| Message ID | 1351238873-25230-2-git-send-email-maxime.ripard@free-electrons.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Oct 26, 2012 at 10:07:52AM +0200, Maxime Ripard wrote:
> This will allow to probe spidev from device tree
So, this isn't really something we should have in DT in this format -
the fact that we happen to control some device from userspace isn't a
generic property of the board really, we may end up changing our minds
on Linux too. The most obvious thing for this seems to be to add the
specific devices to spidev as the OF bindings rather than just register
as some non-specific "spidev" so we can change our minds later about how
to handle the devices. Not sure that's urgently tasteful but it does
mean we move the "we handle this in userspace" bit out of the .dts into
the kernel which seems better.
Hi Mark, Le 28/10/2012 00:19, Mark Brown a écrit : > On Fri, Oct 26, 2012 at 10:07:52AM +0200, Maxime Ripard wrote: >> This will allow to probe spidev from device tree > > So, this isn't really something we should have in DT in this format > - the fact that we happen to control some device from userspace > isn't a generic property of the board really, we may end up > changing our minds on Linux too. The most obvious thing for this > seems to be to add the specific devices to spidev as the OF > bindings rather than just register as some non-specific "spidev" so > we can change our minds later about how to handle the devices. Not > sure that's urgently tasteful but it does mean we move the "we > handle this in userspace" bit out of the .dts into the kernel which > seems better. Ok, so I guess that leaves us with 2 choices here: * Declare the device in the dt as you would have with any other driver, with its own compatible string, and we add this compatible string to the spidev dt ids array. It allows to use the existing code and thus doesn't require any effort at all, but it will generate a lot of noise for the spidev driver, since all of us will need to add its compatible string to spidev. * Rework the spidev code so that it behaves mostly like i2c-dev, that is you have an instance of it for every device enumerated in the dt, regardless of wether it has a driver loaded or not. If the userspace opens the device file corresponding to a device already attached to a driver, you return EBUSY, and that's it. I guess it would be the cleaner solution, since you only select spidev in configuration, but it definitely requires way more development than the first one. What's your views on this? Did you have in mind another solution? Thanks, Maxime
On Mon, Oct 29, 2012 at 04:26:11PM +0100, Maxime Ripard wrote: > Ok, so I guess that leaves us with 2 choices here: > * Declare the device in the dt as you would have with any other > driver, with its own compatible string, and we add this compatible > string to the spidev dt ids array. It allows to use the existing > code and thus doesn't require any effort at all, but it will > generate a lot of noise for the spidev driver, since all of us will > need to add its compatible string to spidev. > * Rework the spidev code so that it behaves mostly like i2c-dev, that > is you have an instance of it for every device enumerated in the dt, > regardless of wether it has a driver loaded or not. If the > userspace opens the device file corresponding to a device already > attached to a driver, you return EBUSY, and that's it. I guess it > would be the cleaner solution, since you only select spidev in > configuration, but it definitely requires way more development than > the first one. > What's your views on this? > Did you have in mind another solution? I think either solution is good, obviously Grant's more the expert here. Adding the IDs is obviously simpler and doesn't preclude later doing the i2c-dev style thing so short term I'd probably add the IDs to get things going and punt on the difficult stuff for the time being but YMMV.
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c index 830adbe..8ae0660 100644 --- a/drivers/spi/spidev.c +++ b/drivers/spi/spidev.c @@ -31,6 +31,8 @@ #include <linux/mutex.h> #include <linux/slab.h> #include <linux/compat.h> +#include <linux/of.h> +#include <linux/of_device.h> #include <linux/spi/spi.h> #include <linux/spi/spidev.h> @@ -642,10 +644,18 @@ static int __devexit spidev_remove(struct spi_device *spi) return 0; } +static const struct of_device_id spidev_dt_ids[] = { + { .compatible = "linux,spidev" }, + {}, +}; + +MODULE_DEVICE_TABLE(of, spidev_dt_ids); + static struct spi_driver spidev_spi_driver = { .driver = { .name = "spidev", .owner = THIS_MODULE, + .of_match_table = of_match_ptr(spidev_dt_ids), }, .probe = spidev_probe, .remove = __devexit_p(spidev_remove),
This will allow to probe spidev from device tree Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> --- drivers/spi/spidev.c | 10 ++++++++++ 1 file changed, 10 insertions(+)