reg-io-width option for UART drivers
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Authored by br on Feb 24 2017, 4:43 PM.

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jhibbits
kan
jchandra
marcel
mmel

Group Reviewers

MIPS
ARM
arm64

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rS314362: Allow setting access-width for UART registers.

Summary

allow setting access width for UART registers

This is required for FDT's standard "reg-io-width" property (similar too "reg-shift" property)

This fixes operation for Altera Arria 10 development kit, where standard ns8250 uart allows 4-byte access only.

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br updated this revision to Diff 25653.Feb 24 2017, 4:43 PM

br retitled this revision from to reg-io-width option for UART drivers.

br updated this object.

br edited the test plan for this revision. (Show Details)

br added reviewers: ARM, arm64, MIPS, mmel.

Herald added a reviewer: jhibbits. · View Herald TranscriptFeb 24 2017, 4:43 PM

Herald added subscribers: emaste, andrew. · View Herald Transcript

br updated this object.Feb 24 2017, 5:01 PM

br edited edge metadata.

br added a reviewer: jchandra.Feb 27 2017, 9:53 AM

use static inline funcs for uart_setreg, uart_getreg and consider reg-io-width == 2

Herald edited edge metadata. · View Herald TranscriptFeb 27 2017, 1:15 PM

br added a reviewer: marcel.Feb 27 2017, 2:40 PM

No objections.

This revision is now accepted and ready to land.Feb 27 2017, 4:01 PM

marcel accepted this revision.Feb 27 2017, 4:52 PM

marcel edited edge metadata.

marcel added inline comments.

sys/dev/uart/uart_core.c
494	I'm ok with the change, but with yet another parameter that ends up in the uart_bas structure, I wonder if it isn't about time we simply pass a uart_bas structure instead. Such would make future changes (are there any left to expect?) a lot easier as well.

I had a different solution of a similar issue for Netlogic XLP. Instead of handling it in UART, I had subclassed the simplebus with a updated implementation of bus_alloc_resource(https://svnweb.freebsd.org/base/head/sys/mips/nlm/xlp_simplebus.c). I provided a different bustag for UART (and other devices) that needed 4-byte access that implementation. The bus implementation took care of reading 4 bytes and extracting and returning the significant byte.

Thought I would mention it, I don't have any objection to this way of doing it either.

Closed by commit rS314362: Allow setting access-width for UART registers. (authored by br). · Explain WhyFeb 27 2017, 8:08 PM

This revision was automatically updated to reflect the committed changes.