// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/*
 * AMD MP2 platform driver
 *
 * Setup the I2C adapters enumerated in the ACPI namespace.
 * MP2 controllers have 2 separate busses, up to 2 I2C adapters may be listed.
 *
 * Authors: Nehal Bakulchandra Shah <Nehal-bakulchandra.shah@amd.com>
 *          Elie Morisse <syniurge@gmail.com>
 */

#include <linux/acpi.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/types.h>

#include "i2c-amd-mp2.h"

#define AMD_MP2_I2C_MAX_RW_LENGTH ((1 << 12) - 1)
#define AMD_I2C_TIMEOUT (msecs_to_jiffies(250))

/**
 * struct amd_i2c_dev - MP2 bus/i2c adapter context
 * @common: shared context with the MP2 PCI driver
 * @pdev: platform driver node
 * @adap: i2c adapter
 * @cmd_complete: xfer completion object
 */
struct amd_i2c_dev {
	struct amd_i2c_common common;
	struct platform_device *pdev;
	struct i2c_adapter adap;
	struct completion cmd_complete;
};

#define amd_i2c_dev_common(__common) \
	container_of(__common, struct amd_i2c_dev, common)

static int i2c_amd_dma_map(struct amd_i2c_common *i2c_common)
{
	struct device *dev_pci = &i2c_common->mp2_dev->pci_dev->dev;
	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
	enum dma_data_direction dma_direction =
			i2c_common->msg->flags & I2C_M_RD ?
			DMA_FROM_DEVICE : DMA_TO_DEVICE;

	i2c_common->dma_buf = i2c_get_dma_safe_msg_buf(i2c_common->msg, 0);
	i2c_common->dma_addr = dma_map_single(dev_pci, i2c_common->dma_buf,
					      i2c_common->msg->len,
					      dma_direction);

	if (unlikely(dma_mapping_error(dev_pci, i2c_common->dma_addr))) {
		dev_err(&i2c_dev->pdev->dev,
			"Error while mapping dma buffer %p\n",
			i2c_common->dma_buf);
		return -EIO;
	}

	return 0;
}

static void i2c_amd_dma_unmap(struct amd_i2c_common *i2c_common)
{
	struct device *dev_pci = &i2c_common->mp2_dev->pci_dev->dev;
	enum dma_data_direction dma_direction =
			i2c_common->msg->flags & I2C_M_RD ?
			DMA_FROM_DEVICE : DMA_TO_DEVICE;

	dma_unmap_single(dev_pci, i2c_common->dma_addr,
			 i2c_common->msg->len, dma_direction);

	i2c_put_dma_safe_msg_buf(i2c_common->dma_buf, i2c_common->msg, true);
}

static void i2c_amd_start_cmd(struct amd_i2c_dev *i2c_dev)
{
	struct amd_i2c_common *i2c_common = &i2c_dev->common;

	reinit_completion(&i2c_dev->cmd_complete);
	i2c_common->cmd_success = false;
}

static void i2c_amd_cmd_completion(struct amd_i2c_common *i2c_common)
{
	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);
	union i2c_event *event = &i2c_common->eventval;

	if (event->r.status == i2c_readcomplete_event)
		dev_dbg(&i2c_dev->pdev->dev, "readdata:%*ph\n", event->r.length,
			i2c_common->msg->buf);

	complete(&i2c_dev->cmd_complete);
}

static int i2c_amd_check_cmd_completion(struct amd_i2c_dev *i2c_dev)
{
	struct amd_i2c_common *i2c_common = &i2c_dev->common;
	unsigned long timeout;

	timeout = wait_for_completion_timeout(&i2c_dev->cmd_complete,
					      i2c_dev->adap.timeout);

	if ((i2c_common->reqcmd == i2c_read ||
	     i2c_common->reqcmd == i2c_write) &&
	    i2c_common->msg->len > 32)
		i2c_amd_dma_unmap(i2c_common);

	if (timeout == 0) {
		amd_mp2_rw_timeout(i2c_common);
		return -ETIMEDOUT;
	}

	amd_mp2_process_event(i2c_common);

	if (!i2c_common->cmd_success)
		return -EIO;

	return 0;
}

static int i2c_amd_enable_set(struct amd_i2c_dev *i2c_dev, bool enable)
{
	struct amd_i2c_common *i2c_common = &i2c_dev->common;

	i2c_amd_start_cmd(i2c_dev);
	amd_mp2_bus_enable_set(i2c_common, enable);

	return i2c_amd_check_cmd_completion(i2c_dev);
}

static int i2c_amd_xfer_msg(struct amd_i2c_dev *i2c_dev, struct i2c_msg *pmsg)
{
	struct amd_i2c_common *i2c_common = &i2c_dev->common;

	i2c_amd_start_cmd(i2c_dev);
	i2c_common->msg = pmsg;

	if (pmsg->len > 32)
		if (i2c_amd_dma_map(i2c_common))
			return -EIO;

	if (pmsg->flags & I2C_M_RD)
		amd_mp2_rw(i2c_common, i2c_read);
	else
		amd_mp2_rw(i2c_common, i2c_write);

	return i2c_amd_check_cmd_completion(i2c_dev);
}

static int i2c_amd_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
	struct amd_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
	int i;
	struct i2c_msg *pmsg;
	int err = 0;

	/* the adapter might have been deleted while waiting for the bus lock */
	if (unlikely(!i2c_dev->common.mp2_dev))
		return -EINVAL;

	amd_mp2_pm_runtime_get(i2c_dev->common.mp2_dev);

	for (i = 0; i < num; i++) {
		pmsg = &msgs[i];
		err = i2c_amd_xfer_msg(i2c_dev, pmsg);
		if (err)
			break;
	}

	amd_mp2_pm_runtime_put(i2c_dev->common.mp2_dev);
	return err ? err : num;
}

static u32 i2c_amd_func(struct i2c_adapter *a)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

static const struct i2c_algorithm i2c_amd_algorithm = {
	.master_xfer = i2c_amd_xfer,
	.functionality = i2c_amd_func,
};

#ifdef CONFIG_PM
static int i2c_amd_suspend(struct amd_i2c_common *i2c_common)
{
	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);

	i2c_amd_enable_set(i2c_dev, false);
	return 0;
}

static int i2c_amd_resume(struct amd_i2c_common *i2c_common)
{
	struct amd_i2c_dev *i2c_dev = amd_i2c_dev_common(i2c_common);

	return i2c_amd_enable_set(i2c_dev, true);
}
#endif

static const u32 supported_speeds[] = {
	I2C_MAX_HIGH_SPEED_MODE_FREQ,
	I2C_MAX_TURBO_MODE_FREQ,
	I2C_MAX_FAST_MODE_PLUS_FREQ,
	I2C_MAX_FAST_MODE_FREQ,
	I2C_MAX_STANDARD_MODE_FREQ,
};

static enum speed_enum i2c_amd_get_bus_speed(struct platform_device *pdev)
{
	u32 acpi_speed;
	int i;

	acpi_speed = i2c_acpi_find_bus_speed(&pdev->dev);
	/* round down to the lowest standard speed */
	for (i = 0; i < ARRAY_SIZE(supported_speeds); i++) {
		if (acpi_speed >= supported_speeds[i])
			break;
	}
	acpi_speed = i < ARRAY_SIZE(supported_speeds) ? supported_speeds[i] : 0;

	switch (acpi_speed) {
	case I2C_MAX_STANDARD_MODE_FREQ:
		return speed100k;
	case I2C_MAX_FAST_MODE_FREQ:
		return speed400k;
	case I2C_MAX_FAST_MODE_PLUS_FREQ:
		return speed1000k;
	case I2C_MAX_TURBO_MODE_FREQ:
		return speed1400k;
	case I2C_MAX_HIGH_SPEED_MODE_FREQ:
		return speed3400k;
	default:
		return speed400k;
	}
}

static const struct i2c_adapter_quirks amd_i2c_dev_quirks = {
	.max_read_len = AMD_MP2_I2C_MAX_RW_LENGTH,
	.max_write_len = AMD_MP2_I2C_MAX_RW_LENGTH,
};

static int i2c_amd_probe(struct platform_device *pdev)
{
	int ret;
	struct amd_i2c_dev *i2c_dev;
	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
	struct amd_mp2_dev *mp2_dev;
	const char *uid;

	if (!adev)
		return -ENODEV;

	/* The ACPI namespace doesn't contain information about which MP2 PCI
	 * device an AMDI0011 ACPI device is related to, so assume that there's
	 * only one MP2 PCI device per system.
	 */
	mp2_dev = amd_mp2_find_device();
	if (!mp2_dev || !mp2_dev->probed)
		/* The MP2 PCI device should get probed later */
		return -EPROBE_DEFER;

	i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
	if (!i2c_dev)
		return -ENOMEM;

	i2c_dev->common.mp2_dev = mp2_dev;
	i2c_dev->pdev = pdev;
	platform_set_drvdata(pdev, i2c_dev);

	i2c_dev->common.cmd_completion = &i2c_amd_cmd_completion;
#ifdef CONFIG_PM
	i2c_dev->common.suspend = &i2c_amd_suspend;
	i2c_dev->common.resume = &i2c_amd_resume;
#endif

	uid = adev->pnp.unique_id;
	if (!uid) {
		dev_err(&pdev->dev, "missing UID/bus id!\n");
		return -EINVAL;
	} else if (strcmp(uid, "0") == 0) {
		i2c_dev->common.bus_id = 0;
	} else if (strcmp(uid, "1") == 0) {
		i2c_dev->common.bus_id = 1;
	} else {
		dev_err(&pdev->dev, "incorrect UID/bus id \"%s\"!\n", uid);
		return -EINVAL;
	}
	dev_dbg(&pdev->dev, "bus id is %u\n", i2c_dev->common.bus_id);

	/* Register the adapter */
	amd_mp2_pm_runtime_get(mp2_dev);

	i2c_dev->common.reqcmd = i2c_none;
	if (amd_mp2_register_cb(&i2c_dev->common))
		return -EINVAL;
	device_link_add(&i2c_dev->pdev->dev, &mp2_dev->pci_dev->dev,
			DL_FLAG_AUTOREMOVE_CONSUMER);

	i2c_dev->common.i2c_speed = i2c_amd_get_bus_speed(pdev);

	/* Setup i2c adapter description */
	i2c_dev->adap.owner = THIS_MODULE;
	i2c_dev->adap.algo = &i2c_amd_algorithm;
	i2c_dev->adap.quirks = &amd_i2c_dev_quirks;
	i2c_dev->adap.dev.parent = &pdev->dev;
	i2c_dev->adap.algo_data = i2c_dev;
	i2c_dev->adap.timeout = AMD_I2C_TIMEOUT;
	ACPI_COMPANION_SET(&i2c_dev->adap.dev, ACPI_COMPANION(&pdev->dev));
	i2c_dev->adap.dev.of_node = pdev->dev.of_node;
	snprintf(i2c_dev->adap.name, sizeof(i2c_dev->adap.name),
		 "AMD MP2 i2c bus %u", i2c_dev->common.bus_id);
	i2c_set_adapdata(&i2c_dev->adap, i2c_dev);

	init_completion(&i2c_dev->cmd_complete);

	/* Enable the bus */
	if (i2c_amd_enable_set(i2c_dev, true))
		dev_err(&pdev->dev, "initial bus enable failed\n");

	/* Attach to the i2c layer */
	ret = i2c_add_adapter(&i2c_dev->adap);

	amd_mp2_pm_runtime_put(mp2_dev);

	if (ret < 0)
		dev_err(&pdev->dev, "i2c add adapter failed = %d\n", ret);

	return ret;
}

static int i2c_amd_remove(struct platform_device *pdev)
{
	struct amd_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
	struct amd_i2c_common *i2c_common = &i2c_dev->common;

	i2c_lock_bus(&i2c_dev->adap, I2C_LOCK_ROOT_ADAPTER);

	i2c_amd_enable_set(i2c_dev, false);
	amd_mp2_unregister_cb(i2c_common);
	i2c_common->mp2_dev = NULL;

	i2c_unlock_bus(&i2c_dev->adap, I2C_LOCK_ROOT_ADAPTER);

	i2c_del_adapter(&i2c_dev->adap);
	return 0;
}

static const struct acpi_device_id i2c_amd_acpi_match[] = {
	{ "AMDI0011" },
	{ },
};
MODULE_DEVICE_TABLE(acpi, i2c_amd_acpi_match);

static struct platform_driver i2c_amd_plat_driver = {
	.probe = i2c_amd_probe,
	.remove = i2c_amd_remove,
	.driver = {
		.name = "i2c_amd_mp2",
		.acpi_match_table = ACPI_PTR(i2c_amd_acpi_match),
	},
};
module_platform_driver(i2c_amd_plat_driver);

MODULE_DESCRIPTION("AMD(R) MP2 I2C Platform Driver");
MODULE_AUTHOR("Nehal Shah <nehal-bakulchandra.shah@amd.com>");
MODULE_AUTHOR("Elie Morisse <syniurge@gmail.com>");
MODULE_LICENSE("Dual BSD/GPL");