crypto: caam - Dynamic memory allocation for caam_rng_ctx object

This patch allocates memory from DMAable region to the caam_rng_ctx object,
earlier it had been statically allocated which resulted in errorneous
behaviour on inserting the caamrng module at the runtime.
Signed-off-by: Nitesh Lal <NiteshNarayanLal@freescale.com>
Acked-by: Ruchika Gupta <ruchika.gupta@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/caam/caamrng.c

@@ -76,7 +76,7 @@ struct caam_rng_ctx {
 	struct buf_data bufs[2];
 };
 
-static struct caam_rng_ctx rng_ctx;
+static struct caam_rng_ctx *rng_ctx;
 
 static inline void rng_unmap_buf(struct device *jrdev, struct buf_data *bd)
 {
@@ -137,7 +137,7 @@ static inline int submit_job(struct caam_rng_ctx *ctx, int to_current)
 
 static int caam_read(struct hwrng *rng, void *data, size_t max, bool wait)
 {
-	struct caam_rng_ctx *ctx = &rng_ctx;
+	struct caam_rng_ctx *ctx = rng_ctx;
 	struct buf_data *bd = &ctx->bufs[ctx->current_buf];
 	int next_buf_idx, copied_idx;
 	int err;
@@ -237,12 +237,12 @@ static void caam_cleanup(struct hwrng *rng)
 	struct buf_data *bd;
 
 	for (i = 0; i < 2; i++) {
-		bd = &rng_ctx.bufs[i];
+		bd = &rng_ctx->bufs[i];
 		if (atomic_read(&bd->empty) == BUF_PENDING)
 			wait_for_completion(&bd->filled);
 	}
 
-	rng_unmap_ctx(&rng_ctx);
+	rng_unmap_ctx(rng_ctx);
 }
 
 static void caam_init_buf(struct caam_rng_ctx *ctx, int buf_id)
@@ -273,8 +273,9 @@ static struct hwrng caam_rng = {
 
 static void __exit caam_rng_exit(void)
 {
-	caam_jr_free(rng_ctx.jrdev);
+	caam_jr_free(rng_ctx->jrdev);
 	hwrng_unregister(&caam_rng);
+	kfree(rng_ctx);
 }
 
 static int __init caam_rng_init(void)
@@ -286,7 +287,9 @@ static int __init caam_rng_init(void)
 		pr_err("Job Ring Device allocation for transform failed\n");
 		return PTR_ERR(dev);
 	}
-
+	rng_ctx = kmalloc(sizeof(struct caam_rng_ctx), GFP_DMA);
+	if (!rng_ctx)
+		return -ENOMEM;
 	caam_init_rng(&rng_ctx, dev);
 
 	dev_info(dev, "registering rng-caam\n");