[v2,1/3] hwrng: imx-rngc - simpler check for available random bytes
Commit Message
The "level" field in the status register contains the number of random
bytes that are available in the FIFO. Use GENMASK to extract this field.
We only want to check if level is 0 or if we can read another byte.
There's no need for the shift or the level variable.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
---
v2:
- remove the shift when checking the fifo level field
drivers/char/hw_random/imx-rngc.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
@@ -17,6 +17,7 @@
#include <linux/hw_random.h>
#include <linux/completion.h>
#include <linux/io.h>
+#include <linux/bitfield.h>
#define RNGC_VER_ID 0x0000
#define RNGC_COMMAND 0x0004
@@ -44,8 +45,7 @@
#define RNGC_CTRL_AUTO_SEED 0x00000010
#define RNGC_STATUS_ERROR 0x00010000
-#define RNGC_STATUS_FIFO_LEVEL_MASK 0x00000f00
-#define RNGC_STATUS_FIFO_LEVEL_SHIFT 8
+#define RNGC_STATUS_FIFO_LEVEL_MASK GENMASK(11, 8)
#define RNGC_STATUS_SEED_DONE 0x00000020
#define RNGC_STATUS_ST_DONE 0x00000010
@@ -122,7 +122,6 @@ static int imx_rngc_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);
unsigned int status;
- unsigned int level;
int retval = 0;
while (max >= sizeof(u32)) {
@@ -132,11 +131,7 @@ static int imx_rngc_read(struct hwrng *rng, void *data, size_t max, bool wait)
if (status & RNGC_STATUS_ERROR)
break;
- /* how many random numbers are in FIFO? [0-16] */
- level = (status & RNGC_STATUS_FIFO_LEVEL_MASK) >>
- RNGC_STATUS_FIFO_LEVEL_SHIFT;
-
- if (level) {
+ if (status & RNGC_STATUS_FIFO_LEVEL_MASK) {
/* retrieve a random number from FIFO */
*(u32 *)data = readl(rngc->base + RNGC_FIFO);