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