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 (4 * CAAM_CMD_SZ)
56
57 /* Buffer, its dma address and lock */
58 struct buf_data {
59 u8 buf[RN_BUF_SIZE] ____cacheline_aligned;
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
rng_unmap_buf(struct device * jrdev,struct buf_data * bd)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
rng_unmap_ctx(struct caam_rng_ctx * ctx)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,
94 desc_bytes(ctx->sh_desc), DMA_TO_DEVICE);
95 rng_unmap_buf(jrdev, &ctx->bufs[0]);
96 rng_unmap_buf(jrdev, &ctx->bufs[1]);
97 }
98
rng_done(struct device * jrdev,u32 * desc,u32 err,void * context)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 caam_jr_strstatus(jrdev, err);
108
109 atomic_set(&bd->empty, BUF_NOT_EMPTY);
110 complete(&bd->filled);
111
112 /* Buffer refilled, invalidate cache */
113 dma_sync_single_for_cpu(jrdev, bd->addr, RN_BUF_SIZE, DMA_FROM_DEVICE);
114
115 #ifdef DEBUG
116 print_hex_dump(KERN_ERR, "rng refreshed buf@: ",
117 DUMP_PREFIX_ADDRESS, 16, 4, bd->buf, RN_BUF_SIZE, 1);
118 #endif
119 }
120
submit_job(struct caam_rng_ctx * ctx,int to_current)121 static inline int submit_job(struct caam_rng_ctx *ctx, int to_current)
122 {
123 struct buf_data *bd = &ctx->bufs[!(to_current ^ ctx->current_buf)];
124 struct device *jrdev = ctx->jrdev;
125 u32 *desc = bd->hw_desc;
126 int err;
127
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);
131 if (err)
132 complete(&bd->filled); /* don't wait on failed job*/
133 else
134 atomic_inc(&bd->empty); /* note if pending */
135
136 return err;
137 }
138
caam_read(struct hwrng * rng,void * data,size_t max,bool wait)139 static int caam_read(struct hwrng *rng, void *data, size_t max, bool wait)
140 {
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;
144 int err;
145
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 */
151 if (err)
152 return 0;
153 }
154 /* no immediate data, so exit if not waiting */
155 if (!wait)
156 return 0;
157
158 /* waiting for pending job */
159 if (atomic_read(&bd->empty))
160 wait_for_completion(&bd->filled);
161 }
162
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);
166
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;
171 return max;
172 }
173
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);
179
180 /* ...refill... */
181 submit_job(ctx, 1);
182
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);
186
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);
190 }
191
rng_create_sh_desc(struct caam_rng_ctx * ctx)192 static inline int rng_create_sh_desc(struct caam_rng_ctx *ctx)
193 {
194 struct device *jrdev = ctx->jrdev;
195 u32 *desc = ctx->sh_desc;
196
197 init_sh_desc(desc, HDR_SHARE_SERIAL);
198
199 /* Propagate errors from shared to job descriptor */
200 append_cmd(desc, SET_OK_NO_PROP_ERRORS | CMD_LOAD);
201
202 /* Generate random bytes */
203 append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG);
204
205 /* Store bytes */
206 append_seq_fifo_store(desc, RN_BUF_SIZE, FIFOST_TYPE_RNGSTORE);
207
208 ctx->sh_desc_dma = dma_map_single(jrdev, desc, desc_bytes(desc),
209 DMA_TO_DEVICE);
210 if (dma_mapping_error(jrdev, ctx->sh_desc_dma)) {
211 dev_err(jrdev, "unable to map shared descriptor\n");
212 return -ENOMEM;
213 }
214 #ifdef DEBUG
215 print_hex_dump(KERN_ERR, "rng shdesc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
216 desc, desc_bytes(desc), 1);
217 #endif
218 return 0;
219 }
220
rng_create_job_desc(struct caam_rng_ctx * ctx,int buf_id)221 static inline int rng_create_job_desc(struct caam_rng_ctx *ctx, int buf_id)
222 {
223 struct device *jrdev = ctx->jrdev;
224 struct buf_data *bd = &ctx->bufs[buf_id];
225 u32 *desc = bd->hw_desc;
226 int sh_len = desc_len(ctx->sh_desc);
227
228 init_job_desc_shared(desc, ctx->sh_desc_dma, sh_len, HDR_SHARE_DEFER |
229 HDR_REVERSE);
230
231 bd->addr = dma_map_single(jrdev, bd->buf, RN_BUF_SIZE, DMA_FROM_DEVICE);
232 if (dma_mapping_error(jrdev, bd->addr)) {
233 dev_err(jrdev, "unable to map dst\n");
234 return -ENOMEM;
235 }
236
237 append_seq_out_ptr_intlen(desc, bd->addr, RN_BUF_SIZE, 0);
238 #ifdef DEBUG
239 print_hex_dump(KERN_ERR, "rng job desc@: ", DUMP_PREFIX_ADDRESS, 16, 4,
240 desc, desc_bytes(desc), 1);
241 #endif
242 return 0;
243 }
244
caam_cleanup(struct hwrng * rng)245 static void caam_cleanup(struct hwrng *rng)
246 {
247 int i;
248 struct buf_data *bd;
249
250 for (i = 0; i < 2; i++) {
251 bd = &rng_ctx->bufs[i];
252 if (atomic_read(&bd->empty) == BUF_PENDING)
253 wait_for_completion(&bd->filled);
254 }
255
256 rng_unmap_ctx(rng_ctx);
257 }
258
caam_init_buf(struct caam_rng_ctx * ctx,int buf_id)259 static int caam_init_buf(struct caam_rng_ctx *ctx, int buf_id)
260 {
261 struct buf_data *bd = &ctx->bufs[buf_id];
262 int err;
263
264 err = rng_create_job_desc(ctx, buf_id);
265 if (err)
266 return err;
267
268 atomic_set(&bd->empty, BUF_EMPTY);
269 submit_job(ctx, buf_id == ctx->current_buf);
270 wait_for_completion(&bd->filled);
271
272 return 0;
273 }
274
caam_init_rng(struct caam_rng_ctx * ctx,struct device * jrdev)275 static int caam_init_rng(struct caam_rng_ctx *ctx, struct device *jrdev)
276 {
277 int err;
278
279 ctx->jrdev = jrdev;
280
281 err = rng_create_sh_desc(ctx);
282 if (err)
283 return err;
284
285 ctx->current_buf = 0;
286 ctx->cur_buf_idx = 0;
287
288 err = caam_init_buf(ctx, 0);
289 if (err)
290 return err;
291
292 err = caam_init_buf(ctx, 1);
293 if (err)
294 return err;
295
296 return 0;
297 }
298
299 static struct hwrng caam_rng = {
300 .name = "rng-caam",
301 .cleanup = caam_cleanup,
302 .read = caam_read,
303 };
304
caam_rng_exit(void)305 static void __exit caam_rng_exit(void)
306 {
307 caam_jr_free(rng_ctx->jrdev);
308 hwrng_unregister(&caam_rng);
309 kfree(rng_ctx);
310 }
311
caam_rng_init(void)312 static int __init caam_rng_init(void)
313 {
314 struct device *dev;
315 struct device_node *dev_node;
316 struct platform_device *pdev;
317 struct device *ctrldev;
318 struct caam_drv_private *priv;
319 int err;
320
321 dev_node = of_find_compatible_node(NULL, NULL, "fsl,sec-v4.0");
322 if (!dev_node) {
323 dev_node = of_find_compatible_node(NULL, NULL, "fsl,sec4.0");
324 if (!dev_node)
325 return -ENODEV;
326 }
327
328 pdev = of_find_device_by_node(dev_node);
329 if (!pdev) {
330 of_node_put(dev_node);
331 return -ENODEV;
332 }
333
334 ctrldev = &pdev->dev;
335 priv = dev_get_drvdata(ctrldev);
336 of_node_put(dev_node);
337
338 /*
339 * If priv is NULL, it's probably because the caam driver wasn't
340 * properly initialized (e.g. RNG4 init failed). Thus, bail out here.
341 */
342 if (!priv)
343 return -ENODEV;
344
345 /* Check for an instantiated RNG before registration */
346 if (!(rd_reg32(&priv->ctrl->perfmon.cha_num_ls) & CHA_ID_LS_RNG_MASK))
347 return -ENODEV;
348
349 dev = caam_jr_alloc();
350 if (IS_ERR(dev)) {
351 pr_err("Job Ring Device allocation for transform failed\n");
352 return PTR_ERR(dev);
353 }
354 rng_ctx = kmalloc(sizeof(*rng_ctx), GFP_DMA);
355 if (!rng_ctx) {
356 err = -ENOMEM;
357 goto free_caam_alloc;
358 }
359 err = caam_init_rng(rng_ctx, dev);
360 if (err)
361 goto free_rng_ctx;
362
363 dev_info(dev, "registering rng-caam\n");
364 return hwrng_register(&caam_rng);
365
366 free_rng_ctx:
367 kfree(rng_ctx);
368 free_caam_alloc:
369 caam_jr_free(dev);
370 return err;
371 }
372
373 module_init(caam_rng_init);
374 module_exit(caam_rng_exit);
375
376 MODULE_LICENSE("GPL");
377 MODULE_DESCRIPTION("FSL CAAM support for hw_random API");
378 MODULE_AUTHOR("Freescale Semiconductor - NMG");
379