Re: [PATCH v5 4/4] platform/x86: Add ACPI i2c-multi-instantiate pseudo driver

[Andy Shevchenko]

On Thu, 2018-08-09 at 11:15 +0200, Hans de Goede wrote:
> On systems with ACPI instantiated i2c-clients, normally there is 1
> fw_node
> per i2c-device and that fw-node contains 1 I2cSerialBus resource for
> that 1
> i2c-device.
> 
> But in some rare cases the manufacturer has decided to describe
> multiple
> i2c-devices in a single ACPI fwnode with multiple I2cSerialBus
> resources.
> 
> An earlier attempt to fix this in the i2c-core resulted in a lot of
> extra
> code to support this corner-case.
> 
> This commit introduces a new i2c-multi-instantiate driver which fixes
> this
> in a different way. This new driver can be built as a module which
> will
> only loaded on affected systems.
> 
> This driver will instantiate a new i2c-client per I2cSerialBus
> resource,
> using the driver_data from the acpi_device_id it is binding to to tell
> it
> which chip-type (and optional irq-resource) to use when instantiating.
> 
> Note this driver depends on a platform device being instantiated for
> the
> ACPI fwnode, see the i2c_multi_instantiate_ids list of ACPI device-ids 
> in
> drivers/acpi/scan.c: acpi_device_enumeration_by_parent().
> 

Acked-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

(From PDx86 prospective)

> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> Changes in v2:
> -Rebase on top of 4.18-rc2
> 
> Changes in v3:
> -Change from an i2c-driver using a hack to allow having multiple i2c
> clients
>  at the same address to a platform-driver
> 
> Changes in v4:
> -Tweak MAINTAINERS entry a bit
> 
> Changes in v5:
> -s/no_clients/num_clients/
> -Change patch Subject prefix to platform/x86
> ---
>  MAINTAINERS                                  |   6 +
>  drivers/platform/x86/Kconfig                 |  11 ++
>  drivers/platform/x86/Makefile                |   1 +
>  drivers/platform/x86/i2c-multi-instantiate.c | 131
> +++++++++++++++++++
>  4 files changed, 149 insertions(+)
>  create mode 100644 drivers/platform/x86/i2c-multi-instantiate.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 9b377508f24f..dbe7836e4f6b 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -367,6 +367,12 @@ L:	linux-acpi@xxxxxxxxxxxxxxx
>  S:	Maintained
>  F:	drivers/acpi/arm64
>  
> +ACPI I2C MULTI INSTANTIATE DRIVER
> +M:	Hans de Goede <hdegoede@xxxxxxxxxx>
> +L:	platform-driver-x86@xxxxxxxxxxxxxxx
> +S:	Maintained
> +F:	drivers/platform/x86/i2c-multi-instantiate.c
> +
>  ACPI PMIC DRIVERS
>  M:	"Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
>  M:	Len Brown <lenb@xxxxxxxxxx>
> diff --git a/drivers/platform/x86/Kconfig
> b/drivers/platform/x86/Kconfig
> index 85a93453237c..64c82592d4b6 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -1219,6 +1219,17 @@ config INTEL_CHTDC_TI_PWRBTN
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called intel_chtdc_ti_pwrbtn.
>  
> +config I2C_MULTI_INSTANTIATE
> +	tristate "I2C multi instantiate pseudo device driver"
> +	depends on I2C && 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.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called i2c-multi-instantiate.
> +
>  endif # X86_PLATFORM_DEVICES
>  
>  config PMC_ATOM
> diff --git a/drivers/platform/x86/Makefile
> b/drivers/platform/x86/Makefile
> index 8d9477114fb5..e6d1becf81ce 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -91,3 +91,4 @@ obj-$(CONFIG_PMC_ATOM)		+= pmc_atom.o
>  obj-$(CONFIG_MLX_PLATFORM)	+= mlx-platform.o
>  obj-$(CONFIG_INTEL_TURBO_MAX_3) += intel_turbo_max_3.o
>  obj-$(CONFIG_INTEL_CHTDC_TI_PWRBTN)	+= intel_chtdc_ti_pwrbtn.o
> +obj-$(CONFIG_I2C_MULTI_INSTANTIATE)	+= i2c-multi-instantiate.o
> diff --git a/drivers/platform/x86/i2c-multi-instantiate.c
> b/drivers/platform/x86/i2c-multi-instantiate.c
> new file mode 100644
> index 000000000000..75c00630ecde
> --- /dev/null
> +++ b/drivers/platform/x86/i2c-multi-instantiate.c
> @@ -0,0 +1,131 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * I2C multi-instantiate driver, pseudo driver to instantiate
> multiple
> + * i2c-clients from a single fwnode.
> + *
> + * Copyright 2018 Hans de Goede <hdegoede@xxxxxxxxxx>
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +struct i2c_inst_data {
> +	const char *type;
> +	int irq_idx;
> +};
> +
> +struct i2c_multi_inst_data {
> +	int num_clients;
> +	struct i2c_client *clients[0];
> +};
> +
> +static int i2c_multi_inst_probe(struct platform_device *pdev)
> +{
> +	struct i2c_multi_inst_data *multi;
> +	const struct acpi_device_id *match;
> +	const struct i2c_inst_data *inst_data;
> +	struct i2c_board_info board_info = {};
> +	struct device *dev = &pdev->dev;
> +	struct acpi_device *adev;
> +	char name[32];
> +	int i, ret;
> +
> +	match = acpi_match_device(dev->driver->acpi_match_table, dev);
> +	if (!match) {
> +		dev_err(dev, "Error ACPI match data is missing\n");
> +		return -ENODEV;
> +	}
> +	inst_data = (const struct i2c_inst_data *)match->driver_data;
> +
> +	adev = ACPI_COMPANION(dev);
> +
> +	/* Count number of clients to instantiate */
> +	for (i = 0; inst_data[i].type; i++) {}
> +
> +	multi = devm_kmalloc(dev,
> +			offsetof(struct i2c_multi_inst_data,
> clients[i]),
> +			GFP_KERNEL);
> +	if (!multi)
> +		return -ENOMEM;
> +
> +	multi->num_clients = i;
> +
> +	for (i = 0; i < multi->num_clients; i++) {
> +		memset(&board_info, 0, sizeof(board_info));
> +		strlcpy(board_info.type, inst_data[i].type,
> I2C_NAME_SIZE);
> +		snprintf(name, sizeof(name), "%s-%s", match->id,
> +			 inst_data[i].type);
> +		board_info.dev_name = name;
> +		board_info.irq = 0;
> +		if (inst_data[i].irq_idx != -1) {
> +			ret = acpi_dev_gpio_irq_get(adev,
> inst_data[i].irq_idx);
> +			if (ret < 0) {
> +				dev_err(dev, "Error requesting irq at
> index %d: %d\n",
> +					inst_data[i].irq_idx, ret);
> +				goto error;
> +			}
> +			board_info.irq = ret;
> +		}
> +		multi->clients[i] = i2c_acpi_new_device(dev, i,
> &board_info);
> +		if (!multi->clients[i]) {
> +			dev_err(dev, "Error creating i2c-client, idx
> %d\n", i);
> +			ret = -ENODEV;
> +			goto error;
> +		}
> +	}
> +
> +	platform_set_drvdata(pdev, multi);
> +	return 0;
> +
> +error:
> +	while (--i >= 0)
> +		i2c_unregister_device(multi->clients[i]);
> +
> +	return ret;
> +}
> +
> +static int i2c_multi_inst_remove(struct platform_device *pdev)
> +{
> +	struct i2c_multi_inst_data *multi = platform_get_drvdata(pdev);
> +	int i;
> +
> +	for (i = 0; i < multi->num_clients; i++)
> +		i2c_unregister_device(multi->clients[i]);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_inst_data bsg1160_data[]  = {
> +	{ "bmc150_accel", 0 },
> +	{ "bmc150_magn", -1 },
> +	{ "bmg160", -1 },
> +	{}
> +};
> +
> +/*
> + * Note new device-ids must also be added to
> i2c_multi_instantiate_ids in
> + * drivers/acpi/scan.c: acpi_device_enumeration_by_parent().
> + */
> +static const struct acpi_device_id i2c_multi_inst_acpi_ids[] = {
> +	{ "BSG1160", (unsigned long)bsg1160_data },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(acpi, i2c_multi_inst_acpi_ids);
> +
> +static struct platform_driver i2c_multi_inst_driver = {
> +	.driver	= {
> +		.name = "I2C multi instantiate pseudo device driver",
> +		.acpi_match_table = ACPI_PTR(i2c_multi_inst_acpi_ids),
> +	},
> +	.probe = i2c_multi_inst_probe,
> +	.remove = i2c_multi_inst_remove,
> +};
> +module_platform_driver(i2c_multi_inst_driver);
> +
> +MODULE_DESCRIPTION("I2C multi instantiate pseudo device driver");
> +MODULE_AUTHOR("Hans de Goede <hdegoede@xxxxxxxxxx>");
> +MODULE_LICENSE("GPL");

-- 
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy