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| Started by | Marc Kleine-Budde <mkl@pengutronix.de> |
|---|---|
| First post | 2016-01-12 09:00 +0100 |
| Last post | 2016-01-12 17:00 +0100 |
| Articles | 2 — 2 participants |
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Re: [PATCH v2 3/3] can: sja1000: of: add compatibility with Technologic Systems version Marc Kleine-Budde <mkl@pengutronix.de> - 2016-01-12 09:00 +0100
Re: [PATCH v2 3/3] can: sja1000: of: add compatibility with Technologic Systems version Damien Riegel <damien.riegel@savoirfairelinux.com> - 2016-01-12 17:00 +0100
| From | Marc Kleine-Budde <mkl@pengutronix.de> |
|---|---|
| Date | 2016-01-12 09:00 +0100 |
| Subject | Re: [PATCH v2 3/3] can: sja1000: of: add compatibility with Technologic Systems version |
| Message-ID | <qQ21X-6gQ-3@gated-at.bofh.it> |
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On 12/24/2015 06:42 PM, Damien Riegel wrote:
> Technologic Systems provides an IP compatible with the SJA1000,
> instantiated in an FPGA. Because of some bus widths issue, access to
> registers is made through a "window" that works like this:
>
> base + 0x0: address to read/write
> base + 0x2: 8-bit register value
Why do you use io{read,write}16 if it's a 8 bit register?
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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| From | Damien Riegel <damien.riegel@savoirfairelinux.com> |
|---|---|
| Date | 2016-01-12 17:00 +0100 |
| Message-ID | <qQ9wv-2Zn-19@gated-at.bofh.it> |
| In reply to | #1307065 |
On Tue, Jan 12, 2016 at 08:55:38AM +0100, Marc Kleine-Budde wrote:
> On 12/24/2015 06:42 PM, Damien Riegel wrote:
> > Technologic Systems provides an IP compatible with the SJA1000,
> > instantiated in an FPGA. Because of some bus widths issue, access to
> > registers is made through a "window" that works like this:
> >
> > base + 0x0: address to read/write
> > base + 0x2: 8-bit register value
>
> Why do you use io{read,write}16 if it's a 8 bit register?
8-bit is at the IP level, but the bus between the SoC and the FPGA only
supports 16-bit wide access. The point of the window is to convert
between 16-bit and 8-bit access.
Damien
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