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 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 }; 88 89 static 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 } 99 100 static 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 */ 109 static 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 } 116 117 static 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 } 199 200 static 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 } 209 210 static 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 } 224 225 static 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 } 238 239 static 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 } 273 274 static 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 299 static const struct acpi_device_id xgene_rng_acpi_match[] = { 300 { "APMC0D18", }, 301 { } 302 }; 303 MODULE_DEVICE_TABLE(acpi, xgene_rng_acpi_match); 304 #endif 305 306 static 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 }; 312 313 static 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 } 359 360 static 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 } 368 369 static const struct of_device_id xgene_rng_of_match[] = { 370 { .compatible = "apm,xgene-rng" }, 371 { } 372 }; 373 374 MODULE_DEVICE_TABLE(of, xgene_rng_of_match); 375 376 static 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 }; 385 386 module_platform_driver(xgene_rng_driver); 387 MODULE_DESCRIPTION("APM X-Gene RNG driver"); 388 MODULE_LICENSE("GPL"); 389