drivers/crypto/caam/caamrng.c

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