[PATCH] uio: add ioctl callback

[PATCH] uio: add ioctl callback

[Neil Armstrong]

[-- Attachment #1: Type: text/plain, Size: 1573 bytes --]

Add an ioctl callback for uio devices.

Signed-off-by: Neil Armstrong <narmstrong@neotion.com>
---

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 2d2440c..38044fb 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -385,6 +385,18 @@ static unsigned int uio_poll(struct file *filep,
poll_table *wait)
     return 0;
 }
 
+static int uio_ioctl(struct inode *inode, struct file *filep,
+            unsigned int cmd, unsigned long arg)
+{
+    struct uio_listener *listener = filep->private_data;
+    struct uio_device *idev = listener->dev;
+
+    if (idev->info->ioctl)
+        return idev->info->ioctl(idev->info, cmd, arg);
+
+    return -ENOSYS;
+}
+
 static ssize_t uio_read(struct file *filep, char __user *buf,
             size_t count, loff_t *ppos)
 {
@@ -590,6 +602,7 @@ static const struct file_operations uio_fops = {
     .mmap        = uio_mmap,
     .poll        = uio_poll,
     .fasync        = uio_fasync,
+    .ioctl        = uio_ioctl,
 };
 
 static int uio_major_init(void)
diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index cdf338d..e44e89b 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -68,6 +68,8 @@ struct uio_info {
     int (*open)(struct uio_info *info, struct inode *inode);
     int (*release)(struct uio_info *info, struct inode *inode);
     int (*irqcontrol)(struct uio_info *info, s32 irq_on);
+    int (*ioctl)(struct uio_info *info, unsigned int cmd,
+            unsigned long arg);
 };
 
 extern int __must_check

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title:Embedded Linux Software Engineer
tel;cell:0667474169
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end:vcard

Re: [PATCH] uio: add ioctl callback

[Hans J. Koch]

On Wed, Nov 12, 2008 at 04:40:01PM +0100, Neil Armstrong wrote:
> Add an ioctl callback for uio devices.

Hi Neil,
sorry, but we don't want to have ioctl() for UIO. UIO devices should be
completely controllable through their mapped memory. Additional
functions can be added by creating custom sysfs files. To switch the
interrupt on and off, we have the irqcontrol hook in the write()
function. I cannot imagine a case where ioctl() could be useful.

You didn't mention why you want ioctl(). If you tell us the problem, we
can probably find a solution that uses the standard UIO interface.

Thanks,
Hans

> 
> Signed-off-by: Neil Armstrong <narmstrong@neotion.com>
> ---
> 
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index 2d2440c..38044fb 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -385,6 +385,18 @@ static unsigned int uio_poll(struct file *filep,
> poll_table *wait)
>      return 0;
>  }
>  
> +static int uio_ioctl(struct inode *inode, struct file *filep,
> +            unsigned int cmd, unsigned long arg)
> +{
> +    struct uio_listener *listener = filep->private_data;
> +    struct uio_device *idev = listener->dev;
> +
> +    if (idev->info->ioctl)
> +        return idev->info->ioctl(idev->info, cmd, arg);
> +
> +    return -ENOSYS;
> +}
> +
>  static ssize_t uio_read(struct file *filep, char __user *buf,
>              size_t count, loff_t *ppos)
>  {
> @@ -590,6 +602,7 @@ static const struct file_operations uio_fops = {
>      .mmap        = uio_mmap,
>      .poll        = uio_poll,
>      .fasync        = uio_fasync,
> +    .ioctl        = uio_ioctl,
>  };
>  
>  static int uio_major_init(void)
> diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
> index cdf338d..e44e89b 100644
> --- a/include/linux/uio_driver.h
> +++ b/include/linux/uio_driver.h
> @@ -68,6 +68,8 @@ struct uio_info {
>      int (*open)(struct uio_info *info, struct inode *inode);
>      int (*release)(struct uio_info *info, struct inode *inode);
>      int (*irqcontrol)(struct uio_info *info, s32 irq_on);
> +    int (*ioctl)(struct uio_info *info, unsigned int cmd,
> +            unsigned long arg);
>  };
>  
>  extern int __must_check

> begin:vcard
> fn:Neil Armstrong
> n:Armstrong;Neil
> org:Neotion;Neotion Sophia Antipolis
> adr:;;;Sophia Antipolis;;;France
> email;internet:narmstrong@neotion.com
> title:Embedded Linux Software Engineer
> tel;cell:0667474169
> note:PGP 0x1166F485
> x-mozilla-html:FALSE
> url:http://www.neotion.com
> version:2.1
> end:vcard
> 

Re: [PATCH] uio: add ioctl callback

[Neil Armstrong]

[-- Attachment #1.1: Type: text/plain, Size: 3165 bytes --]

Hi Hans,

We need an ioctl callback because we need to query some values only
available when the irq handler is running.
For example, we have 3 types of reasons why the irq is triggered and
these bits are no more available when the irq is cleared.

The cleanest way to have this very specific information is to have a
dirty old ioctl returning this data.

Thanks for your time.

Neil

Hans J. Koch a écrit :
> On Wed, Nov 12, 2008 at 04:40:01PM +0100, Neil Armstrong wrote:
>   
>> Add an ioctl callback for uio devices.
>>     
>
> Hi Neil,
> sorry, but we don't want to have ioctl() for UIO. UIO devices should be
> completely controllable through their mapped memory. Additional
> functions can be added by creating custom sysfs files. To switch the
> interrupt on and off, we have the irqcontrol hook in the write()
> function. I cannot imagine a case where ioctl() could be useful.
>
> You didn't mention why you want ioctl(). If you tell us the problem, we
> can probably find a solution that uses the standard UIO interface.
>
> Thanks,
> Hans
>
>   
>> Signed-off-by: Neil Armstrong <narmstrong@neotion.com>
>> ---
>>
>> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
>> index 2d2440c..38044fb 100644
>> --- a/drivers/uio/uio.c
>> +++ b/drivers/uio/uio.c
>> @@ -385,6 +385,18 @@ static unsigned int uio_poll(struct file *filep,
>> poll_table *wait)
>>      return 0;
>>  }
>>  
>> +static int uio_ioctl(struct inode *inode, struct file *filep,
>> +            unsigned int cmd, unsigned long arg)
>> +{
>> +    struct uio_listener *listener = filep->private_data;
>> +    struct uio_device *idev = listener->dev;
>> +
>> +    if (idev->info->ioctl)
>> +        return idev->info->ioctl(idev->info, cmd, arg);
>> +
>> +    return -ENOSYS;
>> +}
>> +
>>  static ssize_t uio_read(struct file *filep, char __user *buf,
>>              size_t count, loff_t *ppos)
>>  {
>> @@ -590,6 +602,7 @@ static const struct file_operations uio_fops = {
>>      .mmap        = uio_mmap,
>>      .poll        = uio_poll,
>>      .fasync        = uio_fasync,
>> +    .ioctl        = uio_ioctl,
>>  };
>>  
>>  static int uio_major_init(void)
>> diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
>> index cdf338d..e44e89b 100644
>> --- a/include/linux/uio_driver.h
>> +++ b/include/linux/uio_driver.h
>> @@ -68,6 +68,8 @@ struct uio_info {
>>      int (*open)(struct uio_info *info, struct inode *inode);
>>      int (*release)(struct uio_info *info, struct inode *inode);
>>      int (*irqcontrol)(struct uio_info *info, s32 irq_on);
>> +    int (*ioctl)(struct uio_info *info, unsigned int cmd,
>> +            unsigned long arg);
>>  };
>>  
>>  extern int __must_check
>>     
>
>   
>> begin:vcard
>> fn:Neil Armstrong
>> n:Armstrong;Neil
>> org:Neotion;Neotion Sophia Antipolis
>> adr:;;;Sophia Antipolis;;;France
>> email;internet:narmstrong@neotion.com
>> title:Embedded Linux Software Engineer
>> tel;cell:0667474169
>> note:PGP 0x1166F485
>> x-mozilla-html:FALSE
>> url:http://www.neotion.com
>> version:2.1
>> end:vcard
>>
>>     
>
>
>   

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fn:Neil Armstrong
n:Armstrong;Neil
org:Neotion;Neotion Sophia Antipolis
adr:;;;Sophia Antipolis;;;France
email;internet:narmstrong@neotion.com
title:Embedded Linux Software Engineer
tel;cell:0667474169
note:PGP 0x1166F485
x-mozilla-html:FALSE
url:http://www.neotion.com
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Re: [PATCH] uio: add ioctl callback

[Greg KH]

On Wed, Nov 12, 2008 at 04:59:56PM +0100, Neil Armstrong wrote:
> Hi Hans,
> 
> We need an ioctl callback because we need to query some values only
> available when the irq handler is running.
> For example, we have 3 types of reasons why the irq is triggered and
> these bits are no more available when the irq is cleared.
> 
> The cleanest way to have this very specific information is to have a
> dirty old ioctl returning this data.

Do you also have a patch for your UIO driver that implements this
functionality?

I really don't think we want to add an ioctl callback, perhaps you could
just use a sysfs file for this?

thanks,

greg k-h

Re: [PATCH] uio: add ioctl callback

[Hans J. Koch]

On Wed, Nov 12, 2008 at 04:59:56PM +0100, Neil Armstrong wrote:
> Hi Hans,
> 
> We need an ioctl callback because we need to query some values only
> available when the irq handler is running.
> For example, we have 3 types of reasons why the irq is triggered and
> these bits are no more available when the irq is cleared.

Ah, that one. That's why we invented the irqcontrol hook. In case of
such broken hardware, you need to mask the irq in the kernel without
touching the register containing those volatile bits. On a system where
you can be sure the irq is not shared, you can simply use disable_irq().

If the irq might be shared, you need to find something else. PCI cards,
for example, often have a register within their PCI bridge that contains
irq mask bits (that's how it is done in uio_cif.c).

Userspace can then reenable the irq by writing the value 1 as a signed
32-bit int to /dev/uioX. You need to implement an irqcontrol() function
in your kernel driver that does the right thing (e.g. call enable_irq()
in the first example).

> 
> The cleanest way to have this very specific information is to have a
> dirty old ioctl returning this data.

The cleanest way would be to throw such hardware into the trash bin :-)

A chip where the irq mask register cannot be written without destroying
the irq status register is simply broken and bad design.

Thanks,
Hans

Re: [PATCH] uio: add ioctl callback

[Neil Armstrong]

[-- Attachment #1: Type: text/plain, Size: 2062 bytes --]

Hi,

I should have specified that I work on a SoC, which does not follow
strict rules like PCI devices.
From a hardware designer point of view, this is a "good" design
especially for this kind of device. (DVB Conditionnal Access Slave
Shared Memory)
If the code was in the kernel space, we could do some processing in irq
mode like other devices of the SoC.

Thanks for your time and comments, I will see the irqcontrol solution as
an alternative.

Just forget my patch since it's only applicable to very specific devices.

Neil

Hans J. Koch a écrit :
> On Wed, Nov 12, 2008 at 04:59:56PM +0100, Neil Armstrong wrote:
>   
>> Hi Hans,
>>
>> We need an ioctl callback because we need to query some values only
>> available when the irq handler is running.
>> For example, we have 3 types of reasons why the irq is triggered and
>> these bits are no more available when the irq is cleared.
>>     
>
> Ah, that one. That's why we invented the irqcontrol hook. In case of
> such broken hardware, you need to mask the irq in the kernel without
> touching the register containing those volatile bits. On a system where
> you can be sure the irq is not shared, you can simply use disable_irq().
>
> If the irq might be shared, you need to find something else. PCI cards,
> for example, often have a register within their PCI bridge that contains
> irq mask bits (that's how it is done in uio_cif.c).
>
> Userspace can then reenable the irq by writing the value 1 as a signed
> 32-bit int to /dev/uioX. You need to implement an irqcontrol() function
> in your kernel driver that does the right thing (e.g. call enable_irq()
> in the first example).
>
>   
>> The cleanest way to have this very specific information is to have a
>> dirty old ioctl returning this data.
>>     
>
> The cleanest way would be to throw such hardware into the trash bin :-)
>
> A chip where the irq mask register cannot be written without destroying
> the irq status register is simply broken and bad design.
>
> Thanks,
> Hans
>   


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