[PATCH v2] gpio/omap: add *remove* callback in platform_driver

[Tarun Kanti DebBarma <tarun.kanti@ti.com>]

Add *remove* callback so that necessary cleanup operations are
performed when device is unregistered. The device is deleted
from the list and associated clock handle is released by
calling clk_put() and irq descriptor is released using the
irq_free_desc() api.

Signed-off-by: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Reported-by: Paul Walmsley <paul@pwsan.com>
Reviewed-by: Jon Hunter <jon-hunter@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Cousson, Benoit <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
---
v2:
Baseline: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
Commit: 0d7614f09c1ebdbaa1599a5aba7593f147bf96ee (Linux 3.6-rc1)

(1) Use irq_free_descs() instead of irq_free_desc().
    Besides, irq_free_desc() was using wrong parameter,
    irq_base, instead of bank->irq.
(2) irq_free_descs() moved outside spin_lock/unlock_*()
    in order to avoid exception warnings.

(3) pm_runtime_disable() added so that bind can happen successfully

Test Detail:
Step 1: Unbind gpio.5 device in order to invoke the *remove* callback.
#echo "omap_gpio.5" > sys/bus/platform/drivers/omap_gpio/unbind

Step 2: Bind gpio.5 device and confirm probe() for the device succeeds.
#echo "omap_gpio.5" > sys/bus/platform/drivers/omap_gpio/bind

Step 3: Execute read/write GPIO test case.

 drivers/gpio/gpio-omap.c |   35 +++++++++++++++++++++++++++++++++++
 1 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index e6efd77..50de875 100644
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -1152,6 +1152,40 @@ static int __devinit omap_gpio_probe(struct platform_device *pdev)
 	return ret;
 }
 
+/**
+ * omap_gpio_remove - cleanup a registered gpio device
+ * @pdev:       pointer to current gpio platform device
+ *
+ * Called by driver framework whenever a gpio device is unregistered.
+ * GPIO is deleted from the list and associated clock handle freed.
+ */
+static int __devexit omap_gpio_remove(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gpio_bank *bank;
+	unsigned long flags;
+	int ret = -EINVAL;
+
+	list_for_each_entry(bank, &omap_gpio_list, node) {
+		spin_lock_irqsave(&bank->lock, flags);
+		if (bank->dev == dev) {
+			clk_put(bank->dbck);
+			list_del(&bank->node);
+			ret = 0;
+			spin_unlock_irqrestore(&bank->lock, flags);
+			break;
+		}
+		spin_unlock_irqrestore(&bank->lock, flags);
+	}
+
+	if (!ret) {
+		pm_runtime_disable(bank->dev);
+		irq_free_descs(bank->irq_base, bank->width);
+	}
+
+	return ret;
+}
+
 #ifdef CONFIG_ARCH_OMAP2PLUS
 
 #if defined(CONFIG_PM_RUNTIME)
@@ -1478,6 +1512,7 @@ MODULE_DEVICE_TABLE(of, omap_gpio_match);
 
 static struct platform_driver omap_gpio_driver = {
 	.probe		= omap_gpio_probe,
+	.remove = __devexit_p(omap_gpio_remove),
 	.driver		= {
 		.name	= "omap_gpio",
 		.pm	= &gpio_pm_ops,
-- 
1.7.0.4