diff mbox series

[-next,3/4] spi: mockup: Add runtime device tree overlay interface

Message ID 20220826144341.532265-4-weiyongjun1@huawei.com (mailing list archive)
State New, archived
Headers show
Series spi: Introduce BPF based SPI mockup controller | expand

Commit Message

Wei Yongjun Aug. 26, 2022, 2:43 p.m. UTC
Add a runtime device tree overlay interface for device need dts file.
With it its possible to use device tree overlays without having to use
a per-platform overlay manager.

Add a new device by command:
$ cat test.dtbo > /sys/class/spi_master/spi0/overlay_fdto

Remove the device by command:
$ echo remove > /sys/class/spi_master/spi0/overlay_fdto

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
---
 drivers/spi/Kconfig      |  2 ++
 drivers/spi/spi-mockup.c | 48 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

Comments

Frank Rowand Aug. 29, 2022, 9:29 p.m. UTC | #1
comment inline below, plus adding to cc: and to: list

On 8/26/22 09:43, Wei Yongjun wrote:
> Add a runtime device tree overlay interface for device need dts file.
> With it its possible to use device tree overlays without having to use
> a per-platform overlay manager.

Why is an overlay needed?  The documentation in patch 4 shows providing
a dtb as an argument to the qemu-system-x86_64 command, which should be
sufficient to supply the appropriate dtb.

-Frank

> 
> Add a new device by command:
> $ cat test.dtbo > /sys/class/spi_master/spi0/overlay_fdto
> 
> Remove the device by command:
> $ echo remove > /sys/class/spi_master/spi0/overlay_fdto
> 
> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
> ---
>  drivers/spi/Kconfig      |  2 ++
>  drivers/spi/spi-mockup.c | 48 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 50 insertions(+)
> 
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index e0f0fa2746ad..4b7c84ddb367 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -1161,6 +1161,8 @@ config SPI_TLE62X0
>  config SPI_MOCKUP
>  	tristate "SPI controller Testing Driver"
>  	depends on OF
> +	select OF_EARLY_FLATTREE
> +	select OF_RESOLVE
>  	select BPF_EVENTS
>  	help
>  	  This enables SPI controller testing driver, which provides a way to
> diff --git a/drivers/spi/spi-mockup.c b/drivers/spi/spi-mockup.c
> index 7a93b194ee53..404ad821bf6a 100644
> --- a/drivers/spi/spi-mockup.c
> +++ b/drivers/spi/spi-mockup.c
> @@ -21,6 +21,9 @@
>  struct mockup_spi {
>  	struct mutex lock;
>  	struct spi_device *devs[MOCKUP_CHIPSELECT_MAX];
> +
> +	void *fdto;
> +	int ovcs_id;
>  };
>  
>  static struct spi_master *to_spi_master(struct device *dev)
> @@ -145,9 +148,53 @@ delete_device_store(struct device *dev, struct device_attribute *attr,
>  }
>  static DEVICE_ATTR_WO(delete_device);
>  
> +static ssize_t
> +overlay_fdto_store(struct device *dev, struct device_attribute *attr,
> +		   const char *buf, size_t count)
> +{
> +	struct spi_master *master = to_spi_master(dev);
> +	struct mockup_spi *mock = spi_master_get_devdata(master);
> +	int ret;
> +
> +	mutex_lock(&mock->lock);
> +
> +	if (strncmp(buf, "remove\n", count) == 0) {
> +		if (mock->ovcs_id < 0) {
> +			ret = -ENOENT;
> +			goto out_unlock;
> +		}
> +		of_overlay_remove(&mock->ovcs_id);
> +		kfree(mock->fdto);
> +		mock->ovcs_id = -1;
> +		mock->fdto = NULL;
> +	} else {
> +		if (mock->ovcs_id >= 0) {
> +			ret = -EINVAL;
> +			goto out_unlock;
> +		}
> +		mock->fdto = kmemdup(buf, count, GFP_KERNEL);
> +		if (!mock->fdto) {
> +			ret = -ENOMEM;
> +			goto out_unlock;
> +		}
> +		ret = of_overlay_fdt_apply(mock->fdto, count, &mock->ovcs_id);
> +		if (ret < 0)
> +			goto out_unlock;
> +	}
> +
> +	mutex_unlock(&mock->lock);
> +	return count;
> +
> +out_unlock:
> +	mutex_unlock(&mock->lock);
> +	return ret;
> +}
> +static DEVICE_ATTR_WO(overlay_fdto);
> +
>  static struct attribute *spi_mockup_attrs[] = {
>  	&dev_attr_new_device.attr,
>  	&dev_attr_delete_device.attr,
> +	&dev_attr_overlay_fdto.attr,
>  	NULL
>  };
>  ATTRIBUTE_GROUPS(spi_mockup);
> @@ -227,6 +274,7 @@ static int spi_mockup_probe(struct platform_device *pdev)
>  
>  	mock = spi_master_get_devdata(master);
>  	mutex_init(&mock->lock);
> +	mock->ovcs_id = -1;
>  
>  	ret = spi_register_master(master);
>  	if (ret) {
Wei Yongjun Aug. 30, 2022, 3:05 a.m. UTC | #2
On 2022/8/30 5:29, Frank Rowand wrote:
> comment inline below, plus adding to cc: and to: list
> 
> On 8/26/22 09:43, Wei Yongjun wrote:
>> Add a runtime device tree overlay interface for device need dts file.
>> With it its possible to use device tree overlays without having to use
>> a per-platform overlay manager.
> 
> Why is an overlay needed?  The documentation in patch 4 shows providing
> a dtb as an argument to the qemu-system-x86_64 command, which should be
> sufficient to supply the appropriate dtb.

Fist, we are aimed to build a device driver regression testsuit. Without
overlay, lots of the dtb fragments must be combined to a very big one, it
may different to maintainence. overlay makes easily to attach/detech as
the device's requirement.

Seconds, overlay dts may be used to found or verification issues related
to of_node_put or others, such as patches like:

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/log/?qt=grep&q=node_put

many of them may found by static check tool, which may leak of tesing.

The documentation I post does not use overlay dts, but when overlay
dts[1] is used, we can found the of node leak:

$ python3 -m kddv.cmds.mock -b spi -d mchp23k256
create spi device mchp23k256 success!
$ ls /sys/bus/spi/drivers/mchp23k256/spi0.0/mtd/
mtd0  mtd0ro
$ python3 -m kddv.cmds.mock -b spi -d mchp23k256 -r
[  233.508565] Deleting MTD partitions on "spi0.0":
[  233.516784] OF: ERROR: memory leak, expected refcount 1 instead of 2,
  of_node_get()/of_node_put() unbalanced - destroy cset entry: attach
  overlay node /spi/spi-sram@0
remove spi device mchp23k256 success!

Not sure it is worth to fix issues like this, but at least, we can
tesing them now.

-[1]---------------------------------------------------------
/dts-v1/;
/plugin/;

&{/spi} {
	spi-sram@0 {
		#address-cells = <1>;
		#size-cells = <1>;
		compatible = "microchip,mchp23k256";
		reg = <0>;
		spi-max-frequency = <20000000>;
	};
};

-------------------------------------------------------

Regards,
Wei Yongjun

> 
> -Frank
> 
>>
>> Add a new device by command:
>> $ cat test.dtbo > /sys/class/spi_master/spi0/overlay_fdto
>>
>> Remove the device by command:
>> $ echo remove > /sys/class/spi_master/spi0/overlay_fdto
>>
>> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
>> ---
>>   drivers/spi/Kconfig      |  2 ++
>>   drivers/spi/spi-mockup.c | 48 ++++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 50 insertions(+)
>>
>> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
>> index e0f0fa2746ad..4b7c84ddb367 100644
>> --- a/drivers/spi/Kconfig
>> +++ b/drivers/spi/Kconfig
>> @@ -1161,6 +1161,8 @@ config SPI_TLE62X0
>>   config SPI_MOCKUP
>>   	tristate "SPI controller Testing Driver"
>>   	depends on OF
>> +	select OF_EARLY_FLATTREE
>> +	select OF_RESOLVE
>>   	select BPF_EVENTS
>>   	help
>>   	  This enables SPI controller testing driver, which provides a way to
>> diff --git a/drivers/spi/spi-mockup.c b/drivers/spi/spi-mockup.c
>> index 7a93b194ee53..404ad821bf6a 100644
>> --- a/drivers/spi/spi-mockup.c
>> +++ b/drivers/spi/spi-mockup.c
>> @@ -21,6 +21,9 @@
>>   struct mockup_spi {
>>   	struct mutex lock;
>>   	struct spi_device *devs[MOCKUP_CHIPSELECT_MAX];
>> +
>> +	void *fdto;
>> +	int ovcs_id;
>>   };
>>   
>>   static struct spi_master *to_spi_master(struct device *dev)
>> @@ -145,9 +148,53 @@ delete_device_store(struct device *dev, struct device_attribute *attr,
>>   }
>>   static DEVICE_ATTR_WO(delete_device);
>>   
>> +static ssize_t
>> +overlay_fdto_store(struct device *dev, struct device_attribute *attr,
>> +		   const char *buf, size_t count)
>> +{
>> +	struct spi_master *master = to_spi_master(dev);
>> +	struct mockup_spi *mock = spi_master_get_devdata(master);
>> +	int ret;
>> +
>> +	mutex_lock(&mock->lock);
>> +
>> +	if (strncmp(buf, "remove\n", count) == 0) {
>> +		if (mock->ovcs_id < 0) {
>> +			ret = -ENOENT;
>> +			goto out_unlock;
>> +		}
>> +		of_overlay_remove(&mock->ovcs_id);
>> +		kfree(mock->fdto);
>> +		mock->ovcs_id = -1;
>> +		mock->fdto = NULL;
>> +	} else {
>> +		if (mock->ovcs_id >= 0) {
>> +			ret = -EINVAL;
>> +			goto out_unlock;
>> +		}
>> +		mock->fdto = kmemdup(buf, count, GFP_KERNEL);
>> +		if (!mock->fdto) {
>> +			ret = -ENOMEM;
>> +			goto out_unlock;
>> +		}
>> +		ret = of_overlay_fdt_apply(mock->fdto, count, &mock->ovcs_id);
>> +		if (ret < 0)
>> +			goto out_unlock;
>> +	}
>> +
>> +	mutex_unlock(&mock->lock);
>> +	return count;
>> +
>> +out_unlock:
>> +	mutex_unlock(&mock->lock);
>> +	return ret;
>> +}
>> +static DEVICE_ATTR_WO(overlay_fdto);
>> +
>>   static struct attribute *spi_mockup_attrs[] = {
>>   	&dev_attr_new_device.attr,
>>   	&dev_attr_delete_device.attr,
>> +	&dev_attr_overlay_fdto.attr,
>>   	NULL
>>   };
>>   ATTRIBUTE_GROUPS(spi_mockup);
>> @@ -227,6 +274,7 @@ static int spi_mockup_probe(struct platform_device *pdev)
>>   
>>   	mock = spi_master_get_devdata(master);
>>   	mutex_init(&mock->lock);
>> +	mock->ovcs_id = -1;
>>   
>>   	ret = spi_register_master(master);
>>   	if (ret) {
>
Mark Brown Aug. 30, 2022, 10:27 a.m. UTC | #3
On Fri, Aug 26, 2022 at 02:43:40PM +0000, Wei Yongjun wrote:

> Add a runtime device tree overlay interface for device need dts file.
> With it its possible to use device tree overlays without having to use
> a per-platform overlay manager.

Why would an entirely virtual device like this need to appear in
DT?  DT is supposed to be a hardware description and this clearly
isn't hardware, nor is it something we're providing to a VM.
Frank Rowand Aug. 30, 2022, 7:24 p.m. UTC | #4
On 8/30/22 05:27, Mark Brown wrote:
> On Fri, Aug 26, 2022 at 02:43:40PM +0000, Wei Yongjun wrote:
> 
>> Add a runtime device tree overlay interface for device need dts file.
>> With it its possible to use device tree overlays without having to use
>> a per-platform overlay manager.
> 
> Why would an entirely virtual device like this need to appear in
> DT?  DT is supposed to be a hardware description and this clearly
> isn't hardware, nor is it something we're providing to a VM.

Good point.  Patch 3 seems to not be needed.

-Frank
Wei Yongjun Aug. 31, 2022, 4:44 a.m. UTC | #5
On 2022/8/31 3:24, Frank Rowand wrote:
> On 8/30/22 05:27, Mark Brown wrote:
>> On Fri, Aug 26, 2022 at 02:43:40PM +0000, Wei Yongjun wrote:
>>
>>> Add a runtime device tree overlay interface for device need dts file.
>>> With it its possible to use device tree overlays without having to use
>>> a per-platform overlay manager.
>>
>> Why would an entirely virtual device like this need to appear in
>> DT?  DT is supposed to be a hardware description and this clearly
>> isn't hardware, nor is it something we're providing to a VM.
> 
> Good point.  Patch 3 seems to not be needed.

Yes, will drop it in next version.

Thanks,
Wei Yongjun
diff mbox series

Patch

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index e0f0fa2746ad..4b7c84ddb367 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -1161,6 +1161,8 @@  config SPI_TLE62X0
 config SPI_MOCKUP
 	tristate "SPI controller Testing Driver"
 	depends on OF
+	select OF_EARLY_FLATTREE
+	select OF_RESOLVE
 	select BPF_EVENTS
 	help
 	  This enables SPI controller testing driver, which provides a way to
diff --git a/drivers/spi/spi-mockup.c b/drivers/spi/spi-mockup.c
index 7a93b194ee53..404ad821bf6a 100644
--- a/drivers/spi/spi-mockup.c
+++ b/drivers/spi/spi-mockup.c
@@ -21,6 +21,9 @@ 
 struct mockup_spi {
 	struct mutex lock;
 	struct spi_device *devs[MOCKUP_CHIPSELECT_MAX];
+
+	void *fdto;
+	int ovcs_id;
 };
 
 static struct spi_master *to_spi_master(struct device *dev)
@@ -145,9 +148,53 @@  delete_device_store(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_WO(delete_device);
 
+static ssize_t
+overlay_fdto_store(struct device *dev, struct device_attribute *attr,
+		   const char *buf, size_t count)
+{
+	struct spi_master *master = to_spi_master(dev);
+	struct mockup_spi *mock = spi_master_get_devdata(master);
+	int ret;
+
+	mutex_lock(&mock->lock);
+
+	if (strncmp(buf, "remove\n", count) == 0) {
+		if (mock->ovcs_id < 0) {
+			ret = -ENOENT;
+			goto out_unlock;
+		}
+		of_overlay_remove(&mock->ovcs_id);
+		kfree(mock->fdto);
+		mock->ovcs_id = -1;
+		mock->fdto = NULL;
+	} else {
+		if (mock->ovcs_id >= 0) {
+			ret = -EINVAL;
+			goto out_unlock;
+		}
+		mock->fdto = kmemdup(buf, count, GFP_KERNEL);
+		if (!mock->fdto) {
+			ret = -ENOMEM;
+			goto out_unlock;
+		}
+		ret = of_overlay_fdt_apply(mock->fdto, count, &mock->ovcs_id);
+		if (ret < 0)
+			goto out_unlock;
+	}
+
+	mutex_unlock(&mock->lock);
+	return count;
+
+out_unlock:
+	mutex_unlock(&mock->lock);
+	return ret;
+}
+static DEVICE_ATTR_WO(overlay_fdto);
+
 static struct attribute *spi_mockup_attrs[] = {
 	&dev_attr_new_device.attr,
 	&dev_attr_delete_device.attr,
+	&dev_attr_overlay_fdto.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(spi_mockup);
@@ -227,6 +274,7 @@  static int spi_mockup_probe(struct platform_device *pdev)
 
 	mock = spi_master_get_devdata(master);
 	mutex_init(&mock->lock);
+	mock->ovcs_id = -1;
 
 	ret = spi_register_master(master);
 	if (ret) {