On 17.07.2018 11:27, Alexander Graf wrote: > On 07/17/2018 11:21 AM, Lokesh Vutla wrote: >> >> On Tuesday 17 July 2018 02:42 PM, Alexander Graf wrote: >>> On 07/17/2018 09:55 AM, Lokesh Vutla wrote: >>>> On Tuesday 17 July 2018 12:32 PM, Felix Brack wrote: >>>>> This patch adds a new Kconfig variable that allows setting >>>>> the register offset shift value for the ns16550 driver to some >>>>> other value then 0 if not defined by the DT. All credit for this >>>>> patch goes to Lokesh Vutla as it was his idea. >>>>> >>>>> The motivation for writing this patch originates in the >>>>> effort of synchronizing U-Boot DT to Linux DT for am33xx SOCs. >>>>> The current am33xx.dtsi file from U-Boot defines the <reg-shift> >>>>> property for all UART nodes. The actual (4.18+) am33xx.dtsi >>>>> file from Linux does not define <reg-shift> anymore. To prevent >>>>> (probably difficult) changes in many .dts and .dtsi files once >>>>> the synchronization is done, one can use this new variable. For >>>>> the pdu001 board, for example, SYS_NS16550_REG_SHIFT is set >>>>> to 2; no need to clutter U-Boot and board specific dts files >>>>> with <reg-shift> properties. >>>>> >>>>> Signed-off-by: Felix Brack <[email protected]> >>> NAK. Please determine the shift value from the compatible instead. >>> Ideally you would create a subclass of the ns16550 device class and set >>> reg_shift in there. >> There was a separate driver for omap_serial initially but was deleted by >> the below commit: >> >> commit c7b9686d5d482c8e952598841ea467e6ec0ec0de >> Author: Thomas Chou <[email protected]> >> Date: Thu Nov 19 21:48:12 2015 +0800 >> >> ns16550: unify serial_omap >> >> Unify serial_omap, and use the generic binding. >> >> Signed-off-by: Thomas Chou <[email protected]> >> Reviewed-by: Tom Rini <[email protected]> >> Acked-by: Simon Glass <[email protected]> > > Sounds like that wasn't a terribly smart move :). > > If you really don't want a separate driver (and I'm not sure why you > wouldn't), declare a separate PORT for ti,omap3-uart in > ns16550_serial_ids and set the shift value based on that in > ns16550_serial_ofdata_to_platdata() if DT doesn't describe one. > Adding a separate driver when you can use a generic one is of no benefit, it just bloats the source code.
Adding a separate PORT in ns16550_serial_ids for a particular architecture, platform or SoC would be an option. However the patch I posted is much more generic as it offers to set the reg-shift property for no matter what architecture, platform or SoC. It can also easily be extended by adding more conditional defaults to the Kconfig file. regards Felix _______________________________________________ U-Boot mailing list [email protected] https://lists.denx.de/listinfo/u-boot
