/* * caam - Freescale FSL CAAM support for hw_random * * Copyright (C) 2011-2015 Freescale Semiconductor, Inc. * * Based on caamalg.c crypto API driver. * * relationship between job descriptors to shared descriptors: * * --------------- -------------- * | JobDesc #0 |-------------------->| ShareDesc | * | *(buffer 0) | |------------->| (generate) | * --------------- | | (move) | * | | (store) | * --------------- | -------------- * | JobDesc #1 |------| * | *(buffer 1) | * --------------- * * A job desc looks like this: * * --------------------- * | Header | * | ShareDesc Pointer | * | SEQ_OUT_PTR | * | (output buffer) | * --------------------- * * The SharedDesc never changes, and each job descriptor points to one of two * buffers for each device, from which the data will be copied into the * requested destination */ #include #include #include #include #include #include #include "regs.h" #include "intern.h" #include "desc_constr.h" #include "jr.h" #include "error.h" /* * Maximum buffer size: maximum number of random, cache-aligned bytes that * will be generated and moved to seq out ptr (extlen not allowed) */ #define RN_BUF_SIZE 32767 /* length of descriptors */ #define DESC_JOB_O_LEN (CAAM_CMD_SZ * 2 + CAAM_PTR_SZ * 2) #define DESC_RNG_LEN (10 * CAAM_CMD_SZ) /* Buffer, its dma address and lock */ struct buf_data { u8 *buf; dma_addr_t addr; u32 hw_desc[DESC_JOB_O_LEN]; #define BUF_NOT_EMPTY 0 #define BUF_EMPTY 1 #define BUF_PENDING 2 /* Empty, but with job pending --don't submit another */ int empty; }; /* rng per-device context */ struct caam_rng_ctx { struct device_d *jrdev; dma_addr_t sh_desc_dma; u32 sh_desc[DESC_RNG_LEN]; unsigned int cur_buf_idx; int current_buf; struct buf_data bufs[2]; struct hwrng rng; }; static struct caam_rng_ctx *rng_ctx; static void rng_done(struct device_d *jrdev, u32 *desc, u32 err, void *context) { struct buf_data *bd; bd = container_of(desc, struct buf_data, hw_desc[0]); if (err) caam_jr_strstatus(jrdev, err); bd->empty = BUF_NOT_EMPTY; /* Buffer refilled, invalidate cache */ dma_sync_single_for_cpu(bd->addr, RN_BUF_SIZE, DMA_FROM_DEVICE); #ifdef DEBUG print_hex_dump(KERN_ERR, "rng refreshed buf@: ", DUMP_PREFIX_OFFSET, 16, 4, bd->buf, RN_BUF_SIZE, 1); #endif } static inline int submit_job(struct caam_rng_ctx *ctx, int to_current) { struct buf_data *bd = &ctx->bufs[!(to_current ^ ctx->current_buf)]; struct device_d *jrdev = ctx->jrdev; u32 *desc = bd->hw_desc; int err; dev_dbg(jrdev, "submitting job %d\n", !(to_current ^ ctx->current_buf)); dma_sync_single_for_device((unsigned long)desc, desc_bytes(desc), DMA_TO_DEVICE); err = caam_jr_enqueue(jrdev, desc, rng_done, ctx); if (!err) bd->empty += 1; /* note if pending */ return err; } static int caam_read(struct hwrng *rng, void *data, size_t max, bool wait) { struct caam_rng_ctx *ctx = container_of(rng, struct caam_rng_ctx, rng); struct buf_data *bd = &ctx->bufs[ctx->current_buf]; int next_buf_idx, copied_idx; int err; if (bd->empty) { /* try to submit job if there wasn't one */ if (bd->empty == BUF_EMPTY) { err = submit_job(ctx, 1); /* if can't submit job, can't even wait */ if (err) return 0; } /* no immediate data, so exit if not waiting */ if (!wait) return 0; } next_buf_idx = ctx->cur_buf_idx + max; dev_dbg(ctx->jrdev, "%s: start reading at buffer %d, idx %d\n", __func__, ctx->current_buf, ctx->cur_buf_idx); /* if enough data in current buffer */ if (next_buf_idx < RN_BUF_SIZE) { memcpy(data, bd->buf + ctx->cur_buf_idx, max); ctx->cur_buf_idx = next_buf_idx; return max; } /* else, copy what's left... */ copied_idx = RN_BUF_SIZE - ctx->cur_buf_idx; memcpy(data, bd->buf + ctx->cur_buf_idx, copied_idx); ctx->cur_buf_idx = 0; bd->empty = BUF_EMPTY; /* ...refill... */ err = submit_job(ctx, 1); if (err) return err; /* and use next buffer */ ctx->current_buf = !ctx->current_buf; dev_dbg(ctx->jrdev, "switched to buffer %d\n", ctx->current_buf); /* since there already is some data read, don't wait */ return copied_idx + caam_read(rng, data + copied_idx, max - copied_idx, false); } static inline int rng_create_sh_desc(struct caam_rng_ctx *ctx) { u32 *desc = ctx->sh_desc; init_sh_desc(desc, HDR_SHARE_SERIAL); /* Propagate errors from shared to job descriptor */ append_cmd(desc, SET_OK_NO_PROP_ERRORS | CMD_LOAD); /* Generate random bytes */ append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG); /* Store bytes */ append_seq_fifo_store(desc, RN_BUF_SIZE, FIFOST_TYPE_RNGSTORE); ctx->sh_desc_dma = (dma_addr_t)desc; dma_sync_single_for_device((unsigned long)desc, desc_bytes(desc), DMA_TO_DEVICE); #ifdef DEBUG print_hex_dump(KERN_ERR, "rng shdesc@: ", DUMP_PREFIX_OFFSET, 16, 4, desc, desc_bytes(desc), 1); #endif return 0; } static inline int rng_create_job_desc(struct caam_rng_ctx *ctx, int buf_id) { struct buf_data *bd = &ctx->bufs[buf_id]; u32 *desc = bd->hw_desc; int sh_len = desc_len(ctx->sh_desc); init_job_desc_shared(desc, ctx->sh_desc_dma, sh_len, HDR_SHARE_DEFER | HDR_REVERSE); append_seq_out_ptr_intlen(desc, bd->addr, RN_BUF_SIZE, 0); #ifdef DEBUG print_hex_dump(KERN_ERR, "rng job desc@: ", DUMP_PREFIX_OFFSET, 16, 4, desc, desc_bytes(desc), 1); #endif return 0; } static int caam_init_buf(struct caam_rng_ctx *ctx, int buf_id) { struct buf_data *bd = &ctx->bufs[buf_id]; int err; bd->buf = dma_alloc_coherent(RN_BUF_SIZE, &bd->addr); err = rng_create_job_desc(ctx, buf_id); if (err) return err; bd->empty = BUF_EMPTY; return submit_job(ctx, buf_id == ctx->current_buf); } static int caam_init_rng(struct caam_rng_ctx *ctx, struct device_d *jrdev) { int err; ctx->jrdev = jrdev; err = rng_create_sh_desc(ctx); if (err) return err; ctx->current_buf = 0; ctx->cur_buf_idx = 0; err = caam_init_buf(ctx, 0); if (err) return err; return caam_init_buf(ctx, 1); } int caam_rng_probe(struct device_d *dev, struct device_d *jrdev) { int err; rng_ctx = xzalloc(sizeof(*rng_ctx)); err = caam_init_rng(rng_ctx, jrdev); if (err) return err; rng_ctx->rng.name = dev->name; rng_ctx->rng.read = caam_read; err = hwrng_register(dev, &rng_ctx->rng); if (err) { dev_err(dev, "rng-caam registering failed (%d)\n", err); return err; } dev_info(dev, "registering rng-caam\n"); return 0; }