[PATCH v5 2/3] fpga: dfl: create a dfl bus type to support DFL devices

[Xu Yilun <yilun.xu@intel.com>]

A new bus type "dfl" is introduced for private features which are not
initialized by DFL feature drivers (dfl-fme & dfl-afu drivers). So these
private features could be handled by separate driver modules.

DFL feature drivers (dfl-fme, dfl-port) will create DFL devices on
enumeration. DFL drivers could be registered on this bus to match these
DFL devices. They are matched by dfl type & feature_id.

Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Wu Hao <hao.wu@intel.com>
Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Reviewed-by: Tom Rix <trix@redhat.com>
---
v2: change the bus uevent format.
    change the dfl device's sysfs name format.
    refactor dfl_dev_add().
    minor fixes for comments from Hao and Tom.
v3: no change.
v4: improve the uevent format, 4 bits for type & 12 bits for id.
    change dfl_device->type to u8.
    A dedicate field in struct dfl_feature for dfl device instance.
    error out if dfl_device already exist on dfl_devs_init().
v5: minor fixes for Hao's comments
---
 Documentation/ABI/testing/sysfs-bus-dfl |  15 ++
 drivers/fpga/dfl.c                      | 263 +++++++++++++++++++++++++++++++-
 drivers/fpga/dfl.h                      |  86 +++++++++++
 3 files changed, 356 insertions(+), 8 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-dfl

diff --git a/Documentation/ABI/testing/sysfs-bus-dfl b/Documentation/ABI/testing/sysfs-bus-dfl
new file mode 100644
index 0000000..23543be
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-dfl
@@ -0,0 +1,15 @@
+What:		/sys/bus/dfl/devices/dfl_dev.X/type
+Date:		Aug 2020
+KernelVersion:	5.10
+Contact:	Xu Yilun <yilun.xu@intel.com>
+Description:	Read-only. It returns type of DFL FIU of the device. Now DFL
+		supports 2 FIU types, 0 for FME, 1 for PORT.
+		Format: 0x%x
+
+What:		/sys/bus/dfl/devices/dfl_dev.X/feature_id
+Date:		Aug 2020
+KernelVersion:	5.10
+Contact:	Xu Yilun <yilun.xu@intel.com>
+Description:	Read-only. It returns feature identifier local to its DFL FIU
+		type.
+		Format: 0x%x
diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index 52cafa2..1a9ad7e 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c
@@ -30,12 +30,6 @@ static DEFINE_MUTEX(dfl_id_mutex);
  * index to dfl_chardevs table. If no chardev support just set devt_type
  * as one invalid index (DFL_FPGA_DEVT_MAX).
  */
-enum dfl_id_type {
-	FME_ID,		/* fme id allocation and mapping */
-	PORT_ID,	/* port id allocation and mapping */
-	DFL_ID_MAX,
-};
-
 enum dfl_fpga_devt_type {
 	DFL_FPGA_DEVT_FME,
 	DFL_FPGA_DEVT_PORT,
@@ -250,6 +244,245 @@ int dfl_fpga_check_port_id(struct platform_device *pdev, void *pport_id)
 }
 EXPORT_SYMBOL_GPL(dfl_fpga_check_port_id);
 
+static DEFINE_IDA(dfl_device_ida);
+
+static const struct dfl_device_id *
+dfl_match_one_device(const struct dfl_device_id *id, struct dfl_device *ddev)
+{
+	if (id->type == ddev->type && id->feature_id == ddev->feature_id)
+		return id;
+
+	return NULL;
+}
+
+static int dfl_bus_match(struct device *dev, struct device_driver *drv)
+{
+	struct dfl_device *ddev = to_dfl_dev(dev);
+	struct dfl_driver *ddrv = to_dfl_drv(drv);
+	const struct dfl_device_id *id_entry = ddrv->id_table;
+
+	if (id_entry) {
+		while (id_entry->feature_id) {
+			if (dfl_match_one_device(id_entry, ddev)) {
+				ddev->id_entry = id_entry;
+				return 1;
+			}
+			id_entry++;
+		}
+	}
+
+	return 0;
+}
+
+static int dfl_bus_probe(struct device *dev)
+{
+	struct dfl_device *ddev = to_dfl_dev(dev);
+	struct dfl_driver *ddrv = to_dfl_drv(dev->driver);
+
+	return ddrv->probe(ddev);
+}
+
+static int dfl_bus_remove(struct device *dev)
+{
+	struct dfl_device *ddev = to_dfl_dev(dev);
+	struct dfl_driver *ddrv = to_dfl_drv(dev->driver);
+
+	if (ddrv->remove)
+		ddrv->remove(ddev);
+
+	return 0;
+}
+
+static int dfl_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct dfl_device *ddev = to_dfl_dev(dev);
+
+	/* The type has 4 valid bits and feature_id has 12 valid bits */
+	return add_uevent_var(env, "MODALIAS=dfl:t%01Xf%03X",
+			      ddev->type, ddev->feature_id);
+}
+
+/* show dfl info fields */
+#define dfl_info_attr(field, format_string)				\
+static ssize_t								\
+field##_show(struct device *dev, struct device_attribute *attr,		\
+	     char *buf)							\
+{									\
+	struct dfl_device *ddev = to_dfl_dev(dev);			\
+									\
+	return sprintf(buf, format_string, ddev->field);		\
+}									\
+static DEVICE_ATTR_RO(field)
+
+dfl_info_attr(type, "0x%x\n");
+dfl_info_attr(feature_id, "0x%x\n");
+
+static struct attribute *dfl_dev_attrs[] = {
+	&dev_attr_type.attr,
+	&dev_attr_feature_id.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(dfl_dev);
+
+static struct bus_type dfl_bus_type = {
+	.name		= "dfl",
+	.match		= dfl_bus_match,
+	.probe		= dfl_bus_probe,
+	.remove		= dfl_bus_remove,
+	.uevent		= dfl_bus_uevent,
+	.dev_groups	= dfl_dev_groups,
+};
+
+static void release_dfl_dev(struct device *dev)
+{
+	struct dfl_device *ddev = to_dfl_dev(dev);
+
+	if (ddev->mmio_res.parent)
+		release_resource(&ddev->mmio_res);
+
+	ida_simple_remove(&dfl_device_ida, ddev->id);
+	kfree(ddev->irqs);
+	kfree(ddev);
+}
+
+static struct dfl_device *
+dfl_dev_add(struct dfl_feature_platform_data *pdata,
+	    struct dfl_feature *feature)
+{
+	struct platform_device *pdev = pdata->dev;
+	struct resource *parent_res;
+	struct dfl_device *ddev;
+	int id, i, ret;
+
+	ddev = kzalloc(sizeof(*ddev), GFP_KERNEL);
+	if (!ddev)
+		return ERR_PTR(-ENOMEM);
+
+	id = ida_simple_get(&dfl_device_ida, 0, 0, GFP_KERNEL);
+	if (id < 0) {
+		dev_err(&pdev->dev, "unable to get id\n");
+		kfree(ddev);
+		return ERR_PTR(id);
+	}
+
+	/* freeing resources by put_device() after device_initialize() */
+	device_initialize(&ddev->dev);
+	ddev->dev.parent = &pdev->dev;
+	ddev->dev.bus = &dfl_bus_type;
+	ddev->dev.release = release_dfl_dev;
+	ddev->id = id;
+	ret = dev_set_name(&ddev->dev, "dfl_dev.%d", id);
+	if (ret)
+		goto put_dev;
+
+	ddev->type = feature_dev_id_type(pdev);
+	ddev->feature_id = feature->id;
+	ddev->cdev = pdata->dfl_cdev;
+
+	/* add mmio resource */
+	parent_res = &pdev->resource[feature->resource_index];
+	ddev->mmio_res.flags = IORESOURCE_MEM;
+	ddev->mmio_res.start = parent_res->start;
+	ddev->mmio_res.end = parent_res->end;
+	ddev->mmio_res.name = dev_name(&ddev->dev);
+	ret = insert_resource(parent_res, &ddev->mmio_res);
+	if (ret) {
+		dev_err(&pdev->dev, "%s failed to claim resource: %pR\n",
+			dev_name(&ddev->dev), &ddev->mmio_res);
+		goto put_dev;
+	}
+
+	/* then add irq resource */
+	if (feature->nr_irqs) {
+		ddev->irqs = kcalloc(feature->nr_irqs,
+				     sizeof(*ddev->irqs), GFP_KERNEL);
+		if (!ddev->irqs) {
+			ret = -ENOMEM;
+			goto put_dev;
+		}
+
+		for (i = 0; i < feature->nr_irqs; i++)
+			ddev->irqs[i] = feature->irq_ctx[i].irq;
+
+		ddev->num_irqs = feature->nr_irqs;
+	}
+
+	ret = device_add(&ddev->dev);
+	if (ret)
+		goto put_dev;
+
+	dev_info(&pdev->dev, "add dfl_dev: %s\n", dev_name(&ddev->dev));
+	return ddev;
+
+put_dev:
+	/* calls release_dfl_dev() which does the clean up  */
+	put_device(&ddev->dev);
+	return ERR_PTR(ret);
+}
+
+static void dfl_devs_remove(struct dfl_feature_platform_data *pdata)
+{
+	struct dfl_feature *feature;
+
+	dfl_fpga_dev_for_each_feature(pdata, feature) {
+		if (feature->ddev) {
+			device_unregister(&feature->ddev->dev);
+			feature->ddev = NULL;
+		}
+	}
+}
+
+static int dfl_devs_add(struct platform_device *pdev)
+{
+	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
+	struct dfl_feature *feature;
+	struct dfl_device *ddev;
+	int ret;
+
+	dfl_fpga_dev_for_each_feature(pdata, feature) {
+		if (feature->ioaddr)
+			continue;
+
+		if (feature->ddev) {
+			ret = -EEXIST;
+			goto err;
+		}
+
+		ddev = dfl_dev_add(pdata, feature);
+		if (IS_ERR(ddev)) {
+			ret = PTR_ERR(ddev);
+			goto err;
+		}
+
+		feature->ddev = ddev;
+	}
+
+	return 0;
+
+err:
+	dfl_devs_remove(pdata);
+	return ret;
+}
+
+int __dfl_driver_register(struct dfl_driver *dfl_drv, struct module *owner)
+{
+	if (!dfl_drv || !dfl_drv->probe || !dfl_drv->id_table)
+		return -EINVAL;
+
+	dfl_drv->drv.owner = owner;
+	dfl_drv->drv.bus = &dfl_bus_type;
+
+	return driver_register(&dfl_drv->drv);
+}
+EXPORT_SYMBOL(__dfl_driver_register);
+
+void dfl_driver_unregister(struct dfl_driver *dfl_drv)
+{
+	driver_unregister(&dfl_drv->drv);
+}
+EXPORT_SYMBOL(dfl_driver_unregister);
+
 #define is_header_feature(feature) ((feature)->id == FEATURE_ID_FIU_HEADER)
 
 /**
@@ -261,12 +494,15 @@ void dfl_fpga_dev_feature_uinit(struct platform_device *pdev)
 	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
 	struct dfl_feature *feature;
 
-	dfl_fpga_dev_for_each_feature(pdata, feature)
+	dfl_devs_remove(pdata);
+
+	dfl_fpga_dev_for_each_feature(pdata, feature) {
 		if (feature->ops) {
 			if (feature->ops->uinit)
 				feature->ops->uinit(pdev, feature);
 			feature->ops = NULL;
 		}
+	}
 }
 EXPORT_SYMBOL_GPL(dfl_fpga_dev_feature_uinit);
 
@@ -347,6 +583,10 @@ int dfl_fpga_dev_feature_init(struct platform_device *pdev,
 		drv++;
 	}
 
+	ret = dfl_devs_add(pdev);
+	if (ret)
+		goto exit;
+
 	return 0;
 exit:
 	dfl_fpga_dev_feature_uinit(pdev);
@@ -1284,11 +1524,17 @@ static int __init dfl_fpga_init(void)
 {
 	int ret;
 
+	ret = bus_register(&dfl_bus_type);
+	if (ret)
+		return ret;
+
 	dfl_ids_init();
 
 	ret = dfl_chardev_init();
-	if (ret)
+	if (ret) {
 		dfl_ids_destroy();
+		bus_unregister(&dfl_bus_type);
+	}
 
 	return ret;
 }
@@ -1626,6 +1872,7 @@ static void __exit dfl_fpga_exit(void)
 {
 	dfl_chardev_uinit();
 	dfl_ids_destroy();
+	bus_unregister(&dfl_bus_type);
 }
 
 module_init(dfl_fpga_init);
diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
index 5973769..fd93f08 100644
--- a/drivers/fpga/dfl.h
+++ b/drivers/fpga/dfl.h
@@ -236,6 +236,7 @@ struct dfl_feature_irq_ctx {
  * @irq_ctx: interrupt context list.
  * @nr_irqs: number of interrupt contexts.
  * @ops: ops of this sub feature.
+ * @ddev: ptr to the dfl device of this sub feature.
  * @priv: priv data of this feature.
  */
 struct dfl_feature {
@@ -246,6 +247,7 @@ struct dfl_feature {
 	struct dfl_feature_irq_ctx *irq_ctx;
 	unsigned int nr_irqs;
 	const struct dfl_feature_ops *ops;
+	struct dfl_device *ddev;
 	void *priv;
 };
 
@@ -514,4 +516,88 @@ long dfl_feature_ioctl_set_irq(struct platform_device *pdev,
 			       struct dfl_feature *feature,
 			       unsigned long arg);
 
+/**
+ * enum dfl_id_type - define the DFL FIU types
+ */
+enum dfl_id_type {
+	FME_ID,
+	PORT_ID,
+	DFL_ID_MAX,
+};
+
+/**
+ * struct dfl_device_id -  dfl device identifier
+ * @type: contains 4 bits DFL FIU type of the device. See enum dfl_id_type.
+ * @feature_id: contains 12 bits feature identifier local to its DFL FIU type.
+ * @driver_data: Driver specific data
+ */
+struct dfl_device_id {
+	u8 type;
+	u16 feature_id;
+	unsigned long driver_data;
+};
+
+/**
+ * struct dfl_device - represent an dfl device on dfl bus
+ *
+ * @dev: Generic device interface.
+ * @id: id of the dfl device
+ * @type: Type of DFL FIU of the device. See enum dfl_id_type.
+ * @feature_id: 16 bits feature identifier local to its DFL FIU type.
+ * @mmio_res: MMIO resource of this dfl device.
+ * @irqs: List of Linux IRQ numbers of this dfl device.
+ * @num_irqs: number of IRQs supported by this dfl device.
+ * @cdev: pointer to DFL FPGA container device this dfl device belongs to.
+ * @id_entry: matched id entry in dfl driver's id table.
+ */
+struct dfl_device {
+	struct device dev;
+	int id;
+	u8 type;
+	u16 feature_id;
+	struct resource mmio_res;
+	int *irqs;
+	unsigned int num_irqs;
+	struct dfl_fpga_cdev *cdev;
+	const struct dfl_device_id *id_entry;
+};
+
+/**
+ * struct dfl_driver - represent an dfl device driver
+ *
+ * @drv: Driver model structure.
+ * @id_table: Pointer to table of device IDs the driver is interested in.
+ *	      { } member terminated.
+ * @probe: Mandatory callback for device binding.
+ * @remove: Callback for device unbinding.
+ */
+struct dfl_driver {
+	struct device_driver drv;
+	const struct dfl_device_id *id_table;
+
+	int (*probe)(struct dfl_device *dfl_dev);
+	void (*remove)(struct dfl_device *dfl_dev);
+};
+
+#define to_dfl_dev(d) container_of(d, struct dfl_device, dev)
+#define to_dfl_drv(d) container_of(d, struct dfl_driver, drv)
+
+/*
+ * use a macro to avoid include chaining to get THIS_MODULE
+ */
+#define dfl_driver_register(drv) \
+	__dfl_driver_register(drv, THIS_MODULE)
+int __dfl_driver_register(struct dfl_driver *dfl_drv, struct module *owner);
+void dfl_driver_unregister(struct dfl_driver *dfl_drv);
+
+/*
+ * module_dfl_driver() - Helper macro for drivers that don't do
+ * anything special in module init/exit.  This eliminates a lot of
+ * boilerplate.  Each module may only use this macro once, and
+ * calling it replaces module_init() and module_exit()
+ */
+#define module_dfl_driver(__dfl_driver) \
+	module_driver(__dfl_driver, dfl_driver_register, \
+		      dfl_driver_unregister)
+
 #endif /* __FPGA_DFL_H */
-- 
2.7.4