| /* |
| * caam - Freescale FSL CAAM support for hw_random |
| * |
| * Copyright 2011 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 <linux/hw_random.h> |
| #include <linux/completion.h> |
| #include <linux/atomic.h> |
| |
| #include "compat.h" |
| |
| #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 (0xffff / L1_CACHE_BYTES * \ |
| L1_CACHE_BYTES) |
| |
| /* 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[RN_BUF_SIZE]; |
| dma_addr_t addr; |
| struct completion filled; |
| 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 */ |
| atomic_t empty; |
| }; |
| |
| /* rng per-device context */ |
| struct caam_rng_ctx { |
| struct device *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]; |
| }; |
| |
| static struct caam_rng_ctx rng_ctx; |
| |
| static inline void rng_unmap_buf(struct device *jrdev, struct buf_data *bd) |
| { |
| if (bd->addr) |
| dma_unmap_single(jrdev, bd->addr, RN_BUF_SIZE, |
| DMA_FROM_DEVICE); |
| } |
| |
| static inline void rng_unmap_ctx(struct caam_rng_ctx *ctx) |
| { |
| struct device *jrdev = ctx->jrdev; |
| |
| if (ctx->sh_desc_dma) |
| dma_unmap_single(jrdev, ctx->sh_desc_dma, DESC_RNG_LEN, |
| DMA_TO_DEVICE); |
| rng_unmap_buf(jrdev, &ctx->bufs[0]); |
| rng_unmap_buf(jrdev, &ctx->bufs[1]); |
| } |
| |
| static void rng_done(struct device *jrdev, u32 *desc, u32 err, void *context) |
| { |
| struct buf_data *bd; |
| |
| bd = (struct buf_data *)((char *)desc - |
| offsetof(struct buf_data, hw_desc)); |
| |
| if (err) { |
| char tmp[CAAM_ERROR_STR_MAX]; |
| |
| dev_err(jrdev, "%08x: %s\n", err, caam_jr_strstatus(tmp, err)); |
| } |
| |
| atomic_set(&bd->empty, BUF_NOT_EMPTY); |
| complete(&bd->filled); |
| #ifdef DEBUG |
| print_hex_dump(KERN_ERR, "rng refreshed buf@: ", |
| DUMP_PREFIX_ADDRESS, 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 *jrdev = ctx->jrdev; |
| u32 *desc = bd->hw_desc; |
| int err; |
| |
| dev_dbg(jrdev, "submitting job %d\n", !(to_current ^ ctx->current_buf)); |
| init_completion(&bd->filled); |
| err = caam_jr_enqueue(jrdev, desc, rng_done, ctx); |
| if (err) |
| complete(&bd->filled); /* don't wait on failed job*/ |
| else |
| atomic_inc(&bd->empty); /* note if pending */ |
| |
| return err; |
| } |
| |
| static int caam_read(struct hwrng *rng, void *data, size_t max, bool wait) |
| { |
| struct caam_rng_ctx *ctx = &rng_ctx; |
| struct buf_data *bd = &ctx->bufs[ctx->current_buf]; |
| int next_buf_idx, copied_idx; |
| int err; |
| |
| if (atomic_read(&bd->empty)) { |
| /* try to submit job if there wasn't one */ |
| if (atomic_read(&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; |
| |
| /* waiting for pending job */ |
| if (atomic_read(&bd->empty)) |
| wait_for_completion(&bd->filled); |
| } |
| |
| 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; |
| atomic_set(&bd->empty, BUF_EMPTY); |
| |
| /* ...refill... */ |
| submit_job(ctx, 1); |
| |
| /* 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 void rng_create_sh_desc(struct caam_rng_ctx *ctx) |
| { |
| struct device *jrdev = ctx->jrdev; |
| 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_map_single(jrdev, desc, desc_bytes(desc), |
| DMA_TO_DEVICE); |
| #ifdef DEBUG |
| print_hex_dump(KERN_ERR, "rng shdesc@: ", DUMP_PREFIX_ADDRESS, 16, 4, |
| desc, desc_bytes(desc), 1); |
| #endif |
| } |
| |
| static inline void rng_create_job_desc(struct caam_rng_ctx *ctx, int buf_id) |
| { |
| struct device *jrdev = ctx->jrdev; |
| 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); |
| |
| bd->addr = dma_map_single(jrdev, bd->buf, RN_BUF_SIZE, DMA_FROM_DEVICE); |
| |
| append_seq_out_ptr_intlen(desc, bd->addr, RN_BUF_SIZE, 0); |
| #ifdef DEBUG |
| print_hex_dump(KERN_ERR, "rng job desc@: ", DUMP_PREFIX_ADDRESS, 16, 4, |
| desc, desc_bytes(desc), 1); |
| #endif |
| } |
| |
| static void caam_cleanup(struct hwrng *rng) |
| { |
| int i; |
| struct buf_data *bd; |
| |
| for (i = 0; i < 2; i++) { |
| bd = &rng_ctx.bufs[i]; |
| if (atomic_read(&bd->empty) == BUF_PENDING) |
| wait_for_completion(&bd->filled); |
| } |
| |
| rng_unmap_ctx(&rng_ctx); |
| } |
| |
| static void caam_init_buf(struct caam_rng_ctx *ctx, int buf_id) |
| { |
| struct buf_data *bd = &ctx->bufs[buf_id]; |
| |
| rng_create_job_desc(ctx, buf_id); |
| atomic_set(&bd->empty, BUF_EMPTY); |
| submit_job(ctx, buf_id == ctx->current_buf); |
| wait_for_completion(&bd->filled); |
| } |
| |
| static void caam_init_rng(struct caam_rng_ctx *ctx, struct device *jrdev) |
| { |
| ctx->jrdev = jrdev; |
| rng_create_sh_desc(ctx); |
| ctx->current_buf = 0; |
| ctx->cur_buf_idx = 0; |
| caam_init_buf(ctx, 0); |
| caam_init_buf(ctx, 1); |
| } |
| |
| static struct hwrng caam_rng = { |
| .name = "rng-caam", |
| .cleanup = caam_cleanup, |
| .read = caam_read, |
| }; |
| |
| static void __exit caam_rng_exit(void) |
| { |
| hwrng_unregister(&caam_rng); |
| } |
| |
| static int __init caam_rng_init(void) |
| { |
| struct device_node *dev_node; |
| struct platform_device *pdev; |
| struct device *ctrldev; |
| struct caam_drv_private *priv; |
| |
| dev_node = of_find_compatible_node(NULL, NULL, "fsl,sec-v4.0"); |
| if (!dev_node) { |
| dev_node = of_find_compatible_node(NULL, NULL, "fsl,sec4.0"); |
| if (!dev_node) |
| return -ENODEV; |
| } |
| |
| pdev = of_find_device_by_node(dev_node); |
| if (!pdev) |
| return -ENODEV; |
| |
| ctrldev = &pdev->dev; |
| priv = dev_get_drvdata(ctrldev); |
| of_node_put(dev_node); |
| |
| /* |
| * If priv is NULL, it's probably because the caam driver wasn't |
| * properly initialized (e.g. RNG4 init failed). Thus, bail out here. |
| */ |
| if (!priv) |
| return -ENODEV; |
| |
| caam_init_rng(&rng_ctx, priv->jrdev[0]); |
| |
| dev_info(priv->jrdev[0], "registering rng-caam\n"); |
| return hwrng_register(&caam_rng); |
| } |
| |
| module_init(caam_rng_init); |
| module_exit(caam_rng_exit); |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_DESCRIPTION("FSL CAAM support for hw_random API"); |
| MODULE_AUTHOR("Freescale Semiconductor - NMG"); |