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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * APM X-Gene SoC RNG Driver
4 *
5 * Copyright (c) 2014, Applied Micro Circuits Corporation
6 * Author: Rameshwar Prasad Sahu <rsahu@apm.com>
7 * Shamal Winchurkar <swinchurkar@apm.com>
8 * Feng Kan <fkan@apm.com>
9 */
10
11#include <linux/acpi.h>
12#include <linux/clk.h>
13#include <linux/delay.h>
14#include <linux/hw_random.h>
15#include <linux/init.h>
16#include <linux/interrupt.h>
17#include <linux/io.h>
18#include <linux/module.h>
19#include <linux/mod_devicetable.h>
20#include <linux/platform_device.h>
21#include <linux/timer.h>
22
23#define RNG_MAX_DATUM 4
24#define MAX_TRY 100
25#define XGENE_RNG_RETRY_COUNT 20
26#define XGENE_RNG_RETRY_INTERVAL 10
27
28/* RNG Registers */
29#define RNG_INOUT_0 0x00
30#define RNG_INTR_STS_ACK 0x10
31#define RNG_CONTROL 0x14
32#define RNG_CONFIG 0x18
33#define RNG_ALARMCNT 0x1c
34#define RNG_FROENABLE 0x20
35#define RNG_FRODETUNE 0x24
36#define RNG_ALARMMASK 0x28
37#define RNG_ALARMSTOP 0x2c
38#define RNG_OPTIONS 0x78
39#define RNG_EIP_REV 0x7c
40
41#define MONOBIT_FAIL_MASK BIT(7)
42#define POKER_FAIL_MASK BIT(6)
43#define LONG_RUN_FAIL_MASK BIT(5)
44#define RUN_FAIL_MASK BIT(4)
45#define NOISE_FAIL_MASK BIT(3)
46#define STUCK_OUT_MASK BIT(2)
47#define SHUTDOWN_OFLO_MASK BIT(1)
48#define READY_MASK BIT(0)
49
50#define MAJOR_HW_REV_RD(src) (((src) & 0x0f000000) >> 24)
51#define MINOR_HW_REV_RD(src) (((src) & 0x00f00000) >> 20)
52#define HW_PATCH_LEVEL_RD(src) (((src) & 0x000f0000) >> 16)
53#define MAX_REFILL_CYCLES_SET(dst, src) \
54 ((dst & ~0xffff0000) | (((u32)src << 16) & 0xffff0000))
55#define MIN_REFILL_CYCLES_SET(dst, src) \
56 ((dst & ~0x000000ff) | (((u32)src) & 0x000000ff))
57#define ALARM_THRESHOLD_SET(dst, src) \
58 ((dst & ~0x000000ff) | (((u32)src) & 0x000000ff))
59#define ENABLE_RNG_SET(dst, src) \
60 ((dst & ~BIT(10)) | (((u32)src << 10) & BIT(10)))
61#define REGSPEC_TEST_MODE_SET(dst, src) \
62 ((dst & ~BIT(8)) | (((u32)src << 8) & BIT(8)))
63#define MONOBIT_FAIL_MASK_SET(dst, src) \
64 ((dst & ~BIT(7)) | (((u32)src << 7) & BIT(7)))
65#define POKER_FAIL_MASK_SET(dst, src) \
66 ((dst & ~BIT(6)) | (((u32)src << 6) & BIT(6)))
67#define LONG_RUN_FAIL_MASK_SET(dst, src) \
68 ((dst & ~BIT(5)) | (((u32)src << 5) & BIT(5)))
69#define RUN_FAIL_MASK_SET(dst, src) \
70 ((dst & ~BIT(4)) | (((u32)src << 4) & BIT(4)))
71#define NOISE_FAIL_MASK_SET(dst, src) \
72 ((dst & ~BIT(3)) | (((u32)src << 3) & BIT(3)))
73#define STUCK_OUT_MASK_SET(dst, src) \
74 ((dst & ~BIT(2)) | (((u32)src << 2) & BIT(2)))
75#define SHUTDOWN_OFLO_MASK_SET(dst, src) \
76 ((dst & ~BIT(1)) | (((u32)src << 1) & BIT(1)))
77
78struct xgene_rng_dev {
79 u32 irq;
80 void __iomem *csr_base;
81 u32 revision;
82 u32 datum_size;
83 u32 failure_cnt; /* Failure count last minute */
84 unsigned long failure_ts;/* First failure timestamp */
85 struct timer_list failure_timer;
86 struct device *dev;
87};
88
89static void xgene_rng_expired_timer(struct timer_list *t)
90{
91 struct xgene_rng_dev *ctx = from_timer(ctx, t, failure_timer);
92
93 /* Clear failure counter as timer expired */
94 disable_irq(ctx->irq);
95 ctx->failure_cnt = 0;
96 del_timer(&ctx->failure_timer);
97 enable_irq(ctx->irq);
98}
99
100static void xgene_rng_start_timer(struct xgene_rng_dev *ctx)
101{
102 ctx->failure_timer.expires = jiffies + 120 * HZ;
103 add_timer(&ctx->failure_timer);
104}
105
106/*
107 * Initialize or reinit free running oscillators (FROs)
108 */
109static void xgene_rng_init_fro(struct xgene_rng_dev *ctx, u32 fro_val)
110{
111 writel(fro_val, ctx->csr_base + RNG_FRODETUNE);
112 writel(0x00000000, ctx->csr_base + RNG_ALARMMASK);
113 writel(0x00000000, ctx->csr_base + RNG_ALARMSTOP);
114 writel(0xFFFFFFFF, ctx->csr_base + RNG_FROENABLE);
115}
116
117static void xgene_rng_chk_overflow(struct xgene_rng_dev *ctx)
118{
119 u32 val;
120
121 val = readl(ctx->csr_base + RNG_INTR_STS_ACK);
122 if (val & MONOBIT_FAIL_MASK)
123 /*
124 * LFSR detected an out-of-bounds number of 1s after
125 * checking 20,000 bits (test T1 as specified in the
126 * AIS-31 standard)
127 */
128 dev_err(ctx->dev, "test monobit failure error 0x%08X\n", val);
129 if (val & POKER_FAIL_MASK)
130 /*
131 * LFSR detected an out-of-bounds value in at least one
132 * of the 16 poker_count_X counters or an out of bounds sum
133 * of squares value after checking 20,000 bits (test T2 as
134 * specified in the AIS-31 standard)
135 */
136 dev_err(ctx->dev, "test poker failure error 0x%08X\n", val);
137 if (val & LONG_RUN_FAIL_MASK)
138 /*
139 * LFSR detected a sequence of 34 identical bits
140 * (test T4 as specified in the AIS-31 standard)
141 */
142 dev_err(ctx->dev, "test long run failure error 0x%08X\n", val);
143 if (val & RUN_FAIL_MASK)
144 /*
145 * LFSR detected an outof-bounds value for at least one
146 * of the running counters after checking 20,000 bits
147 * (test T3 as specified in the AIS-31 standard)
148 */
149 dev_err(ctx->dev, "test run failure error 0x%08X\n", val);
150 if (val & NOISE_FAIL_MASK)
151 /* LFSR detected a sequence of 48 identical bits */
152 dev_err(ctx->dev, "noise failure error 0x%08X\n", val);
153 if (val & STUCK_OUT_MASK)
154 /*
155 * Detected output data registers generated same value twice
156 * in a row
157 */
158 dev_err(ctx->dev, "stuck out failure error 0x%08X\n", val);
159
160 if (val & SHUTDOWN_OFLO_MASK) {
161 u32 frostopped;
162
163 /* FROs shut down after a second error event. Try recover. */
164 if (++ctx->failure_cnt == 1) {
165 /* 1st time, just recover */
166 ctx->failure_ts = jiffies;
167 frostopped = readl(ctx->csr_base + RNG_ALARMSTOP);
168 xgene_rng_init_fro(ctx, frostopped);
169
170 /*
171 * We must start a timer to clear out this error
172 * in case the system timer wrap around
173 */
174 xgene_rng_start_timer(ctx);
175 } else {
176 /* 2nd time failure in lesser than 1 minute? */
177 if (time_after(ctx->failure_ts + 60 * HZ, jiffies)) {
178 dev_err(ctx->dev,
179 "FRO shutdown failure error 0x%08X\n",
180 val);
181 } else {
182 /* 2nd time failure after 1 minutes, recover */
183 ctx->failure_ts = jiffies;
184 ctx->failure_cnt = 1;
185 /*
186 * We must start a timer to clear out this
187 * error in case the system timer wrap
188 * around
189 */
190 xgene_rng_start_timer(ctx);
191 }
192 frostopped = readl(ctx->csr_base + RNG_ALARMSTOP);
193 xgene_rng_init_fro(ctx, frostopped);
194 }
195 }
196 /* Clear them all */
197 writel(val, ctx->csr_base + RNG_INTR_STS_ACK);
198}
199
200static irqreturn_t xgene_rng_irq_handler(int irq, void *id)
201{
202 struct xgene_rng_dev *ctx = id;
203
204 /* RNG Alarm Counter overflow */
205 xgene_rng_chk_overflow(ctx);
206
207 return IRQ_HANDLED;
208}
209
210static int xgene_rng_data_present(struct hwrng *rng, int wait)
211{
212 struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
213 u32 i, val = 0;
214
215 for (i = 0; i < XGENE_RNG_RETRY_COUNT; i++) {
216 val = readl(ctx->csr_base + RNG_INTR_STS_ACK);
217 if ((val & READY_MASK) || !wait)
218 break;
219 udelay(XGENE_RNG_RETRY_INTERVAL);
220 }
221
222 return (val & READY_MASK);
223}
224
225static int xgene_rng_data_read(struct hwrng *rng, u32 *data)
226{
227 struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
228 int i;
229
230 for (i = 0; i < ctx->datum_size; i++)
231 data[i] = readl(ctx->csr_base + RNG_INOUT_0 + i * 4);
232
233 /* Clear ready bit to start next transaction */
234 writel(READY_MASK, ctx->csr_base + RNG_INTR_STS_ACK);
235
236 return ctx->datum_size << 2;
237}
238
239static void xgene_rng_init_internal(struct xgene_rng_dev *ctx)
240{
241 u32 val;
242
243 writel(0x00000000, ctx->csr_base + RNG_CONTROL);
244
245 val = MAX_REFILL_CYCLES_SET(0, 10);
246 val = MIN_REFILL_CYCLES_SET(val, 10);
247 writel(val, ctx->csr_base + RNG_CONFIG);
248
249 val = ALARM_THRESHOLD_SET(0, 0xFF);
250 writel(val, ctx->csr_base + RNG_ALARMCNT);
251
252 xgene_rng_init_fro(ctx, 0);
253
254 writel(MONOBIT_FAIL_MASK |
255 POKER_FAIL_MASK |
256 LONG_RUN_FAIL_MASK |
257 RUN_FAIL_MASK |
258 NOISE_FAIL_MASK |
259 STUCK_OUT_MASK |
260 SHUTDOWN_OFLO_MASK |
261 READY_MASK, ctx->csr_base + RNG_INTR_STS_ACK);
262
263 val = ENABLE_RNG_SET(0, 1);
264 val = MONOBIT_FAIL_MASK_SET(val, 1);
265 val = POKER_FAIL_MASK_SET(val, 1);
266 val = LONG_RUN_FAIL_MASK_SET(val, 1);
267 val = RUN_FAIL_MASK_SET(val, 1);
268 val = NOISE_FAIL_MASK_SET(val, 1);
269 val = STUCK_OUT_MASK_SET(val, 1);
270 val = SHUTDOWN_OFLO_MASK_SET(val, 1);
271 writel(val, ctx->csr_base + RNG_CONTROL);
272}
273
274static int xgene_rng_init(struct hwrng *rng)
275{
276 struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv;
277
278 ctx->failure_cnt = 0;
279 timer_setup(&ctx->failure_timer, xgene_rng_expired_timer, 0);
280
281 ctx->revision = readl(ctx->csr_base + RNG_EIP_REV);
282
283 dev_dbg(ctx->dev, "Rev %d.%d.%d\n",
284 MAJOR_HW_REV_RD(ctx->revision),
285 MINOR_HW_REV_RD(ctx->revision),
286 HW_PATCH_LEVEL_RD(ctx->revision));
287
288 dev_dbg(ctx->dev, "Options 0x%08X",
289 readl(ctx->csr_base + RNG_OPTIONS));
290
291 xgene_rng_init_internal(ctx);
292
293 ctx->datum_size = RNG_MAX_DATUM;
294
295 return 0;
296}
297
298#ifdef CONFIG_ACPI
299static const struct acpi_device_id xgene_rng_acpi_match[] = {
300 { "APMC0D18", },
301 { }
302};
303MODULE_DEVICE_TABLE(acpi, xgene_rng_acpi_match);
304#endif
305
306static struct hwrng xgene_rng_func = {
307 .name = "xgene-rng",
308 .init = xgene_rng_init,
309 .data_present = xgene_rng_data_present,
310 .data_read = xgene_rng_data_read,
311};
312
313static int xgene_rng_probe(struct platform_device *pdev)
314{
315 struct xgene_rng_dev *ctx;
316 struct clk *clk;
317 int rc = 0;
318
319 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
320 if (!ctx)
321 return -ENOMEM;
322
323 ctx->dev = &pdev->dev;
324
325 ctx->csr_base = devm_platform_ioremap_resource(pdev, 0);
326 if (IS_ERR(ctx->csr_base))
327 return PTR_ERR(ctx->csr_base);
328
329 rc = platform_get_irq(pdev, 0);
330 if (rc < 0)
331 return rc;
332 ctx->irq = rc;
333
334 dev_dbg(&pdev->dev, "APM X-Gene RNG BASE %p ALARM IRQ %d",
335 ctx->csr_base, ctx->irq);
336
337 rc = devm_request_irq(&pdev->dev, ctx->irq, xgene_rng_irq_handler, 0,
338 dev_name(&pdev->dev), ctx);
339 if (rc)
340 return dev_err_probe(&pdev->dev, rc, "Could not request RNG alarm IRQ\n");
341
342 /* Enable IP clock */
343 clk = devm_clk_get_optional_enabled(&pdev->dev, NULL);
344 if (IS_ERR(clk))
345 return dev_err_probe(&pdev->dev, PTR_ERR(clk), "Couldn't get the clock for RNG\n");
346
347 xgene_rng_func.priv = (unsigned long) ctx;
348
349 rc = devm_hwrng_register(&pdev->dev, &xgene_rng_func);
350 if (rc)
351 return dev_err_probe(&pdev->dev, rc, "RNG registering failed\n");
352
353 rc = device_init_wakeup(&pdev->dev, 1);
354 if (rc)
355 return dev_err_probe(&pdev->dev, rc, "RNG device_init_wakeup failed\n");
356
357 return 0;
358}
359
360static void xgene_rng_remove(struct platform_device *pdev)
361{
362 int rc;
363
364 rc = device_init_wakeup(&pdev->dev, 0);
365 if (rc)
366 dev_err(&pdev->dev, "RNG init wakeup failed error %d\n", rc);
367}
368
369static const struct of_device_id xgene_rng_of_match[] = {
370 { .compatible = "apm,xgene-rng" },
371 { }
372};
373
374MODULE_DEVICE_TABLE(of, xgene_rng_of_match);
375
376static struct platform_driver xgene_rng_driver = {
377 .probe = xgene_rng_probe,
378 .remove_new = xgene_rng_remove,
379 .driver = {
380 .name = "xgene-rng",
381 .of_match_table = xgene_rng_of_match,
382 .acpi_match_table = ACPI_PTR(xgene_rng_acpi_match),
383 },
384};
385
386module_platform_driver(xgene_rng_driver);
387MODULE_DESCRIPTION("APM X-Gene RNG driver");
388MODULE_LICENSE("GPL");