This skeleton should be a good start for everyone who is still looking for
the documentation :)
The code is based mainly on Herbert's crypto/cryptd.c. The obvious
difference is, that it does not wrap around the complete argument.
As mentioned in the code, process_requests_thread() could be optimized to
call blkcipher_crypt() directly with the parameter (and remove the
function pointer).
Sebastian
Index: linux/crypto/async_drv_skeleton.c
===================================================================
--- /dev/null
+++ linux/crypto/async_drv_skeleton.c
@@ -0,0 +1,402 @@
+/*
+ * Template for async crypto HW
+ *
+ * Code is based mainly on the crypto/cryptd.c code
+ */
+
+#include <crypto/algapi.h>
+#include <linux/module.h>
+#include <linux/crypto.h>
+#include <linux/mutex.h>
+#include <linux/err.h>
+#include <linux/list.h>
+#include <asm/byteorder.h>
+#include <asm/system.h>
+#include <linux/delay.h>
+#include <linux/spinlock.h>
+#include <linux/kthread.h>
+
+
+#define CRYPTO_MAX_QLEN 101
+
+/* not to use the HW twice at the same time */
+struct hw_work_ctx {
+ struct hw_context *hw_ctx;
+ struct mutex mutex;
+};
+
+static struct hw_work_ctx work_ctx;
+
+struct algo_ctx_t {
+ char key[42];
+ int keylen;
+};
+
+#define ALGO_MIN_KEY_SIZE 16
+#define ALGO_MAX_KEY_SIZE 32
+#define ALGO_BLOCKSIZE 16
+
+/* hardware functions */
+#define HW_DECRYPT_ECB 0xbeef
+#define HW_ENCRYPT_ECB 0xbabe
+
+static int hw_set_key(struct hw_context *hw_ctx, const char *inkey, int keylen,
+ char *outkey)
+{
+ return 1;
+}
+
+static int hw_crypt_process(int operation_type, const char *key, const char
*inbuf,
+ char *outbuf, unsigned long size)
+{
+ return 2;
+}
+static void *get_hw_ctx(void)
+{
+ return NULL;
+}
+
+static void free_hw_ctx(struct hw_context *hw_ctx)
+{
+ return;
+}
+
+/* algo -> HW */
+static int _algo_set_key(struct algo_ctx_t *ctx, const u8 *in_key,
+ unsigned int key_len)
+{
+ int ret;
+
+ switch (key_len) {
+ case 16:
+ case 24:
+ case 32:
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ mutex_lock(&work_ctx.mutex);
+
+ ctx->keylen = key_len / 4;
+ ret = hw_set_key(work_ctx.hw_ctx, in_key, key_len, ctx->key);
+ if (ret < 0) {
+ printk("%s() failed\n", __FUNCTION__);
+ }
+
+ mutex_unlock(&work_ctx.mutex);
+ return ret < 0 ? ret : 0;
+}
+
+/*
+ * this is from s390's AES
+ */
+static int mode_algo_crypt(struct blkcipher_desc *desc, struct scatterlist
*dst,
+ struct scatterlist *src, unsigned int nbytes, int op_type)
+{
+ struct algo_ctx_t *algo_ctx = crypto_blkcipher_ctx(desc->tfm);
+ struct blkcipher_walk walk;
+ u8 *out, *in;
+ int ret;
+
+ blkcipher_walk_init(&walk, dst, src, nbytes);
+ ret = blkcipher_walk_virt(desc, &walk);
+
+ while ((nbytes = walk.nbytes)) {
+ /* only use complete blocks */
+ unsigned int n = nbytes & ~(15);
+
+ out = walk.dst.virt.addr;
+ in = walk.src.virt.addr;
+
+ printk("%s(): processing data from %p to %p (%d bytes)\n",
__FUNCTION__,
+ in, out, n);
+
+ mutex_lock(&work_ctx.mutex);
+
+ ret = hw_crypt_process(op_type, algo_ctx->key, in, out, n);
+ mutex_unlock(&work_ctx.mutex);
+
+ if (ret < 0) {
+ printk("hw_crypt error: %d\n", ret);
+ }
+
+ nbytes &= 15;
+ ret = blkcipher_walk_done(desc, &walk, nbytes);
+ }
+ return ret;
+}
+
+/* per ablk cipher data */
+struct async_algo_state {
+ spinlock_t queue_spinlock;
+ struct mutex queue_mutex;
+ struct crypto_queue requests_queue;
+ struct task_struct *requests_thread;
+};
+
+/* per request struct */
+struct async_d_request {
+ crypto_completion_t crypto_complete;
+};
+
+static struct async_algo_state algo_state;
+
+/* set key is NOT async */
+static int algo_set_key_async(struct crypto_ablkcipher *parent,
+ const u8 *key, unsigned int keylen)
+{
+ struct algo_ctx_t *ctx = crypto_ablkcipher_ctx(parent);
+
+ return _algo_set_key(ctx, key, keylen);
+}
+
+static void blkcipher_crypt(struct ablkcipher_request *req,
+ struct algo_ctx_t *ctx,
+ int err,
+ int op_type)
+{
+ struct blkcipher_desc desc;
+
+ printk("%s()\n", __FUNCTION__);
+ if (unlikely(err == -EINPROGRESS)) {
+ printk("err = -EINPROGRESS in %s\n", __FUNCTION__);
+ req->base.complete(&req->base, err);
+ return;
+ }
+
+ /*
+ * desc is required by crypto's scatter code.
+ * info is the IV.
+ */
+ desc.tfm = crypto_blkcipher_cast(req->base.tfm);
+ desc.info = req->info;
+ desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+
+ err = mode_algo_crypt(&desc, req->dst, req->src, req->nbytes, op_type);
+
+ local_bh_disable();
+ /*
+ * call the crypto user and inform him about his request
+ */
+ req->base.complete(&req->base, err);
+ local_bh_enable();
+}
+
+/*
+ * the next two are called from the working thread
+ * ([a_d_ctx|a_d_backreq]->crypto_complete). This could be optimized by calling
+ * blkcipher_crypt() directly with the special parameter
+ */
+static void algo_request_encrypt (struct crypto_async_request *req, int err)
+{
+ struct algo_ctx_t *ctx = crypto_tfm_ctx(req->tfm);
+
+ blkcipher_crypt(ablkcipher_request_cast(req), ctx, err, HW_ENCRYPT_ECB);
+}
+
+static void algo_request_decrypt (struct crypto_async_request *req, int err)
+{
+ struct algo_ctx_t *ctx = crypto_tfm_ctx(req->tfm);
+
+ blkcipher_crypt(ablkcipher_request_cast(req), ctx, err, HW_DECRYPT_ECB);
+}
+
+/*
+ * queue one request and wakeup work thread
+ */
+static int enqueue_request(struct ablkcipher_request *req,
+ crypto_completion_t complete)
+{
+ struct async_d_request *asy_d_ctx = ablkcipher_request_ctx(req);
+ struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
+ int ret;
+
+ asy_d_ctx->crypto_complete = complete;
+
+ spin_lock_bh(&algo_state.queue_spinlock);
+ ret = ablkcipher_enqueue_request(crypto_ablkcipher_alg(tfm), req);
+ spin_unlock_bh(&algo_state.queue_spinlock);
+
+ wake_up_process(algo_state.requests_thread);
+ return ret;
+}
+
+/*
+ * called from crypto user. We queue the crypto function + request.
+ * Crypto request is stored in our per request struct.
+ */
+static int algo_encrypt_ecb_async(struct ablkcipher_request *req)
+{
+
+ return enqueue_request(req, algo_request_encrypt);
+}
+
+static int algo_decrypt_ecb_async(struct ablkcipher_request *req)
+{
+
+ return enqueue_request(req, algo_request_decrypt);
+}
+
+static int async_d_init(struct crypto_tfm *tfm)
+{
+ /* important to save request specific data */
+ printk("currently in %s()\n", __FUNCTION__);
+ tfm->crt_ablkcipher.reqsize = sizeof(struct async_d_request);
+ return 0;
+}
+
+static void async_d_exit(struct crypto_tfm *tfm)
+{
+ printk("currently in %s()\n", __FUNCTION__);
+}
+
+static void async_d_destory(struct crypto_alg *alg)
+{
+ printk("currently in %s()\n", __FUNCTION__);
+}
+
+static struct crypto_alg algo_ecb_alg_async = {
+ .cra_name = "ecb(algo)",
+ .cra_driver_name = "ecb-algohw-async",
+ .cra_priority = 123,
+ .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_ASYNC,
+ .cra_blocksize = ALGO_BLOCKSIZE,
+ .cra_alignmask = 15,
+ .cra_ctxsize = sizeof(struct algo_ctx_t),
+ .cra_type = &crypto_ablkcipher_type,
+ .cra_module = THIS_MODULE,
+ .cra_list = LIST_HEAD_INIT(algo_ecb_alg_async.cra_list),
+ .cra_init = async_d_init,
+ .cra_exit = async_d_exit,
+ .cra_destroy = async_d_destory,
+ .cra_u = {
+ .ablkcipher = {
+ .min_keysize = ALGO_MIN_KEY_SIZE,
+ .max_keysize = ALGO_MAX_KEY_SIZE,
+ .ivsize = 0,
+ .setkey = algo_set_key_async,
+ .encrypt = algo_encrypt_ecb_async,
+ .decrypt = algo_decrypt_ecb_async,
+ .queue = &algo_state.requests_queue,
+ }
+ }
+};
+
+static int process_requests_thread(void *data) {
+
+ struct async_algo_state *state = data;
+ int stop;
+ struct crypto_async_request *req, *backlog;
+ struct ablkcipher_request *ablk_req;
+ struct async_d_request *a_d_ctx, *a_d_backreq;
+
+ printk("thread active\n");
+ do {
+ printk("%s(): Starting request\n", __FUNCTION__);
+ mutex_lock(&state->queue_mutex);
+ __set_current_state(TASK_INTERRUPTIBLE);
+
+ spin_lock_bh(&state->queue_spinlock);
+ backlog = crypto_get_backlog(&state->requests_queue);
+ req = crypto_dequeue_request(&state->requests_queue);
+ spin_unlock_bh(&state->queue_spinlock);
+
+ printk("backlog: %p, req: %p\n", backlog, req);
+
+ stop = kthread_should_stop();
+
+ if (stop || req) {
+
+ __set_current_state(TASK_RUNNING);
+ if (req) {
+ if (backlog) {
+ ablk_req =
ablkcipher_request_cast(backlog);
+ a_d_backreq =
ablkcipher_request_ctx(ablk_req);
+ a_d_backreq->crypto_complete(backlog,
-EINPROGRESS);
+ }
+
+ ablk_req = ablkcipher_request_cast(req);
+ a_d_ctx = ablkcipher_request_ctx(ablk_req);
+ a_d_ctx->crypto_complete(req, 0);
+ }
+ }
+
+ mutex_unlock(&state->queue_mutex);
+ schedule();
+
+ } while(!stop);
+
+ return 0;
+}
+
+static int async_api_init(void) {
+ int ret;
+
+ crypto_init_queue(&algo_state.requests_queue, CRYPTO_MAX_QLEN);
+ mutex_init(&algo_state.queue_mutex);
+ spin_lock_init(&algo_state.queue_spinlock);
+
+ algo_state.requests_thread = kthread_create(process_requests_thread,
&algo_state, "cryptoHW");
+ if (IS_ERR(algo_state.requests_thread)) {
+ printk("kthread_create() failed: %ld\n",
PTR_ERR(algo_state.requests_thread));
+ return PTR_ERR(algo_state.requests_thread);
+ }
+
+ ret = crypto_register_alg(&algo_ecb_alg_async);
+ if (ret) {
+ printk("crypto_register_alg() failed: %d\n", ret);
+ kthread_stop(algo_state.requests_thread);
+ return ret;
+ }
+
+ return 0;
+}
+static int async_api_fini(void) {
+
+ /*
+ * thread should not be busy anymore, nor should receive any
+ * further requests
+ */
+ BUG_ON(algo_state.requests_queue.qlen);
+ crypto_unregister_alg(&algo_ecb_alg_async);
+ kthread_stop(algo_state.requests_thread);
+ return 0;
+}
+
+static int __init algo_init(void)
+{
+ unsigned int ret;
+
+ work_ctx.hw_ctx = get_hw_ctx();
+
+ if (IS_ERR(work_ctx.hw_ctx)) {
+ ret = PTR_ERR(work_ctx.hw_ctx);
+ printk("Can't get HW: %d\n", ret);
+ return ret;
+ }
+ mutex_init(&work_ctx.mutex);
+
+ ret = async_api_init();
+ if (ret) {
+ printk("async_api_init() failed\n");
+ goto out_ctx;
+ }
+ return 0;
+out_ctx:
+ free_hw_ctx(work_ctx.hw_ctx);
+ return ret;
+}
+
+static void __exit algo_fini(void)
+{
+ async_api_fini();
+ free_hw_ctx(work_ctx.hw_ctx);
+}
+
+module_init(algo_init);
+module_exit(algo_fini);
+
+MODULE_DESCRIPTION("Skeleton for ASYNC crypto driver");
+MODULE_LICENSE("GPL");
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