| Message ID | 20230427185357.923412-2-martin@kaiser.cx |
|---|---|
| State | New |
| Headers | show |
| Series | hwrng: imx-rngc - simplify register definitions | expand |
On Thu, Apr 27, 2023 at 08:53:55PM +0200, Martin Kaiser wrote: > > @@ -133,9 +133,7 @@ static int imx_rngc_read(struct hwrng *rng, void *data, size_t max, bool wait) > break; > > /* how many random numbers are in FIFO? [0-16] */ > - level = (status & RNGC_STATUS_FIFO_LEVEL_MASK) >> > - RNGC_STATUS_FIFO_LEVEL_SHIFT; > - > + level = FIELD_GET(RNGC_STATUS_FIFO_LEVEL, status); Wouldn't it be simpler to just get rid of the shift? Thanks,
Thus wrote Herbert Xu (herbert@gondor.apana.org.au): > On Thu, Apr 27, 2023 at 08:53:55PM +0200, Martin Kaiser wrote: > > @@ -133,9 +133,7 @@ static int imx_rngc_read(struct hwrng *rng, void *data, size_t max, bool wait) > > break; > > /* how many random numbers are in FIFO? [0-16] */ > > - level = (status & RNGC_STATUS_FIFO_LEVEL_MASK) >> > > - RNGC_STATUS_FIFO_LEVEL_SHIFT; > > - > > + level = FIELD_GET(RNGC_STATUS_FIFO_LEVEL, status); > Wouldn't it be simpler to just get rid of the shift? Yes, we're only checking that level > 0, there's no need for the shift. I'll submit a new version of the patch. Thanks, Martin
diff --git a/drivers/char/hw_random/imx-rngc.c b/drivers/char/hw_random/imx-rngc.c index a1c24148ed31..861a615ac7df 100644 --- a/drivers/char/hw_random/imx-rngc.c +++ b/drivers/char/hw_random/imx-rngc.c @@ -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 GENMASK(11, 8) #define RNGC_STATUS_SEED_DONE 0x00000020 #define RNGC_STATUS_ST_DONE 0x00000010 @@ -133,9 +133,7 @@ static int imx_rngc_read(struct hwrng *rng, void *data, size_t max, bool wait) break; /* how many random numbers are in FIFO? [0-16] */ - level = (status & RNGC_STATUS_FIFO_LEVEL_MASK) >> - RNGC_STATUS_FIFO_LEVEL_SHIFT; - + level = FIELD_GET(RNGC_STATUS_FIFO_LEVEL, status); if (level) { /* retrieve a random number from FIFO */ *(u32 *)data = readl(rngc->base + RNGC_FIFO);
Use the mechanism from bitfield.h to read the fifo level field in the status register. This makes the code a tiny bit simpler. Signed-off-by: Martin Kaiser <martin@kaiser.cx> --- drivers/char/hw_random/imx-rngc.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)