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SubjectRe: [patch v23 4/4] Documentation: jtag: Add ABI documentation
On Tue, May 29, 2018 at 02:49:05PM +0300, Oleksandr Shamray wrote:
> +++ b/Documentation/ABI/testing/jtag-dev
> @@ -0,0 +1,27 @@
> +What: /dev/jtag[0-9]+
> +Date: May 2018
> +KernelVersion: 4.18
> +Contact: oleksandrs@mellanox.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)
> + The argument flag currently support only one access
> + mode O_RDWR.

Your open call tests for nothing, don't worry about it here at all :)

> +
> + ioctl(2)
> + Initiate various actions.
> + See the inline documentation in [include/uapi]<linux/jtag.h>
> + for descriptions of all ioctls.
> +
> + close(2)
> + Stops and free up the I/O contexts that was associated
> + with the file descriptor.

No, your close() does not do any of that.

> +
> +Users: TBD

No users? They why do we have this api at all?

> +open(), close()
> +-------
> +open() opens JTAG device. Only one open operation per JTAG device
> +can be performed. Two or more open for one device will return error.

Not true :)

> +
> +Open/Close device:
> +- jtag_fd = open("/dev/jtag0", O_RDWR);
> +- close(jtag_fd);
> +
> +ioctl()
> +-------
> +All access operations to JTAG devices are erformed through ioctl interface.
> +The IOCTL interface supports these requests:
> + JTAG_IOCRUNTEST - Force JTAG state machine to RUN_TEST/IDLE state
> + JTAG_SIOCFREQ - Set JTAG TCK frequency
> + JTAG_GIOCFREQ - Get JTAG TCK frequency
> + JTAG_IOCXFER - send JTAG data Xfer
> + JTAG_GIOCSTATUS - get current JTAG TAP status
> + JTAG_SIOCMODE - set JTAG mode flags.
> +
> +JTAG_SIOCFREQ, JTAG_GIOCFREQ
> +------
> +Set/Get JTAG clock speed:
> +
> + unsigned int jtag_fd;
> + ioctl(jtag_fd, JTAG_SIOCFREQ, &frq);
> + ioctl(jtag_fd, JTAG_GIOCFREQ, &frq);
> +
> +JTAG_IOCRUNTEST
> +------
> +Force JTAG state machine to RUN_TEST/IDLE state
> +
> +struct jtag_run_test_idle {
> + __u8 reset;
> + __u8 endstate;
> + __u8 tck;
> +};
> +
> +reset: 0 - run IDLE/PAUSE from current state
> + 1 - go through TEST_LOGIC/RESET state before IDLE/PAUSE

Are you sure your enums are these values? You should explicitly set
them in your .h file to be positive.

thanks,

greg k-h

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