[patch 2.6.25-rc8] omap_rng minor updates

[patch 2.6.25-rc8] omap_rng minor updates

[David Brownell]

Minor cleanups to the OMAP RNG:

 - Comment update re RNG status:
     * yes, it works on 16xx; "rngtest" is quite happy
     * it's fast enough that polling vs IRQ is a non-issue
 - Get rid of BUG_ON
 - Help GCC not be stupid about inlining (object code shrink)
 - Remove "sparse" warning
 - Cope with new hotplug rule requiring "platform:" modalias

And make the file header match kernel conventions.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
 drivers/char/hw_random/omap-rng.c |   26 +++++++++++++-------------
 1 files changed, 13 insertions(+), 13 deletions(-)

--- osk2.orig/drivers/char/hw_random/omap-rng.c	2008-04-10 20:23:31.000000000 -0700
+++ osk2/drivers/char/hw_random/omap-rng.c	2008-04-10 20:38:49.000000000 -0700
@@ -1,7 +1,5 @@
 /*
- * drivers/char/hw_random/omap-rng.c
- *
- * RNG driver for TI OMAP CPU family
+ * omap-rng.c - RNG driver for TI OMAP CPU family
  *
  * Author: Deepak Saxena <dsaxena@plexity.net>
  *
@@ -15,11 +13,6 @@
  * This file is licensed under  the terms of the GNU General Public
  * License version 2. This program is licensed "as is" without any
  * warranty of any kind, whether express or implied.
- *
- * TODO:
- *
- * - Make status updated be interrupt driven so we don't poll
- *
  */
 
 #include <linux/module.h>
@@ -55,17 +48,16 @@ static void __iomem *rng_base;
 static struct clk *rng_ick;
 static struct platform_device *rng_dev;
 
-static u32 omap_rng_read_reg(int reg)
+static inline u32 omap_rng_read_reg(int reg)
 {
 	return __raw_readl(rng_base + reg);
 }
 
-static void omap_rng_write_reg(int reg, u32 val)
+static inline void omap_rng_write_reg(int reg, u32 val)
 {
 	__raw_writel(val, rng_base + reg);
 }
 
-/* REVISIT: Does the status bit really work on 16xx? */
 static int omap_rng_data_present(struct hwrng *rng, int wait)
 {
 	int data, i;
@@ -74,6 +66,11 @@ static int omap_rng_data_present(struct 
 		data = omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1;
 		if (data || !wait)
 			break;
+		/* RNG produces data fast enough (2+ MBit/sec, even
+		 * during "rngtest" loads, that these delays don't
+		 * seem to trigger.  We *could* use the RNG IRQ, but
+		 * that'd be higher overhead ... so why bother?
+		 */
 		udelay(10);
 	}
 	return data;
@@ -101,7 +98,8 @@ static int __init omap_rng_probe(struct 
 	 * A bit ugly, and it will never actually happen but there can
 	 * be only one RNG and this catches any bork
 	 */
-	BUG_ON(rng_dev);
+	if (rng_dev)
+		return -EBUSY;
 
 	if (cpu_is_omap24xx()) {
 		rng_ick = clk_get(NULL, "rng_ick");
@@ -124,7 +122,7 @@ static int __init omap_rng_probe(struct 
 		return -EBUSY;
 
 	dev_set_drvdata(&pdev->dev, mem);
-	rng_base = (u32 __iomem *)io_p2v(res->start);
+	rng_base = (u32 __force __iomem *)io_p2v(res->start);
 
 	ret = hwrng_register(&omap_rng_ops);
 	if (ret) {
@@ -182,6 +180,8 @@ static int omap_rng_resume(struct platfo
 
 #endif
 
+/* work with hotplug and coldplug */
+MODULE_ALIAS("platform:omap_rng");
 
 static struct platform_driver omap_rng_driver = {
 	.driver = {

Re: [patch 2.6.25-rc8] omap_rng minor updates

[Herbert Xu]

On Fri, Apr 11, 2008 at 04:32:03AM +0000, David Brownell wrote:
> Minor cleanups to the OMAP RNG:

Thanks.  I've picked this up in cryptodev-2.6.
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [patch 2.6.25-rc8] omap_rng minor updates

[David Brownell]

On Wednesday 16 April 2008, Herbert Xu wrote:
> > Minor cleanups to the OMAP RNG:
> 
> Thanks.  I've picked this up in cryptodev-2.6.

Is that where the RNG stuff is now getting maintained?


If so, I wonder what should be done with some other
RNG changes sitting in one of my trees.  Briefly,
their initializations come late ... and after kernel
code has already started to use the kernel pool.  So
attacks based on known RNG patterns are possible at
that time.

So the patch I had -- needs reworking -- moves the
RNG driver initializations earlier, and uses the
first one to seed the kernel pool.  Cryptographically
that would be no worse than the current situation (even
if you don't wholly trust the RNG), and in most cases
would be a distinct improvement.

- Dave

Re: [patch 2.6.25-rc8] omap_rng minor updates

[Herbert Xu]

On Wed, Apr 16, 2008 at 10:04:49AM -0700, David Brownell wrote:
> 
> Is that where the RNG stuff is now getting maintained?

For hardware RNG stuff yes.  For the software RNG you should
send them to Matt Mackall as usual.

Thanks,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt