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arm64: Add support for bcm2838 RNG

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The hardware random number generator of the RPi4 differs slightly
from the version found on the RPi3.

This commit extends the existing bcm2835_rng driver to function on the RPi4.

Submitted by:	James Mintram <me at jamesrm dot com>
Reviewed by:	markm, cem, delphij
Approved by:	csprng(cem, markm)
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D22493
This commit is contained in:
Gordon Bergling 2021-03-06 12:28:35 +01:00
parent c743a6bd4f
commit e797dc58bd
1 changed files with 133 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

174
sys/arm/broadcom/bcm2835/bcm2835_rng.c
View File

@ -69,21 +69,26 @@ static device_probe_t bcm2835_rng_probe;
#define RNG_RBG2X 0x00000002 /* RBG 2X SPEED */
#define RNG_RBGEN_BIT 0x00000001 /* Enable RNG bit */
#define RNG_STATUS 0x04 /* RNG status register */
#define RND_VAL_SHIFT 24 /* Shift for valid words */
#define RND_VAL_MASK 0x000000ff /* Number valid words mask */
#define RND_VAL_WARM_CNT 0x40000 /* RNG Warm Up count */
#define RND_WARM_CNT 0xfffff /* RNG Warm Up Count mask */
#define BCM2835_RNG_STATUS 0x04 /* BCM2835 RNG status register */
#define BCM2838_RNG_STATUS 0x18 /* BCM2838 RNG status register */
#define RNG_DATA 0x08 /* RNG Data Register */
#define BCM2838_RNG_COUNT 0x24 /* How many values available */
#define BCM2838_COUNT_VAL_MASK 0x000000ff
#define BCM2835_RND_VAL_SHIFT 24 /* Shift for valid words */
#define BCM2835_RND_VAL_MASK 0x000000ff /* Number valid words mask */
#define BCM2835_RND_VAL_WARM_CNT 0x40000 /* RNG Warm Up count */
#define BCM2835_RND_WARM_CNT 0xfffff /* RNG Warm Up Count mask */
#define BCM2835_RNG_DATA 0x08 /* RNG Data Register */
#define BCM2838_RNG_DATA 0x20
#define RNG_FF_THRES 0x0c
#define RNG_FF_THRES_MASK 0x0000001f
#define RNG_INT_MASK 0x10
#define RNG_INT_OFF_BIT 0x00000001
#define BCM2835_RNG_INT_MASK 0x10
#define BCM2835_RNG_INT_OFF_BIT 0x00000001
#define RNG_FF_DEFAULT 0x10 /* FIFO threshold default */
#define RNG_FIFO_WORDS (RNG_FF_DEFAULT / sizeof(uint32_t))
#define RNG_NUM_OSCILLATORS 6
@ -91,11 +96,55 @@ static device_probe_t bcm2835_rng_probe;
#define RNG_CALLOUT_TICKS (hz * 4)
struct bcm_rng_conf {
bus_size_t control_reg;
bus_size_t status_reg;
bus_size_t count_reg;
bus_size_t data_reg;
bus_size_t intr_mask_reg;
uint32_t intr_disable_bit;
uint32_t count_value_shift;
uint32_t count_value_mask;
uint32_t warmup_count;
bool allow_2x_mode;
bool can_diagnose;
/* XXX diag regs */
};
static const struct bcm_rng_conf bcm2835_rng_conf = {
.control_reg = RNG_CTRL,
.status_reg = BCM2835_RNG_STATUS,
.count_reg = BCM2835_RNG_STATUS, /* Same register */
.data_reg = BCM2835_RNG_DATA,
.intr_mask_reg = BCM2835_RNG_INT_MASK,
.intr_disable_bit = BCM2835_RNG_INT_OFF_BIT,
.count_value_shift = BCM2835_RND_VAL_SHIFT,
.count_value_mask = BCM2835_RND_VAL_MASK,
.warmup_count = BCM2835_RND_VAL_WARM_CNT,
.allow_2x_mode = true,
.can_diagnose = true
};
static const struct bcm_rng_conf bcm2838_rng_conf = {
.control_reg = RNG_CTRL,
.status_reg = BCM2838_RNG_STATUS,
.count_reg = BCM2838_RNG_COUNT,
.data_reg = BCM2838_RNG_DATA,
.intr_mask_reg = 0,
.intr_disable_bit = 0,
.count_value_shift = 0,
.count_value_mask = BCM2838_COUNT_VAL_MASK,
.warmup_count = 0,
.allow_2x_mode = false,
.can_diagnose = false
};
struct bcm2835_rng_softc {
device_t sc_dev;
struct resource * sc_mem_res;
struct resource * sc_irq_res;
void * sc_intr_hdl;
struct bcm_rng_conf const* conf;
uint32_t sc_buf[RNG_FIFO_WORDS];
struct callout sc_rngto;
int sc_stall_count;
@ -104,8 +153,15 @@ struct bcm2835_rng_softc {
};
static struct ofw_compat_data compat_data[] = {
{"broadcom,bcm2835-rng", 1},
{"brcm,bcm2835-rng", 1},
{"broadcom,bcm2835-rng", (uintptr_t)&bcm2835_rng_conf},
{"brcm,bcm2835-rng", (uintptr_t)&bcm2835_rng_conf},
{"brcm,bcm2711-rng200", (uintptr_t)&bcm2838_rng_conf},
{"brcm,bcm2838-rng", (uintptr_t)&bcm2838_rng_conf},
{"brcm,bcm2838-rng200", (uintptr_t)&bcm2838_rng_conf},
{"brcm,bcm7211-rng", (uintptr_t)&bcm2838_rng_conf},
{"brcm,bcm7278-rng", (uintptr_t)&bcm2838_rng_conf},
{"brcm,iproc-rng200", (uintptr_t)&bcm2838_rng_conf},
{NULL, 0}
};
@ -144,8 +200,12 @@ bcm2835_rng_dump_registers(struct bcm2835_rng_softc *sc, struct sbuf *sbp)
uint32_t comblk2_osc, comblk1_osc, jclk_byp_div, val;
int i;
if (!sc->conf->can_diagnose)
/* Not implemented. */
return;
/* Display RNG control register contents */
val = bcm2835_rng_read4(sc, RNG_CTRL);
val = bcm2835_rng_read4(sc, sc->conf->control_reg);
sbuf_printf(sbp, "RNG_CTRL (%08x)\n", val);
comblk2_osc = (val & RNG_COMBLK2_OSC) >> RNG_COMBLK2_OSC_SHIFT;
@ -181,20 +241,20 @@ bcm2835_rng_dump_registers(struct bcm2835_rng_softc *sc, struct sbuf *sbp)
sbuf_cat(sbp, " RNG_RBGEN_BIT: RBG enabled\n");
/* Display RNG status register contents */
val = bcm2835_rng_read4(sc, RNG_STATUS);
val = bcm2835_rng_read4(sc, sc->conf->status_reg);
sbuf_printf(sbp, "RNG_CTRL (%08x)\n", val);
sbuf_printf(sbp, " RND_VAL: %02x\n",
(val >> RND_VAL_SHIFT) & RND_VAL_MASK);
sbuf_printf(sbp, " RND_WARM_CNT: %05x\n", val & RND_WARM_CNT);
(val >> sc->conf->count_value_shift) & sc->conf->count_value_mask);
sbuf_printf(sbp, " RND_WARM_CNT: %05x\n", val & sc->conf->warmup_count);
/* Display FIFO threshold register contents */
val = bcm2835_rng_read4(sc, RNG_FF_THRES);
sbuf_printf(sbp, "RNG_FF_THRES: %05x\n", val & RNG_FF_THRES_MASK);
/* Display interrupt mask register contents */
val = bcm2835_rng_read4(sc, RNG_INT_MASK);
val = bcm2835_rng_read4(sc, sc->conf->intr_mask_reg);
sbuf_printf(sbp, "RNG_INT_MASK: interrupt %s\n",
((val & RNG_INT_OFF_BIT) != 0) ? "disabled" : "enabled");
((val & sc->conf->intr_disable_bit) != 0) ? "disabled" : "enabled");
}
static void
@ -203,9 +263,9 @@ bcm2835_rng_disable_intr(struct bcm2835_rng_softc *sc)
uint32_t mask;
/* Set 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);
mask = bcm2835_rng_read4(sc, sc->conf->intr_mask_reg);
mask |= sc->conf->intr_disable_bit;
bcm2835_rng_write4(sc, sc->conf->intr_mask_reg, mask);
}
static void
@ -214,17 +274,20 @@ bcm2835_rng_start(struct bcm2835_rng_softc *sc)
uint32_t ctrl;
/* Disable the interrupt */
bcm2835_rng_disable_intr(sc);
if (sc->conf->intr_mask_reg)
bcm2835_rng_disable_intr(sc);
/* Set the warmup count */
bcm2835_rng_write4(sc, RNG_STATUS, RND_VAL_WARM_CNT);
if (sc->conf->warmup_count > 0)
bcm2835_rng_write4(sc, sc->conf->status_reg,
sc->conf->warmup_count);
/* Enable the RNG */
ctrl = bcm2835_rng_read4(sc, RNG_CTRL);
ctrl = bcm2835_rng_read4(sc, sc->conf->control_reg);
ctrl |= RNG_RBGEN_BIT;
if (sc->sc_rbg2x)
if (sc->sc_rbg2x && sc->conf->allow_2x_mode)
ctrl |= RNG_RBG2X;
bcm2835_rng_write4(sc, RNG_CTRL, ctrl);
bcm2835_rng_write4(sc, sc->conf->control_reg, ctrl);
}
static void
@ -233,16 +296,39 @@ bcm2835_rng_stop(struct bcm2835_rng_softc *sc)
uint32_t ctrl;
/* Disable the RNG */
ctrl = bcm2835_rng_read4(sc, RNG_CTRL);
ctrl = bcm2835_rng_read4(sc, sc->conf->control_reg);
ctrl &= ~RNG_RBGEN_BIT;
bcm2835_rng_write4(sc, RNG_CTRL, ctrl);
bcm2835_rng_write4(sc, sc->conf->control_reg, ctrl);
}
static void
bcm2835_rng_enqueue_harvest(struct bcm2835_rng_softc *sc, uint32_t nread)
{
char *sc_buf_chunk;
uint32_t chunk_size;
uint32_t cnt;
chunk_size = sizeof(((struct harvest_event *)0)->he_entropy);
cnt = nread * sizeof(uint32_t);
sc_buf_chunk = (void*)sc->sc_buf;
while (cnt > 0) {
uint32_t size;
size = MIN(cnt, chunk_size);
random_harvest_queue(sc_buf_chunk, size, RANDOM_PURE_BROADCOM);
sc_buf_chunk += size;
cnt -= size;
}
}
static void
bcm2835_rng_harvest(void *arg)
{
uint32_t *dest;
uint32_t status;
uint32_t hwcount;
u_int cnt, nread, num_avail, num_words;
int seen_underrun, num_stalls;
struct bcm2835_rng_softc *sc = arg;
@ -250,11 +336,13 @@ bcm2835_rng_harvest(void *arg)
dest = sc->sc_buf;
nread = num_words = 0;
seen_underrun = num_stalls = 0;
for (cnt = sizeof(sc->sc_buf) / sizeof(uint32_t); cnt > 0;
cnt -= num_words) {
/* Read status register to find out how many words available */
status = bcm2835_rng_read4(sc, RNG_STATUS);
num_avail = (status >> RND_VAL_SHIFT) & RND_VAL_MASK;
/* Read count register to find out how many words available */
hwcount = bcm2835_rng_read4(sc, sc->conf->count_reg);
num_avail = (hwcount >> sc->conf->count_value_shift) &
sc->conf->count_value_mask;
/* If we have none... */
if (num_avail == 0) {
@ -282,15 +370,13 @@ bcm2835_rng_harvest(void *arg)
/* Pull MIN(num_avail, cnt) words from the FIFO */
num_words = (num_avail > cnt) ? cnt : num_avail;
bcm2835_rng_read_multi4(sc, RNG_DATA, dest,
bcm2835_rng_read_multi4(sc, sc->conf->data_reg, dest,
num_words);
dest += num_words;
nread += num_words;
}
cnt = nread * sizeof(uint32_t);
if (cnt > 0)
random_harvest_queue(sc->sc_buf, cnt, RANDOM_PURE_BROADCOM);
bcm2835_rng_enqueue_harvest(sc, nread);
callout_reset(&sc->sc_rngto, RNG_CALLOUT_TICKS, bcm2835_rng_harvest, sc);
}
@ -347,7 +433,7 @@ bcm2835_rng_probe(device_t dev)
if (ofw_bus_search_compatible(dev, compat_data)->ocd_data == 0)
return (ENXIO);
device_set_desc(dev, "Broadcom BCM2835 RNG");
device_set_desc(dev, "Broadcom BCM2835/BCM2838 RNG");
return (BUS_PROBE_DEFAULT);
}
@ -363,13 +449,18 @@ bcm2835_rng_attach(device_t dev)
error = 0;
sc = device_get_softc(dev);
sc->sc_dev = dev;
sc->conf = (void const*)ofw_bus_search_compatible(dev, compat_data)->ocd_data;
KASSERT(sc->conf != NULL, ("bcm2835_rng_attach: sc->conf == NULL"));
sc->sc_stall_count = RNG_STALL_COUNT_DEFAULT;
/* Initialize callout */
callout_init(&sc->sc_rngto, CALLOUT_MPSAFE);
TUNABLE_INT_FETCH("bcmrng.2xspeed", &sc->sc_rbg2x);
TUNABLE_INT_FETCH("bcmrng.stall_count", &sc->sc_stall_count);
if (sc->conf->allow_2x_mode)
TUNABLE_INT_FETCH("bcmrng.2xspeed", &sc->sc_rbg2x);
/* Allocate memory resources */
rid = 0;
@ -402,9 +493,10 @@ bcm2835_rng_attach(device_t dev)
SYSCTL_ADD_LONG(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
"underrun", CTLFLAG_RD, &sc->sc_underrun,
"Number of FIFO underruns");
SYSCTL_ADD_PROC(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
"2xspeed", CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, sc, 0,
sysctl_bcm2835_rng_2xspeed, "I", "Enable RBG 2X SPEED");
if (sc->conf->allow_2x_mode)
SYSCTL_ADD_PROC(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
"2xspeed", CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, sc, 0,
sysctl_bcm2835_rng_2xspeed, "I", "Enable RBG 2X SPEED");
SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
"stall_count", CTLFLAG_RW, &sc->sc_stall_count,
RNG_STALL_COUNT_DEFAULT, "Number of underruns to assume RNG stall");
@ -414,7 +506,7 @@ bcm2835_rng_attach(device_t dev)
sysctl_bcm2835_rng_dump, "S", "Dump RNG registers");
#endif
/*
/*
* Schedule the initial harvesting one second from now, which should give the
* hardware RNG plenty of time to generate the first random bytes.
*/