[dpdk-dev] [PATCH v4 1/3] bus/pci: set PCI master in command register

[Haiyue Wang]

Add the API to set 'Bus Master Enable' bit to be enabled or disabled in
the PCI command register.

Signed-off-by: Haiyue Wang <haiyue.wang at intel.com>
---
 drivers/bus/pci/pci_common.c  | 28 ++++++++++++++++++++++++++++
 drivers/bus/pci/rte_bus_pci.h | 14 ++++++++++++++
 drivers/bus/pci/version.map   |  3 +++
 lib/pci/rte_pci.h             |  4 ++++
 4 files changed, 49 insertions(+)

diff --git a/drivers/bus/pci/pci_common.c b/drivers/bus/pci/pci_common.c
index ee7f96635..35d7d092d 100644
--- a/drivers/bus/pci/pci_common.c
+++ b/drivers/bus/pci/pci_common.c
@@ -746,6 +746,34 @@ rte_pci_find_ext_capability(struct rte_pci_device *dev, uint32_t cap)
 	return 0;
 }
 
+int
+rte_pci_set_bus_master(struct rte_pci_device *dev, bool enable)
+{
+	uint16_t old_cmd, cmd;
+
+	if (rte_pci_read_config(dev, &old_cmd, sizeof(old_cmd),
+				RTE_PCI_COMMAND) < 0) {
+		RTE_LOG(ERR, EAL, "error in reading PCI command register\n");
+		return -1;
+	}
+
+	if (enable)
+		cmd = old_cmd | RTE_PCI_COMMAND_MASTER;
+	else
+		cmd = old_cmd & ~RTE_PCI_COMMAND_MASTER;
+
+	if (cmd == old_cmd)
+		return 0;
+
+	if (rte_pci_write_config(dev, &cmd, sizeof(cmd),
+				 RTE_PCI_COMMAND) < 0) {
+		RTE_LOG(ERR, EAL, "error in writing PCI command register\n");
+		return -1;
+	}
+
+	return 0;
+}
+
 struct rte_pci_bus rte_pci_bus = {
 	.bus = {
 		.scan = rte_pci_scan,
diff --git a/drivers/bus/pci/rte_bus_pci.h b/drivers/bus/pci/rte_bus_pci.h
index 64886b473..976c33c92 100644
--- a/drivers/bus/pci/rte_bus_pci.h
+++ b/drivers/bus/pci/rte_bus_pci.h
@@ -249,6 +249,20 @@ void rte_pci_dump(FILE *f);
 __rte_experimental
 off_t rte_pci_find_ext_capability(struct rte_pci_device *dev, uint32_t cap);
 
+/**
+ * Enables/Disables Bus Master for device's PCI command register.
+ *
+ *  @param dev
+ *    A pointer to rte_pci_device structure.
+ *  @param enable
+ *    Enable or disable Bus Master.
+ *
+ *  @return
+ *  0 on success, -1 on error in PCI config space read/write.
+ */
+__rte_experimental
+int rte_pci_set_bus_master(struct rte_pci_device *dev, bool enable);
+
 /**
  * Register a PCI driver.
  *
diff --git a/drivers/bus/pci/version.map b/drivers/bus/pci/version.map
index f33ed0abd..c6e5f797c 100644
--- a/drivers/bus/pci/version.map
+++ b/drivers/bus/pci/version.map
@@ -21,4 +21,7 @@ EXPERIMENTAL {
 	global:
 
 	rte_pci_find_ext_capability;
+
+	# added in 21.05
+	rte_pci_set_bus_master;
 };
diff --git a/lib/pci/rte_pci.h b/lib/pci/rte_pci.h
index a8f8e404a..1f33d687f 100644
--- a/lib/pci/rte_pci.h
+++ b/lib/pci/rte_pci.h
@@ -32,6 +32,10 @@ extern "C" {
 
 #define RTE_PCI_VENDOR_ID	0x00	/* 16 bits */
 #define RTE_PCI_DEVICE_ID	0x02	/* 16 bits */
+#define RTE_PCI_COMMAND		0x04	/* 16 bits */
+
+/* PCI Command Register */
+#define RTE_PCI_COMMAND_MASTER	0x4	/* Bus Master Enable */
 
 /* PCI Express capability registers */
 #define RTE_PCI_EXP_DEVCTL	8	/* Device Control */
-- 
2.31.1