path: root/drivers
diff options
Diffstat (limited to 'drivers')
-rw-r--r--drivers/char/xillybus/Kconfig (renamed from drivers/staging/xillybus/Kconfig)0
-rw-r--r--drivers/char/xillybus/Makefile (renamed from drivers/staging/xillybus/Makefile)0
-rw-r--r--drivers/char/xillybus/xillybus.h (renamed from drivers/staging/xillybus/xillybus.h)0
-rw-r--r--drivers/char/xillybus/xillybus_core.c (renamed from drivers/staging/xillybus/xillybus_core.c)0
-rw-r--r--drivers/char/xillybus/xillybus_of.c (renamed from drivers/staging/xillybus/xillybus_of.c)0
-rw-r--r--drivers/char/xillybus/xillybus_pcie.c (renamed from drivers/staging/xillybus/xillybus_pcie.c)0
12 files changed, 3 insertions, 388 deletions
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 6e9f74a5c095..efefd12a0f7b 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -600,5 +600,7 @@ config TILE_SROM
device appear much like a simple EEPROM, and knows
how to partition a single ROM for multiple purposes.
+source "drivers/char/xillybus/Kconfig"
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index a324f9303e36..d06cde26031b 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -61,3 +61,4 @@ obj-$(CONFIG_JS_RTC) += js-rtc.o
js-rtc-y = rtc.o
obj-$(CONFIG_TILE_SROM) += tile-srom.o
+obj-$(CONFIG_XILLYBUS) += xillybus/
diff --git a/drivers/staging/xillybus/Kconfig b/drivers/char/xillybus/Kconfig
index b53bdf12da0d..b53bdf12da0d 100644
--- a/drivers/staging/xillybus/Kconfig
+++ b/drivers/char/xillybus/Kconfig
diff --git a/drivers/staging/xillybus/Makefile b/drivers/char/xillybus/Makefile
index b68b7ebfd381..b68b7ebfd381 100644
--- a/drivers/staging/xillybus/Makefile
+++ b/drivers/char/xillybus/Makefile
diff --git a/drivers/staging/xillybus/xillybus.h b/drivers/char/xillybus/xillybus.h
index b9a9eb6d4f72..b9a9eb6d4f72 100644
--- a/drivers/staging/xillybus/xillybus.h
+++ b/drivers/char/xillybus/xillybus.h
diff --git a/drivers/staging/xillybus/xillybus_core.c b/drivers/char/xillybus/xillybus_core.c
index b827fa095f1b..b827fa095f1b 100644
--- a/drivers/staging/xillybus/xillybus_core.c
+++ b/drivers/char/xillybus/xillybus_core.c
diff --git a/drivers/staging/xillybus/xillybus_of.c b/drivers/char/xillybus/xillybus_of.c
index 1ca0c7a4f1be..1ca0c7a4f1be 100644
--- a/drivers/staging/xillybus/xillybus_of.c
+++ b/drivers/char/xillybus/xillybus_of.c
diff --git a/drivers/staging/xillybus/xillybus_pcie.c b/drivers/char/xillybus/xillybus_pcie.c
index d8266bc2ae35..d8266bc2ae35 100644
--- a/drivers/staging/xillybus/xillybus_pcie.c
+++ b/drivers/char/xillybus/xillybus_pcie.c
diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
index 6e2d6fd85b89..e3c1a1fa7b4d 100644
--- a/drivers/staging/Kconfig
+++ b/drivers/staging/Kconfig
@@ -104,8 +104,6 @@ source "drivers/staging/mt29f_spinand/Kconfig"
source "drivers/staging/lustre/Kconfig"
-source "drivers/staging/xillybus/Kconfig"
source "drivers/staging/dgnc/Kconfig"
source "drivers/staging/dgap/Kconfig"
diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile
index 74c679e17e77..8e8333f6dd76 100644
--- a/drivers/staging/Makefile
+++ b/drivers/staging/Makefile
@@ -43,7 +43,6 @@ obj-$(CONFIG_DRM_IMX) += imx-drm/
obj-$(CONFIG_FIREWIRE_SERIAL) += fwserial/
obj-$(CONFIG_GOLDFISH) += goldfish/
obj-$(CONFIG_LUSTRE_FS) += lustre/
-obj-$(CONFIG_XILLYBUS) += xillybus/
obj-$(CONFIG_DGNC) += dgnc/
obj-$(CONFIG_DGAP) += dgap/
obj-$(CONFIG_MTD_SPINAND_MT29F) += mt29f_spinand/
diff --git a/drivers/staging/xillybus/README b/drivers/staging/xillybus/README
deleted file mode 100644
index 81d111b4dc28..000000000000
--- a/drivers/staging/xillybus/README
+++ /dev/null
@@ -1,380 +0,0 @@
- ==========================================
- Xillybus driver for generic FPGA interface
- ==========================================
-Author: Eli Billauer, Xillybus Ltd. (http://xillybus.com)
-Email: eli.billauer@gmail.com or as advertised on Xillybus' site.
- - Introduction
- -- Background
- -- Xillybus Overview
- - Usage
- -- User interface
- -- Synchronization
- -- Seekable pipes
-- Internals
- -- Source code organization
- -- Pipe attributes
- -- Host never reads from the FPGA
- -- Channels, pipes, and the message channel
- -- Data streaming
- -- Data granularity
- -- Probing
- -- Buffer allocation
- -- The "nonempty" message (supporting poll)
-An FPGA (Field Programmable Gate Array) is a piece of logic hardware, which
-can be programmed to become virtually anything that is usually found as a
-dedicated chipset: For instance, a display adapter, network interface card,
-or even a processor with its peripherals. FPGAs are the LEGO of hardware:
-Based upon certain building blocks, you make your own toys the way you like
-them. It's usually pointless to reimplement something that is already
-available on the market as a chipset, so FPGAs are mostly used when some
-special functionality is needed, and the production volume is relatively low
-(hence not justifying the development of an ASIC).
-The challenge with FPGAs is that everything is implemented at a very low
-level, even lower than assembly language. In order to allow FPGA designers to
-focus on their specific project, and not reinvent the wheel over and over
-again, pre-designed building blocks, IP cores, are often used. These are the
-FPGA parallels of library functions. IP cores may implement certain
-mathematical functions, a functional unit (e.g. a USB interface), an entire
-processor (e.g. ARM) or anything that might come handy. Think of them as a
-building block, with electrical wires dangling on the sides for connection to
-other blocks.
-One of the daunting tasks in FPGA design is communicating with a fullblown
-operating system (actually, with the processor running it): Implementing the
-low-level bus protocol and the somewhat higher-level interface with the host
-(registers, interrupts, DMA etc.) is a project in itself. When the FPGA's
-function is a well-known one (e.g. a video adapter card, or a NIC), it can
-make sense to design the FPGA's interface logic specifically for the project.
-A special driver is then written to present the FPGA as a well-known interface
-to the kernel and/or user space. In that case, there is no reason to treat the
-FPGA differently than any device on the bus.
-It's however common that the desired data communication doesn't fit any well-
-known peripheral function. Also, the effort of designing an elegant
-abstraction for the data exchange is often considered too big. In those cases,
-a quicker and possibly less elegant solution is sought: The driver is
-effectively written as a user space program, leaving the kernel space part
-with just elementary data transport. This still requires designing some
-interface logic for the FPGA, and write a simple ad-hoc driver for the kernel.
-Xillybus Overview
-Xillybus is an IP core and a Linux driver. Together, they form a kit for
-elementary data transport between an FPGA and the host, providing pipe-like
-data streams with a straightforward user interface. It's intended as a low-
-effort solution for mixed FPGA-host projects, for which it makes sense to
-have the project-specific part of the driver running in a user-space program.
-Since the communication requirements may vary significantly from one FPGA
-project to another (the number of data pipes needed in each direction and
-their attributes), there isn't one specific chunk of logic being the Xillybus
-IP core. Rather, the IP core is configured and built based upon a
-specification given by its end user.
-Xillybus presents independent data streams, which resemble pipes or TCP/IP
-communication to the user. At the host side, a character device file is used
-just like any pipe file. On the FPGA side, hardware FIFOs are used to stream
-the data. This is contrary to a common method of communicating through fixed-
-sized buffers (even though such buffers are used by Xillybus under the hood).
-There may be more than a hundred of these streams on a single IP core, but
-also no more than one, depending on the configuration.
-In order to ease the deployment of the Xillybus IP core, it contains a simple
-data structure which completely defines the core's configuration. The Linux
-driver fetches this data structure during its initialization process, and sets
-up the DMA buffers and character devices accordingly. As a result, a single
-driver is used to work out of the box with any Xillybus IP core.
-The data structure just mentioned should not be confused with PCI's
-configuration space or the Flattened Device Tree.
-User interface
-On the host, all interface with Xillybus is done through /dev/xillybus_*
-device files, which are generated automatically as the drivers loads. The
-names of these files depend on the IP core that is loaded in the FPGA (see
-Probing below). To communicate with the FPGA, open the device file that
-corresponds to the hardware FIFO you want to send data or receive data from,
-and use plain write() or read() calls, just like with a regular pipe. In
-particular, it makes perfect sense to go:
-$ cat mydata > /dev/xillybus_thisfifo
-$ cat /dev/xillybus_thatfifo > hisdata
-possibly pressing CTRL-C as some stage, even though the xillybus_* pipes have
-the capability to send an EOF (but may not use it).
-The driver and hardware are designed to behave sensibly as pipes, including:
-* Supporting non-blocking I/O (by setting O_NONBLOCK on open() ).
-* Supporting poll() and select().
-* Being bandwidth efficient under load (using DMA) but also handle small
- pieces of data sent across (like TCP/IP) by autoflushing.
-A device file can be read only, write only or bidirectional. Bidirectional
-device files are treated like two independent pipes (except for sharing a
-"channel" structure in the implementation code).
-Xillybus pipes are configured (on the IP core) to be either synchronous or
-asynchronous. For a synchronous pipe, write() returns successfully only after
-some data has been submitted and acknowledged by the FPGA. This slows down
-bulk data transfers, and is nearly impossible for use with streams that
-require data at a constant rate: There is no data transmitted to the FPGA
-between write() calls, in particular when the process loses the CPU.
-When a pipe is configured asynchronous, write() returns if there was enough
-room in the buffers to store any of the data in the buffers.
-For FPGA to host pipes, asynchronous pipes allow data transfer from the FPGA
-as soon as the respective device file is opened, regardless of if the data
-has been requested by a read() call. On synchronous pipes, only the amount
-of data requested by a read() call is transmitted.
-In summary, for synchronous pipes, data between the host and FPGA is
-transmitted only to satisfy the read() or write() call currently handled
-by the driver, and those calls wait for the transmission to complete before
-Note that the synchronization attribute has nothing to do with the possibility
-that read() or write() completes less bytes than requested. There is a
-separate configuration flag ("allowpartial") that determines whether such a
-partial completion is allowed.
-Seekable pipes
-A synchronous pipe can be configured to have the stream's position exposed
-to the user logic at the FPGA. Such a pipe is also seekable on the host API.
-With this feature, a memory or register interface can be attached on the
-FPGA side to the seekable stream. Reading or writing to a certain address in
-the attached memory is done by seeking to the desired address, and calling
-read() or write() as required.
-Source code organization
-The Xillybus driver consists of a core module, xillybus_core.c, and modules
-that depend on the specific bus interface (xillybus_of.c and xillybus_pcie.c).
-The bus specific modules are those probed when a suitable device is found by
-the kernel. Since the DMA mapping and synchronization functions, which are bus
-dependent by their nature, are used by the core module, a
-xilly_endpoint_hardware structure is passed to the core module on
-initialization. This structure is populated with pointers to wrapper functions
-which execute the DMA-related operations on the bus.
-Pipe attributes
-Each pipe has a number of attributes which are set when the FPGA component
-(IP core) is built. They are fetched from the IDT (the data structure which
-defines the core's configuration, see Probing below) by xilly_setupchannels()
-in xillybus_core.c as follows:
-* is_writebuf: The pipe's direction. A non-zero value means it's an FPGA to
- host pipe (the FPGA "writes").
-* channelnum: The pipe's identification number in communication between the
- host and FPGA.
-* format: The underlying data width. See Data Granularity below.
-* allowpartial: A non-zero value means that a read() or write() (whichever
- applies) may return with less than the requested number of bytes. The common
- choice is a non-zero value, to match standard UNIX behavior.
-* synchronous: A non-zero value means that the pipe is synchronous. See
- Syncronization above.
-* bufsize: Each DMA buffer's size. Always a power of two.
-* bufnum: The number of buffers allocated for this pipe. Always a power of two.
-* exclusive_open: A non-zero value forces exclusive opening of the associated
- device file. If the device file is bidirectional, and already opened only in
- one direction, the opposite direction may be opened once.
-* seekable: A non-zero value indicates that the pipe is seekable. See
- Seekable pipes above.
-* supports_nonempty: A non-zero value (which is typical) indicates that the
- hardware will send the messages that are necessary to support select() and
- poll() for this pipe.
-Host never reads from the FPGA
-Even though PCI Express is hotpluggable in general, a typical motherboard
-doesn't expect a card to go away all of the sudden. But since the PCIe card
-is based upon reprogrammable logic, a sudden disappearance from the bus is
-quite likely as a result of an accidental reprogramming of the FPGA while the
-host is up. In practice, nothing happens immediately in such a situation. But
-if the host attempts to read from an address that is mapped to the PCI Express
-device, that leads to an immediate freeze of the system on some motherboards,
-even though the PCIe standard requires a graceful recovery.
-In order to avoid these freezes, the Xillybus driver refrains completely from
-reading from the device's register space. All communication from the FPGA to
-the host is done through DMA. In particular, the Interrupt Service Routine
-doesn't follow the common practice of checking a status register when it's
-invoked. Rather, the FPGA prepares a small buffer which contains short
-messages, which inform the host what the interrupt was about.
-This mechanism is used on non-PCIe buses as well for the sake of uniformity.
-Channels, pipes, and the message channel
-Each of the (possibly bidirectional) pipes presented to the user is allocated
-a data channel between the FPGA and the host. The distinction between channels
-and pipes is necessary only because of channel 0, which is used for interrupt-
-related messages from the FPGA, and has no pipe attached to it.
-Data streaming
-Even though a non-segmented data stream is presented to the user at both
-sides, the implementation relies on a set of DMA buffers which is allocated
-for each channel. For the sake of illustration, let's take the FPGA to host
-direction: As data streams into the respective channel's interface in the
-FPGA, the Xillybus IP core writes it to one of the DMA buffers. When the
-buffer is full, the FPGA informs the host about that (appending a
-XILLYMSG_OPCODE_RELEASEBUF message channel 0 and sending an interrupt if
-necessary). The host responds by making the data available for reading through
-the character device. When all data has been read, the host writes on the
-the FPGA's buffer control register, allowing the buffer's overwriting. Flow
-control mechanisms exist on both sides to prevent underflows and overflows.
-This is not good enough for creating a TCP/IP-like stream: If the data flow
-stops momentarily before a DMA buffer is filled, the intuitive expectation is
-that the partial data in buffer will arrive anyhow, despite the buffer not
-being completed. This is implemented by adding a field in the
-XILLYMSG_OPCODE_RELEASEBUF message, through which the FPGA informs not just
-which buffer is submitted, but how much data it contains.
-But the FPGA will submit a partially filled buffer only if directed to do so
-by the host. This situation occurs when the read() method has been blocking
-for XILLY_RX_TIMEOUT jiffies (currently 10 ms), after which the host commands
-the FPGA to submit a DMA buffer as soon as it can. This timeout mechanism
-balances between bus bandwidth efficiency (preventing a lot of partially
-filled buffers being sent) and a latency held fairly low for tails of data.
-A similar setting is used in the host to FPGA direction. The handling of
-partial DMA buffers is somewhat different, though. The user can tell the
-driver to submit all data it has in the buffers to the FPGA, by issuing a
-write() with the byte count set to zero. This is similar to a flush request,
-but it doesn't block. There is also an autoflushing mechanism, which triggers
-an equivalent flush roughly XILLY_RX_TIMEOUT jiffies after the last write().
-This allows the user to be oblivious about the underlying buffering mechanism
-and yet enjoy a stream-like interface.
-Note that the issue of partial buffer flushing is irrelevant for pipes having
-the "synchronous" attribute nonzero, since synchronous pipes don't allow data
-to lay around in the DMA buffers between read() and write() anyhow.
-Data granularity
-The data arrives or is sent at the FPGA as 8, 16 or 32 bit wide words, as
-configured by the "format" attribute. Whenever possible, the driver attempts
-to hide this when the pipe is accessed differently from its natural alignment.
-For example, reading single bytes from a pipe with 32 bit granularity works
-with no issues. Writing single bytes to pipes with 16 or 32 bit granularity
-will also work, but the driver can't send partially completed words to the
-FPGA, so the transmission of up to one word may be held until it's fully
-occupied with user data.
-This somewhat complicates the handling of host to FPGA streams, because
-when a buffer is flushed, it may contain up to 3 bytes don't form a word in
-the FPGA, and hence can't be sent. To prevent loss of data, these leftover
-bytes need to be moved to the next buffer. The parts in xillybus_core.c
-that mention "leftovers" in some way are related to this complication.
-As mentioned earlier, the number of pipes that are created when the driver
-loads and their attributes depend on the Xillybus IP core in the FPGA. During
-the driver's initialization, a blob containing configuration info, the
-Interface Description Table (IDT), is sent from the FPGA to the host. The
-bootstrap process is done in three phases:
-1. Acquire the length of the IDT, so a buffer can be allocated for it. This
- is done by sending a quiesce command to the device, since the acknowledge
- for this command contains the IDT's buffer length.
-2. Acquire the IDT itself.
-3. Create the interfaces according to the IDT.
-Buffer allocation
-In order to simplify the logic that prevents illegal boundary crossings of
-PCIe packets, the following rule applies: If a buffer is smaller than 4kB,
-it must not cross a 4kB boundary. Otherwise, it must be 4kB aligned. The
-xilly_setupchannels() functions allocates these buffers by requesting whole
-pages from the kernel, and diving them into DMA buffers as necessary. Since
-all buffers' sizes are powers of two, it's possible to pack any set of such
-buffers, with a maximal waste of one page of memory.
-All buffers are allocated when the driver is loaded. This is necessary,
-since large continuous physical memory segments are sometimes requested,
-which are more likely to be available when the system is freshly booted.
-The allocation of buffer memory takes place in the same order they appear in
-the IDT. The driver relies on a rule that the pipes are sorted with decreasing
-buffer size in the IDT. If a requested buffer is larger or equal to a page,
-the necessary number of pages is requested from the kernel, and these are
-used for this buffer. If the requested buffer is smaller than a page, one
-single page is requested from the kernel, and that page is partially used.
-Or, if there already is a partially used page at hand, the buffer is packed
-into that page. It can be shown that all pages requested from the kernel
-(except possibly for the last) are 100% utilized this way.
-The "nonempty" message (supporting poll)
-In order to support the "poll" method (and hence select() ), there is a small
-catch regarding the FPGA to host direction: The FPGA may have filled a DMA
-buffer with some data, but not submitted that buffer. If the host waited for
-the buffer's submission by the FPGA, there would be a possibility that the
-FPGA side has sent data, but a select() call would still block, because the
-host has not received any notification about this. This is solved with
-XILLYMSG_OPCODE_NONEMPTY messages sent by the FPGA when a channel goes from
-completely empty to containing some data.
-These messages are used only to support poll() and select(). The IP core can
-be configured not to send them for a slight reduction of bandwidth.
diff --git a/drivers/staging/xillybus/TODO b/drivers/staging/xillybus/TODO
deleted file mode 100644
index 95cfe2f62fcd..000000000000
--- a/drivers/staging/xillybus/TODO
+++ /dev/null
@@ -1,5 +0,0 @@
-- have the driver reviewed
-Please send any patches and/or comments to Eli Billauer,

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