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

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

[Richard Fitzgerald]

Change the Kconfig dependency to (I2C || SPI) so that it doesn't
require both bus subsystems to be enabled. 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.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
---
 drivers/platform/x86/Kconfig                  |  2 +-
 .../platform/x86/serial-multi-instantiate.c   | 32 ++++++++++++++-----
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 665fa9524986..c286742b34ba 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -999,7 +999,7 @@ config TOPSTAR_LAPTOP
 
 config SERIAL_MULTI_INSTANTIATE
 	tristate "Serial bus multi instantiate pseudo device driver"
-	depends on I2C && SPI && ACPI
+	depends on (I2C || SPI) && ACPI
 	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] platform/x86: serial-multi-instantiate: Don't require both I2C and SPI

[Richard Fitzgerald]

On 13/08/2024 12:21, Richard Fitzgerald wrote:
> Change the Kconfig dependency to (I2C || SPI) so that it doesn't
> require both bus subsystems to be enabled. 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.
> 
> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
> ---
>   drivers/platform/x86/Kconfig                  |  2 +-
>   .../platform/x86/serial-multi-instantiate.c   | 32 ++++++++++++++-----
>   2 files changed, 25 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 665fa9524986..c286742b34ba 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -999,7 +999,7 @@ config TOPSTAR_LAPTOP
>   
>   config SERIAL_MULTI_INSTANTIATE
>   	tristate "Serial bus multi instantiate pseudo device driver"
> -	depends on I2C && SPI && ACPI
> +	depends on (I2C || SPI) && ACPI

Please don't take this version.
It works better as:

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

so if I2C or SPI =m then SERIAL_MULTI_INSTANTIATE must be
built as a module.

I will send a V2 with that change.