4 files changed, 59 insertions, 0 deletions

diff --git a/drivers/crypto/nx/nx-842-pseries.c b/drivers/crypto/nx/nx-842-pseries.c
index 9b83c9e7fd73..cb481d81df06 100644
--- a/drivers/crypto/nx/nx-842-pseries.c
+++ b/drivers/crypto/nx/nx-842-pseries.c
@@ -40,6 +40,13 @@ MODULE_DESCRIPTION("842 H/W Compression driver for IBM Power processors");
 /* IO buffer must be 128 byte aligned */
 #define IO_BUFFER_ALIGN 128
 
+static struct nx842_constraints nx842_pseries_constraints = {
+	.alignment =	IO_BUFFER_ALIGN,
+	.multiple =	DDE_BUFFER_LAST_MULT,
+	.minimum =	IO_BUFFER_ALIGN,
+	.maximum =	PAGE_SIZE, /* dynamic, max_sync_size */
+};
+
 struct nx842_header {
 	int blocks_nr; /* number of compressed blocks */
 	int offset; /* offset of the first block (from beginning of header) */
@@ -842,6 +849,8 @@ static int nx842_OF_upd_maxsyncop(struct nx842_devdata *devdata,
 		goto out;
 	}
 
+	nx842_pseries_constraints.maximum = devdata->max_sync_size;
+
 	devdata->max_sync_sg = (unsigned int)min(maxsynccop->comp_sg_limit,
 						maxsynccop->decomp_sg_limit);
 	if (devdata->max_sync_sg < 1) {
@@ -1115,6 +1124,7 @@ static struct attribute_group nx842_attribute_group = {
 
 static struct nx842_driver nx842_pseries_driver = {
 	.owner =	THIS_MODULE,
+	.constraints =	&nx842_pseries_constraints,
 	.compress =	nx842_pseries_compress,
 	.decompress =	nx842_pseries_decompress,
 };
diff --git a/drivers/crypto/nx/nx-842.c b/drivers/crypto/nx/nx-842.c
index f1f378eef373..160fe2d97336 100644
--- a/drivers/crypto/nx/nx-842.c
+++ b/drivers/crypto/nx/nx-842.c
@@ -86,6 +86,44 @@ static void put_driver(struct nx842_driver *driver)
 	module_put(driver->owner);
 }
 
+/**
+ * nx842_constraints
+ *
+ * This provides the driver's constraints.  Different nx842 implementations
+ * may have varying requirements.  The constraints are:
+ *   @alignment:	All buffers should be aligned to this
+ *   @multiple:		All buffer lengths should be a multiple of this
+ *   @minimum:		Buffer lengths must not be less than this amount
+ *   @maximum:		Buffer lengths must not be more than this amount
+ *
+ * The constraints apply to all buffers and lengths, both input and output,
+ * for both compression and decompression, except for the minimum which
+ * only applies to compression input and decompression output; the
+ * compressed data can be less than the minimum constraint.  It can be
+ * assumed that compressed data will always adhere to the multiple
+ * constraint.
+ *
+ * The driver may succeed even if these constraints are violated;
+ * however the driver can return failure or suffer reduced performance
+ * if any constraint is not met.
+ */
+int nx842_constraints(struct nx842_constraints *c)
+{
+	struct nx842_driver *driver = get_driver();
+	int ret = 0;
+
+	if (!driver)
+		return -ENODEV;
+
+	BUG_ON(!c);
+	memcpy(c, driver->constraints, sizeof(*c));
+
+	put_driver(driver);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nx842_constraints);
+
 int nx842_compress(const unsigned char *in, unsigned int in_len,
 		   unsigned char *out, unsigned int *out_len,
 		   void *wrkmem)
diff --git a/drivers/crypto/nx/nx-842.h b/drivers/crypto/nx/nx-842.h
index 2a5d4e197c72..c6ceb0f1d04c 100644
--- a/drivers/crypto/nx/nx-842.h
+++ b/drivers/crypto/nx/nx-842.h
@@ -12,6 +12,8 @@
 struct nx842_driver {
 	struct module *owner;
 
+	struct nx842_constraints *constraints;
+
 	int (*compress)(const unsigned char *in, unsigned int in_len,
 			unsigned char *out, unsigned int *out_len,
 			void *wrkmem);
diff --git a/include/linux/nx842.h b/include/linux/nx842.h
index d919c22b7fd6..aa1a97e90dea 100644
--- a/include/linux/nx842.h
+++ b/include/linux/nx842.h
@@ -5,6 +5,15 @@
 
 #define NX842_MEM_COMPRESS	__NX842_PSERIES_MEM_COMPRESS
 
+struct nx842_constraints {
+	int alignment;
+	int multiple;
+	int minimum;
+	int maximum;
+};
+
+int nx842_constraints(struct nx842_constraints *constraints);
+
 int nx842_compress(const unsigned char *in, unsigned int in_len,
 		   unsigned char *out, unsigned int *out_len, void *wrkmem);
 int nx842_decompress(const unsigned char *in, unsigned int in_len,