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CAAM activation problem on I.MX6

Question asked by Aymen Boudguiga on May 19, 2014

Hi all,


I am trying to activate CAAM on I.MX6 (Nitrogen6x). I am using an Ubuntu (Linaro) image which I downloaded from the following link:, kernel version is 3.0.35. I compile CAAM driver as a loadable module.

When I load caam.ko with insmod, dmesg ouputs the following messages: 

caam caam.0: device ID = 0x0a16010000000000

caam caam.0: job rings = 2, qi = 0

alg: No test for authenc(hmac(md5),cbc(aes)) (authenc-hmac-md5-cbc-aes-caam)

caam caam.0: authenc-hmac-md5-cbc-aes-caam


In addition, /proc/crypto is updated with algorithms related to CAAM with a priority of 3000. Here is the example of SHA256 entry in /proc/crypto:

name     : sha256
driver   : sha256-caam
module   : kernel
priority : 3000
refcnt   : 1
selftest : passed
type     : ahash
async    : yes
blocksize: 64
digestsize: 32



In order to be sure that CAAM driver is well installed, I removed the kernel default SHA256 module so that the unique entry corresponding to SHA256, and kept in /proc/crypto, is the one with driver = sha256-caam.  Then, I coded a simple module using linux crypto API to compute a hash with SHA256. Here is my module init function (all the test module code is in attachment):

int init_module(void)


int nents = 0;

uint8_t *in, *h;

struct hash_desc desc;

struct crypto_hash *tfm;

struct scatterlist *sg;

int hashlen =  32;

int inlen = 1000;


        MODULE_DESCRIPTION("Scatterlist crypto API: hash test");



        printk(KERN_INFO "\n**Scatterlist crypto API: sha256 test start**\n");

        printk(KERN_INFO "**Build date: " BUILD_DATE "**\n\n");

          in = kmalloc(inlen * sizeof(uint8_t), GFP_KERNEL);

        if (IS_ERR(in)) {

            printk("\n*error::input allocation failure\n");

            return 0;


        get_random_bytes(in, inlen);

        nents = sg_init(inlen, in, &sg);

            tfm = crypto_alloc_hash("sha256", 0, CRYPTO_ALG_ASYNC);

        if (IS_ERR(tfm)) {

            printk("\n*error::failed to load sha256-caam transform\n");


        else {

            desc.tfm = tfm;

            desc.flags = 0;


            h = kmalloc(hashlen * sizeof(uint8_t), GFP_KERNEL);

            if (IS_ERR(h)) {

                printk("\n*error::output allocation failure\n");

                return 0;   


            memset(h, 0, hashlen);

            crypto_hash_digest(&desc, sg, inlen, h);

            khexdump(hashlen, h);





        sg_free(sg, nents);   


return 0;


My problem is that after loading this SHA256 test module, I get as output the following error:  "failed to load sha256-caam transform". That is, crypto_alloc_hash() was not able to return a transform corresponding to the CAAM based SHA256.

However, when I load the kernel default SHA256 module (default sha256.ko) and then re-insert my test module (sha256_test.ko), I get a good SHA256 output. That is, kernel SHA256 (priority = 0) is executed instead of CAAM-SHA256 (priority = 3000).

Note that I took SHA256 as an example but CAAM is not working for any crypto algorithm.

I would be grateful for any hint about the origin of this problem. 


Best regards,


Original Attachment has been moved to: sha256_test.tar