Re: [PATCH 4/4] hwrng: bcm2835: Read as much data as available

[Eric Anholt]

Yendapally Reddy Dhananjaya Reddy 
writes:

> Read the requested number of data from the fifo
>
> Signed-off-by: Yendapally Reddy Dhananjaya Reddy 
> 
> ---
>  drivers/char/hw_random/bcm2835-rng.c | 12 ++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/hw_random/bcm2835-rng.c 
> b/drivers/char/hw_random/bcm2835-rng.c
> index b1e8b78..9bbdc07 100644
> --- a/drivers/char/hw_random/bcm2835-rng.c
> +++ b/drivers/char/hw_random/bcm2835-rng.c
> @@ -43,6 +43,8 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, 
> size_t max,
>  bool wait)
>  {
>   void __iomem *rng_base = (void __iomem *)rng->priv;
> + u32 max_words = max/sizeof(u32);

Style fix: Binary operators get a space on each side, so
"max / sizeof(u32);"

> @@ -50,8 +52,14 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, 
> size_t max,
>   cpu_relax();
>   }
>  
> - *(u32 *)buf = __raw_readl(rng_base + RNG_DATA);
> - return sizeof(u32);
> + num_words = (readl(rng_base + RNG_STATUS) >> 24);

Optional cleanup: here and in the return statement, drop the extra
parenthesis.

Functionality-wise, this patch looks great to me, and should make the
driver more efficient.  With at least the binary operators change done,
it will be:

Reviewed-by: Eric Anholt 

Thanks!


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[PATCH 4/4] hwrng: bcm2835: Read as much data as available

[Yendapally Reddy Dhananjaya Reddy]

Read the requested number of data from the fifo

Signed-off-by: Yendapally Reddy Dhananjaya Reddy 
---
 drivers/char/hw_random/bcm2835-rng.c | 12 ++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/char/hw_random/bcm2835-rng.c 
b/drivers/char/hw_random/bcm2835-rng.c
index b1e8b78..9bbdc07 100644
--- a/drivers/char/hw_random/bcm2835-rng.c
+++ b/drivers/char/hw_random/bcm2835-rng.c
@@ -43,6 +43,8 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, 
size_t max,
   bool wait)
 {
void __iomem *rng_base = (void __iomem *)rng->priv;
+   u32 max_words = max/sizeof(u32);
+   u32 num_words, count;
 
while ((__raw_readl(rng_base + RNG_STATUS) >> 24) == 0) {
if (!wait)
@@ -50,8 +52,14 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, 
size_t max,
cpu_relax();
}
 
-   *(u32 *)buf = __raw_readl(rng_base + RNG_DATA);
-   return sizeof(u32);
+   num_words = (readl(rng_base + RNG_STATUS) >> 24);
+   if (num_words > max_words)
+   num_words = max_words;
+
+   for (count = 0; count < num_words; count++)
+   ((u32 *)buf)[count] = readl(rng_base + RNG_DATA);
+
+   return (num_words * sizeof(u32));
 }
 
 static struct hwrng bcm2835_rng_ops = {
-- 
2.1.0

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