[PATCH 1/3] lib: sbi: Introduce IPI device rating
Anup Patel
anup at brainfault.org
Wed Sep 3 00:05:13 PDT 2025
On Wed, Sep 3, 2025 at 12:30 PM Nick Hu <nick.hu at sifive.com> wrote:
>
> On Wed, Sep 3, 2025 at 12:08 AM Anup Patel <apatel at ventanamicro.com> wrote:
> >
> > A platform can have multiple IPI devices (such as ACLINT MSWI,
> > AIA IMSIC, etc). Currently, OpenSBI rely on platform calling
> > the sbi_ipi_set_device() function in correct order and prefer
> > the first avaiable IPI device which is fragile.
> >
> > Instead of the above, introdcue IPI device rating and prefer
> > the highest rated IPI device. This further allows extending
> > the sbi_ipi_raw_clear() to clear all available IPI devices.
> >
> > Signed-off-by: Anup Patel <apatel at ventanamicro.com>
> > ---
> > include/sbi/sbi_ipi.h | 6 +++++-
> > lib/sbi/sbi_init.c | 2 +-
> > lib/sbi/sbi_ipi.c | 28 ++++++++++++++++++++--------
> > lib/utils/ipi/aclint_mswi.c | 1 +
> > lib/utils/ipi/andes_plicsw.c | 1 +
> > lib/utils/irqchip/imsic.c | 1 +
> > 6 files changed, 29 insertions(+), 10 deletions(-)
> >
> > diff --git a/include/sbi/sbi_ipi.h b/include/sbi/sbi_ipi.h
> > index 62d61304..0a9ae03d 100644
> > --- a/include/sbi/sbi_ipi.h
> > +++ b/include/sbi/sbi_ipi.h
> > @@ -14,6 +14,7 @@
> >
> > /* clang-format off */
> >
> > +#define SBI_IPI_DEVICE_MAX (4)
> > #define SBI_IPI_EVENT_MAX (8 * __SIZEOF_LONG__)
> >
> > /* clang-format on */
> > @@ -23,6 +24,9 @@ struct sbi_ipi_device {
> > /** Name of the IPI device */
> > char name[32];
> >
> > + /** Ratings of the IPI device (higher is better) */
> > + unsigned long rating;
> > +
> > /** Send IPI to a target HART index */
> > void (*ipi_send)(u32 hart_index);
> >
> > @@ -87,7 +91,7 @@ void sbi_ipi_process(void);
> >
> > int sbi_ipi_raw_send(u32 hartindex);
> >
> > -void sbi_ipi_raw_clear(void);
> > +void sbi_ipi_raw_clear(bool all_devices);
> >
> > const struct sbi_ipi_device *sbi_ipi_get_device(void);
> >
> > diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
> > index 84a63748..663b486b 100644
> > --- a/lib/sbi/sbi_init.c
> > +++ b/lib/sbi/sbi_init.c
> > @@ -507,7 +507,7 @@ static void __noreturn init_warmboot(struct sbi_scratch *scratch, u32 hartid)
> > if (hstate == SBI_HSM_STATE_SUSPENDED) {
> > init_warm_resume(scratch, hartid);
> > } else {
> > - sbi_ipi_raw_clear();
> > + sbi_ipi_raw_clear(true);
> > init_warm_startup(scratch, hartid);
> > }
> > }
> > diff --git a/lib/sbi/sbi_ipi.c b/lib/sbi/sbi_ipi.c
> > index 2de459b0..b57ec652 100644
> > --- a/lib/sbi/sbi_ipi.c
> > +++ b/lib/sbi/sbi_ipi.c
> > @@ -32,8 +32,9 @@ _Static_assert(
> > "type of sbi_ipi_data.ipi_type has changed, please redefine SBI_IPI_EVENT_MAX"
> > );
> >
> > -static unsigned long ipi_data_off;
> > +static unsigned long ipi_data_off, ipi_dev_count;
> > static const struct sbi_ipi_device *ipi_dev = NULL;
> > +static const struct sbi_ipi_device *ipi_dev_array[SBI_IPI_DEVICE_MAX];
> > static const struct sbi_ipi_event_ops *ipi_ops_array[SBI_IPI_EVENT_MAX];
> >
> > static int sbi_ipi_send(struct sbi_scratch *scratch, u32 remote_hartindex,
> > @@ -248,7 +249,7 @@ void sbi_ipi_process(void)
> > sbi_scratch_offset_ptr(scratch, ipi_data_off);
> >
> > sbi_pmu_ctr_incr_fw(SBI_PMU_FW_IPI_RECVD);
> > - sbi_ipi_raw_clear();
> > + sbi_ipi_raw_clear(false);
> >
> > ipi_type = atomic_raw_xchg_ulong(&ipi_data->ipi_type, 0);
> > ipi_event = 0;
> > @@ -283,10 +284,19 @@ int sbi_ipi_raw_send(u32 hartindex)
> > return 0;
> > }
> >
> > -void sbi_ipi_raw_clear(void)
> > +void sbi_ipi_raw_clear(bool all_devices)
> > {
> > - if (ipi_dev && ipi_dev->ipi_clear)
> > - ipi_dev->ipi_clear();
> > + int i;
> > +
> > + if (all_devices) {
> > + for (i = 0; i < ipi_dev_count; i++) {
> > + if (ipi_dev_array[i]->ipi_clear)
> > + ipi_dev_array[i]->ipi_clear();
> > + }
> > + } else {
> > + if (ipi_dev && ipi_dev->ipi_clear)
> > + ipi_dev->ipi_clear();
> > + }
> >
> > /*
> > * Ensure that memory or MMIO writes after this
> > @@ -307,10 +317,12 @@ const struct sbi_ipi_device *sbi_ipi_get_device(void)
> >
> > void sbi_ipi_set_device(const struct sbi_ipi_device *dev)
> > {
> > - if (!dev || ipi_dev)
> > + if (!dev || ipi_dev_count >= SBI_IPI_DEVICE_MAX)
> > return;
> > + ipi_dev_array[ipi_dev_count++] = dev;
> >
> > - ipi_dev = dev;
> > + if (!ipi_dev || ipi_dev->rating < dev->rating)
> > + ipi_dev = dev;
> > }
> >
> > int sbi_ipi_init(struct sbi_scratch *scratch, bool cold_boot)
> > @@ -347,7 +359,7 @@ int sbi_ipi_init(struct sbi_scratch *scratch, bool cold_boot)
> > ipi_data->ipi_type = 0x00;
> >
> > /* Clear any pending IPIs for the current hart */
> > - sbi_ipi_raw_clear();
> > + sbi_ipi_raw_clear(true);
> Can we put it to the cold boot path since the init_warmboot() already
> cleared the IPI?
sbi_ipi_raw_clear() only clears IPI for the current CPU hence must
be done in init_warmboot(). This also helps when CPU is powered-off
and powered-on.
Regards,
Anup
>
> >
> > /* Enable software interrupts */
> > csr_set(CSR_MIE, MIP_MSIP);
> > diff --git a/lib/utils/ipi/aclint_mswi.c b/lib/utils/ipi/aclint_mswi.c
> > index 9e55078a..23510551 100644
> > --- a/lib/utils/ipi/aclint_mswi.c
> > +++ b/lib/utils/ipi/aclint_mswi.c
> > @@ -62,6 +62,7 @@ static void mswi_ipi_clear(void)
> >
> > static struct sbi_ipi_device aclint_mswi = {
> > .name = "aclint-mswi",
> > + .rating = 100,
> > .ipi_send = mswi_ipi_send,
> > .ipi_clear = mswi_ipi_clear
> > };
> > diff --git a/lib/utils/ipi/andes_plicsw.c b/lib/utils/ipi/andes_plicsw.c
> > index 5d085d85..000fe9fd 100644
> > --- a/lib/utils/ipi/andes_plicsw.c
> > +++ b/lib/utils/ipi/andes_plicsw.c
> > @@ -61,6 +61,7 @@ static void plicsw_ipi_clear(void)
> >
> > static struct sbi_ipi_device plicsw_ipi = {
> > .name = "andes_plicsw",
> > + .rating = 200,
> > .ipi_send = plicsw_ipi_send,
> > .ipi_clear = plicsw_ipi_clear
> > };
> > diff --git a/lib/utils/irqchip/imsic.c b/lib/utils/irqchip/imsic.c
> > index 057b9fa7..3c150c37 100644
> > --- a/lib/utils/irqchip/imsic.c
> > +++ b/lib/utils/irqchip/imsic.c
> > @@ -199,6 +199,7 @@ static void imsic_ipi_send(u32 hart_index)
> >
> > static struct sbi_ipi_device imsic_ipi_device = {
> > .name = "aia-imsic",
> > + .rating = 300,
> > .ipi_send = imsic_ipi_send
> > };
> >
> > --
> > 2.43.0
> >
> >
> > --
> > opensbi mailing list
> > opensbi at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/opensbi
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