Hi Simon,
On Wed, Apr 11, 2018 at 10:22 AM, Simon Horman <horms@xxxxxxxxxxxx> wrote:
> On Tue, Apr 10, 2018 at 05:53:47PM +0200, Geert Uytterhoeven wrote:
>> Vfio-platform requires reset support, provided either by ACPI, or, on DT
>> platforms, by a device-specific reset driver matching against the
>> device's compatible value.
>>
>> On many SoCs, devices are connected to an SoC-internal reset controller.
>> If the reset hierarchy is described in DT using "resets" properties,
>> such devices can be reset in a generic way through the reset controller
>> subsystem. Hence add support for this, avoiding the need to write
>> device-specific reset drivers for each single device on affected SoCs.
>>
>> Devices that do require a more complex reset procedure can still provide
>> a device-specific reset driver, as that takes precedence.
>>
>> Note that this functionality depends on CONFIG_RESET_CONTROLLER=y, and
>> becomes a no-op (as in: "No reset function found for device") if reset
>> controller support is disabled.
>>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>> ---
>> v2:
>> - Don't store error values in vdev->reset_control,
>> - Use of_reset_control_get_exclusive() instead of
>> __of_reset_control_get(),
>> - Improve description.
>> --- a/drivers/vfio/platform/vfio_platform_common.c
>> +++ b/drivers/vfio/platform/vfio_platform_common.c
>> @@ -17,6 +17,7 @@
>> #include <linux/iommu.h>
>> #include <linux/module.h>
>> #include <linux/mutex.h>
>> +#include <linux/reset.h>
>> #include <linux/slab.h>
>> #include <linux/types.h>
>> #include <linux/uaccess.h>
>> @@ -112,11 +113,19 @@ static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
>> if (VFIO_PLATFORM_IS_ACPI(vdev))
>> return vfio_platform_acpi_has_reset(vdev);
>>
>> - return vdev->of_reset ? true : false;
>> + if (vdev->of_reset)
>> + return true;
>> +
>> + if (vdev->reset_control)
>> + return true;
>> +
>> + return false;
>
> I wonder if the above would be better expressed as:
>
> return vdev->of_reset || vdev->reset_control;
Makes sense, now both checks are of the same type.
>> @@ -217,6 +236,9 @@ static int vfio_platform_call_reset(struct vfio_platform_device *vdev,
>> } else if (vdev->of_reset) {
>> dev_info(vdev->device, "reset\n");
>> return vdev->of_reset(vdev);
>> + } else if (vdev->reset_control) {
>> + dev_info(vdev->device, "reset\n");
>
> Would it be useful to differentiate between the above two informational
> messages?
Probably not, there's also no differentiation with the message for the
ACPI case above (out of visible context).
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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