[RFC PATCH v1 01/13] crypto: acomp - Add a poll() operation to acomp_alg and acomp_req

[Kanchana P Sridhar <kanchana.p.sridhar@intel.com>]

For async compress/decompress, provide a way for the caller to poll
for compress/decompress completion, rather than wait for an interrupt
to signal completion.

Callers can submit a compress/decompress using crypto_acomp_compress
and decompress and rather than wait on a completion, call
crypto_acomp_poll() to check for completion.

This is useful for hardware accelerators where the overhead of
interrupts and waiting for completions is too expensive.  Typically
the compress/decompress hw operations complete very quickly and in the
vast majority of cases, adding the overhead of interrupt handling and
waiting for completions simply adds unnecessary delays and cancels the
gains of using the hw acceleration.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@intel.com>
---
 crypto/acompress.c                  |  1 +
 include/crypto/acompress.h          | 18 ++++++++++++++++++
 include/crypto/internal/acompress.h |  1 +
 3 files changed, 20 insertions(+)

diff --git a/crypto/acompress.c b/crypto/acompress.c
index 6fdf0ff9f3c0..00ec7faa2714 100644
--- a/crypto/acompress.c
+++ b/crypto/acompress.c
@@ -71,6 +71,7 @@ static int crypto_acomp_init_tfm(struct crypto_tfm *tfm)
 
 	acomp->compress = alg->compress;
 	acomp->decompress = alg->decompress;
+	acomp->poll = alg->poll;
 	acomp->dst_free = alg->dst_free;
 	acomp->reqsize = alg->reqsize;
 
diff --git a/include/crypto/acompress.h b/include/crypto/acompress.h
index 54937b615239..65b5de30c8b1 100644
--- a/include/crypto/acompress.h
+++ b/include/crypto/acompress.h
@@ -51,6 +51,7 @@ struct acomp_req {
 struct crypto_acomp {
 	int (*compress)(struct acomp_req *req);
 	int (*decompress)(struct acomp_req *req);
+	int (*poll)(struct acomp_req *req);
 	void (*dst_free)(struct scatterlist *dst);
 	unsigned int reqsize;
 	struct crypto_tfm base;
@@ -265,4 +266,21 @@ static inline int crypto_acomp_decompress(struct acomp_req *req)
 	return crypto_acomp_reqtfm(req)->decompress(req);
 }
 
+/**
+ * crypto_acomp_poll() -- Invoke asynchronous poll operation
+ *
+ * Function invokes the asynchronous poll operation
+ *
+ * @req:	asynchronous request
+ *
+ * Return: zero on poll completion, -EAGAIN if not complete, or
+ *         error code in case of error
+ */
+static inline int crypto_acomp_poll(struct acomp_req *req)
+{
+	struct crypto_acomp *tfm = crypto_acomp_reqtfm(req);
+
+	return tfm->poll(req);
+}
+
 #endif
diff --git a/include/crypto/internal/acompress.h b/include/crypto/internal/acompress.h
index 8831edaafc05..fbf5f6c6eeb6 100644
--- a/include/crypto/internal/acompress.h
+++ b/include/crypto/internal/acompress.h
@@ -37,6 +37,7 @@
 struct acomp_alg {
 	int (*compress)(struct acomp_req *req);
 	int (*decompress)(struct acomp_req *req);
+	int (*poll)(struct acomp_req *req);
 	void (*dst_free)(struct scatterlist *dst);
 	int (*init)(struct crypto_acomp *tfm);
 	void (*exit)(struct crypto_acomp *tfm);
-- 
2.27.0