[PATCH v3] OMAP2+: UART: Add mechanism to probe uart pins and configure rx wakeup

[Kevin Hilman]

"Govindraj.R" <govindraj.raja at ti.com> writes:

> From: "Govindraj.R" <govindraj.raja at ti.com>
>
> The commit (bce492c0  ARM: OMAP2+: UART: Fix incorrect population of
> default uart pads) removed default uart pads that where getting populated
> and which was making rx pin wakeup capable. If uart pads were used in
> different mode by any other module then it would fail since the default
> pads took over all the uart pins forcefully. With removal of default pads
> the rx_pad wakeup for console uart while waking up from off mode is broken.
>
> Utilise the mux api available to probe the availability of mux pins
> in uart mode and probe for availability of uart pin in mux mode0
> if uart is available as uart pin itself then configure rx pin
> as wakeup capable.
>
> This patch itself doesn't cater to all boards. Boards using uart rx wakeup
> mechanism should ensure the usage of omap_serial_init_port by configuring
> required uart ports and pass necessary mux data, till then this probing of
> uart pins can cater to enabling of rx pad wakeup to most of the boards.
>
> This patch can also throw some boot warning from _omap_mux_get_by_name
> if pin is requested for availability is not present while dynamically probing
> the uart pins availability such boot warnings can be addressed only when board
> files are patched with omap_serial_init_port calls passing the right pads
> needed for a given port.
>
> Discussion Threads for reference:
> http://www.spinics.net/lists/linux-omap/msg69859.html
> http://www.spinics.net/lists/linux-omap/msg68659.html
>
> Cc: Felipe Balbi <balbi at ti.com>
> Cc: Kevin Hilman <khilman at ti.com>
> Cc: Russ Dill <russ.dill at gmail.com>
> Cc: Tony Lindgren <tony at atomide.com>
> Cc: Paul Walmsley <paul at pwsan.com>
> Cc: Ameya Palande <ameya.palande at ti.com>
> Signed-off-by: Govindraj.R <govindraj.raja at ti.com>

Tony, it's up to you if you're OK with this mux interface, but I can at
least confirm that this gets runtime PM + UART wakeups working again on
the boards I tried: 3530/Overo, 3430/n900, 3530/OMAP3EVM.

Kevin