[PATCH v3 0/2] uio: pdrv_gen_irq and threaded intrerrupts

[PATCH v3 0/2] uio: pdrv_gen_irq and threaded intrerrupts

[Chris Packham]

I've combined these two commits submitted separatedly [1][2] into a small
series. They can be applied separately as they are not dependent on each other.

[1] - https://lore.kernel.org/lkml/20240325015045.778718-1-chris.packham@alliedtelesis.co.nz/
[2] - https://lore.kernel.org/lkml/20240325015045.778718-1-chris.packham@alliedtelesis.co.nz/

Chris Packham (2):
  uio_pdrv_genirq: convert to use device_property APIs
  uio: use threaded interrupts

 drivers/uio/uio.c             | 24 +++++++++++++++++++-----
 drivers/uio/uio_pdrv_genirq.c | 10 +++++-----
 2 files changed, 24 insertions(+), 10 deletions(-)

-- 
2.43.2

[PATCH v3 1/2] uio_pdrv_genirq: convert to use device_property APIs

[Chris Packham]

Convert the uio_pdrv_genirq driver to use the device_property_* APIs
instead of the of_property_* ones. This allows UIO interrupts to be
defined via an ACPI overlay using the Device Tree namespace linkage.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---

Notes:
    Changes in v3:
    - None
    Changes in v2:
    - Remove extraneous newline

 drivers/uio/uio_pdrv_genirq.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/uio/uio_pdrv_genirq.c b/drivers/uio/uio_pdrv_genirq.c
index 63258b6accc4..796f5be0a086 100644
--- a/drivers/uio/uio_pdrv_genirq.c
+++ b/drivers/uio/uio_pdrv_genirq.c
@@ -23,8 +23,8 @@
 #include <linux/irq.h>
 
 #include <linux/of.h>
-#include <linux/of_platform.h>
-#include <linux/of_address.h>
+#include <linux/mod_devicetable.h>
+#include <linux/property.h>
 
 #define DRIVER_NAME "uio_pdrv_genirq"
 
@@ -110,7 +110,7 @@ static void uio_pdrv_genirq_cleanup(void *data)
 static int uio_pdrv_genirq_probe(struct platform_device *pdev)
 {
 	struct uio_info *uioinfo = dev_get_platdata(&pdev->dev);
-	struct device_node *node = pdev->dev.of_node;
+	struct fwnode_handle *node = dev_fwnode(&pdev->dev);
 	struct uio_pdrv_genirq_platdata *priv;
 	struct uio_mem *uiomem;
 	int ret = -EINVAL;
@@ -127,11 +127,11 @@ static int uio_pdrv_genirq_probe(struct platform_device *pdev)
 			return -ENOMEM;
 		}
 
-		if (!of_property_read_string(node, "linux,uio-name", &name))
+		if (!device_property_read_string(&pdev->dev, "linux,uio-name", &name))
 			uioinfo->name = devm_kstrdup(&pdev->dev, name, GFP_KERNEL);
 		else
 			uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
-						       "%pOFn", node);
+						       "%pfwP", node);
 
 		uioinfo->version = "devicetree";
 		/* Multiple IRQs are not supported */
-- 
2.43.2

[PATCH v3 2/2] uio: use threaded interrupts

[Chris Packham]

Split the existing uio_interrupt into a hardirq handler and a thread
function. The hardirq handler deals with the interrupt source in
hardware, the thread function notifies userspace that there is an event
to be handled.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---

Notes:
    I find myself needing to have a UIO interrupt associated with an
    interrupt pin on a PCA9539 (yes I know, it's a terrible chip but HW
    engineers love it because it's cheap).
    
    Prior to this the UIO registration fails with:
    
      [    6.484699] uio_pdrv_genirq detect-gpio-9: unable to register uio device
      [    6.484722] uio_pdrv_genirq detect-gpio-9: probe with driver uio_pdrv_genirq failed with error -22
    
    The -EINVAL ultimately comes from __setup_irq() where it knows the
    interrupt descriptor is nested but we haven't provided a thread_fn.
    
    Changes in v3:
    - Update kerneldoc comment for uio_interrupt_handler()
    - Add kerneldoc comment for uio_interrupt_thread()
    Changes in v2:
    - None

 drivers/uio/uio.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index bb77de6fa067..b424f004404f 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -438,22 +438,36 @@ void uio_event_notify(struct uio_info *info)
 EXPORT_SYMBOL_GPL(uio_event_notify);
 
 /**
- * uio_interrupt - hardware interrupt handler
+ * uio_interrupt_handler - hardware interrupt handler
  * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
  * @dev_id: Pointer to the devices uio_device structure
  */
-static irqreturn_t uio_interrupt(int irq, void *dev_id)
+static irqreturn_t uio_interrupt_handler(int irq, void *dev_id)
 {
 	struct uio_device *idev = (struct uio_device *)dev_id;
 	irqreturn_t ret;
 
 	ret = idev->info->handler(irq, idev->info);
 	if (ret == IRQ_HANDLED)
-		uio_event_notify(idev->info);
+		ret = IRQ_WAKE_THREAD;
 
 	return ret;
 }
 
+/**
+ * uio_interrupt_thread - irq thread handler
+ * @irq: IRQ number
+ * @dev_id: Pointer to the devices uio_device structure
+ */
+static irqreturn_t uio_interrupt_thread(int irq, void *dev_id)
+{
+	struct uio_device *idev = (struct uio_device *)dev_id;
+
+	uio_event_notify(idev->info);
+
+	return IRQ_HANDLED;
+}
+
 struct uio_listener {
 	struct uio_device *dev;
 	s32 event_count;
@@ -1024,8 +1038,8 @@ int __uio_register_device(struct module *owner,
 		 * FDs at the time of unregister and therefore may not be
 		 * freed until they are released.
 		 */
-		ret = request_irq(info->irq, uio_interrupt,
-				  info->irq_flags, info->name, idev);
+		ret = request_threaded_irq(info->irq, uio_interrupt_handler, uio_interrupt_thread,
+					   info->irq_flags, info->name, idev);
 		if (ret) {
 			info->uio_dev = NULL;
 			goto err_request_irq;
-- 
2.43.2

Re: [PATCH v3 0/2] uio: pdrv_gen_irq and threaded intrerrupts

[Greg KH]

On Fri, Apr 12, 2024 at 04:55:34PM +1200, Chris Packham wrote:
> I've combined these two commits submitted separatedly [1][2] into a small
> series. They can be applied separately as they are not dependent on each other.
> 
> [1] - https://lore.kernel.org/lkml/20240325015045.778718-1-chris.packham@alliedtelesis.co.nz/
> [2] - https://lore.kernel.org/lkml/20240325015045.778718-1-chris.packham@alliedtelesis.co.nz/
> 
> Chris Packham (2):
>   uio_pdrv_genirq: convert to use device_property APIs
>   uio: use threaded interrupts
> 
>  drivers/uio/uio.c             | 24 +++++++++++++++++++-----
>  drivers/uio/uio_pdrv_genirq.c | 10 +++++-----
>  2 files changed, 24 insertions(+), 10 deletions(-)
> 
> -- 
> 2.43.2
> 

Can you just send a fix-up patch instead?

thanks,

greg k-h