev_err(&pdev->dev, "No IRQ resource\n");
Andrzej Hajda09185e22015-09-21 15:33:42 +0200348 return rc;
Feng Kana91ae4e2014-08-22 16:26:38 -0700349 }
Andrzej Hajda09185e22015-09-21 15:33:42 +0200350 ctx->irq = rc;
Feng Kana91ae4e2014-08-22 16:26:38 -0700351
352 dev_dbg(&pdev->dev, "APM X-Gene RNG BASE %p ALARM IRQ %d",
353 ctx->csr_base, ctx->irq);
354
355 rc = devm_request_irq(&pdev->dev, ctx->irq, xgene_rng_irq_handler, 0,
356 dev_name(&pdev->dev), ctx);
357 if (rc) {
358 dev_err(&pdev->dev, "Could not request RNG alarm IRQ\n");
359 return rc;
360 }
361
362 /* Enable IP clock */
363 ctx->clk = devm_clk_get(&pdev->dev, NULL);
364 if (IS_ERR(ctx->clk)) {
365 dev_warn(&pdev->dev, "Couldn't get the clock for RNG\n");
366 } else {
367 rc = clk_prepare_enable(ctx->clk);
368 if (rc) {
369 dev_warn(&pdev->dev,
370 "clock prepare enable failed for RNG");
371 return rc;
372 }
373 }
374
375 xgene_rng_func.priv = (unsigned long) ctx;
376
377 rc = hwrng_register(&xgene_rng_func);
378 if (rc) {
379 dev_err(&pdev->dev, "RNG registering failed error %d\n", rc);
380 if (!IS_ERR(ctx->clk))
381 clk_disable_unprepare(ctx->clk);
382 return rc;
383 }
384
385 rc = device_init_wakeup(&pdev->dev, 1);
386 if (rc) {
387 dev_err(&pdev->dev, "RNG device_init_wakeup failed error %d\n",
388 rc);
389 if (!IS_ERR(ctx->clk))
390 clk_disable_unprepare(ctx->clk);
391 hwrng_unregister(&xgene_rng_func);
392 return rc;
393 }
394
395 return 0;
396}
397
398static int xgene_rng_remove(struct platform_device *pdev)
399{
400 struct xgene_rng_dev *ctx = platform_get_drvdata(pdev);
401 int rc;
402
403 rc = device_init_wakeup(&pdev->dev, 0);
404 if (rc)
405 dev_err(&pdev->dev, "RNG init wakeup failed error %d\n", rc);
406 if (!IS_ERR(ctx->clk))
407 clk_disable_unprepare(ctx->clk);
408 hwrng_unregister(&xgene_rng_func);
409
410 return rc;
411}
412
413static const struct of_device_id xgene_rng_of_match[] = {
414 { .compatible = "apm,xgene-rng" },
415 { }
416};
417
418MODULE_DEVICE_TABLE(of, xgene_rng_of_match);
419
420static struct platform_driver xgene_rng_driver = {
421 .probe = xgene_rng_probe,
422 .remove = xgene_rng_remove,
423 .driver = {
424 .name = "xgene-rng",
425 .of_match_table = xgene_rng_of_match,
Feng Kana5084122015-03-06 14:53:15 -0800426 .acpi_match_table = ACPI_PTR(xgene_rng_acpi_match),
Feng Kana91ae4e2014-08-22 16:26:38 -0700427 },
428};
429
430module_platform_driver(xgene_rng_driver);
431MODULE_DESCRIPTION("APM X-Gene RNG driver");
432MODULE_LICENSE("GPL");