drivers/char/hw_random/omap-rng.c

   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/slab.h>
  26 #include <linux/pm_runtime.h>
  27 #include <linux/of.h>
  28 #include <linux/of_device.h>
  29 #include <linux/of_address.h>
  30 #include <linux/interrupt.h>
  31 #include <linux/clk.h>
  32
  33 #include <asm/io.h>
  34
  35 #define RNG_REG_STATUS_RDY                      (1 << 0)
  36
  37 #define RNG_REG_INTACK_RDY_MASK                 (1 << 0)
  38 #define RNG_REG_INTACK_SHUTDOWN_OFLO_MASK       (1 << 1)
  39 #define RNG_SHUTDOWN_OFLO_MASK                  (1 << 1)
  40
  41 #define RNG_CONTROL_STARTUP_CYCLES_SHIFT        16
  42 #define RNG_CONTROL_STARTUP_CYCLES_MASK         (0xffff << 16)
  43 #define RNG_CONTROL_ENABLE_TRNG_SHIFT           10
  44 #define RNG_CONTROL_ENABLE_TRNG_MASK            (1 << 10)
  45
  46 #define RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT       16
  47 #define RNG_CONFIG_MAX_REFIL_CYCLES_MASK        (0xffff << 16)
  48 #define RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT       0
  49 #define RNG_CONFIG_MIN_REFIL_CYCLES_MASK        (0xff << 0)
  50
  51 #define RNG_CONTROL_STARTUP_CYCLES              0xff
  52 #define RNG_CONFIG_MIN_REFIL_CYCLES             0x21
  53 #define RNG_CONFIG_MAX_REFIL_CYCLES             0x22
  54
  55 #define RNG_ALARMCNT_ALARM_TH_SHIFT             0x0
  56 #define RNG_ALARMCNT_ALARM_TH_MASK              (0xff << 0)
  57 #define RNG_ALARMCNT_SHUTDOWN_TH_SHIFT          16
  58 #define RNG_ALARMCNT_SHUTDOWN_TH_MASK           (0x1f << 16)
  59 #define RNG_ALARM_THRESHOLD                     0xff
  60 #define RNG_SHUTDOWN_THRESHOLD                  0x4
  61
  62 #define RNG_REG_FROENABLE_MASK                  0xffffff
  63 #define RNG_REG_FRODETUNE_MASK                  0xffffff
  64
  65 #define OMAP2_RNG_OUTPUT_SIZE                   0x4
  66 #define OMAP4_RNG_OUTPUT_SIZE                   0x8
  67 #define EIP76_RNG_OUTPUT_SIZE                   0x10
  68
  69 enum {
  70         RNG_OUTPUT_0_REG = 0,
  71         RNG_OUTPUT_1_REG,
  72         RNG_OUTPUT_2_REG,
  73         RNG_OUTPUT_3_REG,
  74         RNG_STATUS_REG,
  75         RNG_INTMASK_REG,
  76         RNG_INTACK_REG,
  77         RNG_CONTROL_REG,
  78         RNG_CONFIG_REG,
  79         RNG_ALARMCNT_REG,
  80         RNG_FROENABLE_REG,
  81         RNG_FRODETUNE_REG,
  82         RNG_ALARMMASK_REG,
  83         RNG_ALARMSTOP_REG,
  84         RNG_REV_REG,
  85         RNG_SYSCONFIG_REG,
  86 };
  87
  88 static const u16 reg_map_omap2[] = {
  89         [RNG_OUTPUT_0_REG]      = 0x0,
  90         [RNG_STATUS_REG]        = 0x4,
  91         [RNG_CONFIG_REG]        = 0x28,
  92         [RNG_REV_REG]           = 0x3c,
  93         [RNG_SYSCONFIG_REG]     = 0x40,
  94 };
  95
  96 static const u16 reg_map_omap4[] = {
  97         [RNG_OUTPUT_0_REG]      = 0x0,
  98         [RNG_OUTPUT_1_REG]      = 0x4,
  99         [RNG_STATUS_REG]        = 0x8,
 100         [RNG_INTMASK_REG]       = 0xc,
 101         [RNG_INTACK_REG]        = 0x10,
 102         [RNG_CONTROL_REG]       = 0x14,
 103         [RNG_CONFIG_REG]        = 0x18,
 104         [RNG_ALARMCNT_REG]      = 0x1c,
 105         [RNG_FROENABLE_REG]     = 0x20,
 106         [RNG_FRODETUNE_REG]     = 0x24,
 107         [RNG_ALARMMASK_REG]     = 0x28,
 108         [RNG_ALARMSTOP_REG]     = 0x2c,
 109         [RNG_REV_REG]           = 0x1FE0,
 110         [RNG_SYSCONFIG_REG]     = 0x1FE4,
 111 };
 112
 113 static const u16 reg_map_eip76[] = {
 114         [RNG_OUTPUT_0_REG]      = 0x0,
 115         [RNG_OUTPUT_1_REG]      = 0x4,
 116         [RNG_OUTPUT_2_REG]      = 0x8,
 117         [RNG_OUTPUT_3_REG]      = 0xc,
 118         [RNG_STATUS_REG]        = 0x10,
 119         [RNG_INTACK_REG]        = 0x10,
 120         [RNG_CONTROL_REG]       = 0x14,
 121         [RNG_CONFIG_REG]        = 0x18,
 122         [RNG_ALARMCNT_REG]      = 0x1c,
 123         [RNG_FROENABLE_REG]     = 0x20,
 124         [RNG_FRODETUNE_REG]     = 0x24,
 125         [RNG_ALARMMASK_REG]     = 0x28,
 126         [RNG_ALARMSTOP_REG]     = 0x2c,
 127         [RNG_REV_REG]           = 0x7c,
 128 };
 129
 130 struct omap_rng_dev;
 131 /**
 132  * struct omap_rng_pdata - RNG IP block-specific data
 133  * @regs: Pointer to the register offsets structure.
 134  * @data_size: No. of bytes in RNG output.
 135  * @data_present: Callback to determine if data is available.
 136  * @init: Callback for IP specific initialization sequence.
 137  * @cleanup: Callback for IP specific cleanup sequence.
 138  */
 139 struct omap_rng_pdata {
 140         u16     *regs;
 141         u32     data_size;
 142         u32     (*data_present)(struct omap_rng_dev *priv);
 143         int     (*init)(struct omap_rng_dev *priv);
 144         void    (*cleanup)(struct omap_rng_dev *priv);
 145 };
 146
 147 struct omap_rng_dev {
 148         void __iomem                    *base;
 149         struct device                   *dev;
 150         const struct omap_rng_pdata     *pdata;
 151         struct hwrng rng;
 152         struct clk                      *clk;
 153 };
 154
 155 static inline u32 omap_rng_read(struct omap_rng_dev *priv, u16 reg)
 156 {
 157         return __raw_readl(priv->base + priv->pdata->regs[reg]);
 158 }
 159
 160 static inline void omap_rng_write(struct omap_rng_dev *priv, u16 reg,
 161                                       u32 val)
 162 {
 163         __raw_writel(val, priv->base + priv->pdata->regs[reg]);
 164 }
 165
 166
 167 static int omap_rng_do_read(struct hwrng *rng, void *data, size_t max,
 168                             bool wait)
 169 {
 170         struct omap_rng_dev *priv;
 171         int i, present;
 172
 173         priv = (struct omap_rng_dev *)rng->priv;
 174
 175         if (max < priv->pdata->data_size)
 176                 return 0;
 177
 178         for (i = 0; i < 20; i++) {
 179                 present = priv->pdata->data_present(priv);
 180                 if (present || !wait)
 181                         break;
 182
 183                 udelay(10);
 184         }
 185         if (!present)
 186                 return 0;
 187
 188         memcpy_fromio(data, priv->base + priv->pdata->regs[RNG_OUTPUT_0_REG],
 189                       priv->pdata->data_size);
 190
 191         if (priv->pdata->regs[RNG_INTACK_REG])
 192                 omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_RDY_MASK);
 193
 194         return priv->pdata->data_size;
 195 }
 196
 197 static int omap_rng_init(struct hwrng *rng)
 198 {
 199         struct omap_rng_dev *priv;
 200
 201         priv = (struct omap_rng_dev *)rng->priv;
 202         return priv->pdata->init(priv);
 203 }
 204
 205 static void omap_rng_cleanup(struct hwrng *rng)
 206 {
 207         struct omap_rng_dev *priv;
 208
 209         priv = (struct omap_rng_dev *)rng->priv;
 210         priv->pdata->cleanup(priv);
 211 }
 212
 213
 214 static inline u32 omap2_rng_data_present(struct omap_rng_dev *priv)
 215 {
 216         return omap_rng_read(priv, RNG_STATUS_REG) ? 0 : 1;
 217 }
 218
 219 static int omap2_rng_init(struct omap_rng_dev *priv)
 220 {
 221         omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x1);
 222         return 0;
 223 }
 224
 225 static void omap2_rng_cleanup(struct omap_rng_dev *priv)
 226 {
 227         omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x0);
 228 }
 229
 230 static struct omap_rng_pdata omap2_rng_pdata = {
 231         .regs           = (u16 *)reg_map_omap2,
 232         .data_size      = OMAP2_RNG_OUTPUT_SIZE,
 233         .data_present   = omap2_rng_data_present,
 234         .init           = omap2_rng_init,
 235         .cleanup        = omap2_rng_cleanup,
 236 };
 237
 238 #if defined(CONFIG_OF)
 239 static inline u32 omap4_rng_data_present(struct omap_rng_dev *priv)
 240 {
 241         return omap_rng_read(priv, RNG_STATUS_REG) & RNG_REG_STATUS_RDY;
 242 }
 243
 244 static int eip76_rng_init(struct omap_rng_dev *priv)
 245 {
 246         u32 val;
 247
 248         /* Return if RNG is already running. */
 249         if (omap_rng_read(priv, RNG_CONTROL_REG) & RNG_CONTROL_ENABLE_TRNG_MASK)
 250                 return 0;
 251
 252         /*  Number of 512 bit blocks of raw Noise Source output data that must
 253          *  be processed by either the Conditioning Function or the
 254          *  SP 800-90 DRBG ‘BC_DF’ functionality to yield a ‘full entropy’
 255          *  output value.
 256          */
 257         val = 0x5 << RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT;
 258
 259         /* Number of FRO samples that are XOR-ed together into one bit to be
 260          * shifted into the main shift register
 261          */
 262         val |= RNG_CONFIG_MAX_REFIL_CYCLES << RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT;
 263         omap_rng_write(priv, RNG_CONFIG_REG, val);
 264
 265         /* Enable all available FROs */
 266         omap_rng_write(priv, RNG_FRODETUNE_REG, 0x0);
 267         omap_rng_write(priv, RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);
 268
 269         /* Enable TRNG */
 270         val = RNG_CONTROL_ENABLE_TRNG_MASK;
 271         omap_rng_write(priv, RNG_CONTROL_REG, val);
 272
 273         return 0;
 274 }
 275
 276 static int omap4_rng_init(struct omap_rng_dev *priv)
 277 {
 278         u32 val;
 279
 280         /* Return if RNG is already running. */
 281         if (omap_rng_read(priv, RNG_CONTROL_REG) & RNG_CONTROL_ENABLE_TRNG_MASK)
 282                 return 0;
 283
 284         val = RNG_CONFIG_MIN_REFIL_CYCLES << RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT;
 285         val |= RNG_CONFIG_MAX_REFIL_CYCLES << RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT;
 286         omap_rng_write(priv, RNG_CONFIG_REG, val);
 287
 288         omap_rng_write(priv, RNG_FRODETUNE_REG, 0x0);
 289         omap_rng_write(priv, RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);
 290         val = RNG_ALARM_THRESHOLD << RNG_ALARMCNT_ALARM_TH_SHIFT;
 291         val |= RNG_SHUTDOWN_THRESHOLD << RNG_ALARMCNT_SHUTDOWN_TH_SHIFT;
 292         omap_rng_write(priv, RNG_ALARMCNT_REG, val);
 293
 294         val = RNG_CONTROL_STARTUP_CYCLES << RNG_CONTROL_STARTUP_CYCLES_SHIFT;
 295         val |= RNG_CONTROL_ENABLE_TRNG_MASK;
 296         omap_rng_write(priv, RNG_CONTROL_REG, val);
 297
 298         return 0;
 299 }
 300
 301 static void omap4_rng_cleanup(struct omap_rng_dev *priv)
 302 {
 303         int val;
 304
 305         val = omap_rng_read(priv, RNG_CONTROL_REG);
 306         val &= ~RNG_CONTROL_ENABLE_TRNG_MASK;
 307         omap_rng_write(priv, RNG_CONTROL_REG, val);
 308 }
 309
 310 static irqreturn_t omap4_rng_irq(int irq, void *dev_id)
 311 {
 312         struct omap_rng_dev *priv = dev_id;
 313         u32 fro_detune, fro_enable;
 314
 315         /*
 316          * Interrupt raised by a fro shutdown threshold, do the following:
 317          * 1. Clear the alarm events.
 318          * 2. De tune the FROs which are shutdown.
 319          * 3. Re enable the shutdown FROs.
 320          */
 321         omap_rng_write(priv, RNG_ALARMMASK_REG, 0x0);
 322         omap_rng_write(priv, RNG_ALARMSTOP_REG, 0x0);
 323
 324         fro_enable = omap_rng_read(priv, RNG_FROENABLE_REG);
 325         fro_detune = ~fro_enable & RNG_REG_FRODETUNE_MASK;
 326         fro_detune = fro_detune | omap_rng_read(priv, RNG_FRODETUNE_REG);
 327         fro_enable = RNG_REG_FROENABLE_MASK;
 328
 329         omap_rng_write(priv, RNG_FRODETUNE_REG, fro_detune);
 330         omap_rng_write(priv, RNG_FROENABLE_REG, fro_enable);
 331
 332         omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_SHUTDOWN_OFLO_MASK);
 333
 334         return IRQ_HANDLED;
 335 }
 336
 337 static struct omap_rng_pdata omap4_rng_pdata = {
 338         .regs           = (u16 *)reg_map_omap4,
 339         .data_size      = OMAP4_RNG_OUTPUT_SIZE,
 340         .data_present   = omap4_rng_data_present,
 341         .init           = omap4_rng_init,
 342         .cleanup        = omap4_rng_cleanup,
 343 };
 344
 345 static struct omap_rng_pdata eip76_rng_pdata = {
 346         .regs           = (u16 *)reg_map_eip76,
 347         .data_size      = EIP76_RNG_OUTPUT_SIZE,
 348         .data_present   = omap4_rng_data_present,
 349         .init           = eip76_rng_init,
 350         .cleanup        = omap4_rng_cleanup,
 351 };
 352
 353 static const struct of_device_id omap_rng_of_match[] = {
 354                 {
 355                         .compatible     = "ti,omap2-rng",
 356                         .data           = &omap2_rng_pdata,
 357                 },
 358                 {
 359                         .compatible     = "ti,omap4-rng",
 360                         .data           = &omap4_rng_pdata,
 361                 },
 362                 {
 363                         .compatible     = "inside-secure,safexcel-eip76",
 364                         .data           = &eip76_rng_pdata,
 365                 },
 366                 {},
 367 };
 368 MODULE_DEVICE_TABLE(of, omap_rng_of_match);
 369
 370 static int of_get_omap_rng_device_details(struct omap_rng_dev *priv,
 371                                           struct platform_device *pdev)
 372 {
 373         const struct of_device_id *match;
 374         struct device *dev = &pdev->dev;
 375         int irq, err;
 376
 377         match = of_match_device(of_match_ptr(omap_rng_of_match), dev);
 378         if (!match) {
 379                 dev_err(dev, "no compatible OF match\n");
 380                 return -EINVAL;
 381         }
 382         priv->pdata = match->data;
 383
 384         if (of_device_is_compatible(dev->of_node, "ti,omap4-rng") ||
 385             of_device_is_compatible(dev->of_node, "inside-secure,safexcel-eip76")) {
 386                 irq = platform_get_irq(pdev, 0);
 387                 if (irq < 0) {
 388                         dev_err(dev, "%s: error getting IRQ resource - %d\n",
 389                                 __func__, irq);
 390                         return irq;
 391                 }
 392
 393                 err = devm_request_irq(dev, irq, omap4_rng_irq,
 394                                        IRQF_TRIGGER_NONE, dev_name(dev), priv);
 395                 if (err) {
 396                         dev_err(dev, "unable to request irq %d, err = %d\n",
 397                                 irq, err);
 398                         return err;
 399                 }
 400
 401                 priv->clk = devm_clk_get(&pdev->dev, NULL);
 402                 if (IS_ERR(priv->clk) && PTR_ERR(priv->clk) == -EPROBE_DEFER)
 403                         return -EPROBE_DEFER;
 404                 if (!IS_ERR(priv->clk)) {
 405                         err = clk_prepare_enable(priv->clk);
 406                         if (err)
 407                                 dev_err(&pdev->dev, "unable to enable the clk, "
 408                                                     "err = %d\n", err);
 409                 }
 410
 411                 /*
 412                  * On OMAP4, enabling the shutdown_oflo interrupt is
 413                  * done in the interrupt mask register. There is no
 414                  * such register on EIP76, and it's enabled by the
 415                  * same bit in the control register
 416                  */
 417                 if (priv->pdata->regs[RNG_INTMASK_REG])
 418                         omap_rng_write(priv, RNG_INTMASK_REG,
 419                                        RNG_SHUTDOWN_OFLO_MASK);
 420                 else
 421                         omap_rng_write(priv, RNG_CONTROL_REG,
 422                                        RNG_SHUTDOWN_OFLO_MASK);
 423         }
 424         return 0;
 425 }
 426 #else
 427 static int of_get_omap_rng_device_details(struct omap_rng_dev *omap_rng,
 428                                           struct platform_device *pdev)
 429 {
 430         return -EINVAL;
 431 }
 432 #endif
 433
 434 static int get_omap_rng_device_details(struct omap_rng_dev *omap_rng)
 435 {
 436         /* Only OMAP2/3 can be non-DT */
 437         omap_rng->pdata = &omap2_rng_pdata;
 438         return 0;
 439 }
 440
 441 static int omap_rng_probe(struct platform_device *pdev)
 442 {
 443         struct omap_rng_dev *priv;
 444         struct resource *res;
 445         struct device *dev = &pdev->dev;
 446         int ret;
 447
 448         priv = devm_kzalloc(dev, sizeof(struct omap_rng_dev), GFP_KERNEL);
 449         if (!priv)
 450                 return -ENOMEM;
 451
 452         priv->rng.read = omap_rng_do_read;
 453         priv->rng.init = omap_rng_init;
 454         priv->rng.cleanup = omap_rng_cleanup;
 455
 456         priv->rng.priv = (unsigned long)priv;
 457         platform_set_drvdata(pdev, priv);
 458         priv->dev = dev;
 459
 460         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 461         priv->base = devm_ioremap_resource(dev, res);
 462         if (IS_ERR(priv->base)) {
 463                 ret = PTR_ERR(priv->base);
 464                 goto err_ioremap;
 465         }
 466
 467         priv->rng.name = devm_kstrdup(dev, dev_name(dev), GFP_KERNEL);
 468         if (!priv->rng.name) {
 469                 ret = -ENOMEM;
 470                 goto err_ioremap;
 471         }
 472
 473         pm_runtime_enable(&pdev->dev);
 474         ret = pm_runtime_get_sync(&pdev->dev);
 475         if (ret < 0) {
 476                 dev_err(&pdev->dev, "Failed to runtime_get device: %d\n", ret);
 477                 pm_runtime_put_noidle(&pdev->dev);
 478                 goto err_ioremap;
 479         }
 480
 481         ret = (dev->of_node) ? of_get_omap_rng_device_details(priv, pdev) :
 482                                 get_omap_rng_device_details(priv);
 483         if (ret)
 484                 goto err_register;
 485
 486         ret = hwrng_register(&priv->rng);
 487         if (ret)
 488                 goto err_register;
 489
 490         dev_info(&pdev->dev, "Random Number Generator ver. %02x\n",
 491                  omap_rng_read(priv, RNG_REV_REG));
 492
 493         return 0;
 494
 495 err_register:
 496         priv->base = NULL;
 497         pm_runtime_put_sync(&pdev->dev);
 498         pm_runtime_disable(&pdev->dev);
 499
 500         if (!IS_ERR(priv->clk))
 501                 clk_disable_unprepare(priv->clk);
 502 err_ioremap:
 503         dev_err(dev, "initialization failed.\n");
 504         return ret;
 505 }
 506
 507 static int omap_rng_remove(struct platform_device *pdev)
 508 {
 509         struct omap_rng_dev *priv = platform_get_drvdata(pdev);
 510
 511         hwrng_unregister(&priv->rng);
 512
 513         priv->pdata->cleanup(priv);
 514
 515         pm_runtime_put_sync(&pdev->dev);
 516         pm_runtime_disable(&pdev->dev);
 517
 518         if (!IS_ERR(priv->clk))
 519                 clk_disable_unprepare(priv->clk);
 520
 521         return 0;
 522 }
 523
 524 static int __maybe_unused omap_rng_suspend(struct device *dev)
 525 {
 526         struct omap_rng_dev *priv = dev_get_drvdata(dev);
 527
 528         priv->pdata->cleanup(priv);
 529         pm_runtime_put_sync(dev);
 530
 531         return 0;
 532 }
 533
 534 static int __maybe_unused omap_rng_resume(struct device *dev)
 535 {
 536         struct omap_rng_dev *priv = dev_get_drvdata(dev);
 537         int ret;
 538
 539         ret = pm_runtime_get_sync(dev);
 540         if (ret < 0) {
 541                 dev_err(dev, "Failed to runtime_get device: %d\n", ret);
 542                 pm_runtime_put_noidle(dev);
 543                 return ret;
 544         }
 545
 546         priv->pdata->init(priv);
 547
 548         return 0;
 549 }
 550
 551 static SIMPLE_DEV_PM_OPS(omap_rng_pm, omap_rng_suspend, omap_rng_resume);
 552
 553 static struct platform_driver omap_rng_driver = {
 554         .driver = {
 555                 .name           = "omap_rng",
 556                 .pm             = &omap_rng_pm,
 557                 .of_match_table = of_match_ptr(omap_rng_of_match),
 558         },
 559         .probe          = omap_rng_probe,
 560         .remove         = omap_rng_remove,
 561 };
 562
 563 module_platform_driver(omap_rng_driver);
 564 MODULE_ALIAS("platform:omap_rng");
 565 MODULE_AUTHOR("Deepak Saxena (and others)");
 566 MODULE_LICENSE("GPL");