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
  32 #include <asm/io.h>
  33
  34 #define RNG_REG_STATUS_RDY                      (1 << 0)
  35
  36 #define RNG_REG_INTACK_RDY_MASK                 (1 << 0)
  37 #define RNG_REG_INTACK_SHUTDOWN_OFLO_MASK       (1 << 1)
  38 #define RNG_SHUTDOWN_OFLO_MASK                  (1 << 1)
  39
  40 #define RNG_CONTROL_STARTUP_CYCLES_SHIFT        16
  41 #define RNG_CONTROL_STARTUP_CYCLES_MASK         (0xffff << 16)
  42 #define RNG_CONTROL_ENABLE_TRNG_SHIFT           10
  43 #define RNG_CONTROL_ENABLE_TRNG_MASK            (1 << 10)
  44
  45 #define RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT       16
  46 #define RNG_CONFIG_MAX_REFIL_CYCLES_MASK        (0xffff << 16)
  47 #define RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT       0
  48 #define RNG_CONFIG_MIN_REFIL_CYCLES_MASK        (0xff << 0)
  49
  50 #define RNG_CONTROL_STARTUP_CYCLES              0xff
  51 #define RNG_CONFIG_MIN_REFIL_CYCLES             0x21
  52 #define RNG_CONFIG_MAX_REFIL_CYCLES             0x22
  53
  54 #define RNG_ALARMCNT_ALARM_TH_SHIFT             0x0
  55 #define RNG_ALARMCNT_ALARM_TH_MASK              (0xff << 0)
  56 #define RNG_ALARMCNT_SHUTDOWN_TH_SHIFT          16
  57 #define RNG_ALARMCNT_SHUTDOWN_TH_MASK           (0x1f << 16)
  58 #define RNG_ALARM_THRESHOLD                     0xff
  59 #define RNG_SHUTDOWN_THRESHOLD                  0x4
  60
  61 #define RNG_REG_FROENABLE_MASK                  0xffffff
  62 #define RNG_REG_FRODETUNE_MASK                  0xffffff
  63
  64 #define OMAP2_RNG_OUTPUT_SIZE                   0x4
  65 #define OMAP4_RNG_OUTPUT_SIZE                   0x8
  66
  67 enum {
  68         RNG_OUTPUT_L_REG = 0,
  69         RNG_OUTPUT_H_REG,
  70         RNG_STATUS_REG,
  71         RNG_INTMASK_REG,
  72         RNG_INTACK_REG,
  73         RNG_CONTROL_REG,
  74         RNG_CONFIG_REG,
  75         RNG_ALARMCNT_REG,
  76         RNG_FROENABLE_REG,
  77         RNG_FRODETUNE_REG,
  78         RNG_ALARMMASK_REG,
  79         RNG_ALARMSTOP_REG,
  80         RNG_REV_REG,
  81         RNG_SYSCONFIG_REG,
  82 };
  83
  84 static const u16 reg_map_omap2[] = {
  85         [RNG_OUTPUT_L_REG]      = 0x0,
  86         [RNG_STATUS_REG]        = 0x4,
  87         [RNG_CONFIG_REG]        = 0x28,
  88         [RNG_REV_REG]           = 0x3c,
  89         [RNG_SYSCONFIG_REG]     = 0x40,
  90 };
  91
  92 static const u16 reg_map_omap4[] = {
  93         [RNG_OUTPUT_L_REG]      = 0x0,
  94         [RNG_OUTPUT_H_REG]      = 0x4,
  95         [RNG_STATUS_REG]        = 0x8,
  96         [RNG_INTMASK_REG]       = 0xc,
  97         [RNG_INTACK_REG]        = 0x10,
  98         [RNG_CONTROL_REG]       = 0x14,
  99         [RNG_CONFIG_REG]        = 0x18,
 100         [RNG_ALARMCNT_REG]      = 0x1c,
 101         [RNG_FROENABLE_REG]     = 0x20,
 102         [RNG_FRODETUNE_REG]     = 0x24,
 103         [RNG_ALARMMASK_REG]     = 0x28,
 104         [RNG_ALARMSTOP_REG]     = 0x2c,
 105         [RNG_REV_REG]           = 0x1FE0,
 106         [RNG_SYSCONFIG_REG]     = 0x1FE4,
 107 };
 108
 109 struct omap_rng_dev;
 110 /**
 111  * struct omap_rng_pdata - RNG IP block-specific data
 112  * @regs: Pointer to the register offsets structure.
 113  * @data_size: No. of bytes in RNG output.
 114  * @data_present: Callback to determine if data is available.
 115  * @init: Callback for IP specific initialization sequence.
 116  * @cleanup: Callback for IP specific cleanup sequence.
 117  */
 118 struct omap_rng_pdata {
 119         u16     *regs;
 120         u32     data_size;
 121         u32     (*data_present)(struct omap_rng_dev *priv);
 122         int     (*init)(struct omap_rng_dev *priv);
 123         void    (*cleanup)(struct omap_rng_dev *priv);
 124 };
 125
 126 struct omap_rng_dev {
 127         void __iomem                    *base;
 128         struct device                   *dev;
 129         const struct omap_rng_pdata     *pdata;
 130 };
 131
 132 static inline u32 omap_rng_read(struct omap_rng_dev *priv, u16 reg)
 133 {
 134         return __raw_readl(priv->base + priv->pdata->regs[reg]);
 135 }
 136
 137 static inline void omap_rng_write(struct omap_rng_dev *priv, u16 reg,
 138                                       u32 val)
 139 {
 140         __raw_writel(val, priv->base + priv->pdata->regs[reg]);
 141 }
 142
 143 static int omap_rng_data_present(struct hwrng *rng, int wait)
 144 {
 145         struct omap_rng_dev *priv;
 146         int data, i;
 147
 148         priv = (struct omap_rng_dev *)rng->priv;
 149
 150         for (i = 0; i < 20; i++) {
 151                 data = priv->pdata->data_present(priv);
 152                 if (data || !wait)
 153                         break;
 154                 /* RNG produces data fast enough (2+ MBit/sec, even
 155                  * during "rngtest" loads, that these delays don't
 156                  * seem to trigger.  We *could* use the RNG IRQ, but
 157                  * that'd be higher overhead ... so why bother?
 158                  */
 159                 udelay(10);
 160         }
 161         return data;
 162 }
 163
 164 static int omap_rng_data_read(struct hwrng *rng, u32 *data)
 165 {
 166         struct omap_rng_dev *priv;
 167         u32 data_size, i;
 168
 169         priv = (struct omap_rng_dev *)rng->priv;
 170         data_size = priv->pdata->data_size;
 171
 172         for (i = 0; i < data_size / sizeof(u32); i++)
 173                 data[i] = omap_rng_read(priv, RNG_OUTPUT_L_REG + i);
 174
 175         if (priv->pdata->regs[RNG_INTACK_REG])
 176                 omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_RDY_MASK);
 177         return data_size;
 178 }
 179
 180 static int omap_rng_init(struct hwrng *rng)
 181 {
 182         struct omap_rng_dev *priv;
 183
 184         priv = (struct omap_rng_dev *)rng->priv;
 185         return priv->pdata->init(priv);
 186 }
 187
 188 static void omap_rng_cleanup(struct hwrng *rng)
 189 {
 190         struct omap_rng_dev *priv;
 191
 192         priv = (struct omap_rng_dev *)rng->priv;
 193         priv->pdata->cleanup(priv);
 194 }
 195
 196 static struct hwrng omap_rng_ops = {
 197         .name           = "omap",
 198         .data_present   = omap_rng_data_present,
 199         .data_read      = omap_rng_data_read,
 200         .init           = omap_rng_init,
 201         .cleanup        = omap_rng_cleanup,
 202 };
 203
 204 static inline u32 omap2_rng_data_present(struct omap_rng_dev *priv)
 205 {
 206         return omap_rng_read(priv, RNG_STATUS_REG) ? 0 : 1;
 207 }
 208
 209 static int omap2_rng_init(struct omap_rng_dev *priv)
 210 {
 211         omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x1);
 212         return 0;
 213 }
 214
 215 static void omap2_rng_cleanup(struct omap_rng_dev *priv)
 216 {
 217         omap_rng_write(priv, RNG_SYSCONFIG_REG, 0x0);
 218 }
 219
 220 static struct omap_rng_pdata omap2_rng_pdata = {
 221         .regs           = (u16 *)reg_map_omap2,
 222         .data_size      = OMAP2_RNG_OUTPUT_SIZE,
 223         .data_present   = omap2_rng_data_present,
 224         .init           = omap2_rng_init,
 225         .cleanup        = omap2_rng_cleanup,
 226 };
 227
 228 #if defined(CONFIG_OF)
 229 static inline u32 omap4_rng_data_present(struct omap_rng_dev *priv)
 230 {
 231         return omap_rng_read(priv, RNG_STATUS_REG) & RNG_REG_STATUS_RDY;
 232 }
 233
 234 static int omap4_rng_init(struct omap_rng_dev *priv)
 235 {
 236         u32 val;
 237
 238         /* Return if RNG is already running. */
 239         if (omap_rng_read(priv, RNG_CONTROL_REG) & RNG_CONTROL_ENABLE_TRNG_MASK)
 240                 return 0;
 241
 242         val = RNG_CONFIG_MIN_REFIL_CYCLES << RNG_CONFIG_MIN_REFIL_CYCLES_SHIFT;
 243         val |= RNG_CONFIG_MAX_REFIL_CYCLES << RNG_CONFIG_MAX_REFIL_CYCLES_SHIFT;
 244         omap_rng_write(priv, RNG_CONFIG_REG, val);
 245
 246         omap_rng_write(priv, RNG_FRODETUNE_REG, 0x0);
 247         omap_rng_write(priv, RNG_FROENABLE_REG, RNG_REG_FROENABLE_MASK);
 248         val = RNG_ALARM_THRESHOLD << RNG_ALARMCNT_ALARM_TH_SHIFT;
 249         val |= RNG_SHUTDOWN_THRESHOLD << RNG_ALARMCNT_SHUTDOWN_TH_SHIFT;
 250         omap_rng_write(priv, RNG_ALARMCNT_REG, val);
 251
 252         val = RNG_CONTROL_STARTUP_CYCLES << RNG_CONTROL_STARTUP_CYCLES_SHIFT;
 253         val |= RNG_CONTROL_ENABLE_TRNG_MASK;
 254         omap_rng_write(priv, RNG_CONTROL_REG, val);
 255
 256         return 0;
 257 }
 258
 259 static void omap4_rng_cleanup(struct omap_rng_dev *priv)
 260 {
 261         int val;
 262
 263         val = omap_rng_read(priv, RNG_CONTROL_REG);
 264         val &= ~RNG_CONTROL_ENABLE_TRNG_MASK;
 265         omap_rng_write(priv, RNG_CONTROL_REG, val);
 266 }
 267
 268 static irqreturn_t omap4_rng_irq(int irq, void *dev_id)
 269 {
 270         struct omap_rng_dev *priv = dev_id;
 271         u32 fro_detune, fro_enable;
 272
 273         /*
 274          * Interrupt raised by a fro shutdown threshold, do the following:
 275          * 1. Clear the alarm events.
 276          * 2. De tune the FROs which are shutdown.
 277          * 3. Re enable the shutdown FROs.
 278          */
 279         omap_rng_write(priv, RNG_ALARMMASK_REG, 0x0);
 280         omap_rng_write(priv, RNG_ALARMSTOP_REG, 0x0);
 281
 282         fro_enable = omap_rng_read(priv, RNG_FROENABLE_REG);
 283         fro_detune = ~fro_enable & RNG_REG_FRODETUNE_MASK;
 284         fro_detune = fro_detune | omap_rng_read(priv, RNG_FRODETUNE_REG);
 285         fro_enable = RNG_REG_FROENABLE_MASK;
 286
 287         omap_rng_write(priv, RNG_FRODETUNE_REG, fro_detune);
 288         omap_rng_write(priv, RNG_FROENABLE_REG, fro_enable);
 289
 290         omap_rng_write(priv, RNG_INTACK_REG, RNG_REG_INTACK_SHUTDOWN_OFLO_MASK);
 291
 292         return IRQ_HANDLED;
 293 }
 294
 295 static struct omap_rng_pdata omap4_rng_pdata = {
 296         .regs           = (u16 *)reg_map_omap4,
 297         .data_size      = OMAP4_RNG_OUTPUT_SIZE,
 298         .data_present   = omap4_rng_data_present,
 299         .init           = omap4_rng_init,
 300         .cleanup        = omap4_rng_cleanup,
 301 };
 302
 303 static const struct of_device_id omap_rng_of_match[] = {
 304                 {
 305                         .compatible     = "ti,omap2-rng",
 306                         .data           = &omap2_rng_pdata,
 307                 },
 308                 {
 309                         .compatible     = "ti,omap4-rng",
 310                         .data           = &omap4_rng_pdata,
 311                 },
 312                 {},
 313 };
 314 MODULE_DEVICE_TABLE(of, omap_rng_of_match);
 315
 316 static int of_get_omap_rng_device_details(struct omap_rng_dev *priv,
 317                                           struct platform_device *pdev)
 318 {
 319         const struct of_device_id *match;
 320         struct device *dev = &pdev->dev;
 321         int irq, err;
 322
 323         match = of_match_device(of_match_ptr(omap_rng_of_match), dev);
 324         if (!match) {
 325                 dev_err(dev, "no compatible OF match\n");
 326                 return -EINVAL;
 327         }
 328         priv->pdata = match->data;
 329
 330         if (of_device_is_compatible(dev->of_node, "ti,omap4-rng")) {
 331                 irq = platform_get_irq(pdev, 0);
 332                 if (irq < 0) {
 333                         dev_err(dev, "%s: error getting IRQ resource - %d\n",
 334                                 __func__, irq);
 335                         return irq;
 336                 }
 337
 338                 err = devm_request_irq(dev, irq, omap4_rng_irq,
 339                                        IRQF_TRIGGER_NONE, dev_name(dev), priv);
 340                 if (err) {
 341                         dev_err(dev, "unable to request irq %d, err = %d\n",
 342                                 irq, err);
 343                         return err;
 344                 }
 345                 omap_rng_write(priv, RNG_INTMASK_REG, RNG_SHUTDOWN_OFLO_MASK);
 346         }
 347         return 0;
 348 }
 349 #else
 350 static int of_get_omap_rng_device_details(struct omap_rng_dev *omap_rng,
 351                                           struct platform_device *pdev)
 352 {
 353         return -EINVAL;
 354 }
 355 #endif
 356
 357 static int get_omap_rng_device_details(struct omap_rng_dev *omap_rng)
 358 {
 359         /* Only OMAP2/3 can be non-DT */
 360         omap_rng->pdata = &omap2_rng_pdata;
 361         return 0;
 362 }
 363
 364 static int omap_rng_probe(struct platform_device *pdev)
 365 {
 366         struct omap_rng_dev *priv;
 367         struct resource *res;
 368         struct device *dev = &pdev->dev;
 369         int ret;
 370
 371         priv = devm_kzalloc(dev, sizeof(struct omap_rng_dev), GFP_KERNEL);
 372         if (!priv)
 373                 return -ENOMEM;
 374
 375         omap_rng_ops.priv = (unsigned long)priv;
 376         platform_set_drvdata(pdev, priv);
 377         priv->dev = dev;
 378
 379         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 380         priv->base = devm_ioremap_resource(dev, res);
 381         if (IS_ERR(priv->base)) {
 382                 ret = PTR_ERR(priv->base);
 383                 goto err_ioremap;
 384         }
 385
 386         pm_runtime_enable(&pdev->dev);
 387         ret = pm_runtime_get_sync(&pdev->dev);
 388         if (ret < 0) {
 389                 dev_err(&pdev->dev, "Failed to runtime_get device: %d\n", ret);
 390                 pm_runtime_put_noidle(&pdev->dev);
 391                 goto err_ioremap;
 392         }
 393
 394         ret = (dev->of_node) ? of_get_omap_rng_device_details(priv, pdev) :
 395                                 get_omap_rng_device_details(priv);
 396         if (ret)
 397                 goto err_ioremap;
 398
 399         ret = hwrng_register(&omap_rng_ops);
 400         if (ret)
 401                 goto err_register;
 402
 403         dev_info(&pdev->dev, "OMAP Random Number Generator ver. %02x\n",
 404                  omap_rng_read(priv, RNG_REV_REG));
 405
 406         return 0;
 407
 408 err_register:
 409         priv->base = NULL;
 410         pm_runtime_disable(&pdev->dev);
 411 err_ioremap:
 412         dev_err(dev, "initialization failed.\n");
 413         return ret;
 414 }
 415
 416 static int omap_rng_remove(struct platform_device *pdev)
 417 {
 418         struct omap_rng_dev *priv = platform_get_drvdata(pdev);
 419
 420         hwrng_unregister(&omap_rng_ops);
 421
 422         priv->pdata->cleanup(priv);
 423
 424         pm_runtime_put_sync(&pdev->dev);
 425         pm_runtime_disable(&pdev->dev);
 426
 427         return 0;
 428 }
 429
 430 static int __maybe_unused omap_rng_suspend(struct device *dev)
 431 {
 432         struct omap_rng_dev *priv = dev_get_drvdata(dev);
 433
 434         priv->pdata->cleanup(priv);
 435         pm_runtime_put_sync(dev);
 436
 437         return 0;
 438 }
 439
 440 static int __maybe_unused omap_rng_resume(struct device *dev)
 441 {
 442         struct omap_rng_dev *priv = dev_get_drvdata(dev);
 443         int ret;
 444
 445         ret = pm_runtime_get_sync(dev);
 446         if (ret < 0) {
 447                 dev_err(dev, "Failed to runtime_get device: %d\n", ret);
 448                 pm_runtime_put_noidle(dev);
 449                 return ret;
 450         }
 451
 452         priv->pdata->init(priv);
 453
 454         return 0;
 455 }
 456
 457 static SIMPLE_DEV_PM_OPS(omap_rng_pm, omap_rng_suspend, omap_rng_resume);
 458
 459 static struct platform_driver omap_rng_driver = {
 460         .driver = {
 461                 .name           = "omap_rng",
 462                 .pm             = &omap_rng_pm,
 463                 .of_match_table = of_match_ptr(omap_rng_of_match),
 464         },
 465         .probe          = omap_rng_probe,
 466         .remove         = omap_rng_remove,
 467 };
 468
 469 module_platform_driver(omap_rng_driver);
 470 MODULE_ALIAS("platform:omap_rng");
 471 MODULE_AUTHOR("Deepak Saxena (and others)");
 472 MODULE_LICENSE("GPL");