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omap driver & rs485
Added by michael musset over 11 years ago
Hi,
I've some questions about your patch from this link : http://support.criticallink.com/redmine/projects/armc8-platforms/wiki/Driving_RS-485_transceivers
If I understand correctly, to control the gpio, you are modifying the omap driver. But why do you also modify the 8250 driver ?
My second question is about the ioctl function (plz correct me if I'm wrong):
to use the function ioctl, you modified the struct uart_ops serial_omap_pops and you added the line
.ioctl = serial_omap_ioctl,
with this line it's now possible to call the function serial_omap_ioctl through the function : ioctl(fd, TIOCSRS485, &rs485conf);
Am I wrong ?
Replies (1)
RE: omap driver & rs485 - Added by Michael Williamson over 11 years ago
The omap driver is modified for the MityARM-3359 (the AM335X SOC chips). This patch actually came from support of our MityDSP-L138 product line (the OMAP-L138 / AM-1808 SOC chips). The L138 product line uses an adaptation of the 8250 driver. When we brought over the patches, we had initially thought the AM3359 was using the same driver. You don't need mods to the 8850 driver if you are only using the AM3359. Sorry for the confusion.
You are correct about the other part of your question. The uart_ops allows drivers to override ioctl methods with custom implementations. So calling the ioctl in user space will get mapped to the serial_omap_ioctl implementation.
-Mike
