platform/x86/intel: Introduce Intel Elkhart Lake PSE I/O

Intel Elkhart Lake Programmable Service Engine (PSE) includes two PCI
devices that expose two different capabilities of GPIO and Timed I/O
as a single PCI function through shared MMIO with below layout.

GPIO: 0x0000 - 0x1000
TIO: 0x1000 - 0x2000

This driver enumerates the PCI parent device and creates auxiliary child
devices for these capabilities. The actual functionalities are provided
by their respective auxiliary drivers.

Signed-off-by: Raag Jadav <[e-mail]>
Acked-by: Ilpo Järvinen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bartosz Golaszewski <[e-mail]>

MAINTAINERS

···
 F:	include/drm/intel/
 F:	include/uapi/drm/xe_drm.h
 
+INTEL ELKHART LAKE PSE I/O DRIVER
+M:	Raag Jadav <[e-mail]>
+L:	[e-mail]
+S:	Supported
+F:	drivers/platform/x86/intel/ehl_pse_io.c
+F:	include/linux/ehl_pse_io_aux.h
+
 INTEL ETHERNET DRIVERS
 M:	Tony Nguyen <[e-mail]>
 M:	Przemek Kitszel <[e-mail]>

drivers/platform/x86/intel/Kconfig

···
 	  To compile this driver as a module, choose M here: the module will
 	  be called intel_vbtn.
 
+config INTEL_EHL_PSE_IO
+	tristate "Intel Elkhart Lake PSE I/O driver"
+	depends on PCI
+	select AUXILIARY_BUS
+	help
+	  Select this option to enable Intel Elkhart Lake PSE GPIO and Timed
+	  I/O support. This driver enumerates the PCI parent device and
+	  creates auxiliary child devices for these capabilities. The actual
+	  functionalities are provided by their respective auxiliary drivers.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called intel_ehl_pse_io.
+
 config INTEL_INT0002_VGPIO
 	tristate "Intel ACPI INT0002 Virtual GPIO driver"
 	depends on GPIOLIB && ACPI && PM_SLEEP

drivers/platform/x86/intel/Makefile

···
 intel-target-$(CONFIG_INTEL_VBTN)		+= vbtn.o
 
 # Intel miscellaneous drivers
+intel-target-$(CONFIG_INTEL_EHL_PSE_IO)		+= ehl_pse_io.o
 intel-target-$(CONFIG_INTEL_INT0002_VGPIO)	+= int0002_vgpio.o
 intel-target-$(CONFIG_INTEL_ISHTP_ECLITE)	+= ishtp_eclite.o
 intel-target-$(CONFIG_INTEL_OAKTRAIL)		+= oaktrail.o

drivers/platform/x86/intel/ehl_pse_io.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Intel Elkhart Lake Programmable Service Engine (PSE) I/O
+ *
+ * Copyright (c) 2025 Intel Corporation.
+ *
+ * Author: Raag Jadav <[e-mail]>
+ */
+
+#include <linux/auxiliary_bus.h>
+#include <linux/device/devres.h>
+#include <linux/errno.h>
+#include <linux/gfp_types.h>
+#include <linux/ioport.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/sizes.h>
+#include <linux/types.h>
+
+#include <linux/ehl_pse_io_aux.h>
+
+#define EHL_PSE_IO_DEV_SIZE	SZ_4K
+
+static int ehl_pse_io_dev_create(struct pci_dev *pci, const char *name, int idx)
+{
+	struct device *dev = &pci->dev;
+	struct auxiliary_device *adev;
+	struct ehl_pse_io_data *data;
+	resource_size_t start, offset;
+	u32 id;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	id = (pci_domain_nr(pci->bus) << 16) | pci_dev_id(pci);
+	start = pci_resource_start(pci, 0);
+	offset = EHL_PSE_IO_DEV_SIZE * idx;
+
+	data->mem = DEFINE_RES_MEM(start + offset, EHL_PSE_IO_DEV_SIZE);
+	data->irq = pci_irq_vector(pci, idx);
+
+	adev = __devm_auxiliary_device_create(dev, EHL_PSE_IO_NAME, name, data, id);
+
+	return adev ? 0 : -ENODEV;
+}
+
+static int ehl_pse_io_probe(struct pci_dev *pci, const struct pci_device_id *id)
+{
+	int ret;
+
+	ret = pcim_enable_device(pci);
+	if (ret)
+		return ret;
+
+	pci_set_master(pci);
+
+	ret = pci_alloc_irq_vectors(pci, 2, 2, PCI_IRQ_MSI);
+	if (ret < 0)
+		return ret;
+
+	ret = ehl_pse_io_dev_create(pci, EHL_PSE_GPIO_NAME, 0);
+	if (ret)
+		return ret;
+
+	return ehl_pse_io_dev_create(pci, EHL_PSE_TIO_NAME, 1);
+}
+
+static const struct pci_device_id ehl_pse_io_ids[] = {
+	{ PCI_VDEVICE(INTEL, 0x4b88) },
+	{ PCI_VDEVICE(INTEL, 0x4b89) },
+	{ }
+};
+MODULE_DEVICE_TABLE(pci, ehl_pse_io_ids);
+
+static struct pci_driver ehl_pse_io_driver = {
+	.name		= EHL_PSE_IO_NAME,
+	.id_table	= ehl_pse_io_ids,
+	.probe		= ehl_pse_io_probe,
+};
+module_pci_driver(ehl_pse_io_driver);
+
+MODULE_AUTHOR("Raag Jadav <[e-mail]>");
+MODULE_DESCRIPTION("Intel Elkhart Lake PSE I/O driver");
+MODULE_LICENSE("GPL");

include/linux/ehl_pse_io_aux.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Intel Elkhart Lake PSE I/O Auxiliary Device
+ *
+ * Copyright (c) 2025 Intel Corporation.
+ *
+ * Author: Raag Jadav <[e-mail]>
+ */
+
+#ifndef _EHL_PSE_IO_AUX_H_
+#define _EHL_PSE_IO_AUX_H_
+
+#include <linux/ioport.h>
+
+#define EHL_PSE_IO_NAME		"ehl_pse_io"
+#define EHL_PSE_GPIO_NAME	"gpio"
+#define EHL_PSE_TIO_NAME	"pps_tio"
+
+struct ehl_pse_io_data {
+	struct resource mem;
+	int irq;
+};
+
+#endif /* _EHL_PSE_IO_AUX_H_ */