Re: [PATCH] Input: q40kbd - convert driver to the split model

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On Wed, Jan 11, 2012 at 09:30:51AM -0800, Dmitry Torokhov wrote:
On Wed, Jan 11, 2012 at 10:25:20AM +0100, Geert Uytterhoeven wrote:
On Wed, Jan 11, 2012 at 09:11, Dmitry Torokhov
<dmitry.torokhov@xxxxxxxxx> wrote:
On Wed, Jan 11, 2012 at 08:55:54AM +0100, Geert Uytterhoeven wrote:
On Sat, Dec 31, 2011 at 02:11, Dmitry Torokhov
<dmitry.torokhov@xxxxxxxxx> wrote:

+static struct platform_device q40_kbd_pdev = {
+       .name   = "q40kbd",
+       .id     = -1,
+};
+
+static __init int q40_add_kbd_device(void)
+{
+       return platform_device_register(&q40_kbd_pdev);

If you would use platform_device_register_simple(), you don't need the
q40_kbd_pdev above, reducing memory consumption on non-Q40 platforms.

Isn't this file only compiled on q40 platforms?

No, m68k does support multi-platform kernels.

OK, I'll do dynamic platform device allocation.


+}
+arch_initcall(q40_add_kbd_device);

For the Amiga platform drivers, I used device_initcall().

Won't it potentially race with initialization of q40kbd? It looks like
module_initcall is the same as device_initcall() when module is compiled
in. Given that q40kbd uses platform_dveice_probe() losing race might be
fatal.

So far I haven't encountered any problems on Amiga.
I'll look into this.

I guess link order (arch before drivers) saves you here but it is not
very clean.


-static int __devexit q40kbd_remove(struct platform_device *dev)
+static int __devexit q40kbd_remove(struct platform_device *pdev)
 {
-       serio_unregister_port(q40kbd_port);
+       struct q40kbd *q40kbd = platform_get_drvdata(pdev);
+
+       free_irq(Q40_IRQ_KEYBOARD, q40kbd);
+
+       serio_unregister_port(q40kbd->port);

Should the unregister be done before freeing the IRQ, i.e. reverse
order compared to probe?

Unregister will most likely cause memory being freed; you don't want to
chance IRQ firing here.

And in the probe case that can't happen when request_irq() is called?

We explicitly do q40kbd_stop() before requesting IRQ. Frankly serio
will be stopped by the serio core (via serio->stop() which is
q40kbd_stop()) so freeing IRQ fisrt should be fine, it just was looking
scary. I'll revert the order and add a comment.


OK, so here it is.

-- 
Dmitry


Input: q40kbd - convert driver to the split model

From: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>

Convert the driver to standard spilt model arch-specific code registers
platform device to which driver code can bind later.

Also request IRQ immediately upon binding to the device instead of doing
this when serio port is being opened.

Signed-off-by: Dmitry Torokhov <dtor@xxxxxxx>
---

 arch/m68k/q40/config.c       |    7 ++
 drivers/input/serio/q40kbd.c |  139 ++++++++++++++++++++++++------------------
 2 files changed, 86 insertions(+), 60 deletions(-)


diff --git a/arch/m68k/q40/config.c b/arch/m68k/q40/config.c
index ad10fec..c72a3ed 100644
--- a/arch/m68k/q40/config.c
+++ b/arch/m68k/q40/config.c
@@ -24,6 +24,7 @@
 #include <linux/rtc.h>
 #include <linux/vt_kern.h>
 #include <linux/bcd.h>
+#include <linux/platform_device.h>
 
 #include <asm/io.h>
 #include <asm/rtc.h>
@@ -329,3 +330,9 @@ static int q40_set_rtc_pll(struct rtc_pll_info *pll)
 	} else
 		return -EINVAL;
 }
+
+static __init int q40_add_kbd_device(void)
+{
+	return platform_device_register_simple("q40kbd", -1, NULL, 0);
+}
+arch_initcall(q40_add_kbd_device);
diff --git a/drivers/input/serio/q40kbd.c b/drivers/input/serio/q40kbd.c
index 5eb84b3..0c0df7f 100644
--- a/drivers/input/serio/q40kbd.c
+++ b/drivers/input/serio/q40kbd.c
@@ -44,26 +44,31 @@
 #include <asm/irq.h>
 #include <asm/q40ints.h>
 
+#define DRV_NAME	"q40kbd"
+
 MODULE_AUTHOR("Vojtech Pavlik <vojtech@xxxxxx>");
 MODULE_DESCRIPTION("Q40 PS/2 keyboard controller driver");
 MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);
 
-static DEFINE_SPINLOCK(q40kbd_lock);
-static struct serio *q40kbd_port;
-static struct platform_device *q40kbd_device;
+struct q40kbd {
+	struct serio *port;
+	spinlock_t lock;
+};
 
 static irqreturn_t q40kbd_interrupt(int irq, void *dev_id)
 {
+	struct q40kbd *q40kbd = dev_id;
 	unsigned long flags;
 
-	spin_lock_irqsave(&q40kbd_lock, flags);
+	spin_lock_irqsave(&q40kbd->lock, flags);
 
 	if (Q40_IRQ_KEYB_MASK & master_inb(INTERRUPT_REG))
-		serio_interrupt(q40kbd_port, master_inb(KEYCODE_REG), 0);
+		serio_interrupt(q40kbd->port, master_inb(KEYCODE_REG), 0);
 
 	master_outb(-1, KEYBOARD_UNLOCK_REG);
 
-	spin_unlock_irqrestore(&q40kbd_lock, flags);
+	spin_unlock_irqrestore(&q40kbd->lock, flags);
 
 	return IRQ_HANDLED;
 }
@@ -72,17 +77,23 @@ static irqreturn_t q40kbd_interrupt(int irq, void *dev_id)
  * q40kbd_flush() flushes all data that may be in the keyboard buffers
  */
 
-static void q40kbd_flush(void)
+static void q40kbd_flush(struct q40kbd *q40kbd)
 {
 	int maxread = 100;
 	unsigned long flags;
 
-	spin_lock_irqsave(&q40kbd_lock, flags);
+	spin_lock_irqsave(&q40kbd->lock, flags);
 
 	while (maxread-- && (Q40_IRQ_KEYB_MASK & master_inb(INTERRUPT_REG)))
 		master_inb(KEYCODE_REG);
 
-	spin_unlock_irqrestore(&q40kbd_lock, flags);
+	spin_unlock_irqrestore(&q40kbd->lock, flags);
+}
+
+static void q40kbd_stop(void)
+{
+	master_outb(0, KEY_IRQ_ENABLE_REG);
+	master_outb(-1, KEYBOARD_UNLOCK_REG);
 }
 
 /*
@@ -92,12 +103,9 @@ static void q40kbd_flush(void)
 
 static int q40kbd_open(struct serio *port)
 {
-	q40kbd_flush();
+	struct q40kbd *q40kbd = port->port_data;
 
-	if (request_irq(Q40_IRQ_KEYBOARD, q40kbd_interrupt, 0, "q40kbd", NULL)) {
-		printk(KERN_ERR "q40kbd.c: Can't get irq %d.\n", Q40_IRQ_KEYBOARD);
-		return -EBUSY;
-	}
+	q40kbd_flush(q40kbd);
 
 	/* off we go */
 	master_outb(-1, KEYBOARD_UNLOCK_REG);
@@ -108,36 +116,72 @@ static int q40kbd_open(struct serio *port)
 
 static void q40kbd_close(struct serio *port)
 {
-	master_outb(0, KEY_IRQ_ENABLE_REG);
-	master_outb(-1, KEYBOARD_UNLOCK_REG);
-	free_irq(Q40_IRQ_KEYBOARD, NULL);
+	struct q40kbd *q40kbd = port->port_data;
 
-	q40kbd_flush();
+	q40kbd_stop();
+	q40kbd_flush(q40kbd);
 }
 
-static int __devinit q40kbd_probe(struct platform_device *dev)
+static int __devinit q40kbd_probe(struct platform_device *pdev)
 {
-	q40kbd_port = kzalloc(sizeof(struct serio), GFP_KERNEL);
-	if (!q40kbd_port)
-		return -ENOMEM;
-
-	q40kbd_port->id.type	= SERIO_8042;
-	q40kbd_port->open	= q40kbd_open;
-	q40kbd_port->close	= q40kbd_close;
-	q40kbd_port->dev.parent	= &dev->dev;
-	strlcpy(q40kbd_port->name, "Q40 Kbd Port", sizeof(q40kbd_port->name));
-	strlcpy(q40kbd_port->phys, "Q40", sizeof(q40kbd_port->phys));
-
-	serio_register_port(q40kbd_port);
+	struct q40kbd *q40kbd;
+	struct serio *port;
+	int error;
+
+	q40kbd = kzalloc(sizeof(struct q40kbd), GFP_KERNEL);
+	port = kzalloc(sizeof(struct serio), GFP_KERNEL);
+	if (!q40kbd || !port) {
+		error = -ENOMEM;
+		goto err_free_mem;
+	}
+
+	q40kbd->port = port;
+	spin_lock_init(&q40kbd->lock);
+
+	port->id.type = SERIO_8042;
+	port->open = q40kbd_open;
+	port->close = q40kbd_close;
+	port->port_data = q40kbd;
+	port->dev.parent = &pdev->dev;
+	strlcpy(port->name, "Q40 Kbd Port", sizeof(port->name));
+	strlcpy(port->phys, "Q40", sizeof(port->phys));
+
+	q40kbd_stop();
+
+	error = request_irq(Q40_IRQ_KEYBOARD, q40kbd_interrupt, 0,
+			    DRV_NAME, q40kbd);
+	if (error) {
+		dev_err(&pdev->dev, "Can't get irq %d.\n", Q40_IRQ_KEYBOARD);
+		goto err_free_mem;
+	}
+
+	serio_register_port(q40kbd->port);
+
+	platform_set_drvdata(pdev, q40kbd);
 	printk(KERN_INFO "serio: Q40 kbd registered\n");
 
 	return 0;
+
+err_free_mem:
+	kfree(port);
+	kfree(q40kbd);
+	return error;
 }
 
-static int __devexit q40kbd_remove(struct platform_device *dev)
+static int __devexit q40kbd_remove(struct platform_device *pdev)
 {
-	serio_unregister_port(q40kbd_port);
-
+	struct q40kbd *q40kbd = platform_get_drvdata(pdev);
+
+	/*
+	 * q40kbd_close() will be called as part of unregistering
+	 * and will ensure that IRQ is turned off, so it is safe
+	 * to unregister port first and free IRQ later.
+	 */
+	serio_unregister_port(q40kbd->port);
+	free_irq(Q40_IRQ_KEYBOARD, q40kbd);
+	kfree(q40kbd);
+
+	platform_set_drvdata(pdev, NULL);
 	return 0;
 }
 
@@ -146,41 +190,16 @@ static struct platform_driver q40kbd_driver = {
 		.name	= "q40kbd",
 		.owner	= THIS_MODULE,
 	},
-	.probe		= q40kbd_probe,
 	.remove		= __devexit_p(q40kbd_remove),
 };
 
 static int __init q40kbd_init(void)
 {
-	int error;
-
-	if (!MACH_IS_Q40)
-		return -ENODEV;
-
-	error = platform_driver_register(&q40kbd_driver);
-	if (error)
-		return error;
-
-	q40kbd_device = platform_device_alloc("q40kbd", -1);
-	if (!q40kbd_device)
-		goto err_unregister_driver;
-
-	error = platform_device_add(q40kbd_device);
-	if (error)
-		goto err_free_device;
-
-	return 0;
-
- err_free_device:
-	platform_device_put(q40kbd_device);
- err_unregister_driver:
-	platform_driver_unregister(&q40kbd_driver);
-	return error;
+	return platform_driver_probe(&q40kbd_driver, q40kbd_probe);
 }
 
 static void __exit q40kbd_exit(void)
 {
-	platform_device_unregister(q40kbd_device);
 	platform_driver_unregister(&q40kbd_driver);
 }
 
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