From: David Brownell <david-b@pacbell•net>
To: Andrei Konovalov <akonovalov@ru•mvista.com>
Cc: spi-devel-general@lists•sourceforge.net, linuxppc-embedded@ozlabs•org
Subject: Re: [spi-devel-general] [PATCH] Simple driver for Xilinx SPI controler.
Date: Thu, 7 Jun 2007 12:21:00 -0700 [thread overview]
Message-ID: <200706071221.00571.david-b@pacbell.net> (raw)
In-Reply-To: <466850FB.5030505@ru.mvista.com>
On Thursday 07 June 2007, Andrei Konovalov wrote:
> >> +/* Simple macros to get the code more readable */
> >> +#define xspi_in16(addr) in_be16((u16 __iomem *)(addr))
> >> +#define xspi_in32(addr) in_be32((u32 __iomem *)(addr))
> >> +#define xspi_out16(addr, value) out_be16((u16 __iomem *)(addr), (value))
> >> +#define xspi_out32(addr, value) out_be32((u32 __iomem *)(addr), (value))
> >
> > I'm rather used to seeing I/O addressses passed around as "void __iomem *"
> > so those sorts of cast are not needed... :)
>
> I've decided to make the base_address (u8 __iomem *) to make it easier to
> add the register offsets to the base. Like that:
Adding register offsets works with "void __iomem *" too ...
> > You should not need an abort primitive. ...
>
> I am paranoid enough not to rely 100% on the spi_device's and the spi_bitbang
> doing all that :)
> Agreed, xspi_abort_transfer is bad name here. But I still would like to
> leave these two writes:
>
> + /* Deselect the slave on the SPI bus */
> + xspi_out32(regs_base + XSPI_SSR_OFFSET, 0xffff);
> + /* Disable the transmitter */
> + xspi_out16(regs_base + XSPI_CR_OFFSET,
> + XSPI_CR_TRANS_INHIBIT | XSPI_CR_MANUAL_SSELECT);
>
> in xilinx_spi_remove(). Just in case :)
What happens when you add a BUG_ON to catch the device still being active?
Really, you need to rely on the rest of the system working correctly.
> > I take it you can't support SPI_CS_HIGH??
>
> There is no clear indication in the SPI controller docs that SPI_CS_HIGH
> would work. I suspect it would as we don't use the ability of the controller
> to generate the chip selects automatically (the auto mode doesn't support SPI_CS_HIGH).
> But it is more safe to advertise SPI_CS_HIGH is not supported.
If you don't explicitly support it, it's unlikely to work. :)
- Dave
next prev parent reply other threads:[~2007-06-07 19:27 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-06 14:05 [PATCH] Simple driver for Xilinx SPI controler Andrei Konovalov
2007-06-06 16:03 ` Stephen Neuendorffer
2007-06-06 17:57 ` Andrei Konovalov
2007-06-06 18:06 ` Stephen Neuendorffer
2007-06-06 19:00 ` Grant Likely
2007-06-06 19:06 ` Stephen Neuendorffer
2007-06-06 19:55 ` Grant Likely
2007-06-07 13:50 ` Andrei Konovalov
2007-06-06 20:49 ` Wolfgang Reissnegger
2007-06-06 20:55 ` Grant Likely
2007-06-07 5:09 ` [spi-devel-general] " David Brownell
2007-06-07 18:39 ` Andrei Konovalov
2007-06-07 19:21 ` David Brownell [this message]
2007-06-09 16:58 ` Andrei Konovalov
2007-06-12 16:28 ` David Brownell
2007-06-13 14:55 ` Andrei Konovalov
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