[RFC PATCH 3/9] drm/i915/spi: add driver for on-die spi device

[Jani Nikula]

On Tue, 16 Feb 2021, Tomas Winkler <tomas.winkler at intel.com> wrote:
> Add the platform driver for i915 on-die spi device, exposed via mfd
> framework.
>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> Signed-off-by: Tomas Winkler <tomas.winkler at intel.com>
> ---
>  drivers/gpu/drm/i915/Kconfig             |   2 +
>  drivers/gpu/drm/i915/Makefile            |   3 +
>  drivers/gpu/drm/i915/spi/intel_spi_drv.c | 116 +++++++++++++++++++++++
>  3 files changed, 121 insertions(+)
>  create mode 100644 drivers/gpu/drm/i915/spi/intel_spi_drv.c
>
> diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
> index abcaa8da45ac..13c870e5878e 100644
> --- a/drivers/gpu/drm/i915/Kconfig
> +++ b/drivers/gpu/drm/i915/Kconfig
> @@ -27,6 +27,8 @@ config DRM_I915
>  	select CEC_CORE if CEC_NOTIFIER
>  	select VMAP_PFN
>  	select MFD_CORE
> +	select MTD

Selecting MTD does not seem to be a popular thing to do, which is
usually a clue it's probably the wrong thing to do.

> +	select MTD_PARTITIONED_MASTER
>  	help
>  	  Choose this option if you have a system that has "Intel Graphics
>  	  Media Accelerator" or "HD Graphics" integrated graphics,
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 7fa9120feb8d..f209cd541eec 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -299,6 +299,9 @@ endif
>  obj-$(CONFIG_DRM_I915) += i915.o
>  obj-$(CONFIG_DRM_I915_GVT_KVMGT) += gvt/kvmgt.o
>  
> +obj-m += i915_spi.o

And literally nobody does this.

> +i915_spi-y := spi/intel_spi_drv.o

Time to add a separate Kconfig and Makefile in spi/?

BR,
Jani.

> +
>  # header test
>  
>  # exclude some broken headers from the test coverage
> diff --git a/drivers/gpu/drm/i915/spi/intel_spi_drv.c b/drivers/gpu/drm/i915/spi/intel_spi_drv.c
> new file mode 100644
> index 000000000000..23261f35b71f
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/spi/intel_spi_drv.c
> @@ -0,0 +1,116 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright(c) 2019-2021, Intel Corporation. All rights reserved.
> + */
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/kernel.h>
> +#include <linux/string.h>
> +#include <linux/io.h>
> +#include <linux/device.h>
> +#include <linux/slab.h>
> +#include <linux/platform_device.h>
> +#include <spi/intel_spi.h>

Should this have "" instead of <>?

> +
> +struct i915_spi {
> +	void __iomem *base;
> +	size_t size;
> +	unsigned int nregions;
> +	struct {
> +		const char *name;
> +		u8 id;
> +		u64 offset;
> +		u64 size;
> +	} regions[];
> +};
> +
> +static int i915_spi_probe(struct platform_device *platdev)
> +{
> +	struct resource *bar;
> +	struct device *device;
> +	struct i915_spi *spi;
> +	struct i915_spi_region *regions;
> +	unsigned int nregions;
> +	unsigned int i, n;
> +	size_t size;
> +	char *name;
> +	size_t name_size;
> +
> +	device = &platdev->dev;
> +
> +	regions = dev_get_platdata(&platdev->dev);
> +	if (!regions) {
> +		dev_err(device, "no regions defined\n");
> +		return -ENODEV;
> +	}
> +
> +	/* count available regions */
> +	for (nregions = 0, i = 0; i < I915_SPI_REGIONS; i++) {
> +		if (regions[i].name)
> +			nregions++;
> +	}
> +
> +	if (!nregions) {
> +		dev_err(device, "no regions defined\n");
> +		return -ENODEV;
> +	}
> +
> +	size = sizeof(*spi) + sizeof(spi->regions[0]) * nregions;
> +	spi = devm_kzalloc(device, size, GFP_KERNEL);
> +	if (!spi)
> +		return -ENOMEM;
> +
> +	spi->nregions = nregions;
> +	for (n = 0, i = 0; i < I915_SPI_REGIONS; i++) {
> +		if (regions[i].name) {
> +			name_size = strlen(dev_name(&platdev->dev)) +
> +				    strlen(regions[i].name) + 2; /* for point */
> +			name = devm_kzalloc(device, name_size, GFP_KERNEL);
> +			if (!name)
> +				continue;
> +			snprintf(name, name_size, "%s.%s",
> +				 dev_name(&platdev->dev), regions[i].name);
> +			spi->regions[n].name = name;
> +			spi->regions[n].id = i;
> +			n++;
> +		}
> +	}
> +
> +	bar = platform_get_resource(platdev, IORESOURCE_MEM, 0);
> +	if (!bar)
> +		return -ENODEV;
> +
> +	spi->base = devm_ioremap_resource(device, bar);
> +	if (IS_ERR(spi->base)) {
> +		dev_err(device, "mmio not mapped\n");
> +		return PTR_ERR(spi->base);
> +	}
> +
> +	platform_set_drvdata(platdev, spi);
> +
> +	dev_dbg(device, "i915-spi is bound\n");
> +
> +	return 0;
> +}
> +
> +static int i915_spi_remove(struct platform_device *platdev)
> +{
> +	platform_set_drvdata(platdev, NULL);
> +
> +	return 0;
> +}
> +
> +MODULE_ALIAS("platform:i915-spi");
> +static struct platform_driver i915_spi_driver = {
> +	.probe  = i915_spi_probe,
> +	.remove = i915_spi_remove,
> +	.driver = {
> +		.name = "i915-spi",
> +	},
> +};
> +
> +module_platform_driver(i915_spi_driver);
> +
> +MODULE_LICENSE("GPL and additional rights");
> +MODULE_AUTHOR("Intel Corporation");
> +MODULE_DESCRIPTION("Intel DGFX SPI driver");

-- 
Jani Nikula, Intel Open Source Graphics Center