[RFC 3/4] bus/pci: introduce helper for MMIO read and write

[Chenbo Xia <chenbo.xia@intel.com>]

The MMIO regions may not be mmap-able for VFIO-PCI devices.
In this case, the driver should explicitly do read and write
to access these regions.

Signed-off-by: Chenbo Xia <chenbo.xia@intel.com>
---
 drivers/bus/pci/bsd/pci.c        | 22 +++++++++++++++
 drivers/bus/pci/linux/pci.c      | 46 ++++++++++++++++++++++++++++++
 drivers/bus/pci/linux/pci_init.h | 10 +++++++
 drivers/bus/pci/linux/pci_uio.c  | 22 +++++++++++++++
 drivers/bus/pci/linux/pci_vfio.c | 36 ++++++++++++++++++++++++
 drivers/bus/pci/rte_bus_pci.h    | 48 ++++++++++++++++++++++++++++++++
 drivers/bus/pci/version.map      |  3 ++
 7 files changed, 187 insertions(+)

diff --git a/drivers/bus/pci/bsd/pci.c b/drivers/bus/pci/bsd/pci.c
index a747eca58c..27f12590d4 100644
--- a/drivers/bus/pci/bsd/pci.c
+++ b/drivers/bus/pci/bsd/pci.c
@@ -489,6 +489,28 @@ int rte_pci_write_config(const struct rte_pci_device *dev,
 	return -1;
 }
 
+/* Read PCI MMIO space. */
+int rte_pci_mmio_read(const struct rte_pci_device *dev, int bar,
+		      void *buf, size_t len, off_t offset)
+{
+	if (bar >= PCI_MAX_RESOURCE || dev->mem_resource[bar].addr == NULL ||
+			(uint64_t)offset + len > dev->mem_resource[bar].len)
+		return -1;
+	memcpy(buf, (uint8_t *)dev->mem_resource[bar].addr + offset, len);
+	return len;
+}
+
+/* Write PCI MMIO space. */
+int rte_pci_mmio_write(const struct rte_pci_device *dev, int bar,
+		       const void *buf, size_t len, off_t offset)
+{
+	if (bar >= PCI_MAX_RESOURCE || dev->mem_resource[bar].addr == NULL ||
+			(uint64_t)offset + len > dev->mem_resource[bar].len)
+		return -1;
+	memcpy((uint8_t *)dev->mem_resource[bar].addr + offset, buf, len);
+	return len;
+}
+
 int
 rte_pci_ioport_map(struct rte_pci_device *dev, int bar,
 		struct rte_pci_ioport *p)
diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
index 04e21ae20f..3d237398d9 100644
--- a/drivers/bus/pci/linux/pci.c
+++ b/drivers/bus/pci/linux/pci.c
@@ -680,6 +680,52 @@ int rte_pci_write_config(const struct rte_pci_device *device,
 	}
 }
 
+/* Read PCI MMIO space. */
+int rte_pci_mmio_read(const struct rte_pci_device *device, int bar,
+		void *buf, size_t len, off_t offset)
+{
+	char devname[RTE_DEV_NAME_MAX_LEN] = "";
+
+	switch (device->kdrv) {
+	case RTE_PCI_KDRV_IGB_UIO:
+	case RTE_PCI_KDRV_UIO_GENERIC:
+		return pci_uio_mmio_read(device, bar, buf, len, offset);
+#ifdef VFIO_PRESENT
+	case RTE_PCI_KDRV_VFIO:
+		return pci_vfio_mmio_read(device, bar, buf, len, offset);
+#endif
+	default:
+		rte_pci_device_name(&device->addr, devname,
+				    RTE_DEV_NAME_MAX_LEN);
+		RTE_LOG(ERR, EAL,
+			"Unknown driver type for %s\n", devname);
+		return -1;
+	}
+}
+
+/* Write PCI MMIO space. */
+int rte_pci_mmio_write(const struct rte_pci_device *device, int bar,
+		const void *buf, size_t len, off_t offset)
+{
+	char devname[RTE_DEV_NAME_MAX_LEN] = "";
+
+	switch (device->kdrv) {
+	case RTE_PCI_KDRV_IGB_UIO:
+	case RTE_PCI_KDRV_UIO_GENERIC:
+		return pci_uio_mmio_write(device, bar, buf, len, offset);
+#ifdef VFIO_PRESENT
+	case RTE_PCI_KDRV_VFIO:
+		return pci_vfio_mmio_write(device, bar, buf, len, offset);
+#endif
+	default:
+		rte_pci_device_name(&device->addr, devname,
+				    RTE_DEV_NAME_MAX_LEN);
+		RTE_LOG(ERR, EAL,
+			"Unknown driver type for %s\n", devname);
+		return -1;
+	}
+}
+
 int
 rte_pci_ioport_map(struct rte_pci_device *dev, int bar,
 		struct rte_pci_ioport *p)
diff --git a/drivers/bus/pci/linux/pci_init.h b/drivers/bus/pci/linux/pci_init.h
index 9f6659ba6e..d842809ccd 100644
--- a/drivers/bus/pci/linux/pci_init.h
+++ b/drivers/bus/pci/linux/pci_init.h
@@ -37,6 +37,11 @@ int pci_uio_read_config(const struct rte_intr_handle *intr_handle,
 int pci_uio_write_config(const struct rte_intr_handle *intr_handle,
 			 const void *buf, size_t len, off_t offs);
 
+int pci_uio_mmio_read(const struct rte_pci_device *dev, int bar,
+			void *buf, size_t len, off_t offset);
+int pci_uio_mmio_write(const struct rte_pci_device *dev, int bar,
+			const void *buf, size_t len, off_t offset);
+
 int pci_uio_ioport_map(struct rte_pci_device *dev, int bar,
 		       struct rte_pci_ioport *p);
 void pci_uio_ioport_read(struct rte_pci_ioport *p,
@@ -71,6 +76,11 @@ int pci_vfio_read_config(const struct rte_pci_device *dev,
 int pci_vfio_write_config(const struct rte_pci_device *dev,
 			  const void *buf, size_t len, off_t offs);
 
+int pci_vfio_mmio_read(const struct rte_pci_device *dev, int bar,
+			void *buf, size_t len, off_t offset);
+int pci_vfio_mmio_write(const struct rte_pci_device *dev, int bar,
+			const void *buf, size_t len, off_t offset);
+
 int pci_vfio_ioport_map(struct rte_pci_device *dev, int bar,
 		        struct rte_pci_ioport *p);
 void pci_vfio_ioport_read(struct rte_pci_ioport *p,
diff --git a/drivers/bus/pci/linux/pci_uio.c b/drivers/bus/pci/linux/pci_uio.c
index d52125e49b..2bf16e9369 100644
--- a/drivers/bus/pci/linux/pci_uio.c
+++ b/drivers/bus/pci/linux/pci_uio.c
@@ -55,6 +55,28 @@ pci_uio_write_config(const struct rte_intr_handle *intr_handle,
 	return pwrite(uio_cfg_fd, buf, len, offset);
 }
 
+int
+pci_uio_mmio_read(const struct rte_pci_device *dev, int bar,
+		  void *buf, size_t len, off_t offset)
+{
+	if (bar >= PCI_MAX_RESOURCE || dev->mem_resource[bar].addr == NULL ||
+			(uint64_t)offset + len > dev->mem_resource[bar].len)
+		return -1;
+	memcpy(buf, (uint8_t *)dev->mem_resource[bar].addr + offset, len);
+	return len;
+}
+
+int
+pci_uio_mmio_write(const struct rte_pci_device *dev, int bar,
+		   const void *buf, size_t len, off_t offset)
+{
+	if (bar >= PCI_MAX_RESOURCE || dev->mem_resource[bar].addr == NULL ||
+			(uint64_t)offset + len > dev->mem_resource[bar].len)
+		return -1;
+	memcpy((uint8_t *)dev->mem_resource[bar].addr + offset, buf, len);
+	return len;
+}
+
 static int
 pci_uio_set_bus_master(int dev_fd)
 {
diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
index 1748ad2ae0..f6289c907f 100644
--- a/drivers/bus/pci/linux/pci_vfio.c
+++ b/drivers/bus/pci/linux/pci_vfio.c
@@ -1258,6 +1258,42 @@ pci_vfio_ioport_unmap(struct rte_pci_ioport *p)
 	return -1;
 }
 
+int
+pci_vfio_mmio_read(const struct rte_pci_device *dev, int bar,
+		   void *buf, size_t len, off_t offs)
+{
+	uint64_t size, offset;
+	int fd;
+
+	fd = rte_intr_dev_fd_get(dev->intr_handle);
+
+	if (pci_vfio_get_region(dev, bar, &size, &offset) != 0)
+		return -1;
+
+	if ((uint64_t)len + offs > size)
+		return -1;
+
+	return pread64(fd, buf, len, offset + offs);
+}
+
+int
+pci_vfio_mmio_write(const struct rte_pci_device *dev, int bar,
+		    const void *buf, size_t len, off_t offs)
+{
+	uint64_t size, offset;
+	int fd;
+
+	fd = rte_intr_dev_fd_get(dev->intr_handle);
+
+	if (pci_vfio_get_region(dev, bar, &size, &offset) != 0)
+		return -1;
+
+	if ((uint64_t)len + offs > size)
+		return -1;
+
+	return pwrite64(fd, buf, len, offset + offs);
+}
+
 int
 pci_vfio_is_enabled(void)
 {
diff --git a/drivers/bus/pci/rte_bus_pci.h b/drivers/bus/pci/rte_bus_pci.h
index b193114fe5..82da087f24 100644
--- a/drivers/bus/pci/rte_bus_pci.h
+++ b/drivers/bus/pci/rte_bus_pci.h
@@ -135,6 +135,54 @@ int rte_pci_read_config(const struct rte_pci_device *device,
 int rte_pci_write_config(const struct rte_pci_device *device,
 		const void *buf, size_t len, off_t offset);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Read from a MMIO pci resource.
+ *
+ * @param device
+ *   A pointer to a rte_pci_device structure describing the device
+ *   to use
+ * @param bar
+ *   Index of the io pci resource we want to access.
+ * @param buf
+ *   A data buffer where the bytes should be read into
+ * @param len
+ *   The length of the data buffer.
+ * @param offset
+ *   The offset into MMIO space described by @bar
+ * @return
+ *  Number of bytes read on success, negative on error.
+ */
+__rte_experimental
+int rte_pci_mmio_read(const struct rte_pci_device *device, int bar,
+		void *buf, size_t len, off_t offset);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Write to a MMIO pci resource.
+ *
+ * @param device
+ *   A pointer to a rte_pci_device structure describing the device
+ *   to use
+ * @param bar
+ *   Index of the io pci resource we want to access.
+ * @param buf
+ *   A data buffer containing the bytes should be written
+ * @param len
+ *   The length of the data buffer.
+ * @param offset
+ *   The offset into MMIO space described by @bar
+ * @return
+ *  Number of bytes written on success, negative on error.
+ */
+__rte_experimental
+int rte_pci_mmio_write(const struct rte_pci_device *device, int bar,
+		const void *buf, size_t len, off_t offset);
+
 /**
  * Initialize a rte_pci_ioport object for a pci device io resource.
  *
diff --git a/drivers/bus/pci/version.map b/drivers/bus/pci/version.map
index 161ab86d3b..00fde139ca 100644
--- a/drivers/bus/pci/version.map
+++ b/drivers/bus/pci/version.map
@@ -21,6 +21,9 @@ EXPERIMENTAL {
 
 	# added in 21.08
 	rte_pci_set_bus_master;
+	# added in 23.07
+	rte_pci_mmio_read;
+	rte_pci_mmio_write;
 };
 
 INTERNAL {
-- 
2.17.1