| Message ID | 20171102010408.27736-9-f.fainelli@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Florian Fainelli <f.fainelli@gmail.com> writes: > In preparation for allowing BCM63xx to use this driver, we abstract I/O > accessors such that we can easily change those later on. > > Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> > --- > drivers/char/hw_random/bcm2835-rng.c | 27 +++++++++++++++++++-------- > 1 file changed, 19 insertions(+), 8 deletions(-) > > diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c > index 35928efb52e7..500275d55044 100644 > --- a/drivers/char/hw_random/bcm2835-rng.c > +++ b/drivers/char/hw_random/bcm2835-rng.c > @@ -42,6 +42,17 @@ static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng) > return container_of(rng, struct bcm2835_rng_priv, rng); > } > > +static inline u32 rng_readl(struct bcm2835_rng_priv *priv, u32 offset) > +{ > + return readl(priv->base + offset); > +} > + > +static inline void rng_writel(struct bcm2835_rng_priv *priv, u32 val, > + u32 offset) > +{ > + writel(val, priv->base + offset); > +} > + > static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, > bool wait) > { > @@ -49,18 +60,18 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, > u32 max_words = max / sizeof(u32); > u32 num_words, count; > > - while ((__raw_readl(priv->base + RNG_STATUS) >> 24) == 0) { > + while ((rng_readl(priv, RNG_STATUS) >> 24) == 0) { > if (!wait) > return 0; > cpu_relax(); > } What was the difference between the __raw_readl and readl that's now being done in the new call? Is it important? > /* set warm-up count & enable */ > - __raw_writel(RNG_WARMUP_COUNT, priv->base + RNG_STATUS); > - __raw_writel(RNG_RBGEN, priv->base + RNG_CTRL); > + rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS); > + rng_writel(priv, RNG_RBGEN, RNG_CTRL); Similar question.
On 11/03/2017 01:19 PM, Eric Anholt wrote: > Florian Fainelli <f.fainelli@gmail.com> writes: > >> In preparation for allowing BCM63xx to use this driver, we abstract I/O >> accessors such that we can easily change those later on. >> >> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> >> --- >> drivers/char/hw_random/bcm2835-rng.c | 27 +++++++++++++++++++-------- >> 1 file changed, 19 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c >> index 35928efb52e7..500275d55044 100644 >> --- a/drivers/char/hw_random/bcm2835-rng.c >> +++ b/drivers/char/hw_random/bcm2835-rng.c >> @@ -42,6 +42,17 @@ static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng) >> return container_of(rng, struct bcm2835_rng_priv, rng); >> } >> >> +static inline u32 rng_readl(struct bcm2835_rng_priv *priv, u32 offset) >> +{ >> + return readl(priv->base + offset); >> +} >> + >> +static inline void rng_writel(struct bcm2835_rng_priv *priv, u32 val, >> + u32 offset) >> +{ >> + writel(val, priv->base + offset); >> +} >> + >> static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, >> bool wait) >> { >> @@ -49,18 +60,18 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, >> u32 max_words = max / sizeof(u32); >> u32 num_words, count; >> >> - while ((__raw_readl(priv->base + RNG_STATUS) >> 24) == 0) { >> + while ((rng_readl(priv, RNG_STATUS) >> 24) == 0) { >> if (!wait) >> return 0; >> cpu_relax(); >> } > > What was the difference between the __raw_readl and readl that's now > being done in the new call? Is it important? readl() on ARM contains a memory barrier, which has therefore stronger ordering guarantees than __raw_readl() which does not. In practice I don't think this makes a whole lot of difference in that the above loop does not even have a barrier outside of it to try to have any sort of ordering guarantee so it seems to me like this may be an oversight. I took the liberty to use the stronger operation here because it seems to me like this is what is desired, or at least won't cause functional problems, and because I am not intimately familiar with the 2835 busing architecture. I know for a thing that the Broadcom STB and DSL busses (named GISB and UBUS respectively) do not require such barriers since they do not re-order transactions and are non-posted. > >> /* set warm-up count & enable */ >> - __raw_writel(RNG_WARMUP_COUNT, priv->base + RNG_STATUS); >> - __raw_writel(RNG_RBGEN, priv->base + RNG_CTRL); >> + rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS); >> + rng_writel(priv, RNG_RBGEN, RNG_CTRL); > > Similar question. And here we definitively are not in a hot-path so the more "ordered" variant is acceptable it seems.
diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c index 35928efb52e7..500275d55044 100644 --- a/drivers/char/hw_random/bcm2835-rng.c +++ b/drivers/char/hw_random/bcm2835-rng.c @@ -42,6 +42,17 @@ static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng) return container_of(rng, struct bcm2835_rng_priv, rng); } +static inline u32 rng_readl(struct bcm2835_rng_priv *priv, u32 offset) +{ + return readl(priv->base + offset); +} + +static inline void rng_writel(struct bcm2835_rng_priv *priv, u32 val, + u32 offset) +{ + writel(val, priv->base + offset); +} + static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) { @@ -49,18 +60,18 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max, u32 max_words = max / sizeof(u32); u32 num_words, count; - while ((__raw_readl(priv->base + RNG_STATUS) >> 24) == 0) { + while ((rng_readl(priv, RNG_STATUS) >> 24) == 0) { if (!wait) return 0; cpu_relax(); } - num_words = readl(priv->base + RNG_STATUS) >> 24; + num_words = rng_readl(priv, RNG_STATUS) >> 24; if (num_words > max_words) num_words = max_words; for (count = 0; count < num_words; count++) - ((u32 *)buf)[count] = readl(priv->base + RNG_DATA); + ((u32 *)buf)[count] = rng_readl(priv, RNG_DATA); return num_words * sizeof(u32); } @@ -77,14 +88,14 @@ static int bcm2835_rng_init(struct hwrng *rng) if (priv->mask_interrupts) { /* mask the interrupt */ - val = readl(priv->base + RNG_INT_MASK); + val = rng_readl(priv, RNG_INT_MASK); val |= RNG_INT_OFF; - writel(val, priv->base + RNG_INT_MASK); + rng_writel(priv, val, RNG_INT_MASK); } /* set warm-up count & enable */ - __raw_writel(RNG_WARMUP_COUNT, priv->base + RNG_STATUS); - __raw_writel(RNG_RBGEN, priv->base + RNG_CTRL); + rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS); + rng_writel(priv, RNG_RBGEN, RNG_CTRL); return 0; } @@ -94,7 +105,7 @@ static void bcm2835_rng_cleanup(struct hwrng *rng) struct bcm2835_rng_priv *priv = to_rng_priv(rng); /* disable rng hardware */ - __raw_writel(0, priv->base + RNG_CTRL); + rng_writel(priv, 0, RNG_CTRL); clk_disable_unprepare(priv->clk); }
In preparation for allowing BCM63xx to use this driver, we abstract I/O accessors such that we can easily change those later on. Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> --- drivers/char/hw_random/bcm2835-rng.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-)