359 lines
8.5 KiB
C
359 lines
8.5 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* caam - Freescale FSL CAAM support for hw_random
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*
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* Copyright 2011 Freescale Semiconductor, Inc.
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* Copyright 2018-2019 NXP
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*
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* Based on caamalg.c crypto API driver.
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*
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* relationship between job descriptors to shared descriptors:
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*
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* --------------- --------------
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* | JobDesc #0 |-------------------->| ShareDesc |
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* | *(buffer 0) | |------------->| (generate) |
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* --------------- | | (move) |
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* | | (store) |
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* --------------- | --------------
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* | JobDesc #1 |------|
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* | *(buffer 1) |
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* ---------------
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*
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* A job desc looks like this:
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*
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* ---------------------
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* | Header |
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* | ShareDesc Pointer |
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* | SEQ_OUT_PTR |
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* | (output buffer) |
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* ---------------------
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*
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* The SharedDesc never changes, and each job descriptor points to one of two
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* buffers for each device, from which the data will be copied into the
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* requested destination
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*/
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#include <linux/hw_random.h>
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#include <linux/completion.h>
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#include <linux/atomic.h>
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#include "compat.h"
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#include "regs.h"
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#include "intern.h"
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#include "desc_constr.h"
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#include "jr.h"
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#include "error.h"
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/*
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* Maximum buffer size: maximum number of random, cache-aligned bytes that
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* will be generated and moved to seq out ptr (extlen not allowed)
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*/
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#define RN_BUF_SIZE (0xffff / L1_CACHE_BYTES * \
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L1_CACHE_BYTES)
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/* length of descriptors */
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#define DESC_JOB_O_LEN (CAAM_CMD_SZ * 2 + CAAM_PTR_SZ_MAX * 2)
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#define DESC_RNG_LEN (3 * CAAM_CMD_SZ)
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/* Buffer, its dma address and lock */
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struct buf_data {
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u8 buf[RN_BUF_SIZE] ____cacheline_aligned;
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dma_addr_t addr;
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struct completion filled;
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u32 hw_desc[DESC_JOB_O_LEN];
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#define BUF_NOT_EMPTY 0
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#define BUF_EMPTY 1
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#define BUF_PENDING 2 /* Empty, but with job pending --don't submit another */
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atomic_t empty;
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};
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/* rng per-device context */
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struct caam_rng_ctx {
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struct device *jrdev;
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dma_addr_t sh_desc_dma;
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u32 sh_desc[DESC_RNG_LEN];
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unsigned int cur_buf_idx;
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int current_buf;
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struct buf_data bufs[2];
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};
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static struct caam_rng_ctx *rng_ctx;
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/*
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* Variable used to avoid double free of resources in case
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* algorithm registration was unsuccessful
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*/
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static bool init_done;
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static inline void rng_unmap_buf(struct device *jrdev, struct buf_data *bd)
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{
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if (bd->addr)
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dma_unmap_single(jrdev, bd->addr, RN_BUF_SIZE,
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DMA_FROM_DEVICE);
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}
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static inline void rng_unmap_ctx(struct caam_rng_ctx *ctx)
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{
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struct device *jrdev = ctx->jrdev;
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if (ctx->sh_desc_dma)
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dma_unmap_single(jrdev, ctx->sh_desc_dma,
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desc_bytes(ctx->sh_desc), DMA_TO_DEVICE);
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rng_unmap_buf(jrdev, &ctx->bufs[0]);
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rng_unmap_buf(jrdev, &ctx->bufs[1]);
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}
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static void rng_done(struct device *jrdev, u32 *desc, u32 err, void *context)
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{
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struct buf_data *bd;
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bd = container_of(desc, struct buf_data, hw_desc[0]);
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if (err)
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caam_jr_strstatus(jrdev, err);
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atomic_set(&bd->empty, BUF_NOT_EMPTY);
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complete(&bd->filled);
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/* Buffer refilled, invalidate cache */
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dma_sync_single_for_cpu(jrdev, bd->addr, RN_BUF_SIZE, DMA_FROM_DEVICE);
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print_hex_dump_debug("rng refreshed buf@: ", DUMP_PREFIX_ADDRESS, 16, 4,
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bd->buf, RN_BUF_SIZE, 1);
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}
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static inline int submit_job(struct caam_rng_ctx *ctx, int to_current)
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{
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struct buf_data *bd = &ctx->bufs[!(to_current ^ ctx->current_buf)];
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struct device *jrdev = ctx->jrdev;
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u32 *desc = bd->hw_desc;
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int err;
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dev_dbg(jrdev, "submitting job %d\n", !(to_current ^ ctx->current_buf));
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init_completion(&bd->filled);
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err = caam_jr_enqueue(jrdev, desc, rng_done, ctx);
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if (err)
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complete(&bd->filled); /* don't wait on failed job*/
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else
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atomic_inc(&bd->empty); /* note if pending */
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return err;
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}
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static int caam_read(struct hwrng *rng, void *data, size_t max, bool wait)
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{
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struct caam_rng_ctx *ctx = rng_ctx;
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struct buf_data *bd = &ctx->bufs[ctx->current_buf];
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int next_buf_idx, copied_idx;
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int err;
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if (atomic_read(&bd->empty)) {
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/* try to submit job if there wasn't one */
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if (atomic_read(&bd->empty) == BUF_EMPTY) {
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err = submit_job(ctx, 1);
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/* if can't submit job, can't even wait */
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if (err)
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return 0;
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}
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/* no immediate data, so exit if not waiting */
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if (!wait)
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return 0;
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/* waiting for pending job */
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if (atomic_read(&bd->empty))
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wait_for_completion(&bd->filled);
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}
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next_buf_idx = ctx->cur_buf_idx + max;
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dev_dbg(ctx->jrdev, "%s: start reading at buffer %d, idx %d\n",
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__func__, ctx->current_buf, ctx->cur_buf_idx);
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/* if enough data in current buffer */
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if (next_buf_idx < RN_BUF_SIZE) {
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memcpy(data, bd->buf + ctx->cur_buf_idx, max);
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ctx->cur_buf_idx = next_buf_idx;
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return max;
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}
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/* else, copy what's left... */
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copied_idx = RN_BUF_SIZE - ctx->cur_buf_idx;
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memcpy(data, bd->buf + ctx->cur_buf_idx, copied_idx);
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ctx->cur_buf_idx = 0;
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atomic_set(&bd->empty, BUF_EMPTY);
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/* ...refill... */
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submit_job(ctx, 1);
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/* and use next buffer */
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ctx->current_buf = !ctx->current_buf;
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dev_dbg(ctx->jrdev, "switched to buffer %d\n", ctx->current_buf);
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/* since there already is some data read, don't wait */
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return copied_idx + caam_read(rng, data + copied_idx,
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max - copied_idx, false);
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}
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static inline int rng_create_sh_desc(struct caam_rng_ctx *ctx)
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{
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struct device *jrdev = ctx->jrdev;
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u32 *desc = ctx->sh_desc;
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init_sh_desc(desc, HDR_SHARE_SERIAL);
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/* Generate random bytes */
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append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG);
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/* Store bytes */
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append_seq_fifo_store(desc, RN_BUF_SIZE, FIFOST_TYPE_RNGSTORE);
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ctx->sh_desc_dma = dma_map_single(jrdev, desc, desc_bytes(desc),
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DMA_TO_DEVICE);
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if (dma_mapping_error(jrdev, ctx->sh_desc_dma)) {
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dev_err(jrdev, "unable to map shared descriptor\n");
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return -ENOMEM;
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}
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print_hex_dump_debug("rng shdesc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
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desc, desc_bytes(desc), 1);
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return 0;
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}
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static inline int rng_create_job_desc(struct caam_rng_ctx *ctx, int buf_id)
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{
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struct device *jrdev = ctx->jrdev;
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struct buf_data *bd = &ctx->bufs[buf_id];
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u32 *desc = bd->hw_desc;
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int sh_len = desc_len(ctx->sh_desc);
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init_job_desc_shared(desc, ctx->sh_desc_dma, sh_len, HDR_SHARE_DEFER |
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HDR_REVERSE);
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bd->addr = dma_map_single(jrdev, bd->buf, RN_BUF_SIZE, DMA_FROM_DEVICE);
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if (dma_mapping_error(jrdev, bd->addr)) {
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dev_err(jrdev, "unable to map dst\n");
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return -ENOMEM;
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}
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append_seq_out_ptr_intlen(desc, bd->addr, RN_BUF_SIZE, 0);
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print_hex_dump_debug("rng job desc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
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desc, desc_bytes(desc), 1);
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return 0;
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}
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static void caam_cleanup(struct hwrng *rng)
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{
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int i;
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struct buf_data *bd;
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for (i = 0; i < 2; i++) {
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bd = &rng_ctx->bufs[i];
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if (atomic_read(&bd->empty) == BUF_PENDING)
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wait_for_completion(&bd->filled);
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}
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rng_unmap_ctx(rng_ctx);
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}
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static int caam_init_buf(struct caam_rng_ctx *ctx, int buf_id)
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{
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struct buf_data *bd = &ctx->bufs[buf_id];
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int err;
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err = rng_create_job_desc(ctx, buf_id);
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if (err)
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return err;
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atomic_set(&bd->empty, BUF_EMPTY);
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submit_job(ctx, buf_id == ctx->current_buf);
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wait_for_completion(&bd->filled);
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return 0;
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}
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static int caam_init_rng(struct caam_rng_ctx *ctx, struct device *jrdev)
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{
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int err;
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ctx->jrdev = jrdev;
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err = rng_create_sh_desc(ctx);
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if (err)
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return err;
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ctx->current_buf = 0;
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ctx->cur_buf_idx = 0;
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err = caam_init_buf(ctx, 0);
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if (err)
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return err;
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return caam_init_buf(ctx, 1);
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}
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static struct hwrng caam_rng = {
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.name = "rng-caam",
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.cleanup = caam_cleanup,
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.read = caam_read,
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};
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void caam_rng_exit(void)
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{
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if (!init_done)
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return;
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caam_jr_free(rng_ctx->jrdev);
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hwrng_unregister(&caam_rng);
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kfree(rng_ctx);
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}
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int caam_rng_init(struct device *ctrldev)
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{
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struct device *dev;
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u32 rng_inst;
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struct caam_drv_private *priv = dev_get_drvdata(ctrldev);
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int err;
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init_done = false;
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/* Check for an instantiated RNG before registration */
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if (priv->era < 10)
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rng_inst = (rd_reg32(&priv->ctrl->perfmon.cha_num_ls) &
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CHA_ID_LS_RNG_MASK) >> CHA_ID_LS_RNG_SHIFT;
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else
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rng_inst = rd_reg32(&priv->ctrl->vreg.rng) & CHA_VER_NUM_MASK;
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if (!rng_inst)
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return 0;
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dev = caam_jr_alloc();
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if (IS_ERR(dev)) {
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pr_err("Job Ring Device allocation for transform failed\n");
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return PTR_ERR(dev);
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}
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rng_ctx = kmalloc(sizeof(*rng_ctx), GFP_DMA | GFP_KERNEL);
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if (!rng_ctx) {
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err = -ENOMEM;
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goto free_caam_alloc;
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}
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err = caam_init_rng(rng_ctx, dev);
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if (err)
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goto free_rng_ctx;
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dev_info(dev, "registering rng-caam\n");
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err = hwrng_register(&caam_rng);
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if (!err) {
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init_done = true;
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return err;
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}
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free_rng_ctx:
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kfree(rng_ctx);
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free_caam_alloc:
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caam_jr_free(dev);
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return err;
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}
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