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/module.h> 18 #include <linux/of_platform.h> 19 #include <linux/of_irq.h> 20 #include <linux/of_address.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 78 struct 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 struct clk *clk; 88 }; 89 90 static void xgene_rng_expired_timer(struct timer_list *t) 91 { 92 struct xgene_rng_dev *ctx = from_timer(ctx, t, failure_timer); 93 94 /* Clear failure counter as timer expired */ 95 disable_irq(ctx->irq); 96 ctx->failure_cnt = 0; 97 del_timer(&ctx->failure_timer); 98 enable_irq(ctx->irq); 99 } 100 101 static void xgene_rng_start_timer(struct xgene_rng_dev *ctx) 102 { 103 ctx->failure_timer.expires = jiffies + 120 * HZ; 104 add_timer(&ctx->failure_timer); 105 } 106 107 /* 108 * Initialize or reinit free running oscillators (FROs) 109 */ 110 static void xgene_rng_init_fro(struct xgene_rng_dev *ctx, u32 fro_val) 111 { 112 writel(fro_val, ctx->csr_base + RNG_FRODETUNE); 113 writel(0x00000000, ctx->csr_base + RNG_ALARMMASK); 114 writel(0x00000000, ctx->csr_base + RNG_ALARMSTOP); 115 writel(0xFFFFFFFF, ctx->csr_base + RNG_FROENABLE); 116 } 117 118 static void xgene_rng_chk_overflow(struct xgene_rng_dev *ctx) 119 { 120 u32 val; 121 122 val = readl(ctx->csr_base + RNG_INTR_STS_ACK); 123 if (val & MONOBIT_FAIL_MASK) 124 /* 125 * LFSR detected an out-of-bounds number of 1s after 126 * checking 20,000 bits (test T1 as specified in the 127 * AIS-31 standard) 128 */ 129 dev_err(ctx->dev, "test monobit failure error 0x%08X\n", val); 130 if (val & POKER_FAIL_MASK) 131 /* 132 * LFSR detected an out-of-bounds value in at least one 133 * of the 16 poker_count_X counters or an out of bounds sum 134 * of squares value after checking 20,000 bits (test T2 as 135 * specified in the AIS-31 standard) 136 */ 137 dev_err(ctx->dev, "test poker failure error 0x%08X\n", val); 138 if (val & LONG_RUN_FAIL_MASK) 139 /* 140 * LFSR detected a sequence of 34 identical bits 141 * (test T4 as specified in the AIS-31 standard) 142 */ 143 dev_err(ctx->dev, "test long run failure error 0x%08X\n", val); 144 if (val & RUN_FAIL_MASK) 145 /* 146 * LFSR detected an outof-bounds value for at least one 147 * of the running counters after checking 20,000 bits 148 * (test T3 as specified in the AIS-31 standard) 149 */ 150 dev_err(ctx->dev, "test run failure error 0x%08X\n", val); 151 if (val & NOISE_FAIL_MASK) 152 /* LFSR detected a sequence of 48 identical bits */ 153 dev_err(ctx->dev, "noise failure error 0x%08X\n", val); 154 if (val & STUCK_OUT_MASK) 155 /* 156 * Detected output data registers generated same value twice 157 * in a row 158 */ 159 dev_err(ctx->dev, "stuck out failure error 0x%08X\n", val); 160 161 if (val & SHUTDOWN_OFLO_MASK) { 162 u32 frostopped; 163 164 /* FROs shut down after a second error event. Try recover. */ 165 if (++ctx->failure_cnt == 1) { 166 /* 1st time, just recover */ 167 ctx->failure_ts = jiffies; 168 frostopped = readl(ctx->csr_base + RNG_ALARMSTOP); 169 xgene_rng_init_fro(ctx, frostopped); 170 171 /* 172 * We must start a timer to clear out this error 173 * in case the system timer wrap around 174 */ 175 xgene_rng_start_timer(ctx); 176 } else { 177 /* 2nd time failure in lesser than 1 minute? */ 178 if (time_after(ctx->failure_ts + 60 * HZ, jiffies)) { 179 dev_err(ctx->dev, 180 "FRO shutdown failure error 0x%08X\n", 181 val); 182 } else { 183 /* 2nd time failure after 1 minutes, recover */ 184 ctx->failure_ts = jiffies; 185 ctx->failure_cnt = 1; 186 /* 187 * We must start a timer to clear out this 188 * error in case the system timer wrap 189 * around 190 */ 191 xgene_rng_start_timer(ctx); 192 } 193 frostopped = readl(ctx->csr_base + RNG_ALARMSTOP); 194 xgene_rng_init_fro(ctx, frostopped); 195 } 196 } 197 /* Clear them all */ 198 writel(val, ctx->csr_base + RNG_INTR_STS_ACK); 199 } 200 201 static irqreturn_t xgene_rng_irq_handler(int irq, void *id) 202 { 203 struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) id; 204 205 /* RNG Alarm Counter overflow */ 206 xgene_rng_chk_overflow(ctx); 207 208 return IRQ_HANDLED; 209 } 210 211 static int xgene_rng_data_present(struct hwrng *rng, int wait) 212 { 213 struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv; 214 u32 i, val = 0; 215 216 for (i = 0; i < XGENE_RNG_RETRY_COUNT; i++) { 217 val = readl(ctx->csr_base + RNG_INTR_STS_ACK); 218 if ((val & READY_MASK) || !wait) 219 break; 220 udelay(XGENE_RNG_RETRY_INTERVAL); 221 } 222 223 return (val & READY_MASK); 224 } 225 226 static int xgene_rng_data_read(struct hwrng *rng, u32 *data) 227 { 228 struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv; 229 int i; 230 231 for (i = 0; i < ctx->datum_size; i++) 232 data[i] = readl(ctx->csr_base + RNG_INOUT_0 + i * 4); 233 234 /* Clear ready bit to start next transaction */ 235 writel(READY_MASK, ctx->csr_base + RNG_INTR_STS_ACK); 236 237 return ctx->datum_size << 2; 238 } 239 240 static void xgene_rng_init_internal(struct xgene_rng_dev *ctx) 241 { 242 u32 val; 243 244 writel(0x00000000, ctx->csr_base + RNG_CONTROL); 245 246 val = MAX_REFILL_CYCLES_SET(0, 10); 247 val = MIN_REFILL_CYCLES_SET(val, 10); 248 writel(val, ctx->csr_base + RNG_CONFIG); 249 250 val = ALARM_THRESHOLD_SET(0, 0xFF); 251 writel(val, ctx->csr_base + RNG_ALARMCNT); 252 253 xgene_rng_init_fro(ctx, 0); 254 255 writel(MONOBIT_FAIL_MASK | 256 POKER_FAIL_MASK | 257 LONG_RUN_FAIL_MASK | 258 RUN_FAIL_MASK | 259 NOISE_FAIL_MASK | 260 STUCK_OUT_MASK | 261 SHUTDOWN_OFLO_MASK | 262 READY_MASK, ctx->csr_base + RNG_INTR_STS_ACK); 263 264 val = ENABLE_RNG_SET(0, 1); 265 val = MONOBIT_FAIL_MASK_SET(val, 1); 266 val = POKER_FAIL_MASK_SET(val, 1); 267 val = LONG_RUN_FAIL_MASK_SET(val, 1); 268 val = RUN_FAIL_MASK_SET(val, 1); 269 val = NOISE_FAIL_MASK_SET(val, 1); 270 val = STUCK_OUT_MASK_SET(val, 1); 271 val = SHUTDOWN_OFLO_MASK_SET(val, 1); 272 writel(val, ctx->csr_base + RNG_CONTROL); 273 } 274 275 static int xgene_rng_init(struct hwrng *rng) 276 { 277 struct xgene_rng_dev *ctx = (struct xgene_rng_dev *) rng->priv; 278 279 ctx->failure_cnt = 0; 280 timer_setup(&ctx->failure_timer, xgene_rng_expired_timer, 0); 281 282 ctx->revision = readl(ctx->csr_base + RNG_EIP_REV); 283 284 dev_dbg(ctx->dev, "Rev %d.%d.%d\n", 285 MAJOR_HW_REV_RD(ctx->revision), 286 MINOR_HW_REV_RD(ctx->revision), 287 HW_PATCH_LEVEL_RD(ctx->revision)); 288 289 dev_dbg(ctx->dev, "Options 0x%08X", 290 readl(ctx->csr_base + RNG_OPTIONS)); 291 292 xgene_rng_init_internal(ctx); 293 294 ctx->datum_size = RNG_MAX_DATUM; 295 296 return 0; 297 } 298 299 #ifdef CONFIG_ACPI 300 static const struct acpi_device_id xgene_rng_acpi_match[] = { 301 { "APMC0D18", }, 302 { } 303 }; 304 MODULE_DEVICE_TABLE(acpi, xgene_rng_acpi_match); 305 #endif 306 307 static struct hwrng xgene_rng_func = { 308 .name = "xgene-rng", 309 .init = xgene_rng_init, 310 .data_present = xgene_rng_data_present, 311 .data_read = xgene_rng_data_read, 312 }; 313 314 static int xgene_rng_probe(struct platform_device *pdev) 315 { 316 struct resource *res; 317 struct xgene_rng_dev *ctx; 318 int rc = 0; 319 320 ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL); 321 if (!ctx) 322 return -ENOMEM; 323 324 ctx->dev = &pdev->dev; 325 platform_set_drvdata(pdev, ctx); 326 327 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 328 ctx->csr_base = devm_ioremap_resource(&pdev->dev, res); 329 if (IS_ERR(ctx->csr_base)) 330 return PTR_ERR(ctx->csr_base); 331 332 rc = platform_get_irq(pdev, 0); 333 if (rc < 0) { 334 dev_err(&pdev->dev, "No IRQ resource\n"); 335 return rc; 336 } 337 ctx->irq = rc; 338 339 dev_dbg(&pdev->dev, "APM X-Gene RNG BASE %p ALARM IRQ %d", 340 ctx->csr_base, ctx->irq); 341 342 rc = devm_request_irq(&pdev->dev, ctx->irq, xgene_rng_irq_handler, 0, 343 dev_name(&pdev->dev), ctx); 344 if (rc) { 345 dev_err(&pdev->dev, "Could not request RNG alarm IRQ\n"); 346 return rc; 347 } 348 349 /* Enable IP clock */ 350 ctx->clk = devm_clk_get(&pdev->dev, NULL); 351 if (IS_ERR(ctx->clk)) { 352 dev_warn(&pdev->dev, "Couldn't get the clock for RNG\n"); 353 } else { 354 rc = clk_prepare_enable(ctx->clk); 355 if (rc) { 356 dev_warn(&pdev->dev, 357 "clock prepare enable failed for RNG"); 358 return rc; 359 } 360 } 361 362 xgene_rng_func.priv = (unsigned long) ctx; 363 364 rc = devm_hwrng_register(&pdev->dev, &xgene_rng_func); 365 if (rc) { 366 dev_err(&pdev->dev, "RNG registering failed error %d\n", rc); 367 if (!IS_ERR(ctx->clk)) 368 clk_disable_unprepare(ctx->clk); 369 return rc; 370 } 371 372 rc = device_init_wakeup(&pdev->dev, 1); 373 if (rc) { 374 dev_err(&pdev->dev, "RNG device_init_wakeup failed error %d\n", 375 rc); 376 if (!IS_ERR(ctx->clk)) 377 clk_disable_unprepare(ctx->clk); 378 return rc; 379 } 380 381 return 0; 382 } 383 384 static int xgene_rng_remove(struct platform_device *pdev) 385 { 386 struct xgene_rng_dev *ctx = platform_get_drvdata(pdev); 387 int rc; 388 389 rc = device_init_wakeup(&pdev->dev, 0); 390 if (rc) 391 dev_err(&pdev->dev, "RNG init wakeup failed error %d\n", rc); 392 if (!IS_ERR(ctx->clk)) 393 clk_disable_unprepare(ctx->clk); 394 395 return rc; 396 } 397 398 static const struct of_device_id xgene_rng_of_match[] = { 399 { .compatible = "apm,xgene-rng" }, 400 { } 401 }; 402 403 MODULE_DEVICE_TABLE(of, xgene_rng_of_match); 404 405 static struct platform_driver xgene_rng_driver = { 406 .probe = xgene_rng_probe, 407 .remove = xgene_rng_remove, 408 .driver = { 409 .name = "xgene-rng", 410 .of_match_table = xgene_rng_of_match, 411 .acpi_match_table = ACPI_PTR(xgene_rng_acpi_match), 412 }, 413 }; 414 415 module_platform_driver(xgene_rng_driver); 416 MODULE_DESCRIPTION("APM X-Gene RNG driver"); 417 MODULE_LICENSE("GPL"); 418