Re: [PATCH v4 4/8] i2c: amd-asf: Add ACPI support for AMD ASF Controller

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Wed, Sep 11, 2024 at 05:24:03PM +0530, Shyam Sundar S K wrote:
> The AMD ASF controller is presented to the operating system as an ACPI
> device. The AMD ASF driver can use ACPI to obtain information about the
> ASF controller's attributes, such as the ASF address space and interrupt
> number, and to handle ASF interrupts.
> 
> Currently, the piix4 driver assumes that a specific port address is
> designated for AUX operations. However, with the introduction of ASF, the
> same port address may also be used by the ASF controller. Therefore, a
> check needs to be added to ensure that if ASF is advertised and enabled in
> ACPI, the AUX port should not be configured.

With brief look this is much better than the previous version(s).
Thank you for rewriting it this way!

Some comments below.

...

> +#include <linux/acpi.h>

No need (see below)

+ device.h
+ errno.h
+ gfp_types.h

> +#include <linux/i2c-smbus.h>

This should be i2c.h

+ mod_devicetable.h
+ module.h

> +#include <linux/platform_device.h>

> +#include <linux/slab.h>

Not in use.

+ sprintf.h

> +#include "i2c-piix4.h"
> +
> +static const char *sb800_asf_port_name = " port 1";
> +
> +struct amd_asf_dev {
> +	struct device *dev;
> +	struct i2c_adapter adap;

Make it first member, it might help if we ever do a container_of() against
this.

> +	struct sb800_mmio_cfg mmio_cfg;
> +	unsigned short port_addr;

What you probably want is to have

	void __iomem *addr;

and use devm_ioport_map() somewhere (see
drivers/pinctl/intel/pinctrl-lynxpoint.c, for example)

> +};

> +static int amd_asf_probe(struct platform_device *pdev)
> +{
> +	struct resource_entry *rentry;
> +	struct amd_asf_dev *asf_dev;
> +	struct acpi_device *adev;
> +	LIST_HEAD(res_list);
> +	int ret;

> +	adev = ACPI_COMPANION(&pdev->dev);
> +	if (!adev)
> +		return dev_err_probe(&pdev->dev, -ENODEV, "Failed to get ASF device\n");

No need. You will get here only if enumerated via ACPI (or if it's out-of-tree
board file which we do not care about at all).

> +	asf_dev = devm_kzalloc(&pdev->dev, sizeof(*asf_dev), GFP_KERNEL);
> +	if (!asf_dev)
> +		return dev_err_probe(&pdev->dev, -ENOMEM, "Failed to allocate memory\n");
> +
> +	asf_dev->dev = &pdev->dev;

> +	platform_set_drvdata(pdev, asf_dev);

Is it used?

> +	asf_dev->adap.owner = THIS_MODULE;
> +	asf_dev->mmio_cfg.use_mmio = true;
> +	asf_dev->adap.class = I2C_CLASS_HWMON;

> +	ret = acpi_dev_get_resources(adev, &res_list, NULL, NULL);
> +	if (ret < 0)
> +		return dev_err_probe(&pdev->dev, ret, "Error getting ASF ACPI resource: %d\n", ret);
> +
> +	list_for_each_entry(rentry, &res_list, node) {
> +		switch (resource_type(rentry->res)) {
> +		case IORESOURCE_IO:
> +			asf_dev->port_addr = rentry->res->start;
> +			break;
> +		default:
> +			dev_warn(&adev->dev, "Invalid ASF resource\n");
> +			break;
> +		}
> +	}
> +
> +	acpi_dev_free_resource_list(&res_list);

Now this is a duplicate of what ACPI glue layer does. You have these already
available as platform device resources.

> +	/* Set up the sysfs linkage to our parent device */
> +	asf_dev->adap.dev.parent = &pdev->dev;
> +
> +	snprintf(asf_dev->adap.name, sizeof(asf_dev->adap.name),
> +		 "SMBus ASF adapter%s at %04x", sb800_asf_port_name, asf_dev->port_addr);

> +	i2c_set_adapdata(&asf_dev->adap, asf_dev);

Is it used?

> +	ret = i2c_add_adapter(&asf_dev->adap);

Use devm variant of this casll.

> +	if (ret) {

> +		release_region(asf_dev->port_addr, SMBIOSIZE);

Why?

> +		return ret;
> +	}
> +
> +	return 0;

	return devm_i2c_add_adapter(...);

> +}
> +
> +static void amd_asf_remove(struct platform_device *pdev)
> +{
> +	struct amd_asf_dev *dev = platform_get_drvdata(pdev);

> +	if (dev->port_addr) {

Redundant.

> +		i2c_del_adapter(&dev->adap);

With devm this should be removed.

> +		release_region(dev->port_addr, SMBIOSIZE);

Why?

> +	}
> +}
> +
> +static const struct acpi_device_id amd_asf_acpi_ids[] = {
> +	{"AMDI001A", 0},

	{ "AMDI001A" },

> +	{ }
> +};
> +MODULE_DEVICE_TABLE(acpi, amd_asf_acpi_ids);
> +
> +static struct platform_driver amd_asf_driver = {
> +	.driver = {
> +		.name = "i2c-amd-asf",
> +		.acpi_match_table = amd_asf_acpi_ids,
> +	},
> +	.probe = amd_asf_probe,
> +	.remove_new = amd_asf_remove,
> +};
> +module_platform_driver(amd_asf_driver);

...

> +	status = acpi_get_handle(NULL, (acpi_string)SB800_ASF_ACPI_PATH, &handle);

Does it compile with CONFIG_ACPI=n?

Also don't you need to include acpi.h for this? Or is it already there?
(I haven't checked).

> +	if (ACPI_SUCCESS(status))
> +		is_asf = true;

-- 
With Best Regards,
Andy Shevchenko