crypto/nx: Add sysfs interface to export NX capabilities

Export NX-GZIP capabilities to usrespace in sysfs
/sys/devices/vio/ibm,compression-v1/nx_gzip_caps directory.
These are queried by userspace accelerator libraries to set
minimum length heuristics and maximum limits on request sizes.

NX-GZIP capabilities:
min_compress_len  /*Recommended minimum compress length in bytes*/
min_decompress_len /*Recommended minimum decompress length in bytes*/
req_max_processed_len /* Maximum number of bytes processed in one
			request */

NX will return RMA_Reject if the request buffer size is greater
than req_max_processed_len.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/510da86abbd904878d5f13d74aba72603c37d783.camel@linux.ibm.com

diff --git a/drivers/crypto/nx/nx-common-pseries.c b/drivers/crypto/nx/nx-common-pseries.c
index 9fc2abb5601997dfea6a76242bc1744ab4e118f0..f51a50d40504386a4e5648f721af143171dab9ab 100644 (file)
--- a/drivers/crypto/nx/nx-common-pseries.c
+++ b/drivers/crypto/nx/nx-common-pseries.c
@@ -967,6 +967,36 @@ static struct attribute_group nx842_attribute_group = {
        .attrs = nx842_sysfs_entries,
 };
 
+#define        nxcop_caps_read(_name)                                          \
+static ssize_t nxcop_##_name##_show(struct device *dev,                        \
+                       struct device_attribute *attr, char *buf)       \
+{                                                                      \
+       return sprintf(buf, "%lld\n", nx_cop_caps._name);               \
+}
+
+#define NXCT_ATTR_RO(_name)                                            \
+       nxcop_caps_read(_name);                                         \
+       static struct device_attribute dev_attr_##_name = __ATTR(_name, \
+                                               0444,                   \
+                                               nxcop_##_name##_show,   \
+                                               NULL);
+
+NXCT_ATTR_RO(req_max_processed_len);
+NXCT_ATTR_RO(min_compress_len);
+NXCT_ATTR_RO(min_decompress_len);
+
+static struct attribute *nxcop_caps_sysfs_entries[] = {
+       &dev_attr_req_max_processed_len.attr,
+       &dev_attr_min_compress_len.attr,
+       &dev_attr_min_decompress_len.attr,
+       NULL,
+};
+
+static struct attribute_group nxcop_caps_attr_group = {
+       .name   =       "nx_gzip_caps",
+       .attrs  =       nxcop_caps_sysfs_entries,
+};
+
 static struct nx842_driver nx842_pseries_driver = {
        .name =         KBUILD_MODNAME,
        .owner =        THIS_MODULE,
@@ -1056,6 +1086,16 @@ static int nx842_probe(struct vio_dev *viodev,
                goto error;
        }
 
+       if (caps_feat) {
+               if (sysfs_create_group(&viodev->dev.kobj,
+                                       &nxcop_caps_attr_group)) {
+                       dev_err(&viodev->dev,
+                               "Could not create sysfs NX capability entries\n");
+                       ret = -1;
+                       goto error;
+               }
+       }
+
        return 0;
 
 error_unlock:
@@ -1075,6 +1115,9 @@ static void nx842_remove(struct vio_dev *viodev)
        pr_info("Removing IBM Power 842 compression device\n");
        sysfs_remove_group(&viodev->dev.kobj, &nx842_attribute_group);
 
+       if (caps_feat)
+               sysfs_remove_group(&viodev->dev.kobj, &nxcop_caps_attr_group);
+
        crypto_unregister_alg(&nx842_pseries_alg);
 
        spin_lock_irqsave(&devdata_mutex, flags);