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Message-ID: <50c93654-ca9b-d881-ee21-83fb8f8f0b2a@redhat.com>
Date:   Thu, 20 Jan 2022 17:30:27 +0100
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Subject: Re: [PATCH v4 7/9] platform/x86: bus-multi-instantiate: Add SPI
 support
Content-Language: en-US
To:     Stefan Binding <sbinding@opensource.cirrus.com>,
        Mark Brown <broonie@kernel.org>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>, Mark Gross <markgross@kernel.org>,
        Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>
Cc:     alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org,
        linux-spi@vger.kernel.org, linux-acpi@vger.kernel.org,
        platform-driver-x86@vger.kernel.org, patches@opensource.cirrus.com
References: <20220120134326.5295-1-sbinding@opensource.cirrus.com>
 <20220120134326.5295-8-sbinding@opensource.cirrus.com>
From:   Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <20220120134326.5295-8-sbinding@opensource.cirrus.com>
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Precedence: bulk

Hi,

On 1/20/22 14:43, Stefan Binding wrote:
> Add support for spi bus in bus-multi-instantiate driver
> 
> Some peripherals can have either a I2C or a SPI connection
> to the host (but not both) but use the same HID for both
> types. So it is not possible to use the HID to determine
> whether it is I2C or SPI. The driver must check the node
> to see if it contains I2cSerialBus or SpiSerialBus entries.
> 
> For backwards-compatibility with the existing nodes I2C is
> checked first and if such entries are found ONLY I2C devices
> are created. Since some existing nodes that were already
> handled by this driver could also contain unrelated
> SpiSerialBus nodes that were previously ignored, and this
> preserves that behavior. If there is ever a need to handle
> a node where both I2C and SPI devices must be instantiated
> this can be added in future.
> 
> Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com>
> ---
>  drivers/acpi/scan.c                          |  13 +-
>  drivers/platform/x86/Kconfig                 |  10 +-
>  drivers/platform/x86/bus-multi-instantiate.c | 200 ++++++++++++++++---
>  3 files changed, 182 insertions(+), 41 deletions(-)
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index e4fda14572e7..4fd1346d6e1f 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -1734,12 +1734,13 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device)
>  	bool is_serial_bus_slave = false;
>  	static const struct acpi_device_id ignore_serial_bus_ids[] = {
>  	/*
> -	 * These devices have multiple I2cSerialBus resources and an i2c-client
> -	 * must be instantiated for each, each with its own i2c_device_id.
> -	 * Normally we only instantiate an i2c-client for the first resource,
> -	 * using the ACPI HID as id. These special cases are handled by the
> -	 * drivers/platform/x86/bus-multi-instantiate.c driver, which knows
> -	 * which i2c_device_id to use for each resource.
> +	 * These devices have multiple I2cSerialBus/SpiSerialBus resources
> +	 * and an (i2c/spi)-client must be instantiated for each, each with
> +	 * its own i2c_device_id/spi_device_id.
> +	 * Normally we only instantiate an (i2c/spi)-client for the first
> +	 * resource, using the ACPI HID as id. These special cases are handled
> +	 * by the drivers/platform/x86/bus-multi-instantiate.c driver, which
> +	 * knows which i2c_device_id or spi_device_id to use for each resource.
>  	 */
>  		{"BSG1160", },
>  		{"BSG2150", },
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 616da06aa6b9..7b49d9d1e267 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -991,12 +991,12 @@ config TOPSTAR_LAPTOP
>  	  If you have a Topstar laptop, say Y or M here.
>  
>  config BUS_MULTI_INSTANTIATE
> -	tristate "I2C multi instantiate pseudo device driver"
> -	depends on I2C && ACPI
> +	tristate "I2C and SPI multi instantiate pseudo device driver"
> +	depends on I2C && SPI && ACPI
>  	help
> -	  Some ACPI-based systems list multiple i2c-devices in a single ACPI
> -	  firmware-node. This driver will instantiate separate i2c-clients
> -	  for each device in the firmware-node.
> +	  Some ACPI-based systems list multiple i2c/spi devices in a
> +	  single ACPI firmware-node. This driver will instantiate separate
> +	  i2c-clients or spi-devices for each device in the firmware-node.
>  
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called bus-multi-instantiate.
> diff --git a/drivers/platform/x86/bus-multi-instantiate.c b/drivers/platform/x86/bus-multi-instantiate.c
> index 50f1540762e9..05bc941a38fd 100644
> --- a/drivers/platform/x86/bus-multi-instantiate.c
> +++ b/drivers/platform/x86/bus-multi-instantiate.c
> @@ -1,7 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0+
>  /*
>   * Bus multi-instantiate driver, pseudo driver to instantiate multiple
> - * i2c-clients from a single fwnode.
> + * i2c-clients or spi-devices from a single fwnode.
>   *
>   * Copyright 2018 Hans de Goede <hdegoede@redhat.com>
>   */
> @@ -14,6 +14,7 @@
>  #include <linux/module.h>
>  #include <linux/platform_device.h>
>  #include <linux/property.h>
> +#include <linux/spi/spi.h>
>  #include <linux/types.h>
>  
>  #define IRQ_RESOURCE_TYPE	GENMASK(1, 0)
> @@ -21,15 +22,28 @@
>  #define IRQ_RESOURCE_GPIO	1
>  #define IRQ_RESOURCE_APIC	2
>  
> +enum bmi_bus_type {
> +	BMI_I2C,
> +	BMI_SPI,
> +	BMI_AUTO_DETECT,
> +};
> +
>  struct bmi_instance {
>  	const char *type;
>  	unsigned int flags;
>  	int irq_idx;
>  };
>  
> +struct bmi_node {
> +	enum bmi_bus_type bus_type;
> +	struct bmi_instance instances[];
> +};
> +
>  struct bmi {
>  	int i2c_num;
> +	int spi_num;
>  	struct i2c_client **i2c_devs;
> +	struct spi_device **spi_devs;
>  };
>  
>  static int bmi_get_irq(struct platform_device *pdev, struct acpi_device *adev,
> @@ -60,6 +74,92 @@ static void bmi_devs_unregister(struct bmi *bmi)
>  {
>  	while (bmi->i2c_num > 0)
>  		i2c_unregister_device(bmi->i2c_devs[--bmi->i2c_num]);
> +
> +	while (bmi->spi_num > 0)
> +		spi_unregister_device(bmi->spi_devs[--bmi->spi_num]);
> +}
> +
> +/**
> + * bmi_spi_probe - Instantiate multiple SPI devices from inst array
> + * @pdev:	Platform device
> + * @adev:	ACPI device
> + * @bmi:	Internal struct for Bus multi instantiate driver
> + * @inst:	Array of instances to probe
> + *
> + * Returns the number of SPI devices instantiate, Zero if none is found or a negative error code.
> + */
> +static int bmi_spi_probe(struct platform_device *pdev, struct acpi_device *adev, struct bmi *bmi,
> +			 const struct bmi_instance *inst_array)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct spi_controller *ctlr;
> +	struct spi_device *spi_dev;
> +	char name[50];
> +	int i, ret, count;
> +
> +	ret = acpi_spi_count_resources(adev);
> +	if (ret <= 0)
> +		return ret;

Please change this to:

		return ret == 0 ? -ENODEV : ret;

This helps making return value handler in the caller cleaner.

> +	count = ret;
> +
> +	bmi->spi_devs = devm_kcalloc(dev, count, sizeof(*bmi->spi_devs), GFP_KERNEL);
> +	if (!bmi->spi_devs)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < count && inst_array[i].type; i++) {
> +
> +		spi_dev = acpi_spi_device_alloc(NULL, adev, i, inst_array[i].irq_idx);
> +		if (IS_ERR(spi_dev)) {

Maybe put a dev_probe_error() here ?

> +			ret = PTR_ERR(spi_dev);
> +			goto error;
> +		}
> +
> +		ctlr = spi_dev->controller;
> +
> +		strscpy(spi_dev->modalias, inst_array[i].type, sizeof(spi_dev->modalias));
> +
> +		if (spi_dev->irq < 0) {

As already mentioned please drop this if. This will also allow overriding a
potentially bad IRQ from the ACPI tables (or one only valid for 1 of the SPI clients)
with IRQ_RESOURCE_NONE.


> +			ret = bmi_get_irq(pdev, adev, &inst_array[i]);
> +			if (ret < 0) {
> +				spi_dev_put(spi_dev);
> +				goto error;
> +			}
> +			spi_dev->irq = ret;
> +		}
> +
> +		snprintf(name, sizeof(name), "%s-%s-%s.%d", dev_name(&ctlr->dev), dev_name(dev),
> +			 inst_array[i].type, i);
> +		spi_dev->dev.init_name = name;
> +
> +		ret = spi_add_device(spi_dev);
> +		if (ret) {
> +			dev_err(&ctlr->dev, "failed to add SPI device %s from ACPI: %d\n",
> +				dev_name(&adev->dev), ret);
> +			spi_dev_put(spi_dev);
> +			goto error;
> +		}
> +
> +		dev_dbg(dev, "SPI device %s using chip select %u", name, spi_dev->chip_select);
> +
> +		bmi->spi_devs[i] = spi_dev;
> +		bmi->spi_num++;
> +	}
> +
> +	if (bmi->spi_num < count) {
> +		dev_err(dev, "Error finding driver, idx %d\n", i);
> +		ret = -ENODEV;
> +		goto error;
> +	}
> +
> +	dev_info(dev, "Instantiate %d SPI devices.\n", bmi->spi_num);

Nitpick, please change this to:

	dev_info(dev, "Instantiated %d SPI devices.\n", bmi->spi_num);

IOW do s/Instantiate/Instantiated/

> +
> +	return bmi->spi_num;

And change this to return 0.

> +error:
> +	bmi_devs_unregister(bmi);
> +	dev_err_probe(dev, ret, "SPI error %d\n", ret);

Please drop the dev_err_probe here, with the dev_err_probe()
which I suggested above all the error paths already print
a more detailed error.

> +
> +	return ret;
> +
>  }
>  
>  /**
> @@ -125,14 +225,14 @@ static int bmi_i2c_probe(struct platform_device *pdev, struct acpi_device *adev,
>  
>  static int bmi_probe(struct platform_device *pdev)
>  {
> -	const struct bmi_instance *inst_array;
>  	struct device *dev = &pdev->dev;
> +	const struct bmi_node *node;
>  	struct acpi_device *adev;
>  	struct bmi *bmi;
> -	int ret;
> +	int i2c_ret = 0, spi_ret = 0;
>  
> -	inst_array = device_get_match_data(dev);
> -	if (!inst_array) {
> +	node = device_get_match_data(dev);
> +	if (!node) {
>  		dev_err(dev, "Error ACPI match data is missing\n");
>  		return -ENODEV;
>  	}
> @@ -147,13 +247,44 @@ static int bmi_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, bmi);
>  
> -	ret = bmi_i2c_probe(pdev, adev, bmi, inst_array);
> -	if (ret > 0)
> +	/* Each time this driver probes only one type of bus will be chosen.
> +	 * And I2C has preference, which means that if find a I2cSerialBus it assumes
> +	 * that all following devices will also be I2C.
> +	 * In case there are zero I2C devices, it assumes that all following devices are SPI.
> +	 */
> +	if (node->bus_type != BMI_SPI) {
> +		i2c_ret = bmi_i2c_probe(pdev, adev, bmi, node->instances);
> +		if (i2c_ret > 0)
> +			return 0;
> +		else if (i2c_ret == -EPROBE_DEFER)
> +			return i2c_ret;
> +		if (node->bus_type == BMI_I2C) {
> +			if (i2c_ret == 0)
> +				return -ENODEV;
> +			else
> +				return i2c_ret;
> +		}
> +	}
> +	/* BMI_SPI or BMI_AUTO_DETECT */
> +	spi_ret = bmi_spi_probe(pdev, adev, bmi, node->instances);
> +	if (spi_ret > 0)
>  		return 0;
> -	if (ret == 0)
> -		ret = -ENODEV;
> +	else if (spi_ret == -EPROBE_DEFER)
> +		return -EPROBE_DEFER;
> +	if (node->bus_type == BMI_SPI) {
> +		if (spi_ret == 0)
> +			return -ENODEV;
> +		else
> +			return spi_ret;
> +	}
>  
> -	return ret;
> +	/* The only way to get here is BMI_AUTO_DETECT and i2c_ret <= 0 and spi_ret <= 0 */
> +	if (i2c_ret == 0 && spi_ret == 0)
> +		return -ENODEV;
> +	else if (i2c_ret == 0 && spi_ret)
> +		return spi_ret;
> +
> +	return i2c_ret;

Hmm, the above is rather messy and hard to read. With the changed
return values I suggested earlier this can be changed to:

	switch (node->bus_type) {
	case BMI_I2C:
		return bmi_i2c_probe(pdev, adev, bmi, node->instances);
	case BMI_SPI:
		return bmi_spi_probe(pdev, adev, bmi, node->instances);
	case BMI_AUTO_DETECT:
		if (i2c_acpi_client_count(adev))
			return bmi_i2c_probe(pdev, adev, bmi, node->instances);
		else
			return bmi_spi_probe(pdev, adev, bmi, node->instances);
	}

	return 0; /* never reached */
}

Which IMHO is much cleaner / easier to follow.

Note this has one functional change compared to your original code,
when doing auto-detect and the i2c device instantiating fails with
an error other then -EPROBE_DEFER we now fail the entire probe
(propagate the error to our caller).

Where as before for auto-detect bmi_i2c_probe() errors other then
-EPROBE_DEFER would lead to falling back to SPI probing which
does not seem to be what we want.


>  static int bmi_remove(struct platform_device *pdev)
> @@ -165,27 +296,36 @@ static int bmi_remove(struct platform_device *pdev)
>  	return 0;
>  }
>  
> -static const struct bmi_instance bsg1160_data[]  = {
> -	{ "bmc150_accel", IRQ_RESOURCE_GPIO, 0 },
> -	{ "bmc150_magn" },
> -	{ "bmg160" },
> -	{}
> +static const struct bmi_node bsg1160_data = {
> +	.instances = {
> +		{ "bmc150_accel", IRQ_RESOURCE_GPIO, 0 },
> +		{ "bmc150_magn" },
> +		{ "bmg160" },
> +		{}
> +	},
> +	.bus_type = BMI_I2C,
>  };
>  
> -static const struct bmi_instance bsg2150_data[]  = {
> -	{ "bmc150_accel", IRQ_RESOURCE_GPIO, 0 },
> -	{ "bmc150_magn" },
> -	/* The resources describe a 3th client, but it is not really there. */
> -	{ "bsg2150_dummy_dev" },
> -	{}
> +static const struct bmi_node bsg2150_data = {
> +	.instances = {
> +		{ "bmc150_accel", IRQ_RESOURCE_GPIO, 0 },
> +		{ "bmc150_magn" },
> +		/* The resources describe a 3th client, but it is not really there. */
> +		{ "bsg2150_dummy_dev" },
> +		{}
> +	},
> +	.bus_type = BMI_I2C,
>  };
>  
> -static const struct bmi_instance int3515_data[]  = {
> -	{ "tps6598x", IRQ_RESOURCE_APIC, 0 },
> -	{ "tps6598x", IRQ_RESOURCE_APIC, 1 },
> -	{ "tps6598x", IRQ_RESOURCE_APIC, 2 },
> -	{ "tps6598x", IRQ_RESOURCE_APIC, 3 },
> -	{}
> +static const struct bmi_node int3515_data = {
> +	.instances = {
> +		{ "tps6598x", IRQ_RESOURCE_APIC, 0 },
> +		{ "tps6598x", IRQ_RESOURCE_APIC, 1 },
> +		{ "tps6598x", IRQ_RESOURCE_APIC, 2 },
> +		{ "tps6598x", IRQ_RESOURCE_APIC, 3 },
> +		{}
> +	},
> +	.bus_type = BMI_I2C,
>  };
>  
>  /*
> @@ -193,9 +333,9 @@ static const struct bmi_instance int3515_data[]  = {
>   * drivers/acpi/scan.c: acpi_device_enumeration_by_parent().
>   */
>  static const struct acpi_device_id bmi_acpi_ids[] = {
> -	{ "BSG1160", (unsigned long)bsg1160_data },
> -	{ "BSG2150", (unsigned long)bsg2150_data },
> -	{ "INT3515", (unsigned long)int3515_data },
> +	{ "BSG1160", (unsigned long)&bsg1160_data },
> +	{ "BSG2150", (unsigned long)&bsg2150_data },
> +	{ "INT3515", (unsigned long)&int3515_data },
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(acpi, bmi_acpi_ids);
> 


Regards,

Hans