[PATCH 2/3] irqchip: Add support to remove irqchip driver modules.

[Anirudha Sarangi]

The existing irqchip implementation does not fully support use cases
where an irqchip driver has to be used as a module. In particular there
is no support to remove an irqchip driver module.
The use cases where an irqchip driver has to be loaded and then removed
as a module are really relevant in fpga world. A user can decide to
have a irqchip as part of a removable partial fpga region. In such cases
not only the corresponding irqchip driver has to be loaded as a module,
but must also be removed when the removable partial region is removed.

The existing implementation updates the existing framework to achieve
the above said goal.

Signed-off-by: Anirudha Sarangi <anirudha.sarangi at xilinx.com>
---
 drivers/irqchip/irqchip.c | 38 +++++++++++++++++++++++++++++++++++---
 include/linux/irq.h       | 13 +++++++++++++
 include/linux/of_irq.h    |  1 +
 3 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/drivers/irqchip/irqchip.c b/drivers/irqchip/irqchip.c
index 3570f0a588c4..8687131e7268 100644
--- a/drivers/irqchip/irqchip.c
+++ b/drivers/irqchip/irqchip.c
@@ -15,6 +15,11 @@
 #include <linux/irqchip.h>
 #include <linux/platform_device.h>
 
+struct platform_irqchip_instance {
+	of_irq_init_cb_t irq_init_cb;
+	of_irq_remove_cb_t irq_remove_cb;
+};
+
 /*
  * This special of_device_id is the sentinel at the end of the
  * of_device_id[] array of all irqchips. It is automatically placed at
@@ -34,11 +39,22 @@ void __init irqchip_init(void)
 
 int platform_irqchip_probe(struct platform_device *pdev)
 {
+	struct platform_irqchip_instance *irqchip;
+	const struct irqc_init_remove_funps *irqchip_funps;
 	struct device_node *np = pdev->dev.of_node;
 	struct device_node *par_np = of_irq_find_parent(np);
-	of_irq_init_cb_t irq_init_cb = of_device_get_match_data(&pdev->dev);
 
-	if (!irq_init_cb)
+	irqchip = devm_kzalloc(&pdev->dev, sizeof(*irqchip), GFP_KERNEL);
+	if (!irqchip)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, irqchip);
+
+	irqchip_funps = of_device_get_match_data(&pdev->dev);
+	irqchip->irq_init_cb =	irqchip_funps->irqchip_initp;
+	irqchip->irq_remove_cb = irqchip_funps->irqchip_removep;
+
+	if (!irqchip->irq_init_cb)
 		return -EINVAL;
 
 	if (par_np == np)
@@ -55,6 +71,22 @@ int platform_irqchip_probe(struct platform_device *pdev)
 	if (par_np && !irq_find_matching_host(par_np, DOMAIN_BUS_ANY))
 		return -EPROBE_DEFER;
 
-	return irq_init_cb(np, par_np);
+	return irqchip->irq_init_cb(np, par_np);
 }
 EXPORT_SYMBOL_GPL(platform_irqchip_probe);
+
+int platform_irqchip_remove(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct device_node *par_np = of_irq_find_parent(np);
+	struct platform_irqchip_instance *irqchip = platform_get_drvdata(pdev);
+
+	if (!irqchip->irq_remove_cb)
+		return -EINVAL;
+
+	if (par_np == np)
+		par_np = NULL;
+
+	return irqchip->irq_remove_cb(np, par_np);
+}
+EXPORT_SYMBOL_GPL(platform_irqchip_remove);
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 252fab8074de..d46d28f56bc0 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -1098,6 +1098,19 @@ struct irq_domain_chip_generic {
 	struct irq_chip_generic	*gc[];
 };
 
+/**
+ * struct irqc_init_remove_funps - Stores function pointers for irqc init
+ * and remove APIs. Used when the irqchip driver is to be used as a module.
+ * @irqchip_initp:	Function pointer for init/entry point of a irqchip driver.
+ * @irqchip_removep:Function pointer for irqchip driver remove function.
+ */
+struct irqc_init_remove_funps {
+	int (*irqchip_initp)(struct device_node *irqc,
+			     struct device_node *parent);
+	int (*irqchip_removep)(struct device_node *irqc,
+			       struct device_node *parent);
+};
+
 /* Generic chip callback functions */
 void irq_gc_noop(struct irq_data *d);
 void irq_gc_mask_disable_reg(struct irq_data *d);
diff --git a/include/linux/of_irq.h b/include/linux/of_irq.h
index aaf219bd0354..4210ac64956f 100644
--- a/include/linux/of_irq.h
+++ b/include/linux/of_irq.h
@@ -10,6 +10,7 @@
 #include <linux/of.h>
 
 typedef int (*of_irq_init_cb_t)(struct device_node *, struct device_node *);
+typedef int (*of_irq_remove_cb_t)(struct device_node *, struct device_node *);
 
 /*
  * Workarounds only applied to 32bit powermac machines
-- 
2.17.1