[v2,01/12] spi: add driver for intel graphics on-die spi device

diff --git a/MAINTAINERS b/MAINTAINERS
index d6c90161c7bf..10ee1911629e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11004,6 +11004,13 @@  L:	linux-kernel@vger.kernel.org
 S:	Supported
 F:	arch/x86/include/asm/intel-family.h
 
+INTEL DISCRETE GRAPHIC SPI FLASH DRIVER
+M:	Alexander Usyskin <alexander.usyskin@intel.com>
+L:	linux-spi@vger.kernel.org
+S:	Supported
+F:	drivers/spi/spi-intel-dg.c
+F:	include/linux/intel_dg_spi_aux.h
+
 INTEL DRM DISPLAY FOR XE AND I915 DRIVERS
 M:	Jani Nikula <jani.nikula@linux.intel.com>
 M:	Rodrigo Vivi <rodrigo.vivi@intel.com>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index a2c99ff33e0a..ad6e74ff3223 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -518,6 +518,17 @@  config SPI_INTEL_PLATFORM
 	  To compile this driver as a module, choose M here: the module
 	  will be called spi-intel-platform.
 
+config SPI_INTEL_DG
+	tristate "Intel Discrete Graphic SPI flash driver"
+	depends on AUXILIARY_BUS || COMPILE_TEST
+	depends on MTD
+	help
+	  This enables support for Intel Discrete Graphic SPI
+	  auxiliary device.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called spi-intel-dg.
+
 config SPI_JCORE
 	tristate "J-Core SPI Master"
 	depends on OF && (SUPERH || COMPILE_TEST)
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index e694254dec04..3c48a086c0e0 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -70,6 +70,7 @@  obj-$(CONFIG_SPI_INGENIC)		+= spi-ingenic.o
 obj-$(CONFIG_SPI_INTEL)			+= spi-intel.o
 obj-$(CONFIG_SPI_INTEL_PCI)		+= spi-intel-pci.o
 obj-$(CONFIG_SPI_INTEL_PLATFORM)	+= spi-intel-platform.o
+obj-$(CONFIG_SPI_INTEL_DG)		+= spi-intel-dg.o
 obj-$(CONFIG_SPI_LANTIQ_SSC)		+= spi-lantiq-ssc.o
 obj-$(CONFIG_SPI_JCORE)			+= spi-jcore.o
 obj-$(CONFIG_SPI_LJCA)			+= spi-ljca.o
diff --git a/drivers/spi/spi-intel-dg.c b/drivers/spi/spi-intel-dg.c
new file mode 100644
index 000000000000..7a00d222bb72
--- /dev/null
+++ b/drivers/spi/spi-intel-dg.c
@@ -0,0 +1,142 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright(c) 2019-2024, Intel Corporation. All rights reserved.
+ */
+
+#include <linux/device.h>
+#include <linux/intel_dg_spi_aux.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+struct intel_dg_spi {
+	struct kref refcnt;
+	void __iomem *base;
+	size_t size;
+	unsigned int nregions;
+	struct {
+		const char *name;
+		u8 id;
+		u64 offset;
+		u64 size;
+	} regions[];
+};
+
+static void intel_dg_spi_release(struct kref *kref)
+{
+	struct intel_dg_spi *spi = container_of(kref, struct intel_dg_spi, refcnt);
+	int i;
+
+	pr_debug("freeing spi memory\n");
+	for (i = 0; i < spi->nregions; i++)
+		kfree(spi->regions[i].name);
+	kfree(spi);
+}
+
+static int intel_dg_spi_probe(struct auxiliary_device *aux_dev,
+			  const struct auxiliary_device_id *aux_dev_id)
+{
+	struct intel_dg_spi_dev *ispi = auxiliary_dev_to_intel_dg_spi_dev(aux_dev);
+	struct device *device;
+	struct intel_dg_spi *spi;
+	unsigned int nregions;
+	unsigned int i, n;
+	size_t size;
+	char *name;
+	size_t name_size;
+	int ret;
+
+	device = &aux_dev->dev;
+
+	/* count available regions */
+	for (nregions = 0, i = 0; i < INTEL_DG_SPI_REGIONS; i++) {
+		if (ispi->regions[i].name)
+			nregions++;
+	}
+
+	if (!nregions) {
+		dev_err(device, "no regions defined\n");
+		return -ENODEV;
+	}
+
+	size = sizeof(*spi) + sizeof(spi->regions[0]) * nregions;
+	spi = kzalloc(size, GFP_KERNEL);
+	if (!spi)
+		return -ENOMEM;
+
+	kref_init(&spi->refcnt);
+
+	spi->nregions = nregions;
+	for (n = 0, i = 0; i < INTEL_DG_SPI_REGIONS; i++) {
+		if (ispi->regions[i].name) {
+			name_size = strlen(dev_name(&aux_dev->dev)) +
+				    strlen(ispi->regions[i].name) + 2; /* for point */
+			name = kzalloc(name_size, GFP_KERNEL);
+			if (!name)
+				continue;
+			snprintf(name, name_size, "%s.%s",
+				 dev_name(&aux_dev->dev), ispi->regions[i].name);
+			spi->regions[n].name = name;
+			spi->regions[n].id = i;
+			n++;
+		}
+	}
+
+	spi->base = devm_ioremap_resource(device, &ispi->bar);
+	if (IS_ERR(spi->base)) {
+		dev_err(device, "mmio not mapped\n");
+		ret = PTR_ERR(spi->base);
+		goto err;
+	}
+
+	dev_set_drvdata(&aux_dev->dev, spi);
+
+	return 0;
+
+err:
+	kref_put(&spi->refcnt, intel_dg_spi_release);
+	return ret;
+}
+
+static void intel_dg_spi_remove(struct auxiliary_device *aux_dev)
+{
+	struct intel_dg_spi *spi = dev_get_drvdata(&aux_dev->dev);
+
+	if (!spi)
+		return;
+
+	dev_set_drvdata(&aux_dev->dev, NULL);
+
+	kref_put(&spi->refcnt, intel_dg_spi_release);
+}
+
+static const struct auxiliary_device_id intel_dg_spi_id_table[] = {
+	{
+		.name = "i915.spi",
+	},
+	{
+		.name = "xe.spi",
+	},
+	{
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(auxiliary, intel_dg_spi_id_table);
+
+static struct auxiliary_driver intel_dg_spi_driver = {
+	.probe  = intel_dg_spi_probe,
+	.remove = intel_dg_spi_remove,
+	.driver = {
+		/* auxiliary_driver_register() sets .name to be the modname */
+	},
+	.id_table = intel_dg_spi_id_table
+};
+
+module_auxiliary_driver(intel_dg_spi_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_DESCRIPTION("Intel DGFX SPI driver");
diff --git a/include/linux/intel_dg_spi_aux.h b/include/linux/intel_dg_spi_aux.h
new file mode 100644
index 000000000000..d4c3830d56d6
--- /dev/null
+++ b/include/linux/intel_dg_spi_aux.h
@@ -0,0 +1,27 @@ 
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright(c) 2019-2024, Intel Corporation. All rights reserved.
+ */
+
+#ifndef __INTEL_DG_SPI_AUX_H__
+#define __INTEL_DG_SPI_AUX_H__
+
+#include <linux/auxiliary_bus.h>
+
+#define INTEL_DG_SPI_REGIONS 13
+
+struct intel_dg_spi_region {
+	const char *name;
+};
+
+struct intel_dg_spi_dev {
+	struct auxiliary_device aux_dev;
+	bool writeable_override;
+	struct resource bar;
+	const struct intel_dg_spi_region *regions;
+};
+
+#define auxiliary_dev_to_intel_dg_spi_dev(auxiliary_dev) \
+	container_of(auxiliary_dev, struct intel_dg_spi_dev, aux_dev)
+
+#endif /* __INTEL_DG_SPI_AUX_H__ */