[PATCH v2 2/3] lib: utils/timer: mtimer: add a quirk for lacking mtime register
Icenowy Zheng
uwu at icenowy.me
Tue Dec 13 00:51:10 PST 2022
在 2022-12-13星期二的 16:01 +0800，Xiang W写道：
> 在 2022-12-12星期一的 16:22 +0800，Icenowy Zheng写道：
> > T-Head developers surely have a different understanding of time CSR
> > and
> > CLINT's mtime register with SiFive ones, that they did not
> > implement
> > the mtime register at all -- as shown in openC906 source code,
> > their
> > time CSR value is just exposed at the top of their processor IP
> > block
> > and expects an external continous counter, which makes it not
> > overrideable, and thus mtime register is not implemented, even not
> > for
> > reading. However, if CLINTEE is not enabled in T-Head's MXSTATUS
> > extended CSR, these systems still rely on the mtimecmp registers to
> > generate timer interrupts. This makes it necessary to implement T-
> > Head
> > C9xx CLINT support in OpenSBI MTIMER driver, which skips
> > implementing
> > reading mtime register and falls back to default code that reads
> > time
> > CSR.
> >
> > Add a quirk into MTIMER driver, which represents a mtime register
> > is
> > lacking and time CSR value should be used instead.
> >
> > Signed-off-by: Icenowy Zheng <uwu at icenowy.me>
> > ---
> > Changes in v2:
> > - Dropped has_mtime field in aclint_mtimer_data, use mtime_size = 0
> > (which is disallowed before) to mark absence of mtime.
> > - Dropped the code that specially handle the existence of mtime
> > when
> > registering memory ranges -- the function will just be a no-op
> > when
> > size is 0.
> >
> > lib/utils/timer/aclint_mtimer.c | 11 ++++++++---
> > lib/utils/timer/fdt_timer_mtimer.c | 30 ++++++++++++++++++++------
> > ----
> > 2 files changed, 28 insertions(+), 13 deletions(-)
> >
> > diff --git a/lib/utils/timer/aclint_mtimer.c
> > b/lib/utils/timer/aclint_mtimer.c
> > index 3f00c21..1846a9a 100644
> > --- a/lib/utils/timer/aclint_mtimer.c
> > +++ b/lib/utils/timer/aclint_mtimer.c
> > @@ -149,10 +149,10 @@ int aclint_mtimer_cold_init(struct
> > aclint_mtimer_data *mt,
> > int rc;
> >
> > /* Sanity checks */
> > - if (!mt || !mt->mtime_size ||
> > + if (!mt ||
> > (mt->hart_count && !mt->mtimecmp_size) ||
> > - (mt->mtime_addr & (ACLINT_MTIMER_ALIGN - 1)) ||
> > - (mt->mtime_size & (ACLINT_MTIMER_ALIGN - 1)) ||
> > + (mt->mtime_size && (mt->mtime_addr &
> > (ACLINT_MTIMER_ALIGN - 1))) ||
> typo.
Not a typo, mtime_size = 0 here means the mtime register is just not
available, so we do sanity check on mtime_addr based on the existence
of mtime, thus mtime_size.
> mt->mtime_size should be mt->mtime_addr.
>
> Regards,
> Xiang W
> > + (mt->mtime_size && (mt->mtime_size &
> > (ACLINT_MTIMER_ALIGN - 1))) ||
> > (mt->mtimecmp_addr & (ACLINT_MTIMER_ALIGN - 1)) ||
> > (mt->mtimecmp_size & (ACLINT_MTIMER_ALIGN - 1)) ||
> > (mt->first_hartid >= SBI_HARTMASK_MAX_BITS) ||
> > @@ -178,6 +178,11 @@ int aclint_mtimer_cold_init(struct
> > aclint_mtimer_data *mt,
> > for (i = 0; i < mt->hart_count; i++)
> > mtimer_hartid2data[mt->first_hartid + i] = mt;
> >
> > + if (!mt->mtime_size) {
> > + /* Disable reading mtime when mtime is not
> > available */
> > + mtimer.timer_value = NULL;
> > + }
> > +
> > /* Add MTIMER regions to the root domain */
> > if (mt->mtime_addr == (mt->mtimecmp_addr + mt-
> > >mtimecmp_size)) {
> > rc = sbi_domain_root_add_memrange(mt-
> > >mtimecmp_addr,
> > diff --git a/lib/utils/timer/fdt_timer_mtimer.c
> > b/lib/utils/timer/fdt_timer_mtimer.c
> > index 7b8546b..a0adc70 100644
> > --- a/lib/utils/timer/fdt_timer_mtimer.c
> > +++ b/lib/utils/timer/fdt_timer_mtimer.c
> > @@ -18,6 +18,7 @@
> > struct timer_mtimer_quirks {
> > unsigned int mtime_offset;
> > bool has_64bit_mmio;
> > + bool without_mtime;
> > };
> >
> > static unsigned long mtimer_count = 0;
> > @@ -53,12 +54,16 @@ static int timer_mtimer_cold_init(void *fdt,
> > int nodeoff,
> > /* Set CLINT addresses */
> > mt->mtimecmp_addr = addr[0] +
> > ACLINT_DEFAULT_MTIMECMP_OFFSET;
> > mt->mtimecmp_size = ACLINT_DEFAULT_MTIMECMP_SIZE;
> > - mt->mtime_addr = addr[0] +
> > ACLINT_DEFAULT_MTIME_OFFSET;
> > - mt->mtime_size = size[0] - mt->mtimecmp_size;
> > - /* Adjust MTIMER address and size for CLINT device
> > */
> > - mt->mtime_addr += quirks->mtime_offset;
> > + if (!quirks->without_mtime) {
> > + mt->mtime_addr = addr[0] +
> > ACLINT_DEFAULT_MTIME_OFFSET;
> > + mt->mtime_size = size[0] - mt-
> > >mtimecmp_size;
> > + /* Adjust MTIMER address and size for CLINT
> > device */
> > + mt->mtime_addr += quirks->mtime_offset;
> > + mt->mtime_size -= quirks->mtime_offset;
> > + } else {
> > + mt->mtime_addr = mt->mtime_size = 0;
> > + }
> > mt->mtimecmp_addr += quirks->mtime_offset;
> > - mt->mtime_size -= quirks->mtime_offset;
> > /* Apply additional CLINT quirks */
> > mt->has_64bit_mmio = quirks->has_64bit_mmio;
> > } else { /* RISC-V ACLINT MTIMER */
> > @@ -70,12 +75,17 @@ static int timer_mtimer_cold_init(void *fdt,
> > int nodeoff,
> > }
> >
> > /* Check if MTIMER device has shared MTIME address */
> > - mt->has_shared_mtime = false;
> > - for (i = 0; i < mtimer_count; i++) {
> > - if (mtimer[i].mtime_addr == mt->mtime_addr) {
> > - mt->has_shared_mtime = true;
> > - break;
> > + if (mt->mtime_size) {
> > + mt->has_shared_mtime = false;
> > + for (i = 0; i < mtimer_count; i++) {
> > + if (mtimer[i].mtime_addr == mt->mtime_addr)
> > {
> > + mt->has_shared_mtime = true;
> > + break;
> > + }
> > }
> > + } else {
> > + /* Assume shared time CSR */
> > + mt->has_shared_mtime = true;
> > }
> >
> > /* Initialize the MTIMER device */
> > --
> > 2.38.1
> >
> >
>
>
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