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SubjectRe: [uclinux-dist-devel] [PATCH 2/2] crypto: bfin_crc: CRC hardware accelerator driver for BF60x family processors.
Date
On Friday 25 May 2012 05:54:14 Sonic Zhang wrote:
> --- a/drivers/crypto/Kconfig
> +++ b/drivers/crypto/Kconfig
>
> +config CRYPTO_DEV_BFIN_CRC
> + tristate "Support for Blackfin CRC hareware accelerator"

hardware

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

Newer Blackfin processors have a CRC hardware accelerator.

> --- /dev/null
> +++ b/drivers/crypto/bfin_crc.c
>
> +struct bfin_crypto_crc_list {
> + struct list_head dev_list;
> + spinlock_t lock;
> +} crc_list;

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
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