[PATCH v2 1/2] platform/x86/intel: Introduce Intel Elkhart Lake PSE I/O

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

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 <raag.jadav@intel.com>
---
 MAINTAINERS                             |   7 ++
 drivers/platform/x86/intel/Kconfig      |  13 +++
 drivers/platform/x86/intel/Makefile     |   1 +
 drivers/platform/x86/intel/ehl_pse_io.c | 107 ++++++++++++++++++++++++
 include/linux/ehl_pse_io_aux.h          |  30 +++++++
 5 files changed, 158 insertions(+)
 create mode 100644 drivers/platform/x86/intel/ehl_pse_io.c
 create mode 100644 include/linux/ehl_pse_io_aux.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 46126ce2f968..bd2a009d73c6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12499,6 +12499,13 @@ F:	drivers/gpu/drm/xe/
 F:	include/drm/intel/
 F:	include/uapi/drm/xe_drm.h
 
+INTEL ELKHART LAKE PSE I/O DRIVER
+M:	Raag Jadav <raag.jadav@intel.com>
+L:	platform-driver-x86@vger.kernel.org
+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 <anthony.l.nguyen@intel.com>
 M:	Przemek Kitszel <przemyslaw.kitszel@intel.com>
diff --git a/drivers/platform/x86/intel/Kconfig b/drivers/platform/x86/intel/Kconfig
index 19a2246f2770..2900407d6095 100644
--- a/drivers/platform/x86/intel/Kconfig
+++ b/drivers/platform/x86/intel/Kconfig
@@ -41,6 +41,19 @@ config INTEL_VBTN
 	  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
diff --git a/drivers/platform/x86/intel/Makefile b/drivers/platform/x86/intel/Makefile
index 78acb414e154..138b13756158 100644
--- a/drivers/platform/x86/intel/Makefile
+++ b/drivers/platform/x86/intel/Makefile
@@ -21,6 +21,7 @@ intel-target-$(CONFIG_INTEL_HID_EVENT)		+= hid.o
 intel-target-$(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
diff --git a/drivers/platform/x86/intel/ehl_pse_io.c b/drivers/platform/x86/intel/ehl_pse_io.c
new file mode 100644
index 000000000000..9766d5dec1da
--- /dev/null
+++ b/drivers/platform/x86/intel/ehl_pse_io.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Intel Elkhart Lake Programmable Service Engine (PSE) I/O
+ *
+ * Copyright (c) 2025 Intel Corporation.
+ *
+ * Author: Raag Jadav <raag.jadav@intel.com>
+ */
+
+#include <linux/auxiliary_bus.h>
+#include <linux/device/devres.h>
+#include <linux/device.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 void ehl_pse_io_dev_release(struct device *dev) {}
+
+static void ehl_pse_io_dev_destroy(void *aux_dev)
+{
+	auxiliary_device_destroy(aux_dev);
+}
+
+static int ehl_pse_io_dev_add(struct pci_dev *pci, const char *name, int idx)
+{
+	struct auxiliary_device *aux_dev;
+	struct device *dev = &pci->dev;
+	struct ehl_pse_io_dev *io_dev;
+	resource_size_t start, offset;
+	int ret;
+
+	io_dev = devm_kzalloc(dev, sizeof(*io_dev), GFP_KERNEL);
+	if (!io_dev)
+		return -ENOMEM;
+
+	start = pci_resource_start(pci, 0);
+	offset = EHL_PSE_IO_DEV_SIZE * idx;
+
+	io_dev->irq = pci_irq_vector(pci, idx);
+	io_dev->mem = DEFINE_RES_MEM(start + offset, EHL_PSE_IO_DEV_SIZE);
+
+	aux_dev = &io_dev->aux_dev;
+	aux_dev->name = name;
+	aux_dev->id = (pci_domain_nr(pci->bus) << 16) | pci_dev_id(pci);
+	aux_dev->dev.parent = dev;
+	aux_dev->dev.release = ehl_pse_io_dev_release;
+
+	ret = auxiliary_device_init(aux_dev);
+	if (ret)
+		return ret;
+
+	ret = auxiliary_device_add(aux_dev);
+	if (ret) {
+		auxiliary_device_uninit(aux_dev);
+		return ret;
+	}
+
+	return devm_add_action_or_reset(dev, ehl_pse_io_dev_destroy, aux_dev);
+}
+
+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_add(pci, EHL_PSE_GPIO_NAME, 0);
+	if (ret)
+		return ret;
+
+	return ehl_pse_io_dev_add(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 <raag.jadav@intel.com>");
+MODULE_DESCRIPTION("Intel Elkhart Lake PSE I/O driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/ehl_pse_io_aux.h b/include/linux/ehl_pse_io_aux.h
new file mode 100644
index 000000000000..fff5effbd7f9
--- /dev/null
+++ b/include/linux/ehl_pse_io_aux.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Intel Elkhart Lake PSE I/O Auxiliary Device
+ *
+ * Copyright (c) 2025 Intel Corporation.
+ *
+ * Author: Raag Jadav <raag.jadav@intel.com>
+ */
+
+#ifndef _EHL_PSE_IO_AUX_H_
+#define _EHL_PSE_IO_AUX_H_
+
+#include <linux/auxiliary_bus.h>
+#include <linux/container_of.h>
+#include <linux/ioport.h>
+
+#define EHL_PSE_IO_NAME		"intel_ehl_pse_io"
+#define EHL_PSE_GPIO_NAME	"gpio"
+#define EHL_PSE_TIO_NAME	"pps_tio"
+
+struct ehl_pse_io_dev {
+	struct auxiliary_device aux_dev;
+	struct resource mem;
+	int irq;
+};
+
+#define auxiliary_dev_to_ehl_pse_io_dev(auxiliary_dev) \
+	container_of(auxiliary_dev, struct ehl_pse_io_dev, aux_dev)
+
+#endif /* _EHL_PSE_IO_AUX_H_ */
-- 
2.43.0