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[3/5] gpio/omap: Add DT support to GPIO driver

Message ID CAAwP0s0-VNUoeSKaGbvoDeD7m7kZRdp5rCJ7iVpFoFAaQtXcmQ@mail.gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Javier Martinez Canillas April 17, 2013, 12:41 a.m. UTC
On Wed, Apr 17, 2013 at 1:14 AM, Jon Hunter <jon-hunter@ti.com> wrote:
>
> On 04/16/2013 05:11 PM, Stephen Warren wrote:
>> On 04/16/2013 01:27 PM, Jon Hunter wrote:
>>>
>>> On 04/16/2013 01:40 PM, Stephen Warren wrote:
>>>> On 04/15/2013 05:04 PM, Jon Hunter wrote:
>> ...
>>>>> If some driver is calling gpio_request() directly, then they will most
>>>>> likely just call gpio_to_irq() when requesting the interrupt and so the
>>>>> xlate function would not be called in this case (mmc drivers are a good
>>>>> example). So I don't see that as being a problem. In fact that's the
>>>>> benefit of this approach as AFAICT it solves this problem.
>>>>
>>>> Oh. That assumption seems very fragile. What about drivers that actually
>>>> do have platform data (or DT bindings) that provide both the IRQ and
>>>> GPIO IDs, and hence don't use gpio_to_irq()? That's entirely possible.
>>>
>>> Right. In the DT case though, if someone does provide the IRQ and GPIO
>>> IDs then at least they would use a different xlate function. Another
>>> option to consider would be defining the #interrupt-cells = <3> where we
>>> would have ...
>>>
>>> cell-#1 --> IRQ domain ID
>>> cell-#2 --> Trigger type
>>> cell-#3 --> GPIO ID
>>>
>>> Then we could have a generic xlate for 3 cells that would also request
>>> the GPIO. Again not sure if people are against a gpio being requested in
>>> the xlate but just an idea. Or given that irq_of_parse_and_map() calls
>>> the xlate, we could have this function call gpio_request() if the
>>> interrupt controller is a gpio and there are 3 cells.
>>
>> I rather dislike this approach since:
>>
>> a) It requires changes to the DT bindings, which are already defined.
>> Admittedly it's backwards-compatible, but still.
>>
>> b) There isn't really any need for the DT to represent this; the
>> GPIO+IRQ driver itself already knows which IRQ ID is which GPIO ID and
>> vice-versa (if the HW has such a concept), so there's no need for the DT
>> to contain this information. This seems like pushing Linux's internal
>> requirements into the design of the DT binding.
>
> Yes, so the only alternative is to use irq_to_gpio to avoid this.
>
>> c) I have the feeling that hooking the of_xlate function for this is a
>> bit of an abuse of the function.
>
> I was wondering about that. So I was grep'ing through the various xlate
> implementations and found this [1]. Also you may recall that in the
> of_dma_simple_xlate() we call the dma_request_channel() to allocate the
> channel, which is very similar. However, I don't wish to get a
> reputation as abusing APIs so would be good to know if this really is
> abuse or not ;-)
>
> Cheers
> Jon
>
> [1] http://permalink.gmane.org/gmane.linux.ports.arm.kernel/195124

I was looking at [1] shared by Jon and come up with the following
patch that does something similar for OMAP GPIO. This has the
advantage that is local to gpio-omap instead changing gpiolib-of and
also doesn't require DT changes

But I don't want to get a reputation for abusing APIs neither :-)

Best regards,
Javier

From 23368eb72b125227fcf4b22be19ea70b4ab94556 Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Date: Wed, 17 Apr 2013 02:03:08 +0200
Subject: [PATCH 1/1] gpio/omap: add custom xlate function handler

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
---
 drivers/gpio/gpio-omap.c |   29 ++++++++++++++++++++++++++++-
 1 files changed, 28 insertions(+), 1 deletions(-)

Comments

Hunter, Jon April 17, 2013, 2 a.m. UTC | #1
On 04/16/2013 07:41 PM, Javier Martinez Canillas wrote:
> On Wed, Apr 17, 2013 at 1:14 AM, Jon Hunter <jon-hunter@ti.com> wrote:
>>
>> On 04/16/2013 05:11 PM, Stephen Warren wrote:
>>> On 04/16/2013 01:27 PM, Jon Hunter wrote:
>>>>
>>>> On 04/16/2013 01:40 PM, Stephen Warren wrote:
>>>>> On 04/15/2013 05:04 PM, Jon Hunter wrote:
>>> ...
>>>>>> If some driver is calling gpio_request() directly, then they will most
>>>>>> likely just call gpio_to_irq() when requesting the interrupt and so the
>>>>>> xlate function would not be called in this case (mmc drivers are a good
>>>>>> example). So I don't see that as being a problem. In fact that's the
>>>>>> benefit of this approach as AFAICT it solves this problem.
>>>>>
>>>>> Oh. That assumption seems very fragile. What about drivers that actually
>>>>> do have platform data (or DT bindings) that provide both the IRQ and
>>>>> GPIO IDs, and hence don't use gpio_to_irq()? That's entirely possible.
>>>>
>>>> Right. In the DT case though, if someone does provide the IRQ and GPIO
>>>> IDs then at least they would use a different xlate function. Another
>>>> option to consider would be defining the #interrupt-cells = <3> where we
>>>> would have ...
>>>>
>>>> cell-#1 --> IRQ domain ID
>>>> cell-#2 --> Trigger type
>>>> cell-#3 --> GPIO ID
>>>>
>>>> Then we could have a generic xlate for 3 cells that would also request
>>>> the GPIO. Again not sure if people are against a gpio being requested in
>>>> the xlate but just an idea. Or given that irq_of_parse_and_map() calls
>>>> the xlate, we could have this function call gpio_request() if the
>>>> interrupt controller is a gpio and there are 3 cells.
>>>
>>> I rather dislike this approach since:
>>>
>>> a) It requires changes to the DT bindings, which are already defined.
>>> Admittedly it's backwards-compatible, but still.
>>>
>>> b) There isn't really any need for the DT to represent this; the
>>> GPIO+IRQ driver itself already knows which IRQ ID is which GPIO ID and
>>> vice-versa (if the HW has such a concept), so there's no need for the DT
>>> to contain this information. This seems like pushing Linux's internal
>>> requirements into the design of the DT binding.
>>
>> Yes, so the only alternative is to use irq_to_gpio to avoid this.
>>
>>> c) I have the feeling that hooking the of_xlate function for this is a
>>> bit of an abuse of the function.
>>
>> I was wondering about that. So I was grep'ing through the various xlate
>> implementations and found this [1]. Also you may recall that in the
>> of_dma_simple_xlate() we call the dma_request_channel() to allocate the
>> channel, which is very similar. However, I don't wish to get a
>> reputation as abusing APIs so would be good to know if this really is
>> abuse or not ;-)
>>
>> Cheers
>> Jon
>>
>> [1] http://permalink.gmane.org/gmane.linux.ports.arm.kernel/195124
> 
> I was looking at [1] shared by Jon and come up with the following
> patch that does something similar for OMAP GPIO. This has the
> advantage that is local to gpio-omap instead changing gpiolib-of and
> also doesn't require DT changes
> 
> But I don't want to get a reputation for abusing APIs neither :-)
> 
> Best regards,
> Javier
> 
> From 23368eb72b125227fcf4b22be19ea70b4ab94556 Mon Sep 17 00:00:00 2001
> From: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
> Date: Wed, 17 Apr 2013 02:03:08 +0200
> Subject: [PATCH 1/1] gpio/omap: add custom xlate function handler
> 
> Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
> ---
>  drivers/gpio/gpio-omap.c |   29 ++++++++++++++++++++++++++++-
>  1 files changed, 28 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> index 8524ce5..77216f9 100644
> --- a/drivers/gpio/gpio-omap.c
> +++ b/drivers/gpio/gpio-omap.c
> @@ -1097,6 +1097,33 @@ static void omap_gpio_chip_init(struct gpio_bank *bank)
>  static const struct of_device_id omap_gpio_match[];
>  static void omap_gpio_init_context(struct gpio_bank *p);
> 
> +static int omap_gpio_irq_domain_xlate(struct irq_domain *d,
> +				      struct device_node *ctrlr,
> +				      const u32 *intspec, unsigned int intsize,
> +				      irq_hw_number_t *out_hwirq,
> +				      unsigned int *out_type)
> +{
> +	int ret;
> +	struct gpio_bank *bank = d->host_data;
> +	int gpio = bank->chip.base + intspec[0];
> +
> +	if (WARN_ON(intsize < 2))
> +		return -EINVAL;
> +
> +	ret = gpio_request_one(gpio, GPIOF_IN, ctrlr->full_name);
> +	if (ret)
> +		return ret;
> +
> +	*out_hwirq = intspec[0];
> +	*out_type = (intsize > 1) ? intspec[1] : IRQ_TYPE_NONE;
> +
> +	return 0;
> +}
> +
> +static struct irq_domain_ops omap_gpio_irq_ops = {
> +	.xlate	= omap_gpio_irq_domain_xlate,
> +};
> +
>  static int omap_gpio_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -1144,7 +1171,7 @@ static int omap_gpio_probe(struct platform_device *pdev)
> 
> 
>  	bank->domain = irq_domain_add_linear(node, bank->width,
> -					     &irq_domain_simple_ops, NULL);
> +					     &omap_gpio_irq_ops, bank);
>  	if (!bank->domain)
>  		return -ENODEV;
> 

That would work for omap, in fact I posted pretty much the same thing a
day ago [1] ;-)

I was trying to see if we could find a common solution that everyone
could use as it seems that ideally we should all be requesting the gpio.

Cheers
Jon

[1] http://marc.info/?l=linux-arm-kernel&m=136606204823845&w=1
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Javier Martinez Canillas April 17, 2013, 7:55 a.m. UTC | #2
On Wed, Apr 17, 2013 at 4:00 AM, Jon Hunter <jon-hunter@ti.com> wrote:
>
> On 04/16/2013 07:41 PM, Javier Martinez Canillas wrote:
>> On Wed, Apr 17, 2013 at 1:14 AM, Jon Hunter <jon-hunter@ti.com> wrote:
>>>
>>> On 04/16/2013 05:11 PM, Stephen Warren wrote:
>>>> On 04/16/2013 01:27 PM, Jon Hunter wrote:
>>>>>
>>>>> On 04/16/2013 01:40 PM, Stephen Warren wrote:
>>>>>> On 04/15/2013 05:04 PM, Jon Hunter wrote:
>>>> ...
>>>>>>> If some driver is calling gpio_request() directly, then they will most
>>>>>>> likely just call gpio_to_irq() when requesting the interrupt and so the
>>>>>>> xlate function would not be called in this case (mmc drivers are a good
>>>>>>> example). So I don't see that as being a problem. In fact that's the
>>>>>>> benefit of this approach as AFAICT it solves this problem.
>>>>>>
>>>>>> Oh. That assumption seems very fragile. What about drivers that actually
>>>>>> do have platform data (or DT bindings) that provide both the IRQ and
>>>>>> GPIO IDs, and hence don't use gpio_to_irq()? That's entirely possible.
>>>>>
>>>>> Right. In the DT case though, if someone does provide the IRQ and GPIO
>>>>> IDs then at least they would use a different xlate function. Another
>>>>> option to consider would be defining the #interrupt-cells = <3> where we
>>>>> would have ...
>>>>>
>>>>> cell-#1 --> IRQ domain ID
>>>>> cell-#2 --> Trigger type
>>>>> cell-#3 --> GPIO ID
>>>>>
>>>>> Then we could have a generic xlate for 3 cells that would also request
>>>>> the GPIO. Again not sure if people are against a gpio being requested in
>>>>> the xlate but just an idea. Or given that irq_of_parse_and_map() calls
>>>>> the xlate, we could have this function call gpio_request() if the
>>>>> interrupt controller is a gpio and there are 3 cells.
>>>>
>>>> I rather dislike this approach since:
>>>>
>>>> a) It requires changes to the DT bindings, which are already defined.
>>>> Admittedly it's backwards-compatible, but still.
>>>>
>>>> b) There isn't really any need for the DT to represent this; the
>>>> GPIO+IRQ driver itself already knows which IRQ ID is which GPIO ID and
>>>> vice-versa (if the HW has such a concept), so there's no need for the DT
>>>> to contain this information. This seems like pushing Linux's internal
>>>> requirements into the design of the DT binding.
>>>
>>> Yes, so the only alternative is to use irq_to_gpio to avoid this.
>>>
>>>> c) I have the feeling that hooking the of_xlate function for this is a
>>>> bit of an abuse of the function.
>>>
>>> I was wondering about that. So I was grep'ing through the various xlate
>>> implementations and found this [1]. Also you may recall that in the
>>> of_dma_simple_xlate() we call the dma_request_channel() to allocate the
>>> channel, which is very similar. However, I don't wish to get a
>>> reputation as abusing APIs so would be good to know if this really is
>>> abuse or not ;-)
>>>
>>> Cheers
>>> Jon
>>>
>>> [1] http://permalink.gmane.org/gmane.linux.ports.arm.kernel/195124
>>
>> I was looking at [1] shared by Jon and come up with the following
>> patch that does something similar for OMAP GPIO. This has the
>> advantage that is local to gpio-omap instead changing gpiolib-of and
>> also doesn't require DT changes
>>
>> But I don't want to get a reputation for abusing APIs neither :-)
>>
>> Best regards,
>> Javier
>>
>> From 23368eb72b125227fcf4b22be19ea70b4ab94556 Mon Sep 17 00:00:00 2001
>> From: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
>> Date: Wed, 17 Apr 2013 02:03:08 +0200
>> Subject: [PATCH 1/1] gpio/omap: add custom xlate function handler
>>
>> Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
>> ---
>>  drivers/gpio/gpio-omap.c |   29 ++++++++++++++++++++++++++++-
>>  1 files changed, 28 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
>> index 8524ce5..77216f9 100644
>> --- a/drivers/gpio/gpio-omap.c
>> +++ b/drivers/gpio/gpio-omap.c
>> @@ -1097,6 +1097,33 @@ static void omap_gpio_chip_init(struct gpio_bank *bank)
>>  static const struct of_device_id omap_gpio_match[];
>>  static void omap_gpio_init_context(struct gpio_bank *p);
>>
>> +static int omap_gpio_irq_domain_xlate(struct irq_domain *d,
>> +                                   struct device_node *ctrlr,
>> +                                   const u32 *intspec, unsigned int intsize,
>> +                                   irq_hw_number_t *out_hwirq,
>> +                                   unsigned int *out_type)
>> +{
>> +     int ret;
>> +     struct gpio_bank *bank = d->host_data;
>> +     int gpio = bank->chip.base + intspec[0];
>> +
>> +     if (WARN_ON(intsize < 2))
>> +             return -EINVAL;
>> +
>> +     ret = gpio_request_one(gpio, GPIOF_IN, ctrlr->full_name);
>> +     if (ret)
>> +             return ret;
>> +
>> +     *out_hwirq = intspec[0];
>> +     *out_type = (intsize > 1) ? intspec[1] : IRQ_TYPE_NONE;
>> +
>> +     return 0;
>> +}
>> +
>> +static struct irq_domain_ops omap_gpio_irq_ops = {
>> +     .xlate  = omap_gpio_irq_domain_xlate,
>> +};
>> +
>>  static int omap_gpio_probe(struct platform_device *pdev)
>>  {
>>       struct device *dev = &pdev->dev;
>> @@ -1144,7 +1171,7 @@ static int omap_gpio_probe(struct platform_device *pdev)
>>
>>
>>       bank->domain = irq_domain_add_linear(node, bank->width,
>> -                                          &irq_domain_simple_ops, NULL);
>> +                                          &omap_gpio_irq_ops, bank);
>>       if (!bank->domain)
>>               return -ENODEV;
>>
>
> That would work for omap, in fact I posted pretty much the same thing a
> day ago [1] ;-)
>

Hi Jon,

There are so many patches flying around in this thread that I missed it :-)

Sorry about that...

> I was trying to see if we could find a common solution that everyone
> could use as it seems that ideally we should all be requesting the gpio.
>
> Cheers
> Jon
>
> [1] http://marc.info/?l=linux-arm-kernel&m=136606204823845&w=1

btw, I shared the latest patch with only build testing it, but today I
gave a try and I found a problem with this approach. The .xlate
function is being called twice for each GPIO-IRQ so the first time
gpio_request_one() succeeds but the second time it fails returning
-EBUSY.

This raises a warning on drivers/of/platform.c
(WARN_ON(of_irq_to_resource_table(np, res, num_irq) != num_irq)):

    0.285308] ------------[ cut here ]------------
[    0.285369] WARNING: at drivers/of/platform.c:171
of_device_alloc+0x154/0x168()
[    0.285430] Modules linked in:
[    0.285491] [<c001a944>] (unwind_backtrace+0x0/0xf0) from
[<c0041edc>] (warn_slowpath_common+0x4c/0x68)
[    0.285552] [<c0041edc>] (warn_slowpath_common+0x4c/0x68) from
[<c0041f14>] (warn_slowpath_null+0x1c/0x24)
[    0.285614] [<c0041f14>] (warn_slowpath_null+0x1c/0x24) from
[<c041ac3c>] (of_device_alloc+0x154/0x168)
[    0.285675] [<c041ac3c>] (of_device_alloc+0x154/0x168) from
[<c041ac84>] (of_platform_device_create_pdata+0x34/0x80)
[    0.285736] [<c041ac84>]
(of_platform_device_create_pdata+0x34/0x80) from [<c0027364>]
(gpmc_probe_generic_child+0x180/0x240)
[    0.285827] [<c0027364>] (gpmc_probe_generic_child+0x180/0x240)
from [<c00278d8>] (gpmc_probe+0x4b4/0x614)
[    0.285888] [<c00278d8>] (gpmc_probe+0x4b4/0x614) from [<c0325514>]
(platform_drv_probe+0x18/0x1c)
[    0.285949] [<c0325514>] (platform_drv_probe+0x18/0x1c) from
[<c0324354>] (driver_probe_device+0x108/0x21c)
[    0.286010] [<c0324354>] (driver_probe_device+0x108/0x21c) from
[<c0322b2c>] (bus_for_each_drv+0x5c/0x88)
[    0.286071] [<c0322b2c>] (bus_for_each_drv+0x5c/0x88) from
[<c0324218>] (device_attach+0x78/0x90)
[    0.286132] [<c0324218>] (device_attach+0x78/0x90) from
[<c0323868>] (bus_probe_device+0x88/0xac)
[    0.286193] [<c0323868>] (bus_probe_device+0x88/0xac) from
[<c03220e8>] (device_add+0x4b0/0x584)
[    0.286254] [<c03220e8>] (device_add+0x4b0/0x584) from [<c041acac>]
(of_platform_device_create_pdata+0x5c/0x80)
[    0.286315] [<c041acac>]
(of_platform_device_create_pdata+0x5c/0x80) from [<c041ad9c>]
(of_platform_bus_create+0xcc/0x278)
[    0.286376] [<c041ad9c>] (of_platform_bus_create+0xcc/0x278) from
[<c041adfc>] (of_platform_bus_create+0x12c/0x278)
[    0.286468] [<c041adfc>] (of_platform_bus_create+0x12c/0x278) from
[<c041afa8>] (of_platform_populate+0x60/0x98)
[    0.286529] [<c041afa8>] (of_platform_populate+0x60/0x98) from
[<c070c5f8>] (omap_generic_init+0x24/0x60)
[    0.286590] [<c070c5f8>] (omap_generic_init+0x24/0x60) from
[<c06fe4c4>] (customize_machine+0x1c/0x28)
[    0.286651] [<c06fe4c4>] (customize_machine+0x1c/0x28) from
[<c00086a4>] (do_one_initcall+0x34/0x178)
[    0.286712] [<c00086a4>] (do_one_initcall+0x34/0x178) from
[<c06fb8f4>] (kernel_init_freeable+0xfc/0x1c8)
[    0.286804] [<c06fb8f4>] (kernel_init_freeable+0xfc/0x1c8) from
[<c04e4668>] (kernel_init+0x8/0xe4)
[    0.286865] [<c04e4668>] (kernel_init+0x8/0xe4) from [<c0013170>]
(ret_from_fork+0x14/0x24)
[    0.287139] ---[ end trace d49d2507892be205 ]---

I probably won't have time to dig further on this until later this
week but I wanted to share with you in case you know why is being
calling twice and if you thought about a solution.

It works if I don't check the return gpio_request_one() (or better if
we don't return on omap_gpio_irq_domain_xlate) but of course is not
the right solution.

Thanks a lot and best regards,
Javier
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Hunter, Jon April 17, 2013, 1:25 p.m. UTC | #3
On 04/17/2013 02:55 AM, Javier Martinez Canillas wrote:

...

> There are so many patches flying around in this thread that I missed it :-)
> 
> Sorry about that...

No problem.

>> I was trying to see if we could find a common solution that everyone
>> could use as it seems that ideally we should all be requesting the gpio.
>>
>> Cheers
>> Jon
>>
>> [1] http://marc.info/?l=linux-arm-kernel&m=136606204823845&w=1
> 
> btw, I shared the latest patch with only build testing it, but today I
> gave a try and I found a problem with this approach. The .xlate
> function is being called twice for each GPIO-IRQ so the first time
> gpio_request_one() succeeds but the second time it fails returning
> -EBUSY.

I tried it and I did not see that. I don't see the below warning either.

> This raises a warning on drivers/of/platform.c
> (WARN_ON(of_irq_to_resource_table(np, res, num_irq) != num_irq)):
> 
>     0.285308] ------------[ cut here ]------------
> [    0.285369] WARNING: at drivers/of/platform.c:171
> of_device_alloc+0x154/0x168()
> [    0.285430] Modules linked in:
> [    0.285491] [<c001a944>] (unwind_backtrace+0x0/0xf0) from
> [<c0041edc>] (warn_slowpath_common+0x4c/0x68)
> [    0.285552] [<c0041edc>] (warn_slowpath_common+0x4c/0x68) from
> [<c0041f14>] (warn_slowpath_null+0x1c/0x24)
> [    0.285614] [<c0041f14>] (warn_slowpath_null+0x1c/0x24) from
> [<c041ac3c>] (of_device_alloc+0x154/0x168)
> [    0.285675] [<c041ac3c>] (of_device_alloc+0x154/0x168) from
> [<c041ac84>] (of_platform_device_create_pdata+0x34/0x80)
> [    0.285736] [<c041ac84>]
> (of_platform_device_create_pdata+0x34/0x80) from [<c0027364>]
> (gpmc_probe_generic_child+0x180/0x240)
> [    0.285827] [<c0027364>] (gpmc_probe_generic_child+0x180/0x240)
> from [<c00278d8>] (gpmc_probe+0x4b4/0x614)
> [    0.285888] [<c00278d8>] (gpmc_probe+0x4b4/0x614) from [<c0325514>]
> (platform_drv_probe+0x18/0x1c)
> [    0.285949] [<c0325514>] (platform_drv_probe+0x18/0x1c) from
> [<c0324354>] (driver_probe_device+0x108/0x21c)

Any chance you have still have some additional code in your dts to
request the gpio? I recall you made some hacks to make this work before.

> I probably won't have time to dig further on this until later this
> week but I wanted to share with you in case you know why is being
> calling twice and if you thought about a solution.

Care to post your dts file?

> It works if I don't check the return gpio_request_one() (or better if
> we don't return on omap_gpio_irq_domain_xlate) but of course is not
> the right solution.

Yes we need to check the return value.

Cheers
Jon
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Linus Walleij April 26, 2013, 7:31 a.m. UTC | #4
On Wed, Apr 17, 2013 at 2:41 AM, Javier Martinez Canillas
<martinez.javier@gmail.com> wrote:

So:

> +static int omap_gpio_irq_domain_xlate(struct irq_domain *d,
> +                                     struct device_node *ctrlr,
> +                                     const u32 *intspec, unsigned int intsize,
> +                                     irq_hw_number_t *out_hwirq,
> +                                     unsigned int *out_type)
> +{
> +       int ret;
> +       struct gpio_bank *bank = d->host_data;
> +       int gpio = bank->chip.base + intspec[0];
> +
> +       if (WARN_ON(intsize < 2))
> +               return -EINVAL;
> +
> +       ret = gpio_request_one(gpio, GPIOF_IN, ctrlr->full_name);
> +       if (ret)
> +               return ret;

So how to figure out if a device is already requesting this GPIO
on some orthogonal axis?

if (this_gpio_was_hogged_as_input_in_gpiolib) {
   ret = gpio_request_on()...
}

Is my suggestion, then you can explicitly mark which GPIOs
shall have their IRQs implicitly translated to GPIOs and
requested.

Alas, this requires the DTS:es to have this hogging added, but
it is fully backwards-compatible.

Then the applicabl OMAP drivers (like MMC) can be fixed to
do gpio_to_irq() on  their pins instead of using the IRQ
directly.

Yours,
Linus Walleij
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Hunter, Jon April 26, 2013, 9:31 p.m. UTC | #5
On 04/26/2013 02:31 AM, Linus Walleij wrote:
> On Wed, Apr 17, 2013 at 2:41 AM, Javier Martinez Canillas
> <martinez.javier@gmail.com> wrote:
> 
> So:
> 
>> +static int omap_gpio_irq_domain_xlate(struct irq_domain *d,
>> +                                     struct device_node *ctrlr,
>> +                                     const u32 *intspec, unsigned int intsize,
>> +                                     irq_hw_number_t *out_hwirq,
>> +                                     unsigned int *out_type)
>> +{
>> +       int ret;
>> +       struct gpio_bank *bank = d->host_data;
>> +       int gpio = bank->chip.base + intspec[0];
>> +
>> +       if (WARN_ON(intsize < 2))
>> +               return -EINVAL;
>> +
>> +       ret = gpio_request_one(gpio, GPIOF_IN, ctrlr->full_name);
>> +       if (ret)
>> +               return ret;
> 
> So how to figure out if a device is already requesting this GPIO
> on some orthogonal axis?

I really don't think that is necessary. Hopefully, my other email [1]
elaborates on why. Let me know if this makes sense.

Cheers
Jon

[1] http://marc.info/?l=linux-arm-kernel&m=136701158117966&w=1
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Grant Likely June 11, 2013, 9:25 p.m. UTC | #6
On Fri, 26 Apr 2013 16:31:24 -0500, Jon Hunter <jon-hunter@ti.com> wrote:
> 
> On 04/26/2013 02:31 AM, Linus Walleij wrote:
> > On Wed, Apr 17, 2013 at 2:41 AM, Javier Martinez Canillas
> > <martinez.javier@gmail.com> wrote:
> > 
> > So:
> > 
> >> +static int omap_gpio_irq_domain_xlate(struct irq_domain *d,
> >> +                                     struct device_node *ctrlr,
> >> +                                     const u32 *intspec, unsigned int intsize,
> >> +                                     irq_hw_number_t *out_hwirq,
> >> +                                     unsigned int *out_type)
> >> +{
> >> +       int ret;
> >> +       struct gpio_bank *bank = d->host_data;
> >> +       int gpio = bank->chip.base + intspec[0];
> >> +
> >> +       if (WARN_ON(intsize < 2))
> >> +               return -EINVAL;
> >> +
> >> +       ret = gpio_request_one(gpio, GPIOF_IN, ctrlr->full_name);
> >> +       if (ret)
> >> +               return ret;
> > 
> > So how to figure out if a device is already requesting this GPIO
> > on some orthogonal axis?
> 
> I really don't think that is necessary. Hopefully, my other email [1]
> elaborates on why. Let me know if this makes sense.

I would agree here. If the irq specified happens to be a GPIO; then the
onus is on the GPIO/IRQ controller driver to make sure that GPIO is
actually set up to work as an IRQ.

g.

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Linus Walleij June 12, 2013, 9:43 a.m. UTC | #7
On Tue, Jun 11, 2013 at 11:25 PM, Grant Likely
<grant.likely@secretlab.ca> wrote:
> On Fri, 26 Apr 2013 16:31:24 -0500, Jon Hunter <jon-hunter@ti.com> wrote:
>>
>> On 04/26/2013 02:31 AM, Linus Walleij wrote:
>> > On Wed, Apr 17, 2013 at 2:41 AM, Javier Martinez Canillas
>> > <martinez.javier@gmail.com> wrote:
>> >
>> > So:
>> >
>> >> +static int omap_gpio_irq_domain_xlate(struct irq_domain *d,
>> >> +                                     struct device_node *ctrlr,
>> >> +                                     const u32 *intspec, unsigned int intsize,
>> >> +                                     irq_hw_number_t *out_hwirq,
>> >> +                                     unsigned int *out_type)
>> >> +{
>> >> +       int ret;
>> >> +       struct gpio_bank *bank = d->host_data;
>> >> +       int gpio = bank->chip.base + intspec[0];
>> >> +
>> >> +       if (WARN_ON(intsize < 2))
>> >> +               return -EINVAL;
>> >> +
>> >> +       ret = gpio_request_one(gpio, GPIOF_IN, ctrlr->full_name);
>> >> +       if (ret)
>> >> +               return ret;
>> >
>> > So how to figure out if a device is already requesting this GPIO
>> > on some orthogonal axis?
>>
>> I really don't think that is necessary. Hopefully, my other email [1]
>> elaborates on why. Let me know if this makes sense.
>
> I would agree here. If the irq specified happens to be a GPIO; then the
> onus is on the GPIO/IRQ controller driver to make sure that GPIO is
> actually set up to work as an IRQ.

Hm, re-reading this I guess the gpio_request_one() will block
others from using the pin for anything else.

Isn't that the answer to my actual question...?

It seems more like I was asking a pretty stupid question
actually.

Yours,
Linus Walleij
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diff mbox

Patch

diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index 8524ce5..77216f9 100644
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -1097,6 +1097,33 @@  static void omap_gpio_chip_init(struct gpio_bank *bank)
 static const struct of_device_id omap_gpio_match[];
 static void omap_gpio_init_context(struct gpio_bank *p);

+static int omap_gpio_irq_domain_xlate(struct irq_domain *d,
+				      struct device_node *ctrlr,
+				      const u32 *intspec, unsigned int intsize,
+				      irq_hw_number_t *out_hwirq,
+				      unsigned int *out_type)
+{
+	int ret;
+	struct gpio_bank *bank = d->host_data;
+	int gpio = bank->chip.base + intspec[0];
+
+	if (WARN_ON(intsize < 2))
+		return -EINVAL;
+
+	ret = gpio_request_one(gpio, GPIOF_IN, ctrlr->full_name);
+	if (ret)
+		return ret;
+
+	*out_hwirq = intspec[0];
+	*out_type = (intsize > 1) ? intspec[1] : IRQ_TYPE_NONE;
+
+	return 0;
+}
+
+static struct irq_domain_ops omap_gpio_irq_ops = {
+	.xlate	= omap_gpio_irq_domain_xlate,
+};
+
 static int omap_gpio_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -1144,7 +1171,7 @@  static int omap_gpio_probe(struct platform_device *pdev)


 	bank->domain = irq_domain_add_linear(node, bank->width,
-					     &irq_domain_simple_ops, NULL);
+					     &omap_gpio_irq_ops, bank);
 	if (!bank->domain)
 		return -ENODEV;