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PCI: endpoint: pci-epf-vntb: Add MSI doorbell support
Add MSI doorbell support to reduce latency between PCI host and EP. Before this change: ping 169.254.172.137 64 bytes from 169.254.172.137: icmp_seq=1 ttl=64 time=0.575 ms 64 bytes from 169.254.172.137: icmp_seq=2 ttl=64 time=1.80 ms 64 bytes from 169.254.172.137: icmp_seq=3 ttl=64 time=8.19 ms 64 bytes from 169.254.172.137: icmp_seq=4 ttl=64 time=2.00 ms After this change: ping 169.254.144.71 64 bytes from 169.254.144.71: icmp_seq=1 ttl=64 time=0.215 ms 64 bytes from 169.254.144.71: icmp_seq=2 ttl=64 time=0.456 ms 64 bytes from 169.254.144.71: icmp_seq=3 ttl=64 time=0.448 ms Also, change the data type of 'epf_ntb::db' to 'atomic_64' as multiple doorbell interrupts might trigger at the same time. Signed-off-by: Frank Li <Frank.Li@nxp.com> [mani: added 'pci_epf_' prefix to doorbell IRQ name, minor code cleanups] Signed-off-by: Manivannan Sadhasivam <mani@kernel.org> Link: https://patch.msgid.link/20251015-vntb_msi_doorbell-v6-4-9230298b1910@nxp.com
This commit is contained in:
Frank Li
Manivannan Sadhasivam
parent
0bfc6758f2
commit
dc693d6066
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@ -36,11 +36,13 @@
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* PCIe Root Port PCI EP
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*/
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#include <linux/atomic.h>
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#include <linux/delay.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/pci-ep-msi.h>
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#include <linux/pci-epc.h>
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#include <linux/pci-epf.h>
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#include <linux/ntb.h>
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@ -126,12 +128,13 @@ struct epf_ntb {
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u32 db_count;
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u32 spad_count;
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u64 mws_size[MAX_MW];
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u64 db;
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atomic64_t db;
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u32 vbus_number;
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u16 vntb_pid;
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u16 vntb_vid;
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bool linkup;
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bool msi_doorbell;
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u32 spad_size;
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enum pci_barno epf_ntb_bar[VNTB_BAR_NUM];
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@ -258,9 +261,9 @@ static void epf_ntb_cmd_handler(struct work_struct *work)
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ntb = container_of(work, struct epf_ntb, cmd_handler.work);
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for (i = 1; i < ntb->db_count; i++) {
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for (i = 1; i < ntb->db_count && !ntb->msi_doorbell; i++) {
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if (ntb->epf_db[i]) {
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ntb->db |= 1 << (i - 1);
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atomic64_or(1 << (i - 1), &ntb->db);
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ntb_db_event(&ntb->ntb, i);
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ntb->epf_db[i] = 0;
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}
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@ -319,7 +322,21 @@ static void epf_ntb_cmd_handler(struct work_struct *work)
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reset_handler:
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queue_delayed_work(kpcintb_workqueue, &ntb->cmd_handler,
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msecs_to_jiffies(5));
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ntb->msi_doorbell ? msecs_to_jiffies(500) : msecs_to_jiffies(5));
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}
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static irqreturn_t epf_ntb_doorbell_handler(int irq, void *data)
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{
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struct epf_ntb *ntb = data;
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int i;
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for (i = 1; i < ntb->db_count; i++)
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if (irq == ntb->epf->db_msg[i].virq) {
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atomic64_or(1 << (i - 1), &ntb->db);
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ntb_db_event(&ntb->ntb, i);
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}
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return IRQ_HANDLED;
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}
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/**
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@ -500,6 +517,94 @@ static int epf_ntb_configure_interrupt(struct epf_ntb *ntb)
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return 0;
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}
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static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
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struct pci_epf_bar *db_bar,
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const struct pci_epc_features *epc_features,
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enum pci_barno barno)
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{
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struct pci_epf *epf = ntb->epf;
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dma_addr_t low, high;
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struct msi_msg *msg;
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size_t sz;
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int ret;
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int i;
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ret = pci_epf_alloc_doorbell(epf, ntb->db_count);
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if (ret)
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return ret;
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for (i = 0; i < ntb->db_count; i++) {
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ret = request_irq(epf->db_msg[i].virq, epf_ntb_doorbell_handler,
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0, "pci_epf_vntb_db", ntb);
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if (ret) {
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dev_err(&epf->dev,
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"Failed to request doorbell IRQ: %d\n",
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epf->db_msg[i].virq);
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goto err_free_irq;
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}
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}
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msg = &epf->db_msg[0].msg;
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high = 0;
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low = (u64)msg->address_hi << 32 | msg->address_lo;
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for (i = 0; i < ntb->db_count; i++) {
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struct msi_msg *msg = &epf->db_msg[i].msg;
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dma_addr_t addr = (u64)msg->address_hi << 32 | msg->address_lo;
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low = min(low, addr);
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high = max(high, addr);
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}
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sz = high - low + sizeof(u32);
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ret = pci_epf_assign_bar_space(epf, sz, barno, epc_features, 0, low);
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if (ret) {
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dev_err(&epf->dev, "Failed to assign Doorbell BAR space\n");
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goto err_free_irq;
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}
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ret = pci_epc_set_bar(ntb->epf->epc, ntb->epf->func_no,
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ntb->epf->vfunc_no, db_bar);
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if (ret) {
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dev_err(&epf->dev, "Failed to set Doorbell BAR\n");
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goto err_free_irq;
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}
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for (i = 0; i < ntb->db_count; i++) {
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struct msi_msg *msg = &epf->db_msg[i].msg;
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dma_addr_t addr;
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size_t offset;
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ret = pci_epf_align_inbound_addr(epf, db_bar->barno,
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((u64)msg->address_hi << 32) | msg->address_lo,
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&addr, &offset);
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if (ret) {
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ntb->msi_doorbell = false;
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goto err_free_irq;
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}
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ntb->reg->db_data[i] = msg->data;
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ntb->reg->db_offset[i] = offset;
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}
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ntb->reg->db_entry_size = 0;
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ntb->msi_doorbell = true;
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return 0;
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err_free_irq:
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for (i--; i >= 0; i--)
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free_irq(epf->db_msg[i].virq, ntb);
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pci_epf_free_doorbell(ntb->epf);
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return ret;
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}
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/**
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* epf_ntb_db_bar_init() - Configure Doorbell window BARs
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* @ntb: NTB device that facilitates communication between HOST and VHOST
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@ -520,21 +625,25 @@ static int epf_ntb_db_bar_init(struct epf_ntb *ntb)
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ntb->epf->func_no,
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ntb->epf->vfunc_no);
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barno = ntb->epf_ntb_bar[BAR_DB];
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mw_addr = pci_epf_alloc_space(ntb->epf, size, barno, epc_features, 0);
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if (!mw_addr) {
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dev_err(dev, "Failed to allocate OB address\n");
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return -ENOMEM;
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}
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ntb->epf_db = mw_addr;
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epf_bar = &ntb->epf->bar[barno];
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ret = pci_epc_set_bar(ntb->epf->epc, ntb->epf->func_no, ntb->epf->vfunc_no, epf_bar);
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ret = epf_ntb_db_bar_init_msi_doorbell(ntb, epf_bar, epc_features, barno);
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if (ret) {
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dev_err(dev, "Doorbell BAR set failed\n");
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/* fall back to polling mode */
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mw_addr = pci_epf_alloc_space(ntb->epf, size, barno, epc_features, 0);
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if (!mw_addr) {
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dev_err(dev, "Failed to allocate OB address\n");
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return -ENOMEM;
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}
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ntb->epf_db = mw_addr;
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ret = pci_epc_set_bar(ntb->epf->epc, ntb->epf->func_no,
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ntb->epf->vfunc_no, epf_bar);
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if (ret) {
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dev_err(dev, "Doorbell BAR set failed\n");
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goto err_alloc_peer_mem;
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}
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}
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return ret;
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@ -554,6 +663,16 @@ static void epf_ntb_db_bar_clear(struct epf_ntb *ntb)
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{
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enum pci_barno barno;
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if (ntb->msi_doorbell) {
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int i;
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for (i = 0; i < ntb->db_count; i++)
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free_irq(ntb->epf->db_msg[i].virq, ntb);
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}
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if (ntb->epf->db_msg)
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pci_epf_free_doorbell(ntb->epf);
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barno = ntb->epf_ntb_bar[BAR_DB];
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pci_epf_free_space(ntb->epf, ntb->epf_db, barno, 0);
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pci_epc_clear_bar(ntb->epf->epc,
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@ -1268,7 +1387,7 @@ static u64 vntb_epf_db_read(struct ntb_dev *ndev)
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{
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struct epf_ntb *ntb = ntb_ndev(ndev);
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return ntb->db;
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return atomic64_read(&ntb->db);
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}
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static int vntb_epf_mw_get_align(struct ntb_dev *ndev, int pidx, int idx,
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@ -1308,7 +1427,7 @@ static int vntb_epf_db_clear(struct ntb_dev *ndev, u64 db_bits)
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{
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struct epf_ntb *ntb = ntb_ndev(ndev);
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ntb->db &= ~db_bits;
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atomic64_and(~db_bits, &ntb->db);
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return 0;
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}
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