drivers/gpu/drm/xe/xe_i2c.c

// 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 (IS_ERR(fwnode))
		return PTR_ERR(fwnode);

	/*
	 * 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,
};

void xe_i2c_pm_suspend(struct xe_device *xe)
{
	struct xe_mmio *mmio = xe_root_tile_mmio(xe);

	if (!xe->i2c || xe->i2c->ep.cookie != XE_I2C_EP_COOKIE_DEVICE)
		return;

	xe_mmio_rmw32(mmio, I2C_CONFIG_PMCSR, PCI_PM_CTRL_STATE_MASK, (__force u32)PCI_D3hot);
	drm_dbg(&xe->drm, "pmcsr: 0x%08x\n", xe_mmio_read32(mmio, I2C_CONFIG_PMCSR));
}

void xe_i2c_pm_resume(struct xe_device *xe, bool d3cold)
{
	struct xe_mmio *mmio = xe_root_tile_mmio(xe);

	if (!xe->i2c || xe->i2c->ep.cookie != XE_I2C_EP_COOKIE_DEVICE)
		return;

	if (d3cold)
		xe_mmio_rmw32(mmio, I2C_CONFIG_CMD, 0, PCI_COMMAND_MEMORY);

	xe_mmio_rmw32(mmio, I2C_CONFIG_PMCSR, PCI_PM_CTRL_STATE_MASK, (__force u32)PCI_D0);
	drm_dbg(&xe->drm, "pmcsr: 0x%08x\n", xe_mmio_read32(mmio, I2C_CONFIG_PMCSR));
}

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;

	if (IS_SRIOV_VF(xe))
		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;
	xe->i2c = i2c;

	/* PCI PM isn't aware of this device, bring it up and match it with SGUnit state. */
	xe_i2c_pm_resume(xe, true);

	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;
}