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[rpi] remove IRQ support for BCM233x RNG

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Upstream DTBs don't provide IRQ lines for the RNG. Moreover, harvesting
bytes as often as the RNG interrupt is triggered (87 times per sec) is an
overkill.

For these reasons, get rid of the interrupt mode and make callout mode the
default, with random bits harvested every 4 seconds.

Submitted by:	Sylvain Garrigues <sylgar@gmail.com>
Reviewed by:	ian, imp, manu, mmel
Approved by:	emaste
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D14541
This commit is contained in:
Oleksandr Tymoshenko 2018-03-10 02:49:58 +00:00
parent 71b126549d
commit 8e6a67d5be
3 changed files with 12 additions and 93 deletions
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97
sys/arm/broadcom/bcm2835/bcm2835_rng.c
View File

@ -51,10 +51,6 @@ __FBSDID("$FreeBSD$");
#include <dev/random/randomdev.h>
#include <dev/random/random_harvestq.h>
#if !defined(BCM2835_RNG_USE_CALLOUT)
#define BCM2835_RNG_USE_INTERRUPT
#endif
static device_attach_t bcm2835_rng_attach;
static device_detach_t bcm2835_rng_detach;
static device_probe_t bcm2835_rng_probe;
@ -92,18 +88,15 @@ static device_probe_t bcm2835_rng_probe;
#define RNG_NUM_OSCILLATORS 6
#define RNG_STALL_COUNT_DEFAULT 10
#define RNG_CALLOUT_TICKS (hz * 4)
struct bcm2835_rng_softc {
device_t sc_dev;
struct resource * sc_mem_res;
struct resource * sc_irq_res;
void * sc_intr_hdl;
#if defined(BCM2835_RNG_USE_CALLOUT) || defined(BCM2835_RNG_USE_INTERRUPT)
uint32_t sc_buf[RNG_FIFO_WORDS];
#endif
#if defined(BCM2835_RNG_USE_CALLOUT)
struct callout sc_rngto;
int sc_rnghz;
#endif
int sc_stall_count;
int sc_rbg2x;
long sc_underrun;
@ -214,19 +207,6 @@ bcm2835_rng_disable_intr(struct bcm2835_rng_softc *sc)
bcm2835_rng_write4(sc, RNG_INT_MASK, mask);
}
#if defined(BCM2835_RNG_USE_INTERRUPT)
static void
bcm2835_rng_enable_intr(struct bcm2835_rng_softc *sc)
{
uint32_t mask;
/* Clear the interrupt off bit in the interrupt mask register */
mask = bcm2835_rng_read4(sc, RNG_INT_MASK);
mask &= ~RNG_INT_OFF_BIT;
bcm2835_rng_write4(sc, RNG_INT_MASK, mask);
}
#endif
static void
bcm2835_rng_start(struct bcm2835_rng_softc *sc)
{
@ -244,11 +224,6 @@ bcm2835_rng_start(struct bcm2835_rng_softc *sc)
if (sc->sc_rbg2x)
ctrl |= RNG_RBG2X;
bcm2835_rng_write4(sc, RNG_CTRL, ctrl);
#if defined(BCM2835_RNG_USE_INTERRUPT)
/* Enable the interrupt */
bcm2835_rng_enable_intr(sc);
#endif
}
static void
@ -263,12 +238,13 @@ bcm2835_rng_stop(struct bcm2835_rng_softc *sc)
}
static void
bcm2835_rng_harvest(struct bcm2835_rng_softc *sc)
bcm2835_rng_harvest(void *arg)
{
uint32_t *dest;
uint32_t status;
u_int cnt, nread, num_avail, num_words;
int seen_underrun, num_stalls;
struct bcm2835_rng_softc *sc = arg;
dest = sc->sc_buf;
nread = num_words = 0;
@ -316,9 +292,7 @@ bcm2835_rng_harvest(struct bcm2835_rng_softc *sc)
random_harvest_queue(sc->sc_buf, cnt, cnt * NBBY / 2,
RANDOM_PURE_BROADCOM);
#if defined(BCM2835_RNG_USE_CALLOUT)
callout_reset(&sc->sc_rngto, sc->sc_rnghz, bcm2835_rng_harvest, sc);
#endif
callout_reset(&sc->sc_rngto, RNG_CALLOUT_TICKS, bcm2835_rng_harvest, sc);
}
static int
@ -390,10 +364,10 @@ bcm2835_rng_attach(device_t dev)
sc = device_get_softc(dev);
sc->sc_dev = dev;
sc->sc_stall_count = RNG_STALL_COUNT_DEFAULT;
#ifdef BCM2835_RNG_USE_CALLOUT
/* Initialize callout */
callout_init(&sc->sc_rngto, CALLOUT_MPSAFE);
#endif
TUNABLE_INT_FETCH("bcmrng.2xspeed", &sc->sc_rbg2x);
TUNABLE_INT_FETCH("bcmrng.stall_count", &sc->sc_stall_count);
@ -406,27 +380,6 @@ bcm2835_rng_attach(device_t dev)
return (ENXIO);
}
#if defined(BCM2835_RNG_USE_INTERRUPT)
/* Allocate interrupt resource */
rid = 0;
sc->sc_irq_res = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
RF_SHAREABLE | RF_ACTIVE);
if (sc->sc_irq_res == NULL) {
bcm2835_rng_detach(dev);
return (ENXIO);
}
/* Set up the interrupt handler */
error = bus_setup_intr(dev, sc->sc_irq_res, INTR_TYPE_BIO | INTR_MPSAFE,
NULL, (driver_intr_t *)bcm2835_rng_harvest, sc, &sc->sc_intr_hdl);
if (error) {
device_printf(dev, "Failed to set up IRQ\n");
sc->sc_intr_hdl = NULL;
bcm2835_rng_detach(dev);
return (error);
}
#endif
/* Start the RNG */
bcm2835_rng_start(sc);
@ -461,14 +414,11 @@ bcm2835_rng_attach(device_t dev)
sysctl_bcm2835_rng_dump, "S", "Dump RNG registers");
#endif
#if defined(BCM2835_RNG_USE_CALLOUT)
/* Reset callout */
if (hz >= 100)
sc->sc_rnghz = hz / 100;
else
sc->sc_rnghz = 1;
callout_reset(&sc->sc_rngto, sc->sc_rnghz, bcm2835_rng_harvest, sc);
#endif
/*
* Schedule the initial harvesting one second from now, which should give the
* hardware RNG plenty of time to generate the first random bytes.
*/
callout_reset(&sc->sc_rngto, hz, bcm2835_rng_harvest, sc);
return (0);
}
@ -477,9 +427,6 @@ static int
bcm2835_rng_detach(device_t dev)
{
struct bcm2835_rng_softc *sc;
#if defined(BCM2835_RNG_USE_INTERRUPT)
int error;
#endif
sc = device_get_softc(dev);
@ -487,27 +434,7 @@ bcm2835_rng_detach(device_t dev)
bcm2835_rng_stop(sc);
/* Drain the callout it */
#if defined(BCM2835_RNG_USE_CALLOUT)
callout_drain(&sc->sc_rngto);
#endif
#if defined(BCM2835_RNG_USE_INTERRUPT)
/* Tear down the interrupt */
if (sc->sc_irq_res && sc->sc_intr_hdl) {
error = bus_teardown_intr(dev, sc->sc_irq_res, sc->sc_intr_hdl);
if (error != 0) {
device_printf(dev, "could not tear down IRQ\n");
return (error);
}
sc->sc_intr_hdl = NULL;
}
/* Release interrupt resource */
if (sc->sc_irq_res) {
bus_release_resource(dev, SYS_RES_IRQ, 0, sc->sc_irq_res);
sc->sc_irq_res = NULL;
}
#endif
/* Release memory resource */
if (sc->sc_mem_res != NULL)

4
sys/dts/arm/rpi.dts
View File

@ -51,10 +51,6 @@
status = "okay";
};
rng@7e104000 {
interrupts = <2 29>;
}
spi@7e204000 {
status = "okay";
};

4
sys/dts/arm/rpi2.dts
View File

@ -51,10 +51,6 @@
status = "okay";
};
rng@7e104000 {
interrupts = <2 29>;
}
spi@7e204000 {
status = "okay";
};