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PCI: endpoint: pci-epf-vntb: Reuse pre-exposed doorbells and IRQ flags

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Support doorbell backends where the doorbell target is already exposed
via a platform-owned fixed BAR mapping and/or where the doorbell IRQ
must be requested with specific flags.

When pci_epf_alloc_doorbell() provides db_msg[].bar/offset, reuse the
pre-exposed BAR window and skip programming a new inbound mapping. Also
honor db_msg[].irq_flags when requesting the doorbell IRQ.

Multiple doorbells may share the same Linux IRQ. Avoid duplicate
request_irq() calls by requesting each unique virq once.

Make pci-epf-vntb work with platform-defined or embedded doorbell
backends without exposing backend-specific details to the consumer
layer.

Signed-off-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260414141514.1341429-6-den@valinux.co.jp
This commit is contained in:
Koichiro Den 2026-04-14 23:15:12 +09:00 committed by Bjorn Helgaas
parent a3a079e5c5
commit 0c3f82a584
1 changed files with 58 additions and 3 deletions
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61
drivers/pci/endpoint/functions/pci-epf-vntb.c
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@ -134,6 +134,11 @@ struct epf_ntb {
u16 vntb_vid;
bool linkup;
/*
* True when doorbells are interrupt-driven (MSI or embedded), false
* when polled.
*/
bool msi_doorbell;
u32 spad_size;
@ -517,6 +522,17 @@ static int epf_ntb_configure_interrupt(struct epf_ntb *ntb)
return 0;
}
static bool epf_ntb_db_irq_is_duplicated(const struct pci_epf *epf, unsigned int idx)
{
unsigned int i;
for (i = 0; i < idx; i++)
if (epf->db_msg[i].virq == epf->db_msg[idx].virq)
return true;
return false;
}
static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
struct pci_epf_bar *db_bar,
const struct pci_epc_features *epc_features,
@ -533,9 +549,24 @@ static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
if (ret)
return ret;
/*
* The doorbell target may already be exposed by a platform-owned fixed
* BAR. In that case, we must reuse it and the requested db_bar must
* match.
*/
if (epf->db_msg[0].bar != NO_BAR && epf->db_msg[0].bar != barno) {
ret = -EINVAL;
goto err_free_doorbell;
}
for (req = 0; req < ntb->db_count; req++) {
/* Avoid requesting duplicate handlers */
if (epf_ntb_db_irq_is_duplicated(epf, req))
continue;
ret = request_irq(epf->db_msg[req].virq, epf_ntb_doorbell_handler,
0, "pci_epf_vntb_db", ntb);
epf->db_msg[req].irq_flags, "pci_epf_vntb_db",
ntb);
if (ret) {
dev_err(&epf->dev,
@ -545,6 +576,22 @@ static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
}
}
if (epf->db_msg[0].bar != NO_BAR) {
for (i = 0; i < ntb->db_count; i++) {
msg = &epf->db_msg[i].msg;
if (epf->db_msg[i].bar != barno) {
ret = -EINVAL;
goto err_free_irq;
}
ntb->reg->db_data[i] = msg->data;
ntb->reg->db_offset[i] = epf->db_msg[i].offset;
}
goto out;
}
/* Program inbound mapping for the doorbell */
msg = &epf->db_msg[0].msg;
high = 0;
@ -591,6 +638,7 @@ static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
ntb->reg->db_offset[i] = offset;
}
out:
ntb->reg->db_entry_size = 0;
ntb->msi_doorbell = true;
@ -598,9 +646,13 @@ static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
return 0;
err_free_irq:
for (req--; req >= 0; req--)
for (req--; req >= 0; req--) {
if (epf_ntb_db_irq_is_duplicated(epf, req))
continue;
free_irq(epf->db_msg[req].virq, ntb);
}
err_free_doorbell:
pci_epf_free_doorbell(ntb->epf);
return ret;
}
@ -666,8 +718,11 @@ static void epf_ntb_db_bar_clear(struct epf_ntb *ntb)
if (ntb->msi_doorbell) {
int i;
for (i = 0; i < ntb->db_count; i++)
for (i = 0; i < ntb->db_count; i++) {
if (epf_ntb_db_irq_is_duplicated(ntb->epf, i))
continue;
free_irq(ntb->epf->db_msg[i].virq, ntb);
}
}
if (ntb->epf->db_msg)