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 2018-2019 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_MAX * 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 /*
  84  * Variable used to avoid double free of resources in case
  85  * algorithm registration was unsuccessful
  86  */
  87 static bool init_done;
  88
  89 static inline void rng_unmap_buf(struct device *jrdev, struct buf_data *bd)
  90 {
  91         if (bd->addr)
  92                 dma_unmap_single(jrdev, bd->addr, RN_BUF_SIZE,
  93                                  DMA_FROM_DEVICE);
  94 }
  95
  96 static inline void rng_unmap_ctx(struct caam_rng_ctx *ctx)
  97 {
  98         struct device *jrdev = ctx->jrdev;
  99
 100         if (ctx->sh_desc_dma)
 101                 dma_unmap_single(jrdev, ctx->sh_desc_dma,
 102                                  desc_bytes(ctx->sh_desc), DMA_TO_DEVICE);
 103         rng_unmap_buf(jrdev, &ctx->bufs[0]);
 104         rng_unmap_buf(jrdev, &ctx->bufs[1]);
 105 }
 106
 107 static void rng_done(struct device *jrdev, u32 *desc, u32 err, void *context)
 108 {
 109         struct buf_data *bd;
 110
 111         bd = container_of(desc, struct buf_data, hw_desc[0]);
 112
 113         if (err)
 114                 caam_jr_strstatus(jrdev, err);
 115
 116         atomic_set(&bd->empty, BUF_NOT_EMPTY);
 117         complete(&bd->filled);
 118
 119         /* Buffer refilled, invalidate cache */
 120         dma_sync_single_for_cpu(jrdev, bd->addr, RN_BUF_SIZE, DMA_FROM_DEVICE);
 121
 122         print_hex_dump_debug("rng refreshed buf@: ", DUMP_PREFIX_ADDRESS, 16, 4,
 123                              bd->buf, RN_BUF_SIZE, 1);
 124 }
 125
 126 static inline int submit_job(struct caam_rng_ctx *ctx, int to_current)
 127 {
 128         struct buf_data *bd = &ctx->bufs[!(to_current ^ ctx->current_buf)];
 129         struct device *jrdev = ctx->jrdev;
 130         u32 *desc = bd->hw_desc;
 131         int err;
 132
 133         dev_dbg(jrdev, "submitting job %d\n", !(to_current ^ ctx->current_buf));
 134         init_completion(&bd->filled);
 135         err = caam_jr_enqueue(jrdev, desc, rng_done, ctx);
 136         if (err)
 137                 complete(&bd->filled); /* don't wait on failed job*/
 138         else
 139                 atomic_inc(&bd->empty); /* note if pending */
 140
 141         return err;
 142 }
 143
 144 static int caam_read(struct hwrng *rng, void *data, size_t max, bool wait)
 145 {
 146         struct caam_rng_ctx *ctx = rng_ctx;
 147         struct buf_data *bd = &ctx->bufs[ctx->current_buf];
 148         int next_buf_idx, copied_idx;
 149         int err;
 150
 151         if (atomic_read(&bd->empty)) {
 152                 /* try to submit job if there wasn't one */
 153                 if (atomic_read(&bd->empty) == BUF_EMPTY) {
 154                         err = submit_job(ctx, 1);
 155                         /* if can't submit job, can't even wait */
 156                         if (err)
 157                                 return 0;
 158                 }
 159                 /* no immediate data, so exit if not waiting */
 160                 if (!wait)
 161                         return 0;
 162
 163                 /* waiting for pending job */
 164                 if (atomic_read(&bd->empty))
 165                         wait_for_completion(&bd->filled);
 166         }
 167
 168         next_buf_idx = ctx->cur_buf_idx + max;
 169         dev_dbg(ctx->jrdev, "%s: start reading at buffer %d, idx %d\n",
 170                  __func__, ctx->current_buf, ctx->cur_buf_idx);
 171
 172         /* if enough data in current buffer */
 173         if (next_buf_idx < RN_BUF_SIZE) {
 174                 memcpy(data, bd->buf + ctx->cur_buf_idx, max);
 175                 ctx->cur_buf_idx = next_buf_idx;
 176                 return max;
 177         }
 178
 179         /* else, copy what's left... */
 180         copied_idx = RN_BUF_SIZE - ctx->cur_buf_idx;
 181         memcpy(data, bd->buf + ctx->cur_buf_idx, copied_idx);
 182         ctx->cur_buf_idx = 0;
 183         atomic_set(&bd->empty, BUF_EMPTY);
 184
 185         /* ...refill... */
 186         submit_job(ctx, 1);
 187
 188         /* and use next buffer */
 189         ctx->current_buf = !ctx->current_buf;
 190         dev_dbg(ctx->jrdev, "switched to buffer %d\n", ctx->current_buf);
 191
 192         /* since there already is some data read, don't wait */
 193         return copied_idx + caam_read(rng, data + copied_idx,
 194                                       max - copied_idx, false);
 195 }
 196
 197 static inline int rng_create_sh_desc(struct caam_rng_ctx *ctx)
 198 {
 199         struct device *jrdev = ctx->jrdev;
 200         u32 *desc = ctx->sh_desc;
 201
 202         init_sh_desc(desc, HDR_SHARE_SERIAL);
 203
 204         /* Generate random bytes */
 205         append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG);
 206
 207         /* Store bytes */
 208         append_seq_fifo_store(desc, RN_BUF_SIZE, FIFOST_TYPE_RNGSTORE);
 209
 210         ctx->sh_desc_dma = dma_map_single(jrdev, desc, desc_bytes(desc),
 211                                           DMA_TO_DEVICE);
 212         if (dma_mapping_error(jrdev, ctx->sh_desc_dma)) {
 213                 dev_err(jrdev, "unable to map shared descriptor\n");
 214                 return -ENOMEM;
 215         }
 216
 217         print_hex_dump_debug("rng shdesc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
 218                              desc, desc_bytes(desc), 1);
 219
 220         return 0;
 221 }
 222
 223 static inline int rng_create_job_desc(struct caam_rng_ctx *ctx, int buf_id)
 224 {
 225         struct device *jrdev = ctx->jrdev;
 226         struct buf_data *bd = &ctx->bufs[buf_id];
 227         u32 *desc = bd->hw_desc;
 228         int sh_len = desc_len(ctx->sh_desc);
 229
 230         init_job_desc_shared(desc, ctx->sh_desc_dma, sh_len, HDR_SHARE_DEFER |
 231                              HDR_REVERSE);
 232
 233         bd->addr = dma_map_single(jrdev, bd->buf, RN_BUF_SIZE, DMA_FROM_DEVICE);
 234         if (dma_mapping_error(jrdev, bd->addr)) {
 235                 dev_err(jrdev, "unable to map dst\n");
 236                 return -ENOMEM;
 237         }
 238
 239         append_seq_out_ptr_intlen(desc, bd->addr, RN_BUF_SIZE, 0);
 240
 241         print_hex_dump_debug("rng job desc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
 242                              desc, desc_bytes(desc), 1);
 243
 244         return 0;
 245 }
 246
 247 static void caam_cleanup(struct hwrng *rng)
 248 {
 249         int i;
 250         struct buf_data *bd;
 251
 252         for (i = 0; i < 2; i++) {
 253                 bd = &rng_ctx->bufs[i];
 254                 if (atomic_read(&bd->empty) == BUF_PENDING)
 255                         wait_for_completion(&bd->filled);
 256         }
 257
 258         rng_unmap_ctx(rng_ctx);
 259 }
 260
 261 static int caam_init_buf(struct caam_rng_ctx *ctx, int buf_id)
 262 {
 263         struct buf_data *bd = &ctx->bufs[buf_id];
 264         int err;
 265
 266         err = rng_create_job_desc(ctx, buf_id);
 267         if (err)
 268                 return err;
 269
 270         atomic_set(&bd->empty, BUF_EMPTY);
 271         submit_job(ctx, buf_id == ctx->current_buf);
 272         wait_for_completion(&bd->filled);
 273
 274         return 0;
 275 }
 276
 277 static int caam_init_rng(struct caam_rng_ctx *ctx, struct device *jrdev)
 278 {
 279         int err;
 280
 281         ctx->jrdev = jrdev;
 282
 283         err = rng_create_sh_desc(ctx);
 284         if (err)
 285                 return err;
 286
 287         ctx->current_buf = 0;
 288         ctx->cur_buf_idx = 0;
 289
 290         err = caam_init_buf(ctx, 0);
 291         if (err)
 292                 return err;
 293
 294         return caam_init_buf(ctx, 1);
 295 }
 296
 297 static struct hwrng caam_rng = {
 298         .name           = "rng-caam",
 299         .cleanup        = caam_cleanup,
 300         .read           = caam_read,
 301 };
 302
 303 void caam_rng_exit(void)
 304 {
 305         if (!init_done)
 306                 return;
 307
 308         caam_jr_free(rng_ctx->jrdev);
 309         hwrng_unregister(&caam_rng);
 310         kfree(rng_ctx);
 311 }
 312
 313 int caam_rng_init(struct device *ctrldev)
 314 {
 315         struct device *dev;
 316         u32 rng_inst;
 317         struct caam_drv_private *priv = dev_get_drvdata(ctrldev);
 318         int err;
 319         init_done = false;
 320
 321         /* Check for an instantiated RNG before registration */
 322         if (priv->era < 10)
 323                 rng_inst = (rd_reg32(&priv->ctrl->perfmon.cha_num_ls) &
 324                             CHA_ID_LS_RNG_MASK) >> CHA_ID_LS_RNG_SHIFT;
 325         else
 326                 rng_inst = rd_reg32(&priv->ctrl->vreg.rng) & CHA_VER_NUM_MASK;
 327
 328         if (!rng_inst)
 329                 return 0;
 330
 331         dev = caam_jr_alloc();
 332         if (IS_ERR(dev)) {
 333                 pr_err("Job Ring Device allocation for transform failed\n");
 334                 return PTR_ERR(dev);
 335         }
 336         rng_ctx = kmalloc(sizeof(*rng_ctx), GFP_DMA | GFP_KERNEL);
 337         if (!rng_ctx) {
 338                 err = -ENOMEM;
 339                 goto free_caam_alloc;
 340         }
 341         err = caam_init_rng(rng_ctx, dev);
 342         if (err)
 343                 goto free_rng_ctx;
 344
 345         dev_info(dev, "registering rng-caam\n");
 346
 347         err = hwrng_register(&caam_rng);
 348         if (!err) {
 349                 init_done = true;
 350                 return err;
 351         }
 352
 353 free_rng_ctx:
 354         kfree(rng_ctx);
 355 free_caam_alloc:
 356         caam_jr_free(dev);
 357         return err;
 358 }