1 // SPDX-License-Identifier: GPL-2.0+
3 * caam - Freescale FSL CAAM support for hw_random
5 * Copyright 2011 Freescale Semiconductor, Inc.
7 * Based on caamalg.c crypto API driver.
9 * relationship between job descriptors to shared descriptors:
11 * --------------- --------------
12 * | JobDesc #0 |-------------------->| ShareDesc |
13 * | *(buffer 0) | |------------->| (generate) |
14 * --------------- | | (move) |
16 * --------------- | --------------
17 * | JobDesc #1 |------|
21 * A job desc looks like this:
23 * ---------------------
25 * | ShareDesc Pointer |
28 * ---------------------
30 * The SharedDesc never changes, and each job descriptor points to one of two
31 * buffers for each device, from which the data will be copied into the
32 * requested destination
35 #include <linux/hw_random.h>
36 #include <linux/completion.h>
37 #include <linux/atomic.h>
43 #include "desc_constr.h"
48 * Maximum buffer size: maximum number of random, cache-aligned bytes that
49 * will be generated and moved to seq out ptr (extlen not allowed)
51 #define RN_BUF_SIZE (0xffff / L1_CACHE_BYTES * \
54 /* length of descriptors */
55 #define DESC_JOB_O_LEN (CAAM_CMD_SZ * 2 + CAAM_PTR_SZ * 2)
56 #define DESC_RNG_LEN (3 * CAAM_CMD_SZ)
58 /* Buffer, its dma address and lock */
60 u8 buf[RN_BUF_SIZE] ____cacheline_aligned;
62 struct completion filled;
63 u32 hw_desc[DESC_JOB_O_LEN];
64 #define BUF_NOT_EMPTY 0
66 #define BUF_PENDING 2 /* Empty, but with job pending --don't submit another */
70 /* rng per-device context */
73 dma_addr_t sh_desc_dma;
74 u32 sh_desc[DESC_RNG_LEN];
75 unsigned int cur_buf_idx;
77 struct buf_data bufs[2];
80 static struct caam_rng_ctx *rng_ctx;
82 static inline void rng_unmap_buf(struct device *jrdev, struct buf_data *bd)
85 dma_unmap_single(jrdev, bd->addr, RN_BUF_SIZE,
89 static inline void rng_unmap_ctx(struct caam_rng_ctx *ctx)
91 struct device *jrdev = ctx->jrdev;
94 dma_unmap_single(jrdev, ctx->sh_desc_dma,
95 desc_bytes(ctx->sh_desc), DMA_TO_DEVICE);
96 rng_unmap_buf(jrdev, &ctx->bufs[0]);
97 rng_unmap_buf(jrdev, &ctx->bufs[1]);
100 static void rng_done(struct device *jrdev, u32 *desc, u32 err, void *context)
104 bd = container_of(desc, struct buf_data, hw_desc[0]);
107 caam_jr_strstatus(jrdev, err);
109 atomic_set(&bd->empty, BUF_NOT_EMPTY);
110 complete(&bd->filled);
112 /* Buffer refilled, invalidate cache */
113 dma_sync_single_for_cpu(jrdev, bd->addr, RN_BUF_SIZE, DMA_FROM_DEVICE);
116 print_hex_dump(KERN_ERR, "rng refreshed buf@: ",
117 DUMP_PREFIX_ADDRESS, 16, 4, bd->buf, RN_BUF_SIZE, 1);
121 static inline int submit_job(struct caam_rng_ctx *ctx, int to_current)
123 struct buf_data *bd = &ctx->bufs[!(to_current ^ ctx->current_buf)];
124 struct device *jrdev = ctx->jrdev;
125 u32 *desc = bd->hw_desc;
128 dev_dbg(jrdev, "submitting job %d\n", !(to_current ^ ctx->current_buf));
129 init_completion(&bd->filled);
130 err = caam_jr_enqueue(jrdev, desc, rng_done, ctx);
132 complete(&bd->filled); /* don't wait on failed job*/
134 atomic_inc(&bd->empty); /* note if pending */
139 static int caam_read(struct hwrng *rng, void *data, size_t max, bool wait)
141 struct caam_rng_ctx *ctx = rng_ctx;
142 struct buf_data *bd = &ctx->bufs[ctx->current_buf];
143 int next_buf_idx, copied_idx;
146 if (atomic_read(&bd->empty)) {
147 /* try to submit job if there wasn't one */
148 if (atomic_read(&bd->empty) == BUF_EMPTY) {
149 err = submit_job(ctx, 1);
150 /* if can't submit job, can't even wait */
154 /* no immediate data, so exit if not waiting */
158 /* waiting for pending job */
159 if (atomic_read(&bd->empty))
160 wait_for_completion(&bd->filled);
163 next_buf_idx = ctx->cur_buf_idx + max;
164 dev_dbg(ctx->jrdev, "%s: start reading at buffer %d, idx %d\n",
165 __func__, ctx->current_buf, ctx->cur_buf_idx);
167 /* if enough data in current buffer */
168 if (next_buf_idx < RN_BUF_SIZE) {
169 memcpy(data, bd->buf + ctx->cur_buf_idx, max);
170 ctx->cur_buf_idx = next_buf_idx;
174 /* else, copy what's left... */
175 copied_idx = RN_BUF_SIZE - ctx->cur_buf_idx;
176 memcpy(data, bd->buf + ctx->cur_buf_idx, copied_idx);
177 ctx->cur_buf_idx = 0;
178 atomic_set(&bd->empty, BUF_EMPTY);
183 /* and use next buffer */
184 ctx->current_buf = !ctx->current_buf;
185 dev_dbg(ctx->jrdev, "switched to buffer %d\n", ctx->current_buf);
187 /* since there already is some data read, don't wait */
188 return copied_idx + caam_read(rng, data + copied_idx,
189 max - copied_idx, false);
192 static inline int rng_create_sh_desc(struct caam_rng_ctx *ctx)
194 struct device *jrdev = ctx->jrdev;
195 u32 *desc = ctx->sh_desc;
197 init_sh_desc(desc, HDR_SHARE_SERIAL);
199 /* Generate random bytes */
200 append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG);
203 append_seq_fifo_store(desc, RN_BUF_SIZE, FIFOST_TYPE_RNGSTORE);
205 ctx->sh_desc_dma = dma_map_single(jrdev, desc, desc_bytes(desc),
207 if (dma_mapping_error(jrdev, ctx->sh_desc_dma)) {
208 dev_err(jrdev, "unable to map shared descriptor\n");
212 print_hex_dump(KERN_ERR, "rng shdesc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
213 desc, desc_bytes(desc), 1);
218 static inline int rng_create_job_desc(struct caam_rng_ctx *ctx, int buf_id)
220 struct device *jrdev = ctx->jrdev;
221 struct buf_data *bd = &ctx->bufs[buf_id];
222 u32 *desc = bd->hw_desc;
223 int sh_len = desc_len(ctx->sh_desc);
225 init_job_desc_shared(desc, ctx->sh_desc_dma, sh_len, HDR_SHARE_DEFER |
228 bd->addr = dma_map_single(jrdev, bd->buf, RN_BUF_SIZE, DMA_FROM_DEVICE);
229 if (dma_mapping_error(jrdev, bd->addr)) {
230 dev_err(jrdev, "unable to map dst\n");
234 append_seq_out_ptr_intlen(desc, bd->addr, RN_BUF_SIZE, 0);
236 print_hex_dump(KERN_ERR, "rng job desc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
237 desc, desc_bytes(desc), 1);
242 static void caam_cleanup(struct hwrng *rng)
247 for (i = 0; i < 2; i++) {
248 bd = &rng_ctx->bufs[i];
249 if (atomic_read(&bd->empty) == BUF_PENDING)
250 wait_for_completion(&bd->filled);
253 rng_unmap_ctx(rng_ctx);
256 static int caam_init_buf(struct caam_rng_ctx *ctx, int buf_id)
258 struct buf_data *bd = &ctx->bufs[buf_id];
261 err = rng_create_job_desc(ctx, buf_id);
265 atomic_set(&bd->empty, BUF_EMPTY);
266 submit_job(ctx, buf_id == ctx->current_buf);
267 wait_for_completion(&bd->filled);
272 static int caam_init_rng(struct caam_rng_ctx *ctx, struct device *jrdev)
278 err = rng_create_sh_desc(ctx);
282 ctx->current_buf = 0;
283 ctx->cur_buf_idx = 0;
285 err = caam_init_buf(ctx, 0);
289 return caam_init_buf(ctx, 1);
292 static struct hwrng caam_rng = {
294 .cleanup = caam_cleanup,
298 static void __exit caam_rng_exit(void)
300 caam_jr_free(rng_ctx->jrdev);
301 hwrng_unregister(&caam_rng);
305 static int __init caam_rng_init(void)
308 struct device_node *dev_node;
309 struct platform_device *pdev;
310 struct device *ctrldev;
311 struct caam_drv_private *priv;
314 dev_node = of_find_compatible_node(NULL, NULL, "fsl,sec-v4.0");
316 dev_node = of_find_compatible_node(NULL, NULL, "fsl,sec4.0");
321 pdev = of_find_device_by_node(dev_node);
323 of_node_put(dev_node);
327 ctrldev = &pdev->dev;
328 priv = dev_get_drvdata(ctrldev);
329 of_node_put(dev_node);
332 * If priv is NULL, it's probably because the caam driver wasn't
333 * properly initialized (e.g. RNG4 init failed). Thus, bail out here.
338 /* Check for an instantiated RNG before registration */
339 if (!(rd_reg32(&priv->ctrl->perfmon.cha_num_ls) & CHA_ID_LS_RNG_MASK))
342 dev = caam_jr_alloc();
344 pr_err("Job Ring Device allocation for transform failed\n");
347 rng_ctx = kmalloc(sizeof(*rng_ctx), GFP_DMA | GFP_KERNEL);
350 goto free_caam_alloc;
352 err = caam_init_rng(rng_ctx, dev);
356 dev_info(dev, "registering rng-caam\n");
357 return hwrng_register(&caam_rng);
366 module_init(caam_rng_init);
367 module_exit(caam_rng_exit);
369 MODULE_LICENSE("GPL");
370 MODULE_DESCRIPTION("FSL CAAM support for hw_random API");
371 MODULE_AUTHOR("Freescale Semiconductor - NMG");