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Message-Id: <20200413222920.4722-5-ernesto.corona@intel.com>
Date: Mon, 13 Apr 2020 15:29:18 -0700
From: Ernesto Corona <ernesto.corona@...el.com>
To: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-aspeed@...ts.ozlabs.org
Cc: Ernesto Corona <ernesto.corona@...el.com>,
Oleksandr Shamray <oleksandrs@...lanox.com>,
Jonathan Corbet <corbet@....net>,
Arnd Bergmann <arnd@...db.de>,
Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
Linus Walleij <linus.walleij@...aro.org>,
Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
Jeffrey Hugo <jhugo@...eaurora.org>,
Steven Filary <steven.a.filary@...el.com>,
Jiri Pirko <jiri@...lanox.com>,
Vadim Pasternak <vadimp@...lanox.com>,
Amithash Prasad <amithash@...com>,
Patrick Williams <patrickw3@...com>, Rgrs <rgrs@...tonmail.com>
Subject: [PATCH v29 4/6] Documentation: jtag: Add ABI documentation
Added document that describe the ABI for JTAG class driver
Signed-off-by: Oleksandr Shamray <oleksandrs@...lanox.com>
Signed-off-by: Ernesto Corona <ernesto.corona@...el.com>
Acked-by: Arnd Bergmann <arnd@...db.de>
Cc: Jonathan Corbet <corbet@....net>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Cc: Linus Walleij <linus.walleij@...aro.org>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Jeffrey Hugo <jhugo@...eaurora.org>
Cc: Steven Filary <steven.a.filary@...el.com>
Cc: Jiri Pirko <jiri@...lanox.com>
Cc: Vadim Pasternak <vadimp@...lanox.com>
Cc: Amithash Prasad <amithash@...com>
Cc: Patrick Williams <patrickw3@...com>
Cc: Rgrs <rgrs@...tonmail.com>
---
v28->v29
- Change ABI documentation to reStructuredText (rst) format.
v27->v28
Comments pointed by Steven Filary <steven.a.filary@...el.com>
- Replace JTAG_IOCRUNTEST with JTAG_SIOCSTATE adding support for all TAPC
end states in SW mode using a lookup table to navigate across states.
- Add support for simultaneous READ/WRITE transfers(JTAG_READ_WRITE_XFER).
- Support for switching JTAG controller mode between slave and master
mode.
- Setup JTAG controller mode to master only when the driver is opened,
letting other HW to own the JTAG bus when it isn't in use.
- Include JTAG bit bang IOCTL for low level JTAG control usage
(JTAG_IOCBITBANG).
v26->v27
v25->v26
Comments pointed by Randy Dunlap <rdunlap@...radead.org>
- fix spell in ABI documentation
v24->v25
Comments pointed by Greg KH <gregkh@...uxfoundation.org>
- Fixed documentation according to new open() behavior
v23->v24
v22->v23
Comments pointed by Randy Dunlap <rdunlap@...radead.org>
- fix spell in ABI doccumentation
v21->v22
Comments pointed by Randy Dunlap <rdunlap@...radead.org>
- fix spell in ABI doccumentation
v20->v21
Comments pointed by Randy Dunlap <rdunlap@...radead.org>
- Fix JTAG dirver help in Kconfig
v19->v20
Comments pointed by Randy Dunlap <rdunlap@...radead.org>
- Fix JTAG doccumentation
v18->v19
Pavel Machek <pavel@....cz>
- Added JTAG doccumentation to Documentation/jtag
v17->v18
v16->v17
v15->v16
v14->v15
v13->v14
v12->v13
v11->v12 Tobias Klauser <tklauser@...tanz.ch>
Comments pointed by
- rename /Documentation/ABI/testing/jatg-dev -> jtag-dev
- Typo: s/interfase/interface
v10->v11
v9->v10
Fixes added by Oleksandr:
- change jtag-cdev to jtag-dev in documentation
- update KernelVersion and Date in jtag-dev documentation;
v8->v9
v7->v8
v6->v7
Comments pointed by Pavel Machek <pavel@....cz>
- Added jtag-cdev documentation to Documentation/ABI/testing folder
---
Documentation/ABI/testing/jtag-dev | 23 ++++
Documentation/index.rst | 1 +
Documentation/jtag/index.rst | 18 +++
Documentation/jtag/jtag-summary.rst | 47 +++++++
Documentation/jtag/jtagdev.rst | 194 ++++++++++++++++++++++++++++
5 files changed, 283 insertions(+)
create mode 100644 Documentation/ABI/testing/jtag-dev
create mode 100644 Documentation/jtag/index.rst
create mode 100644 Documentation/jtag/jtag-summary.rst
create mode 100644 Documentation/jtag/jtagdev.rst
diff --git a/Documentation/ABI/testing/jtag-dev b/Documentation/ABI/testing/jtag-dev
new file mode 100644
index 000000000000..423baab18761
--- /dev/null
+++ b/Documentation/ABI/testing/jtag-dev
@@ -0,0 +1,23 @@
+What: /dev/jtag[0-9]+
+Date: July 2018
+KernelVersion: 4.20
+Contact: oleksandrs@...lanox.com
+Description:
+ The misc device files /dev/jtag* are the interface
+ between JTAG master interface and userspace.
+
+ The ioctl(2)-based ABI is defined and documented in
+ [include/uapi]<linux/jtag.h>.
+
+ The following file operations are supported:
+
+ open(2)
+ Opens and allocates file descriptor.
+
+ ioctl(2)
+ Initiate various actions.
+ See the inline documentation in [include/uapi]<linux/jtag.h>
+ for descriptions of all ioctls.
+
+Users:
+ userspace tools which wants to access to JTAG bus
diff --git a/Documentation/index.rst b/Documentation/index.rst
index 9599c0f3eea8..f75e8fa17d0e 100644
--- a/Documentation/index.rst
+++ b/Documentation/index.rst
@@ -108,6 +108,7 @@ needed).
iio/index
isdn/index
infiniband/index
+ jtag/index
leds/index
media/index
netlabel/index
diff --git a/Documentation/jtag/index.rst b/Documentation/jtag/index.rst
new file mode 100644
index 000000000000..8a2761d1c17e
--- /dev/null
+++ b/Documentation/jtag/index.rst
@@ -0,0 +1,18 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============================
+Joint Test Action Group (JTAG)
+==============================
+
+.. toctree::
+ :maxdepth: 1
+
+ jtag-summary
+ jtagdev
+
+.. only:: subproject and html
+
+ Indices
+ =======
+
+ * :ref:`genindex`
diff --git a/Documentation/jtag/jtag-summary.rst b/Documentation/jtag/jtag-summary.rst
new file mode 100644
index 000000000000..7d3211be9096
--- /dev/null
+++ b/Documentation/jtag/jtag-summary.rst
@@ -0,0 +1,47 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====================================
+Linux kernel JTAG support
+====================================
+
+Introduction to JTAG
+====================
+
+JTAG is an industry standard for verifying hardware. JTAG provides access to
+many logic signals of a complex integrated circuit, including the device pins.
+
+A JTAG interface is a special interface added to a chip.
+Depending on the version of JTAG, two, four, or five pins are added.
+
+The connector pins are:
+ * TDI (Test Data In)
+ * TDO (Test Data Out)
+ * TCK (Test Clock)
+ * TMS (Test Mode Select)
+ * TRST (Test Reset) optional
+
+JTAG interface is designed to have two parts - basic core driver and
+hardware specific driver. The basic driver introduces a general interface
+which is not dependent of specific hardware. It provides communication
+between user space and hardware specific driver.
+Each JTAG device is represented as a char device from (jtag0, jtag1, ...).
+Access to a JTAG device is performed through IOCTL calls.
+
+Call flow example:
+::
+
+ User: open -> /dev/jatgX -> JTAG core driver -> JTAG hardware specific driver
+ User: ioctl -> /dev/jtagX -> JTAG core driver -> JTAG hardware specific driver
+ User: close -> /dev/jatgX -> JTAG core driver -> JTAG hardware specific driver
+
+
+THANKS TO
+---------
+Contributors to Linux-JTAG discussions include (in alphabetical order,
+by last name):
+
+- Ernesto Corona
+- Jiri Pirko
+- Oleksandr Shamray
+- Steven Filary
+- Vadim Pasternak
diff --git a/Documentation/jtag/jtagdev.rst b/Documentation/jtag/jtagdev.rst
new file mode 100644
index 000000000000..445f0b9c5b4d
--- /dev/null
+++ b/Documentation/jtag/jtagdev.rst
@@ -0,0 +1,194 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==================
+JTAG userspace API
+==================
+JTAG master devices can be accessed through a character misc-device.
+
+Each JTAG master interface can be accessed by using /dev/jtagN.
+
+JTAG system calls set:
+ * SIR (Scan Instruction Register, IEEE 1149.1 Instruction Register scan);
+ * SDR (Scan Data Register, IEEE 1149.1 Data Register scan);
+ * RUNTEST (Forces the IEEE 1149.1 bus to a run state for a specified number of clocks.
+
+open(), close()
+---------------
+Open/Close device:
+::
+
+ jtag_fd = open("/dev/jtag0", O_RDWR);
+ close(jtag_fd);
+
+ioctl()
+-------
+All access operations to JTAG devices are performed through ioctl interface.
+The IOCTL interface supports these requests:
+::
+
+ JTAG_SIOCSTATE - Force JTAG state machine to go into a TAPC state
+ JTAG_SIOCFREQ - Set JTAG TCK frequency
+ JTAG_GIOCFREQ - Get JTAG TCK frequency
+ JTAG_IOCXFER - send/receive JTAG data Xfer
+ JTAG_GIOCSTATUS - get current JTAG TAP state
+ JTAG_SIOCMODE - set JTAG mode flags.
+ JTAG_IOCBITBANG - JTAG bitbang low level control.
+
+JTAG_SIOCFREQ
+~~~~~~~~~~~~~
+Set JTAG clock speed:
+::
+
+ unsigned int jtag_fd;
+ ioctl(jtag_fd, JTAG_SIOCFREQ, &frq);
+
+JTAG_GIOCFREQ
+~~~~~~~~~~~~~
+Get JTAG clock speed:
+::
+
+ unsigned int jtag_fd;
+ ioctl(jtag_fd, JTAG_GIOCFREQ, &frq);
+
+JTAG_SIOCSTATE
+~~~~~~~~~~~~~~
+Force JTAG state machine to go into a TAPC state
+::
+
+ struct jtag_end_tap_state {
+ __u8 reset;
+ __u8 endstate;
+ __u8 tck;
+ };
+
+reset: one of below options
+::
+
+ JTAG_NO_RESET - go through selected endstate from current state
+ JTAG_FORCE_RESET - go through TEST_LOGIC/RESET state before selected endstate
+
+endstate: any state listed in jtag_endstate enum
+::
+
+ enum jtag_endstate {
+ JTAG_STATE_TLRESET,
+ JTAG_STATE_IDLE,
+ JTAG_STATE_SELECTDR,
+ JTAG_STATE_CAPTUREDR,
+ JTAG_STATE_SHIFTDR,
+ JTAG_STATE_EXIT1DR,
+ JTAG_STATE_PAUSEDR,
+ JTAG_STATE_EXIT2DR,
+ JTAG_STATE_UPDATEDR,
+ JTAG_STATE_SELECTIR,
+ JTAG_STATE_CAPTUREIR,
+ JTAG_STATE_SHIFTIR,
+ JTAG_STATE_EXIT1IR,
+ JTAG_STATE_PAUSEIR,
+ JTAG_STATE_EXIT2IR,
+ JTAG_STATE_UPDATEIR
+ };
+
+tck: clock counter
+
+Example:
+::
+
+ struct jtag_end_tap_state end_state;
+
+ end_state.endstate = JTAG_STATE_IDLE;
+ end_state.reset = 0;
+ end_state.tck = data_p->tck;
+ usleep(25 * 1000);
+ ioctl(jtag_fd, JTAG_SIOCSTATE, &end_state);
+
+JTAG_GIOCSTATUS
+~~~~~~~~~~~~~~~
+Get JTAG TAPC current machine state
+::
+
+ unsigned int jtag_fd;
+ jtag_endstate endstate;
+ ioctl(jtag_fd, JTAG_GIOCSTATUS, &endstate);
+
+JTAG_IOCXFER
+~~~~~~~~~~~~
+Send SDR/SIR transaction
+::
+
+ struct jtag_xfer {
+ __u8 type;
+ __u8 direction;
+ __u8 endstate;
+ __u8 padding;
+ __u32 length;
+ __u64 tdio;
+ };
+
+type: transfer type - JTAG_SIR_XFER/JTAG_SDR_XFER
+
+direction: xfer direction - JTAG_READ_XFER/JTAG_WRITE_XFER/JTAG_READ_WRITE_XFER
+
+length: xfer data length in bits
+
+tdio : xfer data array
+
+endstate: end state after transaction finish any of jtag_endstate enum
+
+Example:
+::
+
+ struct jtag_xfer xfer;
+ static char buf[64];
+ static unsigned int buf_len = 0;
+ [...]
+ xfer.type = JTAG_SDR_XFER;
+ xfer.tdio = (__u64)buf;
+ xfer.length = buf_len;
+ xfer.endstate = JTAG_STATE_IDLE;
+
+ if (is_read)
+ xfer.direction = JTAG_READ_XFER;
+ else if (is_write)
+ xfer.direction = JTAG_WRITE_XFER;
+ else
+ xfer.direction = JTAG_READ_WRITE_XFER;
+
+ ioctl(jtag_fd, JTAG_IOCXFER, &xfer);
+
+JTAG_SIOCMODE
+~~~~~~~~~~~~~
+If hardware driver can support different running modes you can change it.
+
+Example:
+::
+
+ struct jtag_mode mode;
+ mode.feature = JTAG_XFER_MODE;
+ mode.mode = JTAG_XFER_HW_MODE;
+ ioctl(jtag_fd, JTAG_SIOCMODE, &mode);
+
+JTAG_IOCBITBANG
+~~~~~~~~~~~~~~~
+JTAG Bitbang low level operation.
+
+Example:
+::
+
+ struct tck_bitbang bitbang
+ bitbang.tms = 1;
+ bitbang.tdi = 0;
+ ioctl(jtag_fd, JTAG_IOCBITBANG, &bitbang);
+ tdo = bitbang.tdo;
+
+
+THANKS TO
+---------
+Contributors to Linux-JTAG discussions include (in alphabetical order,
+by last name):
+
+- Ernesto Corona
+- Jiri Pirko
+- Oleksandr Shamray
+- Steven Filary
+- Vadim Pasternak
--
2.17.1
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