[dpdk-dev] [RFC PATCH 2/6] eal: introduce bus-device-driver structure

[Shreyansh Jain <shreyansh.jain@nxp.com>]

A device is connected to a bus and services by a driver associated with
the bus. It is responsibility of the bus to identify the devices (scan)
and then assign each device to a matching driver.

A PMD would allocate a rte_xxx_driver and rte_xxx_device.
rte_xxx_driver has rte_driver and rte_bus embedded. Similarly, rte_xxx_device
has rte_device and rte_bus embedded.

When a ethernet or crypto device (rte_eth_dev, rte_cryptodev) is allocated,
it contains a reference of rte_device and rte_driver.
Each ethernet device implementation would use container_of for finding the
enclosing structure of rte_xxx_*.

                            +-------------------+
 +--------------+           |rte_pci_device     |
 |rte_eth_dev   |           |+-----------------+|
 |+------------+|   .-------->rte_device       ||
 ||rte_device*-----'        |+-----------------+|
 |+------------+|           ||rte_bus          ||
 |              |           |+-----------------+|
 /              /           +-------------------+

Signed-off-by: Shreyansh Jain <shreyansh.jain@nxp.com>
---
 lib/librte_eal/common/include/rte_bus.h | 243 ++++++++++++++++++++++++++++++++
 lib/librte_eal/common/include/rte_dev.h |  36 ++---
 2 files changed, 261 insertions(+), 18 deletions(-)
 create mode 100644 lib/librte_eal/common/include/rte_bus.h

diff --git a/lib/librte_eal/common/include/rte_bus.h b/lib/librte_eal/common/include/rte_bus.h
new file mode 100644
index 0000000..dc3aeb8
--- /dev/null
+++ b/lib/librte_eal/common/include/rte_bus.h
@@ -0,0 +1,243 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2016 NXP
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of NXP nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _RTE_BUS_H_
+#define _RTE_BUS_H_
+
+/**
+ * @file
+ *
+ * RTE PMD Bus Abstraction interfaces
+ *
+ * This file exposes APIs and Interfaces for Bus Abstraction over the devices
+ * drivers in EAL.
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdio.h>
+#include <sys/queue.h>
+
+#include <rte_log.h>
+#include <rte_dev.h>
+
+
+/** Double linked list of buses */
+TAILQ_HEAD(rte_bus_list, rte_bus);
+
+/**
+ * Bus specific scan for devices attached on the bus.
+ * For each bus object, the scan would be reponsible for finding devices and
+ * adding them to its private device list.
+ *
+ * Successful detection of a device results in rte_device object which is
+ * embedded within the respective device type (rte_pci_device, for example).
+ * Thereafter, PCI specific bus would need to perform
+ * container_of(rte_pci_device) to obtain PCI device object.
+ *
+ * Scan failure of a bus is not treated as exit criteria for application. Scan
+ * for all other buses would still continue.
+ *
+ * @param void
+ * @return
+ *	0 for successful scan
+ *	!0 (<0) for unsuccessful scan with error value
+ */
+typedef int (* bus_scan_t)(void);
+
+/**
+ * Bus specific match for devices and drivers which can service them.
+ * For each scanned device, during probe the match would link the devices with
+ * drivers which can service the device.
+ *
+ * It is the work of each bus handler to obtain the specific device object
+ * using container_of (or typecasting, as a less preferred way).
+ *
+ * @param drv
+ *	Driver object attached to the bus
+ * @param dev
+ *	Device object which is being probed.
+ * @return
+ *	0 for successful match
+ *	!0 for unsuccessful match
+ */
+typedef int (* bus_match_t)(struct rte_driver *drv, struct rte_device *dev);
+
+/**
+ * Dump the devices on the bus.
+ * Each bus type can define its own definition of information to dump.
+ *
+ * @param bus
+ *	Handle for bus, device from which are to be dumped.
+ * @param f
+ *	Handle to output device or file.
+ * @return void
+ */
+typedef void (* bus_dump_t)(struct rte_bus *bus, FILE *f);
+
+/**
+ * Search for a specific device in device list of the bus
+ * This would rely on the bus specific addressing. Each implementation would
+ * extract its specific device type and perform address compare.
+ *
+ * @param dev
+ *	device handle to search for.
+ * @return
+ *	rte_device handle for matched device, or NULL
+ */
+typedef struct rte_device * (* bus_device_get_t)(struct rte_device *dev);
+
+struct rte_bus {
+	TAILQ_ENTRY(rte_bus) next;   /**< Next bus object in linked list */
+	struct rte_driver_list driver_list; /**< List of all drivers of bus */
+	struct rte_device_list device_list; /**< List of all devices on bus */
+	const char *name;            /**< Name of the bus */
+	/* Mandatory hooks */
+	bus_scan_t *scan;            /**< Hook for scanning for devices */
+	bus_match_t *match;          /**< Hook for matching device & driver */
+	/* Optional hooks */
+	bus_dump_t *dump_dev;        /**< Hook for dumping devices on bus */
+	bus_device_get_t *find_dev;  /**< Search for a device on bus */
+};
+
+/** @internal
+ * Add a device to a bus.
+ *
+ * @param bus
+ *	Bus on which device is to be added
+ * @param dev
+ *	Device handle
+ * @return
+ *	None
+ */
+void
+rte_eal_bus_add_device(struct rte_bus *bus, struct rte_device *dev);
+
+/** @internal
+ * Remove a device from its bus.
+ *
+ * @param dev
+ *	Device handle to remove
+ * @return
+ *	None
+ */
+void
+rte_eal_bus_remove_device(struct rte_device *dev);
+
+/** @internal
+ * Associate a driver with a bus.
+ *
+ * @param bus
+ *	Bus on which driver is to be added
+ * @param dev
+ *	Driver handle
+ * @return
+ *	None
+ */
+void
+rte_eal_bus_add_driver(struct rte_bus *bus, struct rte_driver *drv);
+
+/** @internal
+ * Disassociate a driver from its bus.
+ *
+ * @param dev
+ *	Driver handle to remove
+ * @return
+ *	None
+ */
+void
+rte_eal_bus_remove_driver(struct rte_driver *drv);
+
+/**
+ * Register a Bus handler.
+ *
+ * @param driver
+ *   A pointer to a rte_bus structure describing the bus
+ *   to be registered.
+ */
+void rte_eal_bus_register(struct rte_bus *bus);
+
+/**
+ * Unregister a Bus handler.
+ *
+ * @param driver
+ *   A pointer to a rte_bus structure describing the bus
+ *   to be unregistered.
+ */
+void rte_eal_bus_unregister(struct rte_bus *bus);
+
+/**
+ * Obtain handle for bus given its name.
+ *
+ * @param bus_name
+ *	Name of the bus handle to search
+ * @return
+ *	Pointer to Bus object if name matches any registered bus object
+ *	NULL, if no matching bus found
+ */
+struct rte_bus * rte_eal_get_bus(const char *bus_name);
+
+/**
+ * Register a device driver.
+ *
+ * @param driver
+ *   A pointer to a rte_dev structure describing the driver
+ *   to be registered.
+ */
+void rte_eal_driver_register(struct rte_driver *driver);
+
+/**
+ * Unregister a device driver.
+ *
+ * @param driver
+ *   A pointer to a rte_dev structure describing the driver
+ *   to be unregistered.
+ */
+void rte_eal_driver_unregister(struct rte_driver *driver);
+
+/** Helper for Bus registration */
+#define RTE_PMD_REGISTER_BUS(nm, bus) \
+RTE_INIT(businitfn_ ##nm); \
+static void businitfn_ ##nm(void) \
+{\
+	(bus).name = RTE_STR(nm);\
+	rte_eal_bus_register(&bus); \
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _RTE_BUS_H */
diff --git a/lib/librte_eal/common/include/rte_dev.h b/lib/librte_eal/common/include/rte_dev.h
index 8840380..b08bab5 100644
--- a/lib/librte_eal/common/include/rte_dev.h
+++ b/lib/librte_eal/common/include/rte_dev.h
@@ -116,12 +116,14 @@ TAILQ_HEAD(rte_device_list, rte_device);
 
 /* Forward declaration */
 struct rte_driver;
+struct rte_bus;
 
 /**
  * A structure describing a generic device.
  */
 struct rte_device {
 	TAILQ_ENTRY(rte_device) next; /**< Next device */
+	struct rte_bus *bus;          /**< Bus on which device is placed */
 	struct rte_driver *driver;    /**< Associated driver */
 	int numa_node;                /**< NUMA node connection */
 	struct rte_devargs *devargs;  /**< Device user arguments */
@@ -144,31 +146,29 @@ void rte_eal_device_insert(struct rte_device *dev);
 void rte_eal_device_remove(struct rte_device *dev);
 
 /**
- * A structure describing a device driver.
+ * @internal
+ * TODO
  */
-struct rte_driver {
-	TAILQ_ENTRY(rte_driver) next;  /**< Next in list. */
-	const char *name;                   /**< Driver name. */
-	const char *alias;              /**< Driver alias. */
-};
+typedef int (*driver_init_t)(struct rte_device *eth_dev);
 
 /**
- * Register a device driver.
- *
- * @param driver
- *   A pointer to a rte_dev structure describing the driver
- *   to be registered.
+ * @internal
+ * TODO
  */
-void rte_eal_driver_register(struct rte_driver *driver);
+typedef int (*driver_uninit_t)(struct rte_device *eth_dev);
 
 /**
- * Unregister a device driver.
- *
- * @param driver
- *   A pointer to a rte_dev structure describing the driver
- *   to be unregistered.
+ * A structure describing a device driver.
  */
-void rte_eal_driver_unregister(struct rte_driver *driver);
+struct rte_driver {
+	TAILQ_ENTRY(rte_driver) next;  /**< Next in list. */
+	struct rte_bus *bus;           /**< Bus which drivers services */
+	const char *name;              /**< Driver name. */
+	const char *alias;             /**< Driver alias. */
+	driver_init_t *init;           /**< Driver initialization */
+	driver_uninit_t *uninit;       /**< Driver uninitialization */
+	unsigned int dev_private_size; /**< Size of device private data ??*/
+};
 
 /**
  * Initalize all the registered drivers in this process
-- 
2.7.4