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authorRajithaY <rajithax.yerrumsetty@intel.com>2017-04-25 03:31:15 -0700
committerRajitha Yerrumchetty <rajithax.yerrumsetty@intel.com>2017-05-22 06:48:08 +0000
commitbb756eebdac6fd24e8919e2c43f7d2c8c4091f59 (patch)
treeca11e03542edf2d8f631efeca5e1626d211107e3 /qemu/roms/u-boot/doc/README.drivers.eth
parenta14b48d18a9ed03ec191cf16b162206998a895ce (diff)
Adding qemu as a submodule of KVMFORNFV
This Patch includes the changes to add qemu as a submodule to kvmfornfv repo and make use of the updated latest qemu for the execution of all testcase Change-Id: I1280af507a857675c7f81d30c95255635667bdd7 Signed-off-by:RajithaY<rajithax.yerrumsetty@intel.com>
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------------------------
- Ethernet Driver Guide
------------------------
-
-The networking stack in Das U-Boot is designed for multiple network devices
-to be easily added and controlled at runtime. This guide is meant for people
-who wish to review the net driver stack with an eye towards implementing your
-own ethernet device driver. Here we will describe a new pseudo 'APE' driver.
-
-------------------
- Driver Functions
-------------------
-
-All functions you will be implementing in this document have the return value
-meaning of 0 for success and non-zero for failure.
-
- ----------
- Register
- ----------
-
-When U-Boot initializes, it will call the common function eth_initialize().
-This will in turn call the board-specific board_eth_init() (or if that fails,
-the cpu-specific cpu_eth_init()). These board-specific functions can do random
-system handling, but ultimately they will call the driver-specific register
-function which in turn takes care of initializing that particular instance.
-
-Keep in mind that you should code the driver to avoid storing state in global
-data as someone might want to hook up two of the same devices to one board.
-Any such information that is specific to an interface should be stored in a
-private, driver-defined data structure and pointed to by eth->priv (see below).
-
-So the call graph at this stage would look something like:
-board_init()
- eth_initialize()
- board_eth_init() / cpu_eth_init()
- driver_register()
- initialize eth_device
- eth_register()
-
-At this point in time, the only thing you need to worry about is the driver's
-register function. The pseudo code would look something like:
-int ape_register(bd_t *bis, int iobase)
-{
- struct ape_priv *priv;
- struct eth_device *dev;
-
- priv = malloc(sizeof(*priv));
- if (priv == NULL)
- return 1;
-
- dev = malloc(sizeof(*dev));
- if (dev == NULL) {
- free(priv);
- return 1;
- }
-
- /* setup whatever private state you need */
-
- memset(dev, 0, sizeof(*dev));
- sprintf(dev->name, "APE");
-
- /* if your device has dedicated hardware storage for the
- * MAC, read it and initialize dev->enetaddr with it
- */
- ape_mac_read(dev->enetaddr);
-
- dev->iobase = iobase;
- dev->priv = priv;
- dev->init = ape_init;
- dev->halt = ape_halt;
- dev->send = ape_send;
- dev->recv = ape_recv;
- dev->write_hwaddr = ape_write_hwaddr;
-
- eth_register(dev);
-
-#ifdef CONFIG_CMD_MII)
- miiphy_register(dev->name, ape_mii_read, ape_mii_write);
-#endif
-
- return 1;
-}
-
-The exact arguments needed to initialize your device are up to you. If you
-need to pass more/less arguments, that's fine. You should also add the
-prototype for your new register function to include/netdev.h.
-
-The return value for this function should be as follows:
-< 0 - failure (hardware failure, not probe failure)
->=0 - number of interfaces detected
-
-You might notice that many drivers seem to use xxx_initialize() rather than
-xxx_register(). This is the old naming convention and should be avoided as it
-causes confusion with the driver-specific init function.
-
-Other than locating the MAC address in dedicated hardware storage, you should
-not touch the hardware in anyway. That step is handled in the driver-specific
-init function. Remember that we are only registering the device here, we are
-not checking its state or doing random probing.
-
- -----------
- Callbacks
- -----------
-
-Now that we've registered with the ethernet layer, we can start getting some
-real work done. You will need five functions:
- int ape_init(struct eth_device *dev, bd_t *bis);
- int ape_send(struct eth_device *dev, volatile void *packet, int length);
- int ape_recv(struct eth_device *dev);
- int ape_halt(struct eth_device *dev);
- int ape_write_hwaddr(struct eth_device *dev);
-
-The init function checks the hardware (probing/identifying) and gets it ready
-for send/recv operations. You often do things here such as resetting the MAC
-and/or PHY, and waiting for the link to autonegotiate. You should also take
-the opportunity to program the device's MAC address with the dev->enetaddr
-member. This allows the rest of U-Boot to dynamically change the MAC address
-and have the new settings be respected.
-
-The send function does what you think -- transmit the specified packet whose
-size is specified by length (in bytes). You should not return until the
-transmission is complete, and you should leave the state such that the send
-function can be called multiple times in a row.
-
-The recv function should process packets as long as the hardware has them
-readily available before returning. i.e. you should drain the hardware fifo.
-For each packet you receive, you should call the NetReceive() function on it
-along with the packet length. The common code sets up packet buffers for you
-already in the .bss (NetRxPackets), so there should be no need to allocate your
-own. This doesn't mean you must use the NetRxPackets array however; you're
-free to call the NetReceive() function with any buffer you wish. So the pseudo
-code here would look something like:
-int ape_recv(struct eth_device *dev)
-{
- int length, i = 0;
- ...
- while (packets_are_available()) {
- ...
- length = ape_get_packet(&NetRxPackets[i]);
- ...
- NetReceive(&NetRxPackets[i], length);
- ...
- if (++i >= PKTBUFSRX)
- i = 0;
- ...
- }
- ...
- return 0;
-}
-
-The halt function should turn off / disable the hardware and place it back in
-its reset state. It can be called at any time (before any call to the related
-init function), so make sure it can handle this sort of thing.
-
-The write_hwaddr function should program the MAC address stored in dev->enetaddr
-into the Ethernet controller.
-
-So the call graph at this stage would look something like:
-some net operation (ping / tftp / whatever...)
- eth_init()
- dev->init()
- eth_send()
- dev->send()
- eth_rx()
- dev->recv()
- eth_halt()
- dev->halt()
-
------------------------------
- CONFIG_MII / CONFIG_CMD_MII
------------------------------
-
-If your device supports banging arbitrary values on the MII bus (pretty much
-every device does), you should add support for the mii command. Doing so is
-fairly trivial and makes debugging mii issues a lot easier at runtime.
-
-After you have called eth_register() in your driver's register function, add
-a call to miiphy_register() like so:
-#if defined(CONFIG_MII) || defined(CONFIG_CMD_MII)
- miiphy_register(dev->name, mii_read, mii_write);
-#endif
-
-And then define the mii_read and mii_write functions if you haven't already.
-Their syntax is straightforward:
- int mii_read(char *devname, uchar addr, uchar reg, ushort *val);
- int mii_write(char *devname, uchar addr, uchar reg, ushort val);
-
-The read function should read the register 'reg' from the phy at address 'addr'
-and store the result in the pointer 'val'. The implementation for the write
-function should logically follow.