Re: [PATCH v4 7/9] platform/x86: bus-multi-instantiate: Add SPI support

From: Hans de Goede
Date: Thu Jan 20 2022 - 11:30:36 EST

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In reply to: Stefan Binding: "[PATCH v4 7/9] platform/x86: bus-multi-instantiate: Add SPI support"
Next in thread: Stefan Binding: "[PATCH v4 2/9] spi: Create helper API to lookup ACPI info for spi device"
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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@xxxxxxxxxxxxxxxxxxxxx>
> ---
> 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@xxxxxxxxxx>
> */
> @@ -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

Next message: Hans de Goede: "Re: [PATCH v4 9/9] ACPI / scan: Create platform device for CS35L41"
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Next in thread: Stefan Binding: "[PATCH v4 2/9] spi: Create helper API to lookup ACPI info for spi device"
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