Re: [uclinux-dist-devel] [PATCH 2/2] crypto: bfin_crc: CRC hardware accelerator driver for BF60x family processors.

On Friday 25 May 2012 05:54:14 Sonic Zhang wrote:

hardware

+	depends on BF60x
+	help
+	  Blackfin processors have CRC hardware accelerator.

Newer Blackfin processors have a CRC hardware accelerator.

static

+	if (sg_count(req->src) > CRC_MAX_DMA_DESC) {
+		dev_dbg(crc->dev, "init: requested sg list is too big > %d\n",
+			CRC_MAX_DMA_DESC);
+		return -EINVAL;
+	}

do you need to do this ?  considering the crc is stream based, why can't you 
fill up as many as possible, wait for it to finish, and then send more data ?

+	/* init crc results */
+	*(__le32 *)req->result =
+		cpu_to_le32p(&crc_ctx->key);

right handed casts are generally frowned upon if not banned.  plus, result is 
a u8*, so it seems like a pretty bad idea to do this on a Blackfin (which 
doesn't allow unaligned accesses).  isn't this what you want:
	put_unaligned_le32(crc_ctx->key, req->result);

+		/* chop current sg dma len to multiply of 32 bits */

"multiply" -> "multiple"

+		dma_count = (dma_count >> 2) << 2;

dma_count &= ~0x3;

+	if (i == 0)
+		return ;

no space before the ;

+#define MIN(x,y) ((x) < (y) ? x : y)

linux/kernel.h already provides min() macros for you

+		/* Pack small data which is less than 32bit to buffer for next 

update.*/

needs a space after the period

+		/* punch crc buffer size to multiply of 32 bit */

i think you mean "chop" rather than "punch", and it should be "multiple" 
rather than "multiply"

+		ctx->sg_buflen = (ctx->sg_buflen >> 2) << 2;

ctx->sg_buflen &= ~0x3;

+			memset(ctx->bufnext, 0,	CHKSUM_DIGEST_SIZE);

use a space after the , not a tab

+			nextlen = ctx->bufnext_len;
+			for (i = nsg - 1; i >= 0; i--) {
+				sg = sg_get(ctx->sg, nsg, i);

this is the only place you use sg_get(), and it looks like it's extremely 
inefficient.  i guess it's not possible to re-order the pointer walking though.

+static int bfin_crypto_crc_setkey(struct crypto_ahash *tfm, const u8 *key,
+		      unsigned int keylen)
+{
+	struct bfin_crypto_crc_ctx *crc_ctx = crypto_ahash_ctx(tfm);
+
+	dev_dbg(crc_ctx->crc->dev, "crc_setkey\n");
+        if (keylen != CHKSUM_DIGEST_SIZE) {
+                crypto_ahash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
+                return -EINVAL;
+        }

indentation seems to be off here.  suggest you run this through checkpatch.pl.

+	crc_ctx->key = le32_to_cpu(*(__le32 *)key);

shouldn't this be get_unaligned_le32 ?

+		/* prepare results */
+		*(__le32 *)crc->req->result =
+			cpu_to_le32p((u32 *)&crc->regs->result);

put_unaligned_le32()

+static int bfin_crypto_crc_suspend(struct platform_device *pdev,
pm_message_t state) +{
+	struct bfin_crypto_crc *crc = platform_get_drvdata(pdev);
+	int i = 100000;
+
+	while ((crc->regs->control & BLKEN) && --i)
+		cpu_relax();
+
+	if (i == 0)
+		crc->regs->control &= ~BLKEN;
+
+	return 0;
+}

should this return -EBUSY instead of clearing BLKEN ?

+static int bfin_crypto_crc_resume(struct platform_device *pdev)
+{
+	return 0;
+}

if there's nothing to resume, do you need to provide your own func ?

+static int __devinit bfin_crypto_crc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	struct bfin_crypto_crc *crc = NULL;

not much point in setting this to NULL considering the first thing you do is 
allocate it

+	ret = request_irq(crc->irq, bfin_crypto_crc_handler, IRQF_SHARED,
DRIVER_NAME, crc);

you could use dev_name() rather than DRIVER_NAME

+	ret = request_dma(crc->dma_ch, DRIVER_NAME);

same here

+	/* need at most CRC_MAX_DMA_DESC sg + CRC_MAX_DMA_DESC middle  +
+	   1 last + 1 next dma descriptors
+	 */

multiline comments look like:
	/*
	 * foo
	 * bar
	 */

+	while (!(crc->regs->status & LUTDONE) && (--timeout) > 0)
+		cpu_relax();

no need for paren around the timeout decrement, and this should be an actual 
timer based timeout rather than some big integer.  pretty easy to do with 
wait_for_completion_timeout().

+static int __devexit bfin_crypto_crc_remove(struct platform_device *pdev)
+{
+	struct bfin_crypto_crc *crc = platform_get_drvdata(pdev);
+
+	if (!crc)
+		return -ENODEV;

is this even possible ?

+static int __init bfin_crypto_crc_mod_init(void)
+{
+	int ret;
+
+	pr_info("Blackfin hardware CRC crypto driver\n");
+
+	INIT_LIST_HEAD(&crc_list.dev_list);
+	spin_lock_init(&crc_list.lock);
+
+	ret = platform_driver_register(&bfin_crypto_crc_driver);
+	if (ret) {
+		pr_info(KERN_ERR "unable to register driver\n");
+		return ret;
+	}
+
+	return 0;
+}

if you declare the list/spin_lock separately and not together in a structure, 
you could statically initialize them (rather than needing to do it at 
runtime), and then you could drop the init/exit functions here and replace 
them with a single module_platform_driver(bfin_crypto_crc_driver).
-mike