Re: [PATCH v2 2/2] vfio: platform: Add generic DT reset controller support

[Simon Horman]

Hi Geert,

On Wed, Apr 11, 2018 at 10:39:19AM +0200, Geert Uytterhoeven wrote:
> Hi Simon,
> 
> On Wed, Apr 11, 2018 at 10:22 AM, Simon Horman  wrote:
> > On Tue, Apr 10, 2018 at 05:53:47PM +0200, Geert Uytterhoeven wrote:

...

> >> @@ -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).

Thanks, I agree that it seems fine to leave things as you have them above.

Re: [PATCH v2 2/2] vfio: platform: Add generic DT reset controller support

[Geert Uytterhoeven]

Hi Philipp,

On Wed, Apr 11, 2018 at 10:22 AM, Philipp Zabel  wrote:
> On Tue, 2018-04-10 at 17:53 +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 
>
> Reviewed-by: Philipp Zabel 

Thanks!

>> --- a/drivers/vfio/platform/vfio_platform_common.c
>> +++ b/drivers/vfio/platform/vfio_platform_common.c
> [...]
>> @@ -127,8 +136,16 @@ static int vfio_platform_get_reset(struct 
>> vfio_platform_device *vdev)
>>   vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
>>   >reset_module);
>>   }
>> + if (vdev->of_reset)
>> + return 0;
>> +
>> + rstc = of_reset_control_get_exclusive(vdev->device->of_node, NULL);
>
> If vdev->device->of_node == NULL, this will return -EINVAL ...
>
>> + if (!IS_ERR(rstc)) {
>> + vdev->reset_control = rstc;
>> + return 0;
>> + }
>>
>> - return vdev->of_reset ? 0 : -ENOENT;
>> + return PTR_ERR(rstc);
>
> ... instead of -ENOENT, if that makes any difference.

Not really. The single caller (vfio_platform_probe_common()) already returns
-EINVAL if no IOMMU group is found, so this should be handled fine.

Gr{oetje,eeting}s,

Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org

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

Re: [PATCH v2 2/2] vfio: platform: Add generic DT reset controller support

[Geert Uytterhoeven]

Hi Simon,

On Wed, Apr 11, 2018 at 10:22 AM, Simon Horman  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 
>> ---
>> 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 
>>  #include 
>>  #include 
>> +#include 
>>  #include 
>>  #include 
>>  #include 
>> @@ -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 -- ge...@linux-m68k.org

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

Re: [PATCH v2 2/2] vfio: platform: Add generic DT reset controller support

[Philipp Zabel]

On Tue, 2018-04-10 at 17:53 +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 

Reviewed-by: Philipp Zabel 

> ---
> v2:
>   - Don't store error values in vdev->reset_control,
>   - Use of_reset_control_get_exclusive() instead of
> __of_reset_control_get(),
>   - Improve description.
> ---
>  drivers/vfio/platform/vfio_platform_common.c  | 26 --
>  drivers/vfio/platform/vfio_platform_private.h |  1 +
>  2 files changed, 25 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_common.c 
> b/drivers/vfio/platform/vfio_platform_common.c
> index b60bb5326668498c..3c13327b2777f8ec 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
[...]
> @@ -127,8 +136,16 @@ static int vfio_platform_get_reset(struct 
> vfio_platform_device *vdev)
>   vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
>   >reset_module);
>   }
> + if (vdev->of_reset)
> + return 0;
> +
> + rstc = of_reset_control_get_exclusive(vdev->device->of_node, NULL);

If vdev->device->of_node == NULL, this will return -EINVAL ...

> + if (!IS_ERR(rstc)) {
> + vdev->reset_control = rstc;
> + return 0;
> + }
>  
> - return vdev->of_reset ? 0 : -ENOENT;
> + return PTR_ERR(rstc);

... instead of -ENOENT, if that makes any difference.

regards
Philipp

Re: [PATCH v2 2/2] vfio: platform: Add generic DT reset controller support

[Simon Horman]

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 
> ---
> v2:
>   - Don't store error values in vdev->reset_control,
>   - Use of_reset_control_get_exclusive() instead of
> __of_reset_control_get(),
>   - Improve description.
> ---
>  drivers/vfio/platform/vfio_platform_common.c  | 26 --
>  drivers/vfio/platform/vfio_platform_private.h |  1 +
>  2 files changed, 25 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_common.c 
> b/drivers/vfio/platform/vfio_platform_common.c
> index b60bb5326668498c..3c13327b2777f8ec 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -17,6 +17,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  #include 
>  #include 
>  #include 
> @@ -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;

>  }
>  
>  static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
>  {
> + struct reset_control *rstc;
> +
>   if (VFIO_PLATFORM_IS_ACPI(vdev))
>   return vfio_platform_acpi_has_reset(vdev) ? 0 : -ENOENT;
>  
> @@ -127,8 +136,16 @@ static int vfio_platform_get_reset(struct 
> vfio_platform_device *vdev)
>   vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
>   >reset_module);
>   }
> + if (vdev->of_reset)
> + return 0;
> +
> + rstc = of_reset_control_get_exclusive(vdev->device->of_node, NULL);
> + if (!IS_ERR(rstc)) {
> + vdev->reset_control = rstc;
> + return 0;
> + }
>  
> - return vdev->of_reset ? 0 : -ENOENT;
> + return PTR_ERR(rstc);
>  }
>  
>  static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
> @@ -138,6 +155,8 @@ static void vfio_platform_put_reset(struct 
> vfio_platform_device *vdev)
>  
>   if (vdev->of_reset)
>   module_put(vdev->reset_module);
> +
> + reset_control_put(vdev->reset_control);
>  }
>  
>  static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
> @@ -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?

> + return reset_control_reset(vdev->reset_control);
>   }
>  
>   dev_warn(vdev->device, "no reset function found!\n");
> diff --git a/drivers/vfio/platform/vfio_platform_private.h 
> b/drivers/vfio/platform/vfio_platform_private.h
> index 85ffe5d9d1abd94e..a56e80ae5986540b 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -60,6 +60,7 @@ struct vfio_platform_device {
>   const char  *compat;
>   const char  *acpihid;
>   struct module   *reset_module;
> + struct reset_control*reset_control;
>   struct device   *device;
>  
>   /*
> -- 
> 2.7.4
> 

[PATCH v2 2/2] vfio: platform: Add generic DT reset controller support

[Geert Uytterhoeven]

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 
---
v2:
  - Don't store error values in vdev->reset_control,
  - Use of_reset_control_get_exclusive() instead of
__of_reset_control_get(),
  - Improve description.
---
 drivers/vfio/platform/vfio_platform_common.c  | 26 --
 drivers/vfio/platform/vfio_platform_private.h |  1 +
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/platform/vfio_platform_common.c 
b/drivers/vfio/platform/vfio_platform_common.c
index b60bb5326668498c..3c13327b2777f8ec 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -17,6 +17,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -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;
 }
 
 static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
 {
+   struct reset_control *rstc;
+
if (VFIO_PLATFORM_IS_ACPI(vdev))
return vfio_platform_acpi_has_reset(vdev) ? 0 : -ENOENT;
 
@@ -127,8 +136,16 @@ static int vfio_platform_get_reset(struct 
vfio_platform_device *vdev)
vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
>reset_module);
}
+   if (vdev->of_reset)
+   return 0;
+
+   rstc = of_reset_control_get_exclusive(vdev->device->of_node, NULL);
+   if (!IS_ERR(rstc)) {
+   vdev->reset_control = rstc;
+   return 0;
+   }
 
-   return vdev->of_reset ? 0 : -ENOENT;
+   return PTR_ERR(rstc);
 }
 
 static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
@@ -138,6 +155,8 @@ static void vfio_platform_put_reset(struct 
vfio_platform_device *vdev)
 
if (vdev->of_reset)
module_put(vdev->reset_module);
+
+   reset_control_put(vdev->reset_control);
 }
 
 static int vfio_platform_regions_init(struct vfio_platform_device *vdev)
@@ -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");
+   return reset_control_reset(vdev->reset_control);
}
 
dev_warn(vdev->device, "no reset function found!\n");
diff --git a/drivers/vfio/platform/vfio_platform_private.h 
b/drivers/vfio/platform/vfio_platform_private.h
index 85ffe5d9d1abd94e..a56e80ae5986540b 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -60,6 +60,7 @@ struct vfio_platform_device {
const char  *compat;
const char  *acpihid;
struct module   *reset_module;
+   struct reset_control*reset_control;
struct device   *device;
 
/*
-- 
2.7.4