Re: [PATCH v9 02/12] mtd: add driver for intel graphics non-volatile memory device

[Raag Jadav <raag.jadav@intel.com>]

On Thu, Apr 24, 2025 at 04:25:26PM +0300, Alexander Usyskin wrote:
> Add auxiliary driver for intel discrete graphics
> non-volatile memory device.

...

> +static int intel_dg_mtd_probe(struct auxiliary_device *aux_dev,
> +			      const struct auxiliary_device_id *aux_dev_id)
> +{
> +	struct intel_dg_nvm_dev *invm = auxiliary_dev_to_intel_dg_nvm_dev(aux_dev);
> +	struct device *device;
> +	struct intel_dg_nvm *nvm;
> +	unsigned int nregions;
> +	unsigned int i, n;
> +	char *name;

Perhaps move this to the loop it is being used in?

> +	int ret;
> +
> +	device = &aux_dev->dev;
> +
> +	/* count available regions */
> +	for (nregions = 0, i = 0; i < INTEL_DG_NVM_REGIONS; i++) {
> +		if (invm->regions[i].name)
> +			nregions++;
> +	}
> +
> +	if (!nregions) {
> +		dev_err(device, "no regions defined\n");
> +		return -ENODEV;
> +	}
> +
> +	nvm = kzalloc(struct_size(nvm, regions, nregions), GFP_KERNEL);
> +	if (!nvm)
> +		return -ENOMEM;
> +
> +	kref_init(&nvm->refcnt);
> +
> +	nvm->nregions = nregions;

Is this assignment useful?

> +	for (n = 0, i = 0; i < INTEL_DG_NVM_REGIONS; i++) {
> +		if (!invm->regions[i].name)
> +			continue;
> +
> +		name = kasprintf(GFP_KERNEL, "%s.%s",
> +				 dev_name(&aux_dev->dev), invm->regions[i].name);
> +		if (!name)
> +			continue;
> +		nvm->regions[n].name = name;
> +		nvm->regions[n].id = i;
> +		n++;
> +	}
> +	nvm->nregions = n; /* in case where kasprintf fail */

Considering kasprintf failure, should we move forward if n == 0?

> +	nvm->base = devm_ioremap_resource(device, &invm->bar);
> +	if (IS_ERR(nvm->base)) {
> +		dev_err(device, "mmio not mapped\n");

Is this useful? Perhaps the helper already does it for us.

> +		ret = PTR_ERR(nvm->base);
> +		goto err;
> +	}
> +
> +	dev_set_drvdata(&aux_dev->dev, nvm);
> +
> +	return 0;
> +
> +err:
> +	kref_put(&nvm->refcnt, intel_dg_nvm_release);
> +	return ret;
> +}
> +
> +static void intel_dg_mtd_remove(struct auxiliary_device *aux_dev)
> +{
> +	struct intel_dg_nvm *nvm = dev_get_drvdata(&aux_dev->dev);
> +
> +	if (!nvm)
> +		return;

Are we expecting this?

> +	dev_set_drvdata(&aux_dev->dev, NULL);

Do we need this?

> +	kref_put(&nvm->refcnt, intel_dg_nvm_release);
> +}
> +
> +static const struct auxiliary_device_id intel_dg_mtd_id_table[] = {
> +	{
> +		.name = "i915.nvm",
> +	},
> +	{
> +		.name = "xe.nvm",
> +	},
> +	{
> +		/* sentinel */
> +	}
> +};
> +MODULE_DEVICE_TABLE(auxiliary, intel_dg_mtd_id_table);
> +
> +static struct auxiliary_driver intel_dg_mtd_driver = {
> +	.probe  = intel_dg_mtd_probe,
> +	.remove = intel_dg_mtd_remove,
> +	.driver = {
> +		/* auxiliary_driver_register() sets .name to be the modname */
> +	},
> +	.id_table = intel_dg_mtd_id_table
> +};

> +

Nit: Redundant blank line.

> +module_auxiliary_driver(intel_dg_mtd_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Intel Corporation");
> +MODULE_DESCRIPTION("Intel DGFX MTD driver");
> diff --git a/include/linux/intel_dg_nvm_aux.h b/include/linux/intel_dg_nvm_aux.h
> new file mode 100644
> index 000000000000..68df634c994c
> --- /dev/null
> +++ b/include/linux/intel_dg_nvm_aux.h
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright(c) 2019-2025, Intel Corporation. All rights reserved.
> + */
> +
> +#ifndef __INTEL_DG_NVM_AUX_H__
> +#define __INTEL_DG_NVM_AUX_H__
> +
> +#include <linux/auxiliary_bus.h>

Missing types.h, container_of.h

> +#define INTEL_DG_NVM_REGIONS 13
> +
> +struct intel_dg_nvm_region {
> +	const char *name;
> +};
> +
> +struct intel_dg_nvm_dev {
> +	struct auxiliary_device aux_dev;
> +	bool writable_override;
> +	struct resource bar;
> +	const struct intel_dg_nvm_region *regions;
> +};
> +
> +#define auxiliary_dev_to_intel_dg_nvm_dev(auxiliary_dev) \
> +	container_of(auxiliary_dev, struct intel_dg_nvm_dev, aux_dev)
> +
> +#endif /* __INTEL_DG_NVM_AUX_H__ */
> -- 
> 2.43.0
>