On Tue, Apr 15, 2008 at 03:22:33PM +0200, Laurent Pinchart wrote: > Hi everybody, > > I'm implementing flow control and modem control lines support in the cpm_uart > driver. > > The implementation is based on the GPIO lib. Modem control lines are > described > in the device tree as GPIO resources and accessed through the OF GPIO > bindings. The I/O ports have to be initialized as GPIOs in the > platform-specific code. > > Reading and writing the modem control lines isn't an issue, but activating > hardware flow control is more complex. The driver needs to turn dedicated > functions on and off for the RTS and CTS signals, and the GPIO API doesn't > provide a way to access the PPAR* registers (which does make sense - although > arguably - as PPAR* control specific functions, not GPIOs). > > Hardcoding RTS and CTS lines control in the driver is not an option I want to > consider. Extending the GPIO API to handled special functions has been nacked > in the past (see > http://ozlabs.org/pipermail/linuxppc-dev/2008-February/051241.html). An > option would be to export gpio_to_chip from drivers/gpio/gpiolib.c and use > cpm1/2_set_pin in the cpm_uart driver.
Since you have successfuly ported QE USB controller onto CPM USB hardware, now it's obvious that we will need generic gpio_set_dedicated() function. So I would rather beg David to accept gpio_set_dedicated() approach instead of exporting gpio_to_chip(). That way we'll kill two birds with one stone. -- Anton Vorontsov email: [EMAIL PROTECTED] irc://irc.freenode.net/bd2 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
