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 (10 * CAAM_CMD_SZ) 56 57 /* Buffer, its dma address and lock */ 58 struct buf_data { 59 u8 buf[RN_BUF_SIZE]; 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, DESC_RNG_LEN, 94 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 char tmp[CAAM_ERROR_STR_MAX]; 108 109 dev_err(jrdev, "%08x: %s\n", err, caam_jr_strstatus(tmp, err)); 110 } 111 112 atomic_set(&bd->empty, BUF_NOT_EMPTY); 113 complete(&bd->filled); 114 #ifdef DEBUG 115 print_hex_dump(KERN_ERR, "rng refreshed buf@: ", 116 DUMP_PREFIX_ADDRESS, 16, 4, bd->buf, RN_BUF_SIZE, 1); 117 #endif 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 void 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 /* Propagate errors from shared to job descriptor */ 199 append_cmd(desc, SET_OK_NO_PROP_ERRORS | CMD_LOAD); 200 201 /* Generate random bytes */ 202 append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG); 203 204 /* Store bytes */ 205 append_seq_fifo_store(desc, RN_BUF_SIZE, FIFOST_TYPE_RNGSTORE); 206 207 ctx->sh_desc_dma = dma_map_single(jrdev, desc, desc_bytes(desc), 208 DMA_TO_DEVICE); 209 #ifdef DEBUG 210 print_hex_dump(KERN_ERR, "rng shdesc@: ", DUMP_PREFIX_ADDRESS, 16, 4, 211 desc, desc_bytes(desc), 1); 212 #endif 213 } 214 215 static inline void rng_create_job_desc(struct caam_rng_ctx *ctx, int buf_id) 216 { 217 struct device *jrdev = ctx->jrdev; 218 struct buf_data *bd = &ctx->bufs[buf_id]; 219 u32 *desc = bd->hw_desc; 220 int sh_len = desc_len(ctx->sh_desc); 221 222 init_job_desc_shared(desc, ctx->sh_desc_dma, sh_len, HDR_SHARE_DEFER | 223 HDR_REVERSE); 224 225 bd->addr = dma_map_single(jrdev, bd->buf, RN_BUF_SIZE, DMA_FROM_DEVICE); 226 227 append_seq_out_ptr_intlen(desc, bd->addr, RN_BUF_SIZE, 0); 228 #ifdef DEBUG 229 print_hex_dump(KERN_ERR, "rng job desc@: ", DUMP_PREFIX_ADDRESS, 16, 4, 230 desc, desc_bytes(desc), 1); 231 #endif 232 } 233 234 static void caam_cleanup(struct hwrng *rng) 235 { 236 int i; 237 struct buf_data *bd; 238 239 for (i = 0; i < 2; i++) { 240 bd = &rng_ctx.bufs[i]; 241 if (atomic_read(&bd->empty) == BUF_PENDING) 242 wait_for_completion(&bd->filled); 243 } 244 245 rng_unmap_ctx(&rng_ctx); 246 } 247 248 static void caam_init_buf(struct caam_rng_ctx *ctx, int buf_id) 249 { 250 struct buf_data *bd = &ctx->bufs[buf_id]; 251 252 rng_create_job_desc(ctx, buf_id); 253 atomic_set(&bd->empty, BUF_EMPTY); 254 submit_job(ctx, buf_id == ctx->current_buf); 255 wait_for_completion(&bd->filled); 256 } 257 258 static void caam_init_rng(struct caam_rng_ctx *ctx, struct device *jrdev) 259 { 260 ctx->jrdev = jrdev; 261 rng_create_sh_desc(ctx); 262 ctx->current_buf = 0; 263 ctx->cur_buf_idx = 0; 264 caam_init_buf(ctx, 0); 265 caam_init_buf(ctx, 1); 266 } 267 268 static struct hwrng caam_rng = { 269 .name = "rng-caam", 270 .cleanup = caam_cleanup, 271 .read = caam_read, 272 }; 273 274 static void __exit caam_rng_exit(void) 275 { 276 caam_jr_free(rng_ctx.jrdev); 277 hwrng_unregister(&caam_rng); 278 } 279 280 static int __init caam_rng_init(void) 281 { 282 struct device *dev; 283 284 dev = caam_jr_alloc(); 285 if (IS_ERR(dev)) { 286 pr_err("Job Ring Device allocation for transform failed\n"); 287 return PTR_ERR(dev); 288 } 289 290 caam_init_rng(&rng_ctx, dev); 291 292 dev_info(dev, "registering rng-caam\n"); 293 return hwrng_register(&caam_rng); 294 } 295 296 module_init(caam_rng_init); 297 module_exit(caam_rng_exit); 298 299 MODULE_LICENSE("GPL"); 300 MODULE_DESCRIPTION("FSL CAAM support for hw_random API"); 301 MODULE_AUTHOR("Freescale Semiconductor - NMG"); 302