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

From: [email-masked] (Kevin Hilman)
Date: Thu, 09 Aug 2012 07:58:44 -0700

"DebBarma, Tarun Kanti" <[email-masked]> writes:

> On Wed, Aug 8, 2012 at 10:40 PM, Kevin Hilman <[email-masked]> wrote:
>> Tarun Kanti DebBarma <[email-masked]> writes:
>>
>>> 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 <[email-masked]>
>>> Reported-by: Paul Walmsley <[email-masked]>
>>> Reviewed-by: Jon Hunter <[email-masked]>
>>> Cc: Kevin Hilman <[email-masked]>
>>> Cc: Rajendra Nayak <[email-masked]>
>>> Cc: Santosh Shilimkar <[email-masked]>
>>> Cc: Cousson, Benoit <[email-masked]>
>>> Cc: Paul Walmsley <[email-masked]>
>>> ---
>>> 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.
>>
>> What happens when GPIOs are in use (requested)?
> If I try to unbind a currently active GPIO bank then I see an exception
> after the irq descriptor is freed by the remove. I believe this is expected
> because interrupt raised by the system would not be handled.

... and the GPIO is still configured to trigger interrupts.

The point is that there is lots to cleanup/unconfigure properly for this
to work properly.

Kevin

> [   18.859405] irq_free_descs: calling free_desc(192)...
> [   18.866180] irq_free_descs: calling free_desc(192)...
> [   18.872680] irq_free_descs: calling free_desc(192)...
> [   18.877990] irq_free_descs: calling free_desc(192)...
> [   18.883270] irq_free_descs: calling free_desc(192)...
> [   18.888549] irq_free_descs: calling free_desc(192)...
> [   18.893859] irq_free_descs: calling free_desc(192)...
> [   18.899139] irq_free_descs: calling free_desc(192)...
> [   18.904418] irq_free_descs: calling free_desc(192)...
> [   18.909729] irq_free_descs: calling free_desc(192)...
> [   18.915008] irq_free_descs: calling free_desc(192)...
> [   18.920288] irq_free_descs: calling free_desc(192)...
> [   18.925598] irq_free_descs: calling free_desc(192)...
> [   18.930877] irq_free_descs: calling free_desc(192)...
> [   18.936157] irq_free_descs: calling free_desc(192)...
> [   18.941467] irq_free_descs: calling free_desc(192)...
> [   18.946746] irq_free_descs: calling free_desc(192)...
> [   18.952026] irq_free_descs: calling free_desc(192)...
> [   18.957336] irq_free_descs: calling free_desc(192)...
> [   18.962615] irq_free_descs: calling free_desc(192)...
> [   18.967895] irq_free_descs: calling free_desc(192)...
> [   18.973205] irq_free_descs: calling free_desc(192)...
> [   18.978485] irq_free_descs: calling free_desc(192)...
> [   18.983764] irq_free_descs: calling free_desc(192)...
> [   18.989074] irq_free_descs: calling free_desc(192)...
> [   18.994354] irq_free_descs: calling free_desc(192)...
> [   18.999633] irq_free_descs: calling free_desc(192)...
> [   19.004913] irq_free_descs: calling free_desc(192)...
> [   19.010223] irq_free_descs: calling free_desc(192)...
> [   19.015502] irq_free_descs: calling free_desc(192)...
> [   19.020782] irq_free_descs: calling free_desc(192)...
> [   19.026092] irq_free_descs: calling free_desc(192)...
> [   19.032440] irq 194, desc: c072f340, depth: 1, count: 0, unhandled: 0
> [   19.039154] ->handle_irq():  c00a3e08, handle_bad_irq+0x0/0x260
> [   19.045379] ->irq_data.chip(): c078ff7c, no_irq_chip+0x0/0x5c
> [   19.051391] ->action(): ef0d42c0
> [   19.054748] ->action->handler(): c0399ee0, ks8851_irq+0x0/0x1c
> [   19.060852]    IRQ_NOPROBE set
> [   19.064056]  IRQ_NOREQUEST set
> [   19.067230] Unable to handle kernel paging request at virtual address 203a6c9
> [   19.074768] pgd = c0004000
> [   19.077606] [203a6c99] *pgd=00000000
> [   19.081329] Internal error: Oops: 5 [#1] SMP ARM
> [   19.086151] Modules linked in:
> [   19.089355] CPU: 0    Not tainted  (3.6.0-rc1-00003-g43a916d-dirty #885)
> [   19.096374] PC is at gpio_irq_handler+0x7c/0x26c
> [   19.101165] LR is at handle_bad_irq+0x1cc/0x260
> [   19.105895] pc : [<c02e13b0>]    lr : [<c00a3fd4>]    psr: 60000093
> [   19.105895] sp : c0725df8  ip : 00006fc6  fp : 00000001
> [   19.117889] r10: 00000000  r9 : fa05502c  r8 : 00000020
> [   19.123352] r7 : 00000000  r6 : 00000000  r5 : 00000000  r4 : ef0bbe10
> [   19.130157] r3 : ef0c1980  r2 : 203a6c65  r1 : 00000034  r0 : 00000000
> [   19.136993] Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment kel
> [   19.144714] Control: 10c53c7d  Table: ae89804a  DAC: 00000017
> [   19.150695] Process swapper/0 (pid: 0, stack limit = 0xc07242f8)
> [   19.156982] Stack: (0xc0725df8 to 0xc0726000)
> [   19.161529] 5de0:                                                       c0740
> [   19.170074] 5e00: c0724000 c0724000 c07440d8 c07224a4 0000003e 00000000 c0740
> [   19.178619] 5e20: c0725edc c00a3670 000001da c0015380 fa24010c c0742d30 c0720
> [   19.187164] 5e40: 00000001 c000846c c0746980 c04f8c74 20000013 ffffffff c0724
> [   19.195709] 5e60: 0005ebb2 00000001 00000000 c0746980 c1530ac0 ee8cfe00 c1530
> [   19.204223] 5e80: 00000001 c07440d8 ee8cfe00 c0725edc 00000001 c0725ea8 00054
> [   19.212768] 5ea0: 20000013 ffffffff c0724000 c007425c 00000002 00000000 c0077
> [   19.221313] 5ec0: ef320b00 c0746980 00000000 c1530ac0 ef320b00 c0722ac0 c0720
> [   19.229858] 5ee0: c152ec20 c00696cc 00000000 00000000 c0724000 c0724000 c1524
> [   19.238403] 5f00: c152ec20 c0015e14 c0722ac0 c0722ac0 c0722ac0 c0722ac0 c0720
> [   19.246948] 5f20: c0722ac0 c0722ac0 6e6b0f0d 00000004 00000000 00000000 c0080
> [   19.255493] 5f40: 00000001 00000000 00000000 501539bc 00000004 c0091654 c1528
> [   19.264038] 5f60: c07d55b8 5006c071 00000000 c008cab8 00000000 00000002 50064
> [   19.272552] 5f80: c0748078 c0724000 c07c0548 c0504510 c0747e60 00000000 411f8
> [   19.281097] 5fa0: 00000000 c0015e14 00000000 c0743e1c c07c0480 c07057dc bfffa
> [   19.289642] 5fc0: 00000000 c06d48d8 ffffffff ffffffff c06d4450 00000000 0000c
> [   19.298187] 5fe0: 00000000 10c53c7d c0742d08 c07057ac c0747e54 80008044 00000
> [   19.306732] [<c02e13b0>] (gpio_irq_handler+0x7c/0x26c) from [<c00a3670>] (ge)
> [   19.316558] [<c00a3670>] (generic_handle_irq+0x34/0x44) from [<c0015380>] (h)
> [   19.325744] [<c0015380>] (handle_IRQ+0x4c/0xac) from [<c000846c>] (gic_handl)
> [   19.334564] [<c000846c>] (gic_handle_irq+0x2c/0x60) from [<c04f8ee4>] (__irq)
> [   19.343292] Exception stack(0xc0725e60 to 0xc0725ea8)
> [   19.348571] 5e60: 0005ebb2 00000001 00000000 c0746980 c1530ac0 ee8cfe00 c1530
> [   19.357116] 5e80: 00000001 c07440d8 ee8cfe00 c0725edc 00000001 c0725ea8 00054
> [   19.365631] 5ea0: 20000013 ffffffff
> [   19.369293] [<c04f8ee4>] (__irq_svc+0x44/0x5c) from [<c04f8c74>] (_raw_spin_)
> [   19.378570] [<c04f8c74>] (_raw_spin_unlock_irq+0x28/0x2c) from [<c007425c>] )
> [   19.388732] [<c007425c>] (finish_task_switch+0x84/0x198) from [<c04f7760>] ()
> [   19.398193] [<c04f7760>] (__schedule+0x404/0x870) from [<c0015e14>] (cpu_idl)
> [   19.406768] [<c0015e14>] (cpu_idle+0xe8/0x114) from [<c06d48d8>] (start_kern)
> [   19.415466] Code: e59480e4 e1d311b4 e5d36034 e1a0a81b (e7920001)
> [   19.421844] ---[ end trace 3eb9bf4b81babe15 ]---
> [   19.426666] Kernel panic - not syncing: Fatal exception in interrupt
> [   19.433288] CPU1: stopping
> [   19.436157] [<c001beac>] (unwind_backtrace+0x0/0xf4) from [<c0019db4>] (hand)
> [   19.445220] [<c0019db4>] (handle_IPI+0x130/0x15c) from [<c0008498>] (gic_han)
> [   19.454223] [<c0008498>] (gic_handle_irq+0x58/0x60) from [<c04f8ee4>] (__irq)
> [   19.462951] Exception stack(0xef06ff88 to 0xef06ffd0)
> [   19.468231] ff80:                   c079f960 c079f960 00000000 00000000 ef068
> [   19.476745] ffa0: c0504510 c0747e60 00000000 411fc092 c0748078 00000000 00000
> [   19.485290] ffc0: c0015570 c0015574 60000113 ffffffff
> [   19.490570] [<c04f8ee4>] (__irq_svc+0x44/0x5c) from [<c0015574>] (default_id)
> [   19.499114] [<c0015574>] (default_idle+0x20/0x44) from [<c0015dc8>] (cpu_idl)
> [   19.507659] [<c0015dc8>] (cpu_idle+0x9c/0x114) from [<804f1d94>] (0x804f1d94)
> ---
> Tarun
>>
>> Kevin
>>
>>>  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,
> --
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