crypto: omap-aes - Don't idle/start AES device between Encrypt operations

Calling runtime PM API for every block causes serious perf hit to
crypto operations that are done on a long buffer.
As crypto is performed on a page boundary, encrypting large buffers can
cause a series of crypto operations divided by page. The runtime PM API
is also called those many times.

We call runtime_pm_get_sync only at beginning on the session (cra_init)
and runtime_pm_put at the end. This result in upto a 50% speedup as below.
This doesn't make the driver to keep the system awake as runtime get/put
is only called during a crypto session which completes usually quickly.

Before:
root@beagleboard:~# time -v openssl speed -evp aes-128-cbc
Doing aes-128-cbc for 3s on 16 size blocks: 13310 aes-128-cbc's in 0.01s
Doing aes-128-cbc for 3s on 64 size blocks: 13040 aes-128-cbc's in 0.04s
Doing aes-128-cbc for 3s on 256 size blocks: 9134 aes-128-cbc's in 0.03s
Doing aes-128-cbc for 3s on 1024 size blocks: 8939 aes-128-cbc's in 0.01s
Doing aes-128-cbc for 3s on 8192 size blocks: 4299 aes-128-cbc's in 0.00s

After:
root@beagleboard:~# time -v openssl speed -evp aes-128-cbc
Doing aes-128-cbc for 3s on 16 size blocks: 18911 aes-128-cbc's in 0.02s
Doing aes-128-cbc for 3s on 64 size blocks: 18878 aes-128-cbc's in 0.02s
Doing aes-128-cbc for 3s on 256 size blocks: 11878 aes-128-cbc's in 0.10s
Doing aes-128-cbc for 3s on 1024 size blocks: 11538 aes-128-cbc's in 0.05s
Doing aes-128-cbc for 3s on 8192 size blocks: 4857 aes-128-cbc's in 0.03s

While at it, also drop enter and exit pr_debugs, in related code. tracers
can be used for that.

Tested on a Beaglebone (AM335x SoC) board.

Signed-off-by: Joel A Fernandes <joelagnel@ti.com>
Acked-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/omap-aes.c

@@ -203,13 +203,6 @@ static void omap_aes_write_n(struct omap_aes_dev *dd, u32 offset,
 
 static int omap_aes_hw_init(struct omap_aes_dev *dd)
 {
-	/*
-	 * clocks are enabled when request starts and disabled when finished.
-	 * It may be long delays between requests.
-	 * Device might go to off mode to save power.
-	 */
-	pm_runtime_get_sync(dd->dev);
-
 	if (!(dd->flags & FLAGS_INIT)) {
 		dd->flags |= FLAGS_INIT;
 		dd->err = 0;
@@ -636,7 +629,6 @@ static void omap_aes_finish_req(struct omap_aes_dev *dd, int err)
 
 	pr_debug("err: %d\n", err);
 
-	pm_runtime_put(dd->dev);
 	dd->flags &= ~FLAGS_BUSY;
 
 	req->base.complete(&req->base, err);
@@ -837,8 +829,16 @@ static int omap_aes_ctr_decrypt(struct ablkcipher_request *req)
 
 static int omap_aes_cra_init(struct crypto_tfm *tfm)
 {
-	pr_debug("enter\n");
+	struct omap_aes_dev *dd = NULL;
+
+	/* Find AES device, currently picks the first device */
+	spin_lock_bh(&list_lock);
+	list_for_each_entry(dd, &dev_list, list) {
+		break;
+	}
+	spin_unlock_bh(&list_lock);
 
+	pm_runtime_get_sync(dd->dev);
 	tfm->crt_ablkcipher.reqsize = sizeof(struct omap_aes_reqctx);
 
 	return 0;
@@ -846,7 +846,16 @@ static int omap_aes_cra_init(struct crypto_tfm *tfm)
 
 static void omap_aes_cra_exit(struct crypto_tfm *tfm)
 {
-	pr_debug("enter\n");
+	struct omap_aes_dev *dd = NULL;
+
+	/* Find AES device, currently picks the first device */
+	spin_lock_bh(&list_lock);
+	list_for_each_entry(dd, &dev_list, list) {
+		break;
+	}
+	spin_unlock_bh(&list_lock);
+
+	pm_runtime_put_sync(dd->dev);
 }
 
 /* ********************** ALGS ************************************ */