drivers/crypto/caam/caamrng.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * caam - Freescale FSL CAAM support for hw_random
   4  *
   5  * Copyright 2011 Freescale Semiconductor, Inc.
   6  * Copyright 2018 NXP
   7  *
   8  * Based on caamalg.c crypto API driver.
   9  *
  10  * relationship between job descriptors to shared descriptors:
  11  *
  12  * ---------------                     --------------
  13  * | JobDesc #0  |-------------------->| ShareDesc  |
  14  * | *(buffer 0) |      |------------->| (generate) |
  15  * ---------------      |              | (move)     |
  16  *                      |              | (store)    |
  17  * ---------------      |              --------------
  18  * | JobDesc #1  |------|
  19  * | *(buffer 1) |
  20  * ---------------
  21  *
  22  * A job desc looks like this:
  23  *
  24  * ---------------------
  25  * | Header            |
  26  * | ShareDesc Pointer |
  27  * | SEQ_OUT_PTR       |
  28  * | (output buffer)   |
  29  * ---------------------
  30  *
  31  * The SharedDesc never changes, and each job descriptor points to one of two
  32  * buffers for each device, from which the data will be copied into the
  33  * requested destination
  34  */
  35
  36 #include <linux/hw_random.h>
  37 #include <linux/completion.h>
  38 #include <linux/atomic.h>
  39
  40 #include "compat.h"
  41
  42 #include "regs.h"
  43 #include "intern.h"
  44 #include "desc_constr.h"
  45 #include "jr.h"
  46 #include "error.h"
  47
  48 /*
  49  * Maximum buffer size: maximum number of random, cache-aligned bytes that
  50  * will be generated and moved to seq out ptr (extlen not allowed)
  51  */
  52 #define RN_BUF_SIZE                     (0xffff / L1_CACHE_BYTES * \
  53                                          L1_CACHE_BYTES)
  54
  55 /* length of descriptors */
  56 #define DESC_JOB_O_LEN                  (CAAM_CMD_SZ * 2 + CAAM_PTR_SZ * 2)
  57 #define DESC_RNG_LEN                    (3 * CAAM_CMD_SZ)
  58
  59 /* Buffer, its dma address and lock */
  60 struct buf_data {
  61         u8 buf[RN_BUF_SIZE] ____cacheline_aligned;
  62         dma_addr_t addr;
  63         struct completion filled;
  64         u32 hw_desc[DESC_JOB_O_LEN];
  65 #define BUF_NOT_EMPTY 0
  66 #define BUF_EMPTY 1
  67 #define BUF_PENDING 2  /* Empty, but with job pending --don't submit another */
  68         atomic_t empty;
  69 };
  70
  71 /* rng per-device context */
  72 struct caam_rng_ctx {
  73         struct device *jrdev;
  74         dma_addr_t sh_desc_dma;
  75         u32 sh_desc[DESC_RNG_LEN];
  76         unsigned int cur_buf_idx;
  77         int current_buf;
  78         struct buf_data bufs[2];
  79 };
  80
  81 static struct caam_rng_ctx *rng_ctx;
  82
  83 static inline void rng_unmap_buf(struct device *jrdev, struct buf_data *bd)
  84 {
  85         if (bd->addr)
  86                 dma_unmap_single(jrdev, bd->addr, RN_BUF_SIZE,
  87                                  DMA_FROM_DEVICE);
  88 }
  89
  90 static inline void rng_unmap_ctx(struct caam_rng_ctx *ctx)
  91 {
  92         struct device *jrdev = ctx->jrdev;
  93
  94         if (ctx->sh_desc_dma)
  95                 dma_unmap_single(jrdev, ctx->sh_desc_dma,
  96                                  desc_bytes(ctx->sh_desc), DMA_TO_DEVICE);
  97         rng_unmap_buf(jrdev, &ctx->bufs[0]);
  98         rng_unmap_buf(jrdev, &ctx->bufs[1]);
  99 }
 100
 101 static void rng_done(struct device *jrdev, u32 *desc, u32 err, void *context)
 102 {
 103         struct buf_data *bd;
 104
 105         bd = container_of(desc, struct buf_data, hw_desc[0]);
 106
 107         if (err)
 108                 caam_jr_strstatus(jrdev, err);
 109
 110         atomic_set(&bd->empty, BUF_NOT_EMPTY);
 111         complete(&bd->filled);
 112
 113         /* Buffer refilled, invalidate cache */
 114         dma_sync_single_for_cpu(jrdev, bd->addr, RN_BUF_SIZE, DMA_FROM_DEVICE);
 115
 116 #ifdef DEBUG
 117         print_hex_dump(KERN_ERR, "rng refreshed buf@: ",
 118                        DUMP_PREFIX_ADDRESS, 16, 4, bd->buf, RN_BUF_SIZE, 1);
 119 #endif
 120 }
 121
 122 static inline int submit_job(struct caam_rng_ctx *ctx, int to_current)
 123 {
 124         struct buf_data *bd = &ctx->bufs[!(to_current ^ ctx->current_buf)];
 125         struct device *jrdev = ctx->jrdev;
 126         u32 *desc = bd->hw_desc;
 127         int err;
 128
 129         dev_dbg(jrdev, "submitting job %d\n", !(to_current ^ ctx->current_buf));
 130         init_completion(&bd->filled);
 131         err = caam_jr_enqueue(jrdev, desc, rng_done, ctx);
 132         if (err)
 133                 complete(&bd->filled); /* don't wait on failed job*/
 134         else
 135                 atomic_inc(&bd->empty); /* note if pending */
 136
 137         return err;
 138 }
 139
 140 static int caam_read(struct hwrng *rng, void *data, size_t max, bool wait)
 141 {
 142         struct caam_rng_ctx *ctx = rng_ctx;
 143         struct buf_data *bd = &ctx->bufs[ctx->current_buf];
 144         int next_buf_idx, copied_idx;
 145         int err;
 146
 147         if (atomic_read(&bd->empty)) {
 148                 /* try to submit job if there wasn't one */
 149                 if (atomic_read(&bd->empty) == BUF_EMPTY) {
 150                         err = submit_job(ctx, 1);
 151                         /* if can't submit job, can't even wait */
 152                         if (err)
 153                                 return 0;
 154                 }
 155                 /* no immediate data, so exit if not waiting */
 156                 if (!wait)
 157                         return 0;
 158
 159                 /* waiting for pending job */
 160                 if (atomic_read(&bd->empty))
 161                         wait_for_completion(&bd->filled);
 162         }
 163
 164         next_buf_idx = ctx->cur_buf_idx + max;
 165         dev_dbg(ctx->jrdev, "%s: start reading at buffer %d, idx %d\n",
 166                  __func__, ctx->current_buf, ctx->cur_buf_idx);
 167
 168         /* if enough data in current buffer */
 169         if (next_buf_idx < RN_BUF_SIZE) {
 170                 memcpy(data, bd->buf + ctx->cur_buf_idx, max);
 171                 ctx->cur_buf_idx = next_buf_idx;
 172                 return max;
 173         }
 174
 175         /* else, copy what's left... */
 176         copied_idx = RN_BUF_SIZE - ctx->cur_buf_idx;
 177         memcpy(data, bd->buf + ctx->cur_buf_idx, copied_idx);
 178         ctx->cur_buf_idx = 0;
 179         atomic_set(&bd->empty, BUF_EMPTY);
 180
 181         /* ...refill... */
 182         submit_job(ctx, 1);
 183
 184         /* and use next buffer */
 185         ctx->current_buf = !ctx->current_buf;
 186         dev_dbg(ctx->jrdev, "switched to buffer %d\n", ctx->current_buf);
 187
 188         /* since there already is some data read, don't wait */
 189         return copied_idx + caam_read(rng, data + copied_idx,
 190                                       max - copied_idx, false);
 191 }
 192
 193 static inline int rng_create_sh_desc(struct caam_rng_ctx *ctx)
 194 {
 195         struct device *jrdev = ctx->jrdev;
 196         u32 *desc = ctx->sh_desc;
 197
 198         init_sh_desc(desc, HDR_SHARE_SERIAL);
 199
 200         /* Generate random bytes */
 201         append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG);
 202
 203         /* Store bytes */
 204         append_seq_fifo_store(desc, RN_BUF_SIZE, FIFOST_TYPE_RNGSTORE);
 205
 206         ctx->sh_desc_dma = dma_map_single(jrdev, desc, desc_bytes(desc),
 207                                           DMA_TO_DEVICE);
 208         if (dma_mapping_error(jrdev, ctx->sh_desc_dma)) {
 209                 dev_err(jrdev, "unable to map shared descriptor\n");
 210                 return -ENOMEM;
 211         }
 212 #ifdef DEBUG
 213         print_hex_dump(KERN_ERR, "rng shdesc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
 214                        desc, desc_bytes(desc), 1);
 215 #endif
 216         return 0;
 217 }
 218
 219 static inline int rng_create_job_desc(struct caam_rng_ctx *ctx, int buf_id)
 220 {
 221         struct device *jrdev = ctx->jrdev;
 222         struct buf_data *bd = &ctx->bufs[buf_id];
 223         u32 *desc = bd->hw_desc;
 224         int sh_len = desc_len(ctx->sh_desc);
 225
 226         init_job_desc_shared(desc, ctx->sh_desc_dma, sh_len, HDR_SHARE_DEFER |
 227                              HDR_REVERSE);
 228
 229         bd->addr = dma_map_single(jrdev, bd->buf, RN_BUF_SIZE, DMA_FROM_DEVICE);
 230         if (dma_mapping_error(jrdev, bd->addr)) {
 231                 dev_err(jrdev, "unable to map dst\n");
 232                 return -ENOMEM;
 233         }
 234
 235         append_seq_out_ptr_intlen(desc, bd->addr, RN_BUF_SIZE, 0);
 236 #ifdef DEBUG
 237         print_hex_dump(KERN_ERR, "rng job desc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
 238                        desc, desc_bytes(desc), 1);
 239 #endif
 240         return 0;
 241 }
 242
 243 static void caam_cleanup(struct hwrng *rng)
 244 {
 245         int i;
 246         struct buf_data *bd;
 247
 248         for (i = 0; i < 2; i++) {
 249                 bd = &rng_ctx->bufs[i];
 250                 if (atomic_read(&bd->empty) == BUF_PENDING)
 251                         wait_for_completion(&bd->filled);
 252         }
 253
 254         rng_unmap_ctx(rng_ctx);
 255 }
 256
 257 static int caam_init_buf(struct caam_rng_ctx *ctx, int buf_id)
 258 {
 259         struct buf_data *bd = &ctx->bufs[buf_id];
 260         int err;
 261
 262         err = rng_create_job_desc(ctx, buf_id);
 263         if (err)
 264                 return err;
 265
 266         atomic_set(&bd->empty, BUF_EMPTY);
 267         submit_job(ctx, buf_id == ctx->current_buf);
 268         wait_for_completion(&bd->filled);
 269
 270         return 0;
 271 }
 272
 273 static int caam_init_rng(struct caam_rng_ctx *ctx, struct device *jrdev)
 274 {
 275         int err;
 276
 277         ctx->jrdev = jrdev;
 278
 279         err = rng_create_sh_desc(ctx);
 280         if (err)
 281                 return err;
 282
 283         ctx->current_buf = 0;
 284         ctx->cur_buf_idx = 0;
 285
 286         err = caam_init_buf(ctx, 0);
 287         if (err)
 288                 return err;
 289
 290         return caam_init_buf(ctx, 1);
 291 }
 292
 293 static struct hwrng caam_rng = {
 294         .name           = "rng-caam",
 295         .cleanup        = caam_cleanup,
 296         .read           = caam_read,
 297 };
 298
 299 static void __exit caam_rng_exit(void)
 300 {
 301         caam_jr_free(rng_ctx->jrdev);
 302         hwrng_unregister(&caam_rng);
 303         kfree(rng_ctx);
 304 }
 305
 306 static int __init caam_rng_init(void)
 307 {
 308         struct device *dev;
 309         struct device_node *dev_node;
 310         struct platform_device *pdev;
 311         struct caam_drv_private *priv;
 312         u32 rng_inst;
 313         int err;
 314
 315         dev_node = of_find_compatible_node(NULL, NULL, "fsl,sec-v4.0");
 316         if (!dev_node) {
 317                 dev_node = of_find_compatible_node(NULL, NULL, "fsl,sec4.0");
 318                 if (!dev_node)
 319                         return -ENODEV;
 320         }
 321
 322         pdev = of_find_device_by_node(dev_node);
 323         if (!pdev) {
 324                 of_node_put(dev_node);
 325                 return -ENODEV;
 326         }
 327
 328         priv = dev_get_drvdata(&pdev->dev);
 329         of_node_put(dev_node);
 330
 331         /*
 332          * If priv is NULL, it's probably because the caam driver wasn't
 333          * properly initialized (e.g. RNG4 init failed). Thus, bail out here.
 334          */
 335         if (!priv) {
 336                 err = -ENODEV;
 337                 goto out_put_dev;
 338         }
 339
 340         /* Check for an instantiated RNG before registration */
 341         if (priv->era < 10)
 342                 rng_inst = (rd_reg32(&priv->ctrl->perfmon.cha_num_ls) &
 343                             CHA_ID_LS_RNG_MASK) >> CHA_ID_LS_RNG_SHIFT;
 344         else
 345                 rng_inst = rd_reg32(&priv->ctrl->vreg.rng) & CHA_VER_NUM_MASK;
 346
 347         if (!rng_inst) {
 348                 err = -ENODEV;
 349                 goto out_put_dev;
 350         }
 351
 352         dev = caam_jr_alloc();
 353         if (IS_ERR(dev)) {
 354                 pr_err("Job Ring Device allocation for transform failed\n");
 355                 err = PTR_ERR(dev);
 356                 goto out_put_dev;
 357         }
 358         rng_ctx = kmalloc(sizeof(*rng_ctx), GFP_DMA | GFP_KERNEL);
 359         if (!rng_ctx) {
 360                 err = -ENOMEM;
 361                 goto free_caam_alloc;
 362         }
 363         err = caam_init_rng(rng_ctx, dev);
 364         if (err)
 365                 goto free_rng_ctx;
 366
 367         put_device(&pdev->dev);
 368         dev_info(dev, "registering rng-caam\n");
 369         return hwrng_register(&caam_rng);
 370
 371 free_rng_ctx:
 372         kfree(rng_ctx);
 373 free_caam_alloc:
 374         caam_jr_free(dev);
 375 out_put_dev:
 376         put_device(&pdev->dev);
 377         return err;
 378 }
 379
 380 module_init(caam_rng_init);
 381 module_exit(caam_rng_exit);
 382
 383 MODULE_LICENSE("GPL");
 384 MODULE_DESCRIPTION("FSL CAAM support for hw_random API");
 385 MODULE_AUTHOR("Freescale Semiconductor - NMG");