drm/xe: Support for I2C attached MCUs

Adding adaption/glue layer where the I2C host adapter
(Synopsys DesignWare I2C adapter) and the I2C clients (the
microcontroller units) are enumerated.

The microcontroller units (MCU) that are attached to the GPU
depend on the OEM. The initially supported MCU will be the
Add-In Management Controller (AMC).

Co-developed-by: Michael J. Ruhl <[email protected]>
Signed-off-by: Michael J. Ruhl <[email protected]>
Signed-off-by: Heikki Krogerus <[email protected]>
Reviewed-by: Rodrigo Vivi <[email protected]>
Reviewed-by: Andi Shyti <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Rodrigo Vivi <[email protected]>
[Rodrigo fixed the co-developed tags and SPDX format in the .c file]

Author: Heikki Krogerus

drivers/gpu/drm/xe/Kconfig

@@ -45,6 +45,7 @@ config DRM_XE
 	select WANT_DEV_COREDUMP
 	select AUXILIARY_BUS
 	select HMM_MIRROR
+	select REGMAP if I2C
 	help
 	  Driver for Intel Xe2 series GPUs and later. Experimental support
 	  for Xe series is also available.

drivers/gpu/drm/xe/Makefile

@@ -125,6 +125,7 @@ xe-y += xe_bb.o \
 	xe_wait_user_fence.o \
 	xe_wopcm.o
 
+xe-$(CONFIG_I2C)	+= xe_i2c.o
 xe-$(CONFIG_HMM_MIRROR) += xe_hmm.o
 xe-$(CONFIG_DRM_XE_GPUSVM) += xe_svm.o
 

drivers/gpu/drm/xe/regs/xe_i2c_regs.h

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: MIT */
+#ifndef _XE_I2C_REGS_H_
+#define _XE_I2C_REGS_H_
+
+#include "xe_reg_defs.h"
+#include "xe_regs.h"
+
+#define I2C_BRIDGE_OFFSET		(SOC_BASE + 0xd9000)
+#define I2C_CONFIG_SPACE_OFFSET		(SOC_BASE + 0xf6000)
+#define I2C_MEM_SPACE_OFFSET		(SOC_BASE + 0xf7400)
+
+#define REG_SG_REMAP_ADDR_PREFIX	XE_REG(SOC_BASE + 0x0164)
+#define REG_SG_REMAP_ADDR_POSTFIX	XE_REG(SOC_BASE + 0x0168)
+
+#endif /* _XE_I2C_REGS_H_ */

drivers/gpu/drm/xe/regs/xe_irq_regs.h

@@ -19,6 +19,7 @@
 #define   MASTER_IRQ				REG_BIT(31)
 #define   GU_MISC_IRQ				REG_BIT(29)
 #define   DISPLAY_IRQ				REG_BIT(16)
+#define   I2C_IRQ				REG_BIT(12)
 #define   GT_DW_IRQ(x)				REG_BIT(x)
 
 /*

drivers/gpu/drm/xe/regs/xe_pmt.h

@@ -5,7 +5,7 @@
 #ifndef _XE_PMT_H_
 #define _XE_PMT_H_
 
-#define SOC_BASE			0x280000
+#include "xe_regs.h"
 
 #define BMG_PMT_BASE_OFFSET		0xDB000
 #define BMG_DISCOVERY_OFFSET		(SOC_BASE + BMG_PMT_BASE_OFFSET)

drivers/gpu/drm/xe/regs/xe_regs.h

@@ -7,6 +7,8 @@
 
 #include "regs/xe_reg_defs.h"
 
+#define SOC_BASE				0x280000
+
 #define GU_CNTL_PROTECTED			XE_REG(0x10100C)
 #define   DRIVERINT_FLR_DIS			REG_BIT(31)
 

drivers/gpu/drm/xe/xe_device.c

@@ -43,6 +43,7 @@
 #include "xe_guc_pc.h"
 #include "xe_hw_engine_group.h"
 #include "xe_hwmon.h"
+#include "xe_i2c.h"
 #include "xe_irq.h"
 #include "xe_mmio.h"
 #include "xe_module.h"
@@ -902,6 +903,10 @@ int xe_device_probe(struct xe_device *xe)
 	if (err)
 		goto err_unregister_display;
 
+	err = xe_i2c_probe(xe);
+	if (err)
+		goto err_unregister_display;
+
 	for_each_gt(gt, xe, id)
 		xe_gt_sanitize_freq(gt);
 

drivers/gpu/drm/xe/xe_device_types.h

@@ -34,6 +34,7 @@ struct dram_info;
 struct intel_display;
 struct intel_dg_nvm_dev;
 struct xe_ggtt;
+struct xe_i2c;
 struct xe_pat_ops;
 struct xe_pxp;
 
@@ -585,6 +586,9 @@ struct xe_device {
 	/** @pmu: performance monitoring unit */
 	struct xe_pmu pmu;
 
+	/** @i2c: I2C host controller */
+	struct xe_i2c *i2c;
+
 	/** @atomic_svm_timeslice_ms: Atomic SVM fault timeslice MS */
 	u32 atomic_svm_timeslice_ms;
 

drivers/gpu/drm/xe/xe_i2c.c

@@ -0,0 +1,300 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+/*
+ * Intel Xe I2C attached Microcontroller Units (MCU)
+ *
+ * Copyright (C) 2025 Intel Corporation.
+ */
+
+#include <linux/array_size.h>
+#include <linux/container_of.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/ioport.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/notifier.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/sprintf.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+#include "regs/xe_i2c_regs.h"
+#include "regs/xe_irq_regs.h"
+
+#include "xe_device.h"
+#include "xe_device_types.h"
+#include "xe_i2c.h"
+#include "xe_mmio.h"
+#include "xe_platform_types.h"
+
+/**
+ * DOC: Xe I2C devices
+ *
+ * Register a platform device for the I2C host controller (Synpsys DesignWare
+ * I2C) if the registers of that controller are mapped to the MMIO, and also the
+ * I2C client device for the Add-In Management Controller (the MCU) attached to
+ * the host controller.
+ *
+ * See drivers/i2c/busses/i2c-designware-* for more information on the I2C host
+ * controller.
+ */
+
+static const char adapter_name[] = "i2c_designware";
+
+static const struct property_entry xe_i2c_adapter_properties[] = {
+	PROPERTY_ENTRY_STRING("compatible", "intel,xe-i2c"),
+	PROPERTY_ENTRY_U32("clock-frequency", I2C_MAX_FAST_MODE_PLUS_FREQ),
+	{ }
+};
+
+static inline void xe_i2c_read_endpoint(struct xe_mmio *mmio, void *ep)
+{
+	u32 *val = ep;
+
+	val[0] = xe_mmio_read32(mmio, REG_SG_REMAP_ADDR_PREFIX);
+	val[1] = xe_mmio_read32(mmio, REG_SG_REMAP_ADDR_POSTFIX);
+}
+
+static void xe_i2c_client_work(struct work_struct *work)
+{
+	struct xe_i2c *i2c = container_of(work, struct xe_i2c, work);
+	struct i2c_board_info info = {
+		.type	= "amc",
+		.flags	= I2C_CLIENT_HOST_NOTIFY,
+		.addr	= i2c->ep.addr[1],
+	};
+
+	i2c->client[0] = i2c_new_client_device(i2c->adapter, &info);
+}
+
+static int xe_i2c_notifier(struct notifier_block *nb, unsigned long action, void *data)
+{
+	struct xe_i2c *i2c = container_of(nb, struct xe_i2c, bus_notifier);
+	struct i2c_adapter *adapter = i2c_verify_adapter(data);
+	struct device *dev = data;
+
+	if (action == BUS_NOTIFY_ADD_DEVICE &&
+	    adapter && dev->parent == &i2c->pdev->dev) {
+		i2c->adapter = adapter;
+		schedule_work(&i2c->work);
+		return NOTIFY_OK;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static int xe_i2c_register_adapter(struct xe_i2c *i2c)
+{
+	struct pci_dev *pci = to_pci_dev(i2c->drm_dev);
+	struct platform_device *pdev;
+	struct fwnode_handle *fwnode;
+	int ret;
+
+	fwnode = fwnode_create_software_node(xe_i2c_adapter_properties, NULL);
+	if (!fwnode)
+		return -ENOMEM;
+
+	/*
+	 * Not using platform_device_register_full() here because we don't have
+	 * a handle to the platform_device before it returns. xe_i2c_notifier()
+	 * uses that handle, but it may be called before
+	 * platform_device_register_full() is done.
+	 */
+	pdev = platform_device_alloc(adapter_name, pci_dev_id(pci));
+	if (!pdev) {
+		ret = -ENOMEM;
+		goto err_fwnode_remove;
+	}
+
+	if (i2c->adapter_irq) {
+		struct resource res;
+
+		res = DEFINE_RES_IRQ_NAMED(i2c->adapter_irq, "xe_i2c");
+
+		ret = platform_device_add_resources(pdev, &res, 1);
+		if (ret)
+			goto err_pdev_put;
+	}
+
+	pdev->dev.parent = i2c->drm_dev;
+	pdev->dev.fwnode = fwnode;
+	i2c->adapter_node = fwnode;
+	i2c->pdev = pdev;
+
+	ret = platform_device_add(pdev);
+	if (ret)
+		goto err_pdev_put;
+
+	return 0;
+
+err_pdev_put:
+	platform_device_put(pdev);
+err_fwnode_remove:
+	fwnode_remove_software_node(fwnode);
+
+	return ret;
+}
+
+static void xe_i2c_unregister_adapter(struct xe_i2c *i2c)
+{
+	platform_device_unregister(i2c->pdev);
+	fwnode_remove_software_node(i2c->adapter_node);
+}
+
+/**
+ * xe_i2c_irq_handler: Handler for I2C interrupts
+ * @xe: xe device instance
+ * @master_ctl: interrupt register
+ *
+ * Forward interrupts generated by the I2C host adapter to the I2C host adapter
+ * driver.
+ */
+void xe_i2c_irq_handler(struct xe_device *xe, u32 master_ctl)
+{
+	if (!xe->i2c || !xe->i2c->adapter_irq)
+		return;
+
+	if (master_ctl & I2C_IRQ)
+		generic_handle_irq_safe(xe->i2c->adapter_irq);
+}
+
+static int xe_i2c_irq_map(struct irq_domain *h, unsigned int virq,
+			  irq_hw_number_t hw_irq_num)
+{
+	irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq);
+	return 0;
+}
+
+static const struct irq_domain_ops xe_i2c_irq_ops = {
+	.map = xe_i2c_irq_map,
+};
+
+static int xe_i2c_create_irq(struct xe_i2c *i2c)
+{
+	struct irq_domain *domain;
+
+	if (!(i2c->ep.capabilities & XE_I2C_EP_CAP_IRQ))
+		return 0;
+
+	domain = irq_domain_create_linear(dev_fwnode(i2c->drm_dev), 1, &xe_i2c_irq_ops, NULL);
+	if (!domain)
+		return -ENOMEM;
+
+	i2c->adapter_irq = irq_create_mapping(domain, 0);
+	i2c->irqdomain = domain;
+
+	return 0;
+}
+
+static void xe_i2c_remove_irq(struct xe_i2c *i2c)
+{
+	if (!i2c->irqdomain)
+		return;
+
+	irq_dispose_mapping(i2c->adapter_irq);
+	irq_domain_remove(i2c->irqdomain);
+}
+
+static int xe_i2c_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct xe_i2c *i2c = context;
+
+	*val = xe_mmio_read32(i2c->mmio, XE_REG(reg + I2C_MEM_SPACE_OFFSET));
+
+	return 0;
+}
+
+static int xe_i2c_write(void *context, unsigned int reg, unsigned int val)
+{
+	struct xe_i2c *i2c = context;
+
+	xe_mmio_write32(i2c->mmio, XE_REG(reg + I2C_MEM_SPACE_OFFSET), val);
+
+	return 0;
+}
+
+static const struct regmap_config i2c_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_read = xe_i2c_read,
+	.reg_write = xe_i2c_write,
+	.fast_io = true,
+};
+
+static void xe_i2c_remove(void *data)
+{
+	struct xe_i2c *i2c = data;
+	unsigned int i;
+
+	for (i = 0; i < XE_I2C_MAX_CLIENTS; i++)
+		i2c_unregister_device(i2c->client[i]);
+
+	bus_unregister_notifier(&i2c_bus_type, &i2c->bus_notifier);
+	xe_i2c_unregister_adapter(i2c);
+	xe_i2c_remove_irq(i2c);
+}
+
+/**
+ * xe_i2c_probe: Probe the I2C host adapter and the I2C clients attached to it
+ * @xe: xe device instance
+ *
+ * Register all the I2C devices described in the I2C Endpoint data structure.
+ *
+ * Return: 0 on success, error code on failure
+ */
+int xe_i2c_probe(struct xe_device *xe)
+{
+	struct device *drm_dev = xe->drm.dev;
+	struct xe_i2c_endpoint ep;
+	struct regmap *regmap;
+	struct xe_i2c *i2c;
+	int ret;
+
+	if (xe->info.platform != XE_BATTLEMAGE)
+		return 0;
+
+	xe_i2c_read_endpoint(xe_root_tile_mmio(xe), &ep);
+	if (ep.cookie != XE_I2C_EP_COOKIE_DEVICE)
+		return 0;
+
+	i2c = devm_kzalloc(drm_dev, sizeof(*i2c), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
+
+	INIT_WORK(&i2c->work, xe_i2c_client_work);
+	i2c->mmio = xe_root_tile_mmio(xe);
+	i2c->drm_dev = drm_dev;
+	i2c->ep = ep;
+
+	regmap = devm_regmap_init(drm_dev, NULL, i2c, &i2c_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	i2c->bus_notifier.notifier_call = xe_i2c_notifier;
+	ret = bus_register_notifier(&i2c_bus_type, &i2c->bus_notifier);
+	if (ret)
+		return ret;
+
+	ret = xe_i2c_create_irq(i2c);
+	if (ret)
+		goto err_unregister_notifier;
+
+	ret = xe_i2c_register_adapter(i2c);
+	if (ret)
+		goto err_remove_irq;
+
+	return devm_add_action_or_reset(drm_dev, xe_i2c_remove, i2c);
+
+err_remove_irq:
+	xe_i2c_remove_irq(i2c);
+
+err_unregister_notifier:
+	bus_unregister_notifier(&i2c_bus_type, &i2c->bus_notifier);
+
+	return ret;
+}