diff options
author | Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2020-04-30 19:04:14 +0300 |
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committer | David S. Miller <davem@davemloft.net> | 2020-04-30 22:56:37 +0300 |
commit | 32c01266c0aab060550f592b3fe59405be8ab022 (patch) | |
tree | 47396d9c7fa7b84c5422edd6eb4cdb0a98b59ef4 /Documentation/networking | |
parent | c1e4535f24bcfeef55a7ed409a5f50548e284426 (diff) | |
download | linux-32c01266c0aab060550f592b3fe59405be8ab022.tar.xz |
docs: networking: convert PLIP.txt to ReST
- add SPDX header;
- mark code blocks and literals as such;
- adjust identation, whitespaces and blank lines where needed;
- add to networking/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
-rw-r--r-- | Documentation/networking/index.rst | 1 | ||||
-rw-r--r-- | Documentation/networking/plip.rst (renamed from Documentation/networking/PLIP.txt) | 43 |
2 files changed, 26 insertions, 18 deletions
diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst index 696181a96e3c..18bb10239cad 100644 --- a/Documentation/networking/index.rst +++ b/Documentation/networking/index.rst @@ -92,6 +92,7 @@ Contents: packet_mmap phonet pktgen + plip .. only:: subproject and html diff --git a/Documentation/networking/PLIP.txt b/Documentation/networking/plip.rst index ad7e3f7c3bbf..0eda745050ff 100644 --- a/Documentation/networking/PLIP.txt +++ b/Documentation/networking/plip.rst @@ -1,4 +1,8 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================================================ PLIP: The Parallel Line Internet Protocol Device +================================================ Donald Becker (becker@super.org) I.D.A. Supercomputing Research Center, Bowie MD 20715 @@ -83,7 +87,7 @@ When the PLIP driver is used in IRQ mode, the timeout used for triggering a data transfer (the maximal time the PLIP driver would allow the other side before announcing a timeout, when trying to handshake a transfer of some data) is, by default, 500usec. As IRQ delivery is more or less immediate, -this timeout is quite sufficient. +this timeout is quite sufficient. When in IRQ-less mode, the PLIP driver polls the parallel port HZ times per second (where HZ is typically 100 on most platforms, and 1024 on an @@ -115,7 +119,7 @@ printer "null" cable to transfer data four bits at a time using data bit outputs connected to status bit inputs. The second data transfer method relies on both machines having -bi-directional parallel ports, rather than output-only ``printer'' +bi-directional parallel ports, rather than output-only ``printer`` ports. This allows byte-wide transfers and avoids reconstructing nibbles into bytes, leading to much faster transfers. @@ -132,7 +136,7 @@ bits with standard status register implementation. A cable that implements this protocol is available commercially as a "Null Printer" or "Turbo Laplink" cable. It can be constructed with -two DB-25 male connectors symmetrically connected as follows: +two DB-25 male connectors symmetrically connected as follows:: STROBE output 1* D0->ERROR 2 - 15 15 - 2 @@ -146,7 +150,8 @@ two DB-25 male connectors symmetrically connected as follows: SLCTIN 17 - 17 extra grounds are 18*,19*,20*,21*,22*,23*,24* GROUND 25 - 25 -* Do not connect these pins on either end + + * Do not connect these pins on either end If the cable you are using has a metallic shield it should be connected to the metallic DB-25 shell at one end only. @@ -155,14 +160,14 @@ Parallel Transfer Mode 1 ======================== The second data transfer method relies on both machines having -bi-directional parallel ports, rather than output-only ``printer'' +bi-directional parallel ports, rather than output-only ``printer`` ports. This allows byte-wide transfers, and avoids reconstructing nibbles into bytes. This cable should not be used on unidirectional -``printer'' (as opposed to ``parallel'') ports or when the machine +``printer`` (as opposed to ``parallel``) ports or when the machine isn't configured for PLIP, as it will result in output driver conflicts and the (unlikely) possibility of damage. -The cable for this transfer mode should be constructed as follows: +The cable for this transfer mode should be constructed as follows:: STROBE->BUSY 1 - 11 D0->D0 2 - 2 @@ -179,7 +184,8 @@ The cable for this transfer mode should be constructed as follows: GND->ERROR 18 - 15 extra grounds are 19*,20*,21*,22*,23*,24* GROUND 25 - 25 -* Do not connect these pins on either end + + * Do not connect these pins on either end Once again, if the cable you are using has a metallic shield it should be connected to the metallic DB-25 shell at one end only. @@ -188,7 +194,7 @@ PLIP Mode 0 transfer protocol ============================= The PLIP driver is compatible with the "Crynwr" parallel port transfer -standard in Mode 0. That standard specifies the following protocol: +standard in Mode 0. That standard specifies the following protocol:: send header nibble '0x8' count-low octet @@ -196,20 +202,21 @@ standard in Mode 0. That standard specifies the following protocol: ... data octets checksum octet -Each octet is sent as +Each octet is sent as:: + <wait for rx. '0x1?'> <send 0x10+(octet&0x0F)> <wait for rx. '0x0?'> <send 0x00+((octet>>4)&0x0F)> To start a transfer the transmitting machine outputs a nibble 0x08. That raises the ACK line, triggering an interrupt in the receiving machine. The receiving machine disables interrupts and raises its own ACK -line. +line. -Restated: +Restated:: -(OUT is bit 0-4, OUT.j is bit j from OUT. IN likewise) -Send_Byte: - OUT := low nibble, OUT.4 := 1 - WAIT FOR IN.4 = 1 - OUT := high nibble, OUT.4 := 0 - WAIT FOR IN.4 = 0 + (OUT is bit 0-4, OUT.j is bit j from OUT. IN likewise) + Send_Byte: + OUT := low nibble, OUT.4 := 1 + WAIT FOR IN.4 = 1 + OUT := high nibble, OUT.4 := 0 + WAIT FOR IN.4 = 0 |