[v2] platform/x86: serial-multi-instantiate: Don't require both I2C and SPI

[PATCH v2] platform/x86: serial-multi-instantiate: Don't require both I2C and SPI

Posted by Richard Fitzgerald 1 year, 5 months ago

Change the Kconfig dependency so that it doesn't require both I2C and SPI
subsystems to be built. Make a few small changes to the code so that the
code for a bus is only called if the bus is being built.

When SPI support was added to serial-multi-instantiate it created a
dependency that both CONFIG_I2C and CONFIG_SPI must be enabled.
Typically they are, but there's no reason why this should be a
requirement. A specific kernel build could have only I2C devices
or only SPI devices. It should be possible to use serial-multi-instantiate
if only I2C or only SPI is enabled.

The dependency formula used is:

  depends on (I2C && !SPI) || (!I2C && SPI) || (I2C && SPI)

The advantage of this approach is that if I2C=m or SPI=m then
SERIAL_MULTI_INSTANTIATE is limited to n/m.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
---
Changes from V1:
Use a different 'depends on' formula so that serial-multi-instantiate
must be built as a module if any dependencies are a module.

 drivers/platform/x86/Kconfig                  |  3 +-
 .../platform/x86/serial-multi-instantiate.c   | 32 ++++++++++++++-----
 2 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 665fa9524986..0dcf4d8eac56 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -999,7 +999,8 @@ config TOPSTAR_LAPTOP
 
 config SERIAL_MULTI_INSTANTIATE
 	tristate "Serial bus multi instantiate pseudo device driver"
-	depends on I2C && SPI && ACPI
+	depends on ACPI
+	depends on (I2C && !SPI) || (!I2C && SPI) || (I2C && SPI)
 	help
 	  Some ACPI-based systems list multiple devices in a single ACPI
 	  firmware-node. This driver will instantiate separate clients
diff --git a/drivers/platform/x86/serial-multi-instantiate.c b/drivers/platform/x86/serial-multi-instantiate.c
index 3be016cfe601..7c04cc9e5891 100644
--- a/drivers/platform/x86/serial-multi-instantiate.c
+++ b/drivers/platform/x86/serial-multi-instantiate.c
@@ -83,11 +83,15 @@ static int smi_get_irq(struct platform_device *pdev, struct acpi_device *adev,
 
 static void smi_devs_unregister(struct smi *smi)
 {
+#if IS_REACHABLE(CONFIG_I2C)
 	while (smi->i2c_num--)
 		i2c_unregister_device(smi->i2c_devs[smi->i2c_num]);
+#endif
 
-	while (smi->spi_num--)
-		spi_unregister_device(smi->spi_devs[smi->spi_num]);
+	if (IS_REACHABLE(CONFIG_SPI)) {
+		while (smi->spi_num--)
+			spi_unregister_device(smi->spi_devs[smi->spi_num]);
+	}
 }
 
 /**
@@ -258,9 +262,15 @@ static int smi_probe(struct platform_device *pdev)
 
 	switch (node->bus_type) {
 	case SMI_I2C:
-		return smi_i2c_probe(pdev, smi, node->instances);
+		if (IS_REACHABLE(CONFIG_I2C))
+			return smi_i2c_probe(pdev, smi, node->instances);
+
+		return -ENODEV;
 	case SMI_SPI:
-		return smi_spi_probe(pdev, smi, node->instances);
+		if (IS_REACHABLE(CONFIG_SPI))
+			return smi_spi_probe(pdev, smi, node->instances);
+
+		return -ENODEV;
 	case SMI_AUTO_DETECT:
 		/*
 		 * For backwards-compatibility with the existing nodes I2C
@@ -270,10 +280,16 @@ static int smi_probe(struct platform_device *pdev)
 		 * SpiSerialBus nodes that were previously ignored, and this
 		 * preserves that behavior.
 		 */
-		ret = smi_i2c_probe(pdev, smi, node->instances);
-		if (ret != -ENOENT)
-			return ret;
-		return smi_spi_probe(pdev, smi, node->instances);
+		if (IS_REACHABLE(CONFIG_I2C)) {
+			ret = smi_i2c_probe(pdev, smi, node->instances);
+			if (ret != -ENOENT)
+				return ret;
+		}
+
+		if (IS_REACHABLE(CONFIG_SPI))
+			return smi_spi_probe(pdev, smi, node->instances);
+
+		return -ENODEV;
 	default:
 		return -EINVAL;
 	}
-- 
2.39.2

Re: [PATCH v2] platform/x86: serial-multi-instantiate: Don't require both I2C and SPI

Posted by Andy Shevchenko 1 year, 5 months ago

Wed, Aug 14, 2024 at 02:29:39PM +0100, Richard Fitzgerald kirjoitti:
> Change the Kconfig dependency so that it doesn't require both I2C and SPI
> subsystems to be built. Make a few small changes to the code so that the
> code for a bus is only called if the bus is being built.
> 
> When SPI support was added to serial-multi-instantiate it created a
> dependency that both CONFIG_I2C and CONFIG_SPI must be enabled.
> Typically they are, but there's no reason why this should be a
> requirement. A specific kernel build could have only I2C devices
> or only SPI devices. It should be possible to use serial-multi-instantiate
> if only I2C or only SPI is enabled.
> 
> The dependency formula used is:
> 
>   depends on (I2C && !SPI) || (!I2C && SPI) || (I2C && SPI)
> 
> The advantage of this approach is that if I2C=m or SPI=m then
> SERIAL_MULTI_INSTANTIATE is limited to n/m.

...

>  static void smi_devs_unregister(struct smi *smi)
>  {
> +#if IS_REACHABLE(CONFIG_I2C)

There is no explanation why ugly ifdeffery is used here, while normal
conditionals elsewhere.

>  	while (smi->i2c_num--)
>  		i2c_unregister_device(smi->i2c_devs[smi->i2c_num]);
> +#endif
>  
> -	while (smi->spi_num--)
> -		spi_unregister_device(smi->spi_devs[smi->spi_num]);
> +	if (IS_REACHABLE(CONFIG_SPI)) {
> +		while (smi->spi_num--)
> +			spi_unregister_device(smi->spi_devs[smi->spi_num]);
> +	}
>  }

There are ways to solve this:
1) add a stub for I2C=n for i2c_unregister_device();
2) resplit this driver to have several built modules:
   core, I2C parts, SPI parts.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2] platform/x86: serial-multi-instantiate: Don't require both I2C and SPI

Posted by Hans de Goede 1 year, 5 months ago

Hi Andy,

On 8/26/24 10:10 PM, Andy Shevchenko wrote:
> Wed, Aug 14, 2024 at 02:29:39PM +0100, Richard Fitzgerald kirjoitti:
>> Change the Kconfig dependency so that it doesn't require both I2C and SPI
>> subsystems to be built. Make a few small changes to the code so that the
>> code for a bus is only called if the bus is being built.
>>
>> When SPI support was added to serial-multi-instantiate it created a
>> dependency that both CONFIG_I2C and CONFIG_SPI must be enabled.
>> Typically they are, but there's no reason why this should be a
>> requirement. A specific kernel build could have only I2C devices
>> or only SPI devices. It should be possible to use serial-multi-instantiate
>> if only I2C or only SPI is enabled.
>>
>> The dependency formula used is:
>>
>>   depends on (I2C && !SPI) || (!I2C && SPI) || (I2C && SPI)
>>
>> The advantage of this approach is that if I2C=m or SPI=m then
>> SERIAL_MULTI_INSTANTIATE is limited to n/m.
> 
> ...
> 
>>  static void smi_devs_unregister(struct smi *smi)
>>  {
>> +#if IS_REACHABLE(CONFIG_I2C)
> 
> There is no explanation why ugly ifdeffery is used here, while normal
> conditionals elsewhere.

Note that this has already been merged as is, as you've figured
out yourself the reason to use #ifdef here is because
there is no i2c_unregister_device() prototype declared when
CONFIG_I2C=n

> 
>>  	while (smi->i2c_num--)
>>  		i2c_unregister_device(smi->i2c_devs[smi->i2c_num]);
>> +#endif
>>  
>> -	while (smi->spi_num--)
>> -		spi_unregister_device(smi->spi_devs[smi->spi_num]);
>> +	if (IS_REACHABLE(CONFIG_SPI)) {
>> +		while (smi->spi_num--)
>> +			spi_unregister_device(smi->spi_devs[smi->spi_num]);
>> +	}
>>  }
> 
> There are ways to solve this:
> 1) add a stub for I2C=n for i2c_unregister_device();

Yes that would be an option to clean this up a bit as a follow-up
patch series.

Note no need for a stub, just move the declaration out of
the #if IS_ENABLED(CONFIG_I2C) block, using if (IS_REACHABLE)
only requires a prototype.

> 2) resplit this driver to have several built modules:
>    core, I2C parts, SPI parts.
> 

Regards,

Hans

Re: [PATCH v2] platform/x86: serial-multi-instantiate: Don't require both I2C and SPI

Posted by Hans de Goede 1 year, 5 months ago

Hi,

On 8/14/24 3:29 PM, Richard Fitzgerald wrote:
> Change the Kconfig dependency so that it doesn't require both I2C and SPI
> subsystems to be built. Make a few small changes to the code so that the
> code for a bus is only called if the bus is being built.
> 
> When SPI support was added to serial-multi-instantiate it created a
> dependency that both CONFIG_I2C and CONFIG_SPI must be enabled.
> Typically they are, but there's no reason why this should be a
> requirement. A specific kernel build could have only I2C devices
> or only SPI devices. It should be possible to use serial-multi-instantiate
> if only I2C or only SPI is enabled.
> 
> The dependency formula used is:
> 
>   depends on (I2C && !SPI) || (!I2C && SPI) || (I2C && SPI)
> 
> The advantage of this approach is that if I2C=m or SPI=m then
> SERIAL_MULTI_INSTANTIATE is limited to n/m.
> 
> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>

Thank you for your patch, I've applied this patch to my review-hans 
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

Once I've run some tests on this branch the patches there will be
added to the platform-drivers-x86/for-next branch and eventually
will be included in the pdx86 pull-request to Linus for the next
merge-window.

Regards,

Hans




> ---
> Changes from V1:
> Use a different 'depends on' formula so that serial-multi-instantiate
> must be built as a module if any dependencies are a module.
> 
>  drivers/platform/x86/Kconfig                  |  3 +-
>  .../platform/x86/serial-multi-instantiate.c   | 32 ++++++++++++++-----
>  2 files changed, 26 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 665fa9524986..0dcf4d8eac56 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -999,7 +999,8 @@ config TOPSTAR_LAPTOP
>  
>  config SERIAL_MULTI_INSTANTIATE
>  	tristate "Serial bus multi instantiate pseudo device driver"
> -	depends on I2C && SPI && ACPI
> +	depends on ACPI
> +	depends on (I2C && !SPI) || (!I2C && SPI) || (I2C && SPI)
>  	help
>  	  Some ACPI-based systems list multiple devices in a single ACPI
>  	  firmware-node. This driver will instantiate separate clients
> diff --git a/drivers/platform/x86/serial-multi-instantiate.c b/drivers/platform/x86/serial-multi-instantiate.c
> index 3be016cfe601..7c04cc9e5891 100644
> --- a/drivers/platform/x86/serial-multi-instantiate.c
> +++ b/drivers/platform/x86/serial-multi-instantiate.c
> @@ -83,11 +83,15 @@ static int smi_get_irq(struct platform_device *pdev, struct acpi_device *adev,
>  
>  static void smi_devs_unregister(struct smi *smi)
>  {
> +#if IS_REACHABLE(CONFIG_I2C)
>  	while (smi->i2c_num--)
>  		i2c_unregister_device(smi->i2c_devs[smi->i2c_num]);
> +#endif
>  
> -	while (smi->spi_num--)
> -		spi_unregister_device(smi->spi_devs[smi->spi_num]);
> +	if (IS_REACHABLE(CONFIG_SPI)) {
> +		while (smi->spi_num--)
> +			spi_unregister_device(smi->spi_devs[smi->spi_num]);
> +	}
>  }
>  
>  /**
> @@ -258,9 +262,15 @@ static int smi_probe(struct platform_device *pdev)
>  
>  	switch (node->bus_type) {
>  	case SMI_I2C:
> -		return smi_i2c_probe(pdev, smi, node->instances);
> +		if (IS_REACHABLE(CONFIG_I2C))
> +			return smi_i2c_probe(pdev, smi, node->instances);
> +
> +		return -ENODEV;
>  	case SMI_SPI:
> -		return smi_spi_probe(pdev, smi, node->instances);
> +		if (IS_REACHABLE(CONFIG_SPI))
> +			return smi_spi_probe(pdev, smi, node->instances);
> +
> +		return -ENODEV;
>  	case SMI_AUTO_DETECT:
>  		/*
>  		 * For backwards-compatibility with the existing nodes I2C
> @@ -270,10 +280,16 @@ static int smi_probe(struct platform_device *pdev)
>  		 * SpiSerialBus nodes that were previously ignored, and this
>  		 * preserves that behavior.
>  		 */
> -		ret = smi_i2c_probe(pdev, smi, node->instances);
> -		if (ret != -ENOENT)
> -			return ret;
> -		return smi_spi_probe(pdev, smi, node->instances);
> +		if (IS_REACHABLE(CONFIG_I2C)) {
> +			ret = smi_i2c_probe(pdev, smi, node->instances);
> +			if (ret != -ENOENT)
> +				return ret;
> +		}
> +
> +		if (IS_REACHABLE(CONFIG_SPI))
> +			return smi_spi_probe(pdev, smi, node->instances);
> +
> +		return -ENODEV;
>  	default:
>  		return -EINVAL;
>  	}