On Tue, Jun 24, 2014 at 11:49 PM, Torrie Fischer
[off-list ref] wrote:

Apparently all I had to do was set the type attribute on the uart_port
structure to anything that isn't PORT_UNKNOWN.

Arhh.. I see. I overlooked that since tty->type was being set. Good to
know you got it working.

Here's a functional driver that takes a GPIO pin and creates a read-only
serial TTY:

So multiple open don't harm? The startup routine is called only once
is that right?

https://github.com/tdfischer/gpio_serial/blob/master/gpiotty.c

:)

On Tuesday, June 24, 2014 21:27:46 Pranay Srivastava wrote:

quoted

Hi Torrie,

On Tue, Jun 24, 2014 at 6:26 PM, Torrie Fischer

[off-list ref] wrote:

quoted

Hi, Pranay.

Thanks for having a look.

On Tuesday, June 24, 2014 13:42:35 Pranay Srivastava wrote:

quoted

I looked at uart_register code, it seems there's no read callback so
that's why you are getting that -EIO.

From what I understand, I'm supposed to set up the interrupts needed in
the
startup function which is called when the device is opened. This never
happens though, as adding a printk results in no output.

I think this might be causing it, if you see tty_open then it has a call to
,

tty_open_current_tty , this seems to be the only one which I think is
not making the driver being looked up and hence no uport->open

so in case there's an already a tty attached to current then i think
it isn't opening
a new one. Maybe you need to detach this tty? Not so sure I'll look
again what can be done.

quoted

quoted

I think you can put this call in your start_tx since uart_start is
calling port->start_tx at the end so i guess you should be good there.

I suspect that start_tx is not getting called since adding a printk in my
start_tx function doesn't result in any output.

quoted

I don't have much idea how will you read from it though.

I'm able to read from it by waiting for a rising edge interrupt and then
bit- banging the GPIO line in userspace, though at a slow baud that is
unusable. I need 9600 to read from my device :)

Ok good!. I don't have much idea about GPIO. While searching I found
there's a GPIO library for Raspi. I don't know how much help that
would be but i
guess you don't want to use it.

-- 
        ---P.K.S