On Sat, Feb 07, 2026 at 02:26:44AM +0900, Koichiro Den wrote: > Extend pci-epf-test with an "embedded doorbell" variant that does not > rely on the EPC doorbell/MSI mechanism. > > When the host sets FLAG_DB_EMBEDDED, query EPC remote resources to > locate the embedded DMA MMIO window and a per-channel > interrupt-emulation doorbell register offset. Map the MMIO window into a > free BAR and return BAR+offset to the host as the doorbell target. > > Handle the resulting shared IRQ by deferring completion signalling to a > work item, then update the test status and raise the completion IRQ back > to the host. > > The existing MSI doorbell remains the default when FLAG_DB_EMBEDDED is > not set. > > Signed-off-by: Koichiro Den <[email protected]> > ---
Can you change pci_epf_alloc_doorbell() directly? Let it fall back to edma implement. Frank > drivers/pci/endpoint/functions/pci-epf-test.c | 193 +++++++++++++++++- > 1 file changed, 185 insertions(+), 8 deletions(-) > > diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c > b/drivers/pci/endpoint/functions/pci-epf-test.c > index 6952ee418622..5871da8cbddf 100644 > --- a/drivers/pci/endpoint/functions/pci-epf-test.c > +++ b/drivers/pci/endpoint/functions/pci-epf-test.c > @@ -6,6 +6,7 @@ > * Author: Kishon Vijay Abraham I <[email protected]> > */ > > +#include <linux/bitops.h> > #include <linux/crc32.h> > #include <linux/delay.h> > #include <linux/dmaengine.h> > @@ -56,6 +57,7 @@ > #define STATUS_BAR_SUBRANGE_CLEAR_FAIL BIT(17) > > #define FLAG_USE_DMA BIT(0) > +#define FLAG_DB_EMBEDDED BIT(1) > > #define TIMER_RESOLUTION 1 > > @@ -69,6 +71,12 @@ > > static struct workqueue_struct *kpcitest_workqueue; > > +enum pci_epf_test_doorbell_variant { > + PCI_EPF_TEST_DB_NONE = 0, > + PCI_EPF_TEST_DB_MSI, > + PCI_EPF_TEST_DB_EMBEDDED, > +}; > + > struct pci_epf_test { > void *reg[PCI_STD_NUM_BARS]; > struct pci_epf *epf; > @@ -85,7 +93,11 @@ struct pci_epf_test { > bool dma_supported; > bool dma_private; > const struct pci_epc_features *epc_features; > + enum pci_epf_test_doorbell_variant db_variant; > struct pci_epf_bar db_bar; > + int db_irq; > + unsigned long db_irq_pending; > + struct work_struct db_work; > size_t bar_size[PCI_STD_NUM_BARS]; > }; > > @@ -696,7 +708,7 @@ static void pci_epf_test_raise_irq(struct pci_epf_test > *epf_test, > } > } > > -static irqreturn_t pci_epf_test_doorbell_handler(int irq, void *data) > +static irqreturn_t pci_epf_test_doorbell_msi_handler(int irq, void *data) > { > struct pci_epf_test *epf_test = data; > enum pci_barno test_reg_bar = epf_test->test_reg_bar; > @@ -710,19 +722,58 @@ static irqreturn_t pci_epf_test_doorbell_handler(int > irq, void *data) > return IRQ_HANDLED; > } > > +static void pci_epf_test_doorbell_embedded_work(struct work_struct *work) > +{ > + struct pci_epf_test *epf_test = > + container_of(work, struct pci_epf_test, db_work); > + enum pci_barno test_reg_bar = epf_test->test_reg_bar; > + struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar]; > + u32 status = le32_to_cpu(reg->status); > + > + status |= STATUS_DOORBELL_SUCCESS; > + reg->status = cpu_to_le32(status); > + pci_epf_test_raise_irq(epf_test, reg); > + > + clear_bit(0, &epf_test->db_irq_pending); > +} > + > +static irqreturn_t pci_epf_test_doorbell_embedded_irq_handler(int irq, void > *data) > +{ > + struct pci_epf_test *epf_test = data; > + > + if (READ_ONCE(epf_test->db_variant) != PCI_EPF_TEST_DB_EMBEDDED) > + return IRQ_NONE; > + > + if (test_and_set_bit(0, &epf_test->db_irq_pending)) > + return IRQ_HANDLED; > + > + queue_work(kpcitest_workqueue, &epf_test->db_work); > + return IRQ_HANDLED; > +} > + > static void pci_epf_test_doorbell_cleanup(struct pci_epf_test *epf_test) > { > struct pci_epf_test_reg *reg = epf_test->reg[epf_test->test_reg_bar]; > struct pci_epf *epf = epf_test->epf; > > - free_irq(epf->db_msg[0].virq, epf_test); > - reg->doorbell_bar = cpu_to_le32(NO_BAR); > + if (epf_test->db_irq) { > + free_irq(epf_test->db_irq, epf_test); > + epf_test->db_irq = 0; > + } > + > + if (epf_test->db_variant == PCI_EPF_TEST_DB_EMBEDDED) { > + cancel_work_sync(&epf_test->db_work); > + clear_bit(0, &epf_test->db_irq_pending); > + } else if (epf_test->db_variant == PCI_EPF_TEST_DB_MSI) { > + pci_epf_free_doorbell(epf); > + } > > - pci_epf_free_doorbell(epf); > + reg->doorbell_bar = cpu_to_le32(NO_BAR); > + epf_test->db_variant = PCI_EPF_TEST_DB_NONE; > } > > -static void pci_epf_test_enable_doorbell(struct pci_epf_test *epf_test, > - struct pci_epf_test_reg *reg) > +static void pci_epf_test_enable_doorbell_msi(struct pci_epf_test *epf_test, > + struct pci_epf_test_reg *reg) > { > u32 status = le32_to_cpu(reg->status); > struct pci_epf *epf = epf_test->epf; > @@ -736,20 +787,23 @@ static void pci_epf_test_enable_doorbell(struct > pci_epf_test *epf_test, > if (ret) > goto set_status_err; > > + epf_test->db_variant = PCI_EPF_TEST_DB_MSI; > msg = &epf->db_msg[0].msg; > bar = pci_epc_get_next_free_bar(epf_test->epc_features, > epf_test->test_reg_bar + 1); > if (bar < BAR_0) > goto err_doorbell_cleanup; > > ret = request_threaded_irq(epf->db_msg[0].virq, NULL, > - pci_epf_test_doorbell_handler, IRQF_ONESHOT, > - "pci-ep-test-doorbell", epf_test); > + pci_epf_test_doorbell_msi_handler, > + IRQF_ONESHOT, "pci-ep-test-doorbell", > + epf_test); > if (ret) { > dev_err(&epf->dev, > "Failed to request doorbell IRQ: %d\n", > epf->db_msg[0].virq); > goto err_doorbell_cleanup; > } > + epf_test->db_irq = epf->db_msg[0].virq; > > reg->doorbell_data = cpu_to_le32(msg->data); > reg->doorbell_bar = cpu_to_le32(bar); > @@ -782,6 +836,125 @@ static void pci_epf_test_enable_doorbell(struct > pci_epf_test *epf_test, > reg->status = cpu_to_le32(status); > } > > +static void pci_epf_test_enable_doorbell_embedded(struct pci_epf_test > *epf_test, > + struct pci_epf_test_reg *reg) > +{ > + struct pci_epc_remote_resource *dma_ctrl = NULL, *chan0 = NULL; > + const char *irq_name = "pci-ep-test-doorbell-embedded"; > + u32 status = le32_to_cpu(reg->status); > + struct pci_epf *epf = epf_test->epf; > + struct pci_epc *epc = epf->epc; > + struct device *dev = &epf->dev; > + enum pci_barno bar; > + size_t align_off; > + unsigned int i; > + int cnt, ret; > + u32 db_off; > + > + cnt = pci_epc_get_remote_resources(epc, epf->func_no, epf->vfunc_no, > + NULL, 0); > + if (cnt <= 0) { > + dev_err(dev, "No remote resources available for embedded > doorbell\n"); > + goto set_status_err; > + } > + > + struct pci_epc_remote_resource *resources __free(kfree) = > + kcalloc(cnt, sizeof(*resources), GFP_KERNEL); > + if (!resources) > + goto set_status_err; > + > + ret = pci_epc_get_remote_resources(epc, epf->func_no, epf->vfunc_no, > + resources, cnt); > + if (ret < 0) { > + dev_err(dev, "Failed to get remote resources: %d\n", ret); > + goto set_status_err; > + } > + cnt = ret; > + > + for (i = 0; i < cnt; i++) { > + if (resources[i].type == PCI_EPC_RR_DMA_CTRL_MMIO) > + dma_ctrl = &resources[i]; > + else if (resources[i].type == PCI_EPC_RR_DMA_CHAN_DESC && > + !chan0) > + chan0 = &resources[i]; > + } > + > + if (!dma_ctrl || !chan0) { > + dev_err(dev, "Missing DMA ctrl MMIO or channel #0 info\n"); > + goto set_status_err; > + } > + > + bar = pci_epc_get_next_free_bar(epf_test->epc_features, > + epf_test->test_reg_bar + 1); > + if (bar < BAR_0) { > + dev_err(dev, "No free BAR for embedded doorbell\n"); > + goto set_status_err; > + } > + > + ret = pci_epf_align_inbound_addr(epf, bar, dma_ctrl->phys_addr, > + &epf_test->db_bar.phys_addr, > + &align_off); > + if (ret) > + goto set_status_err; > + > + db_off = chan0->u.dma_chan_desc.db_offset; > + if (db_off >= dma_ctrl->size || > + align_off + db_off >= epf->bar[bar].size) { > + dev_err(dev, "BAR%d too small for embedded doorbell (off %#zx + > %#x)\n", > + bar, align_off, db_off); > + goto set_status_err; > + } > + > + epf_test->db_variant = PCI_EPF_TEST_DB_EMBEDDED; > + > + ret = request_irq(chan0->u.dma_chan_desc.irq, > + pci_epf_test_doorbell_embedded_irq_handler, > + IRQF_SHARED, irq_name, epf_test); > + if (ret) { > + dev_err(dev, "Failed to request embedded doorbell IRQ: %d\n", > + chan0->u.dma_chan_desc.irq); > + goto err_cleanup; > + } > + epf_test->db_irq = chan0->u.dma_chan_desc.irq; > + > + reg->doorbell_data = cpu_to_le32(0); > + reg->doorbell_bar = cpu_to_le32(bar); > + reg->doorbell_offset = cpu_to_le32(align_off + db_off); > + > + epf_test->db_bar.barno = bar; > + epf_test->db_bar.size = epf->bar[bar].size; > + epf_test->db_bar.flags = epf->bar[bar].flags; > + > + ret = pci_epc_set_bar(epc, epf->func_no, epf->vfunc_no, > &epf_test->db_bar); > + if (ret) > + goto err_cleanup; > + > + status |= STATUS_DOORBELL_ENABLE_SUCCESS; > + reg->status = cpu_to_le32(status); > + return; > + > +err_cleanup: > + pci_epf_test_doorbell_cleanup(epf_test); > +set_status_err: > + status |= STATUS_DOORBELL_ENABLE_FAIL; > + reg->status = cpu_to_le32(status); > +} > + > +static void pci_epf_test_enable_doorbell(struct pci_epf_test *epf_test, > + struct pci_epf_test_reg *reg) > +{ > + u32 flags = le32_to_cpu(reg->flags); > + > + /* If already enabled, drop previous setup first. */ > + if (epf_test->db_variant != PCI_EPF_TEST_DB_NONE) > + pci_epf_test_doorbell_cleanup(epf_test); > + > + if (flags & FLAG_DB_EMBEDDED) > + pci_epf_test_enable_doorbell_embedded(epf_test, reg); > + else > + pci_epf_test_enable_doorbell_msi(epf_test, reg); > +} > + > static void pci_epf_test_disable_doorbell(struct pci_epf_test *epf_test, > struct pci_epf_test_reg *reg) > { > @@ -1309,6 +1482,9 @@ static void pci_epf_test_unbind(struct pci_epf *epf) > > cancel_delayed_work_sync(&epf_test->cmd_handler); > if (epc->init_complete) { > + /* In case userspace never disabled doorbell explicitly. */ > + if (epf_test->db_variant != PCI_EPF_TEST_DB_NONE) > + pci_epf_test_doorbell_cleanup(epf_test); > pci_epf_test_clean_dma_chan(epf_test); > pci_epf_test_clear_bar(epf); > } > @@ -1427,6 +1603,7 @@ static int pci_epf_test_probe(struct pci_epf *epf, > epf_test->bar_size[bar] = default_bar_size[bar]; > > INIT_DELAYED_WORK(&epf_test->cmd_handler, pci_epf_test_cmd_handler); > + INIT_WORK(&epf_test->db_work, pci_epf_test_doorbell_embedded_work); > > epf->event_ops = &pci_epf_test_event_ops; > > -- > 2.51.0 >
