[PATCH 5/6] crypto: omap-aes: make fallback size configurable

[Tero Kristo <t-kristo@xxxxxx>]

Crypto driver fallback size can now be configured from userspace. This
allows optimizing the DMA usage based on use case. Detault fallback
size of 200 is still used.

Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
---
 drivers/crypto/omap-aes.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 47 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/omap-aes.c b/drivers/crypto/omap-aes.c
index fbec0a2..76bc94f 100644
--- a/drivers/crypto/omap-aes.c
+++ b/drivers/crypto/omap-aes.c
@@ -47,6 +47,8 @@
 static LIST_HEAD(dev_list);
 static DEFINE_SPINLOCK(list_lock);
 
+static int aes_fallback_sz = 200;
+
 #ifdef DEBUG
 #define omap_aes_read(dd, offset)				\
 ({								\
@@ -517,7 +519,7 @@ static int omap_aes_crypt(struct ablkcipher_request *req, unsigned long mode)
 		  !!(mode & FLAGS_ENCRYPT),
 		  !!(mode & FLAGS_CBC));
 
-	if (req->nbytes < 200) {
+	if (req->nbytes < aes_fallback_sz) {
 		SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback);
 
 		skcipher_request_set_tfm(subreq, ctx->fallback);
@@ -1029,6 +1031,44 @@ static int omap_aes_get_res_pdev(struct omap_aes_dev *dd,
 	return err;
 }
 
+static ssize_t fallback_show(struct device *dev, struct device_attribute *attr,
+			     char *buf)
+{
+	return sprintf(buf, "%d\n", aes_fallback_sz);
+}
+
+static ssize_t fallback_store(struct device *dev, struct device_attribute *attr,
+			      const char *buf, size_t size)
+{
+	ssize_t status;
+	long value;
+
+	status = kstrtol(buf, 0, &value);
+	if (status)
+		return status;
+
+	/* HW accelerator only works with buffers > 9 */
+	if (value < 9) {
+		dev_err(dev, "minimum fallback size 9\n");
+		return -EINVAL;
+	}
+
+	aes_fallback_sz = value;
+
+	return size;
+}
+
+static DEVICE_ATTR_RW(fallback);
+
+static struct attribute *omap_aes_attrs[] = {
+	&dev_attr_fallback.attr,
+	NULL,
+};
+
+static struct attribute_group omap_aes_attr_group = {
+	.attrs = omap_aes_attrs,
+};
+
 static int omap_aes_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -1159,6 +1199,12 @@ static int omap_aes_probe(struct platform_device *pdev)
 		}
 	}
 
+	err = sysfs_create_group(&dev->kobj, &omap_aes_attr_group);
+	if (err) {
+		dev_err(dev, "could not create sysfs device attrs\n");
+		goto err_aead_algs;
+	}
+
 	return 0;
 err_aead_algs:
 	for (i = dd->pdata->aead_algs_info->registered - 1; i >= 0; i--) {
-- 
1.9.1

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