fpga: dfl: afu: add interrupt support for port error reporting

Error reporting interrupt is very useful to notify users that some
errors are detected by the hardware. Once users are notified, they
could query hardware logged error states, no need to continuously
poll on these states.

This patch adds interrupt support for port error reporting sub feature.
It follows the common DFL interrupt notification and handling mechanism,
implements two ioctl commands below for user to query number of irqs
supported, and set/unset interrupt triggers.

Ioctls:
* DFL_FPGA_PORT_ERR_GET_IRQ_NUM
get the number of irqs, which is used to determine whether/how many
interrupts error reporting feature supports.

* DFL_FPGA_PORT_ERR_SET_IRQ
set/unset given eventfds as error interrupt triggers.

Signed-off-by: Luwei Kang <[e-mail]>
Signed-off-by: Wu Hao <[e-mail]>
Signed-off-by: Xu Yilun <[e-mail]>
Reviewed-by: Marcelo Tosatti <[e-mail]>
Acked-by: Wu Hao <[e-mail]>
Signed-off-by: Moritz Fischer <[e-mail]>

drivers/fpga/dfl-afu-error.c

···
  *   Mitchel Henry <[e-mail]>
  */
 
+#include <linux/fpga-dfl.h>
 #include <linux/uaccess.h>
 
 #include "dfl-afu.h"
···
 	afu_port_err_mask(&pdev->dev, true);
 }
 
+static long
+port_err_ioctl(struct platform_device *pdev, struct dfl_feature *feature,
+	       unsigned int cmd, unsigned long arg)
+{
+	switch (cmd) {
+	case DFL_FPGA_PORT_ERR_GET_IRQ_NUM:
+		return dfl_feature_ioctl_get_num_irqs(pdev, feature, arg);
+	case DFL_FPGA_PORT_ERR_SET_IRQ:
+		return dfl_feature_ioctl_set_irq(pdev, feature, arg);
+	default:
+		dev_dbg(&pdev->dev, "%x cmd not handled", cmd);
+		return -ENODEV;
+	}
+}
+
 const struct dfl_feature_id port_err_id_table[] = {
 	{.id = PORT_FEATURE_ID_ERROR,},
 	{0,}
···
 const struct dfl_feature_ops port_err_ops = {
 	.init = port_err_init,
 	.uinit = port_err_uinit,
+	.ioctl = port_err_ioctl,
 };

drivers/fpga/dfl-afu-main.c

···
 {
 	struct platform_device *pdev = filp->private_data;
 	struct dfl_feature_platform_data *pdata;
+	struct dfl_feature *feature;
 
 	dev_dbg(&pdev->dev, "Device File Release\n");
 
···
 	dfl_feature_dev_use_end(pdata);
 
 	if (!dfl_feature_dev_use_count(pdata)) {
+		dfl_fpga_dev_for_each_feature(pdata, feature)
+			dfl_fpga_set_irq_triggers(feature, 0,
+						  feature->nr_irqs, NULL);
 		__port_reset(pdev);
 		afu_dma_region_destroy(pdata);
 	}

include/uapi/linux/fpga-dfl.h

···
 	__s32 evtfds[];
 };
 
+/**
+ * DFL_FPGA_PORT_ERR_GET_IRQ_NUM - _IOR(DFL_FPGA_MAGIC, DFL_PORT_BASE + 5,
+ *								__u32 num_irqs)
+ *
+ * Get the number of irqs supported by the fpga port error reporting private
+ * feature. Currently hardware supports up to 1 irq.
+ * Return: 0 on success, -errno on failure.
+ */
+#define DFL_FPGA_PORT_ERR_GET_IRQ_NUM	_IOR(DFL_FPGA_MAGIC,	\
+					     DFL_PORT_BASE + 5, __u32)
+
+/**
+ * DFL_FPGA_PORT_ERR_SET_IRQ - _IOW(DFL_FPGA_MAGIC, DFL_PORT_BASE + 6,
+ *						struct dfl_fpga_irq_set)
+ *
+ * Set fpga port error reporting interrupt trigger if evtfds[n] is valid.
+ * Unset related interrupt trigger if evtfds[n] is a negative value.
+ * Return: 0 on success, -errno on failure.
+ */
+#define DFL_FPGA_PORT_ERR_SET_IRQ	_IOW(DFL_FPGA_MAGIC,	\
+					     DFL_PORT_BASE + 6,	\
+					     struct dfl_fpga_irq_set)
+
 /* IOCTLs for FME file descriptor */
 
 /**