// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Linux I2C core ACPI support code
 *
 * Copyright (C) 2014 Intel Corp, Author: Lan Tianyu <tianyu.lan@intel.com>
 */

#include <linux/acpi.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/slab.h>

#include "i2c-core.h"

struct i2c_acpi_handler_data {
        struct acpi_connection_info info;
        struct i2c_adapter *adapter;
};

struct gsb_buffer {
        u8      status;
        u8      len;
        union {
                u16     wdata;
                u8      bdata;
                u8      data[0];
        };
} __packed;

struct i2c_acpi_lookup {
        struct i2c_board_info *info;
        acpi_handle adapter_handle;
        acpi_handle device_handle;
        acpi_handle search_handle;
        int n;
        int index;
        u32 speed;
        u32 min_speed;
        u32 force_speed;
};

/**
 * i2c_acpi_get_i2c_resource - Gets I2cSerialBus resource if type matches
 * @ares:       ACPI resource
 * @i2c:        Pointer to I2cSerialBus resource will be returned here
 *
 * Checks if the given ACPI resource is of type I2cSerialBus.
 * In this case, returns a pointer to it to the caller.
 *
 * Returns true if resource type is of I2cSerialBus, otherwise false.
 */
bool i2c_acpi_get_i2c_resource(struct acpi_resource *ares,
                               struct acpi_resource_i2c_serialbus **i2c)
{
        struct acpi_resource_i2c_serialbus *sb;

        if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
                return false;

        sb = &ares->data.i2c_serial_bus;
        if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
                return false;

        *i2c = sb;
        return true;
}
EXPORT_SYMBOL_GPL(i2c_acpi_get_i2c_resource);

static int i2c_acpi_fill_info(struct acpi_resource *ares, void *data)
{
        struct i2c_acpi_lookup *lookup = data;
        struct i2c_board_info *info = lookup->info;
        struct acpi_resource_i2c_serialbus *sb;
        acpi_status status;

        if (info->addr || !i2c_acpi_get_i2c_resource(ares, &sb))
                return 1;

        if (lookup->index != -1 && lookup->n++ != lookup->index)
                return 1;

        status = acpi_get_handle(lookup->device_handle,
                                 sb->resource_source.string_ptr,
                                 &lookup->adapter_handle);
        if (ACPI_FAILURE(status))
                return 1;

        info->addr = sb->slave_address;
        lookup->speed = sb->connection_speed;
        if (sb->access_mode == ACPI_I2C_10BIT_MODE)
                info->flags |= I2C_CLIENT_TEN;

        return 1;
}

static const struct acpi_device_id i2c_acpi_ignored_device_ids[] = {
        /*
         * ACPI video acpi_devices, which are handled by the acpi-video driver
         * sometimes contain a SERIAL_TYPE_I2C ACPI resource, ignore these.
         */
        { ACPI_VIDEO_HID, 0 },
        {}
};

static int i2c_acpi_do_lookup(struct acpi_device *adev,
                              struct i2c_acpi_lookup *lookup)
{
        struct i2c_board_info *info = lookup->info;
        struct list_head resource_list;
        int ret;

        if (acpi_bus_get_status(adev) || !adev->status.present)
                return -EINVAL;

        if (acpi_match_device_ids(adev, i2c_acpi_ignored_device_ids) == 0)
                return -ENODEV;

        memset(info, 0, sizeof(*info));
        lookup->device_handle = acpi_device_handle(adev);

        /* Look up for I2cSerialBus resource */
        INIT_LIST_HEAD(&resource_list);
        ret = acpi_dev_get_resources(adev, &resource_list,
                                     i2c_acpi_fill_info, lookup);
        acpi_dev_free_resource_list(&resource_list);

        if (ret < 0 || !info->addr)
                return -EINVAL;

        return 0;
}

static int i2c_acpi_add_resource(struct acpi_resource *ares, void *data)
{
        int *irq = data;
        struct resource r;

        if (*irq <= 0 && acpi_dev_resource_interrupt(ares, 0, &r))
                *irq = i2c_dev_irq_from_resources(&r, 1);

        return 1; /* No need to add resource to the list */
}

/**
 * i2c_acpi_get_irq - get device IRQ number from ACPI
 * @client: Pointer to the I2C client device
 *
 * Find the IRQ number used by a specific client device.
 *
 * Return: The IRQ number or an error code.
 */
int i2c_acpi_get_irq(struct i2c_client *client)
{
        struct acpi_device *adev = ACPI_COMPANION(&client->dev);
        struct list_head resource_list;
        int irq = -ENOENT;
        int ret;

        INIT_LIST_HEAD(&resource_list);

        ret = acpi_dev_get_resources(adev, &resource_list,
                                     i2c_acpi_add_resource, &irq);
        if (ret < 0)
                return ret;

        acpi_dev_free_resource_list(&resource_list);

        if (irq == -ENOENT)
                irq = acpi_dev_gpio_irq_get(adev, 0);

        return irq;
}

static int i2c_acpi_get_info(struct acpi_device *adev,
                             struct i2c_board_info *info,
                             struct i2c_adapter *adapter,
                             acpi_handle *adapter_handle)
{
        struct i2c_acpi_lookup lookup;
        int ret;

        memset(&lookup, 0, sizeof(lookup));
        lookup.info = info;
        lookup.index = -1;

        if (acpi_device_enumerated(adev))
                return -EINVAL;

        ret = i2c_acpi_do_lookup(adev, &lookup);
        if (ret)
                return ret;

        if (adapter) {
                /* The adapter must match the one in I2cSerialBus() connector */
                if (ACPI_HANDLE(&adapter->dev) != lookup.adapter_handle)
                        return -ENODEV;
        } else {
                struct acpi_device *adapter_adev;

                /* The adapter must be present */
                if (acpi_bus_get_device(lookup.adapter_handle, &adapter_adev))
                        return -ENODEV;
                if (acpi_bus_get_status(adapter_adev) ||
                    !adapter_adev->status.present)
                        return -ENODEV;
        }

        info->fwnode = acpi_fwnode_handle(adev);
        if (adapter_handle)
                *adapter_handle = lookup.adapter_handle;

        acpi_set_modalias(adev, dev_name(&adev->dev), info->type,
                          sizeof(info->type));

        return 0;
}

static void i2c_acpi_register_device(struct i2c_adapter *adapter,
                                     struct acpi_device *adev,
                                     struct i2c_board_info *info)
{
        adev->power.flags.ignore_parent = true;
        acpi_device_set_enumerated(adev);

        if (IS_ERR(i2c_new_client_device(adapter, info)))
                adev->power.flags.ignore_parent = false;
}

static acpi_status i2c_acpi_add_device(acpi_handle handle, u32 level,
                                       void *data, void **return_value)
{
        struct i2c_adapter *adapter = data;
        struct acpi_device *adev;
        struct i2c_board_info info;

        if (acpi_bus_get_device(handle, &adev))
                return AE_OK;

        if (i2c_acpi_get_info(adev, &info, adapter, NULL))
                return AE_OK;

        i2c_acpi_register_device(adapter, adev, &info);

        return AE_OK;
}

#define I2C_ACPI_MAX_SCAN_DEPTH 32

/**
 * i2c_acpi_register_devices - enumerate I2C slave devices behind adapter
 * @adap: pointer to adapter
 *
 * Enumerate all I2C slave devices behind this adapter by walking the ACPI
 * namespace. When a device is found it will be added to the Linux device
 * model and bound to the corresponding ACPI handle.
 */
void i2c_acpi_register_devices(struct i2c_adapter *adap)
{
        acpi_status status;
        acpi_handle handle;

        if (!has_acpi_companion(&adap->dev))
                return;

        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
                                     I2C_ACPI_MAX_SCAN_DEPTH,
                                     i2c_acpi_add_device, NULL,
                                     adap, NULL);
        if (ACPI_FAILURE(status))
                dev_warn(&adap->dev, "failed to enumerate I2C slaves\n");

        if (!adap->dev.parent)
                return;

        handle = ACPI_HANDLE(adap->dev.parent);
        if (!handle)
                return;

        acpi_walk_dep_device_list(handle);
}

static const struct acpi_device_id i2c_acpi_force_400khz_device_ids[] = {
        /*
         * These Silead touchscreen controllers only work at 400KHz, for
         * some reason they do not work at 100KHz. On some devices the ACPI
         * tables list another device at their bus as only being capable
         * of 100KHz, testing has shown that these other devices work fine
         * at 400KHz (as can be expected of any recent i2c hw) so we force
         * the speed of the bus to 400 KHz if a Silead device is present.
         */
        { "MSSL1680", 0 },
        {}
};

static acpi_status i2c_acpi_lookup_speed(acpi_handle handle, u32 level,
                                           void *data, void **return_value)
{
        struct i2c_acpi_lookup *lookup = data;
        struct acpi_device *adev;

        if (acpi_bus_get_device(handle, &adev))
                return AE_OK;

        if (i2c_acpi_do_lookup(adev, lookup))
                return AE_OK;

        if (lookup->search_handle != lookup->adapter_handle)
                return AE_OK;

        if (lookup->speed <= lookup->min_speed)
                lookup->min_speed = lookup->speed;

        if (acpi_match_device_ids(adev, i2c_acpi_force_400khz_device_ids) == 0)
                lookup->force_speed = I2C_MAX_FAST_MODE_FREQ;

        return AE_OK;
}

/**
 * i2c_acpi_find_bus_speed - find I2C bus speed from ACPI
 * @dev: The device owning the bus
 *
 * Find the I2C bus speed by walking the ACPI namespace for all I2C slaves
 * devices connected to this bus and use the speed of slowest device.
 *
 * Returns the speed in Hz or zero
 */
u32 i2c_acpi_find_bus_speed(struct device *dev)
{
        struct i2c_acpi_lookup lookup;
        struct i2c_board_info dummy;
        acpi_status status;

        if (!has_acpi_companion(dev))
                return 0;

        memset(&lookup, 0, sizeof(lookup));
        lookup.search_handle = ACPI_HANDLE(dev);
        lookup.min_speed = UINT_MAX;
        lookup.info = &dummy;
        lookup.index = -1;

        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
                                     I2C_ACPI_MAX_SCAN_DEPTH,
                                     i2c_acpi_lookup_speed, NULL,
                                     &lookup, NULL);

        if (ACPI_FAILURE(status)) {
                dev_warn(dev, "unable to find I2C bus speed from ACPI\n");
                return 0;
        }

        if (lookup.force_speed) {
                if (lookup.force_speed != lookup.min_speed)
                        dev_warn(dev, FW_BUG "DSDT uses known not-working I2C bus speed %d, forcing it to %d\n",
                                 lookup.min_speed, lookup.force_speed);
                return lookup.force_speed;
        } else if (lookup.min_speed != UINT_MAX) {
                return lookup.min_speed;
        } else {
                return 0;
        }
}
EXPORT_SYMBOL_GPL(i2c_acpi_find_bus_speed);

static int i2c_acpi_find_match_adapter(struct device *dev, const void *data)
{
        struct i2c_adapter *adapter = i2c_verify_adapter(dev);

        if (!adapter)
                return 0;

        return ACPI_HANDLE(dev) == (acpi_handle)data;
}

struct i2c_adapter *i2c_acpi_find_adapter_by_handle(acpi_handle handle)
{
        struct device *dev;

        dev = bus_find_device(&i2c_bus_type, NULL, handle,
                              i2c_acpi_find_match_adapter);

        return dev ? i2c_verify_adapter(dev) : NULL;
}
EXPORT_SYMBOL_GPL(i2c_acpi_find_adapter_by_handle);

static struct i2c_client *i2c_acpi_find_client_by_adev(struct acpi_device *adev)
{
        struct device *dev;
        struct i2c_client *client;

        dev = bus_find_device_by_acpi_dev(&i2c_bus_type, adev);
        if (!dev)
                return NULL;

        client = i2c_verify_client(dev);
        if (!client)
                put_device(dev);

        return client;
}

static int i2c_acpi_notify(struct notifier_block *nb, unsigned long value,
                           void *arg)
{
        struct acpi_device *adev = arg;
        struct i2c_board_info info;
        acpi_handle adapter_handle;
        struct i2c_adapter *adapter;
        struct i2c_client *client;

        switch (value) {
        case ACPI_RECONFIG_DEVICE_ADD:
                if (i2c_acpi_get_info(adev, &info, NULL, &adapter_handle))
                        break;

                adapter = i2c_acpi_find_adapter_by_handle(adapter_handle);
                if (!adapter)
                        break;

                i2c_acpi_register_device(adapter, adev, &info);
                break;
        case ACPI_RECONFIG_DEVICE_REMOVE:
                if (!acpi_device_enumerated(adev))
                        break;

                client = i2c_acpi_find_client_by_adev(adev);
                if (!client)
                        break;

                i2c_unregister_device(client);
                put_device(&client->dev);
                break;
        }

        return NOTIFY_OK;
}

struct notifier_block i2c_acpi_notifier = {
        .notifier_call = i2c_acpi_notify,
};

/**
 * i2c_acpi_new_device - Create i2c-client for the Nth I2cSerialBus resource
 * @dev:     Device owning the ACPI resources to get the client from
 * @index:   Index of ACPI resource to get
 * @info:    describes the I2C device; note this is modified (addr gets set)
 * Context: can sleep
 *
 * By default the i2c subsys creates an i2c-client for the first I2cSerialBus
 * resource of an acpi_device, but some acpi_devices have multiple I2cSerialBus
 * resources, in that case this function can be used to create an i2c-client
 * for other I2cSerialBus resources in the Current Resource Settings table.
 *
 * Also see i2c_new_client_device, which this function calls to create the
 * i2c-client.
 *
 * Returns a pointer to the new i2c-client, or error pointer in case of failure.
 * Specifically, -EPROBE_DEFER is returned if the adapter is not found.
 */
struct i2c_client *i2c_acpi_new_device(struct device *dev, int index,
                                       struct i2c_board_info *info)
{
        struct acpi_device *adev = ACPI_COMPANION(dev);
        struct i2c_acpi_lookup lookup;
        struct i2c_adapter *adapter;
        LIST_HEAD(resource_list);
        int ret;

        memset(&lookup, 0, sizeof(lookup));
        lookup.info = info;
        lookup.device_handle = acpi_device_handle(adev);
        lookup.index = index;

        ret = acpi_dev_get_resources(adev, &resource_list,
                                     i2c_acpi_fill_info, &lookup);
        if (ret < 0)
                return ERR_PTR(ret);

        acpi_dev_free_resource_list(&resource_list);

        if (!info->addr)
                return ERR_PTR(-EADDRNOTAVAIL);

        adapter = i2c_acpi_find_adapter_by_handle(lookup.adapter_handle);
        if (!adapter)
                return ERR_PTR(-EPROBE_DEFER);

        return i2c_new_client_device(adapter, info);
}
EXPORT_SYMBOL_GPL(i2c_acpi_new_device);

#ifdef CONFIG_ACPI_I2C_OPREGION
static int acpi_gsb_i2c_read_bytes(struct i2c_client *client,
                u8 cmd, u8 *data, u8 data_len)
{

        struct i2c_msg msgs[2];
        int ret;
        u8 *buffer;

        buffer = kzalloc(data_len, GFP_KERNEL);
        if (!buffer)
                return AE_NO_MEMORY;

        msgs[0].addr = client->addr;
        msgs[0].flags = client->flags;
        msgs[0].len = 1;
        msgs[0].buf = &cmd;

        msgs[1].addr = client->addr;
        msgs[1].flags = client->flags | I2C_M_RD;
        msgs[1].len = data_len;
        msgs[1].buf = buffer;

        ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
        if (ret < 0) {
                /* Getting a NACK is unfortunately normal with some DSTDs */
                if (ret == -EREMOTEIO)
                        dev_dbg(&client->adapter->dev, "i2c read %d bytes from client@%#x starting at reg %#x failed, error: %d\n",
                                data_len, client->addr, cmd, ret);
                else
                        dev_err(&client->adapter->dev, "i2c read %d bytes from client@%#x starting at reg %#x failed, error: %d\n",
                                data_len, client->addr, cmd, ret);
        /* 2 transfers must have completed successfully */
        } else if (ret == 2) {
                memcpy(data, buffer, data_len);
                ret = 0;
        } else {
                ret = -EIO;
        }

        kfree(buffer);
        return ret;
}

static int acpi_gsb_i2c_write_bytes(struct i2c_client *client,
                u8 cmd, u8 *data, u8 data_len)
{

        struct i2c_msg msgs[1];
        u8 *buffer;
        int ret = AE_OK;

        buffer = kzalloc(data_len + 1, GFP_KERNEL);
        if (!buffer)
                return AE_NO_MEMORY;

        buffer[0] = cmd;
        memcpy(buffer + 1, data, data_len);

        msgs[0].addr = client->addr;
        msgs[0].flags = client->flags;
        msgs[0].len = data_len + 1;
        msgs[0].buf = buffer;

        ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));

        kfree(buffer);

        if (ret < 0) {
                dev_err(&client->adapter->dev, "i2c write failed: %d\n", ret);
                return ret;
        }

        /* 1 transfer must have completed successfully */
        return (ret == 1) ? 0 : -EIO;
}

static acpi_status
i2c_acpi_space_handler(u32 function, acpi_physical_address command,
                        u32 bits, u64 *value64,
                        void *handler_context, void *region_context)
{
        struct gsb_buffer *gsb = (struct gsb_buffer *)value64;
        struct i2c_acpi_handler_data *data = handler_context;
        struct acpi_connection_info *info = &data->info;
        struct acpi_resource_i2c_serialbus *sb;
        struct i2c_adapter *adapter = data->adapter;
        struct i2c_client *client;
        struct acpi_resource *ares;
        u32 accessor_type = function >> 16;
        u8 action = function & ACPI_IO_MASK;
        acpi_status ret;
        int status;

        ret = acpi_buffer_to_resource(info->connection, info->length, &ares);
        if (ACPI_FAILURE(ret))
                return ret;

        client = kzalloc(sizeof(*client), GFP_KERNEL);
        if (!client) {
                ret = AE_NO_MEMORY;
                goto err;
        }

        if (!value64 || !i2c_acpi_get_i2c_resource(ares, &sb)) {
                ret = AE_BAD_PARAMETER;
                goto err;
        }

        client->adapter = adapter;
        client->addr = sb->slave_address;

        if (sb->access_mode == ACPI_I2C_10BIT_MODE)
                client->flags |= I2C_CLIENT_TEN;

        switch (accessor_type) {
        case ACPI_GSB_ACCESS_ATTRIB_SEND_RCV:
                if (action == ACPI_READ) {
                        status = i2c_smbus_read_byte(client);
                        if (status >= 0) {
                                gsb->bdata = status;
                                status = 0;
                        }
                } else {
                        status = i2c_smbus_write_byte(client, gsb->bdata);
                }
                break;

        case ACPI_GSB_ACCESS_ATTRIB_BYTE:
                if (action == ACPI_READ) {
                        status = i2c_smbus_read_byte_data(client, command);
                        if (status >= 0) {
                                gsb->bdata = status;
                                status = 0;
                        }
                } else {
                        status = i2c_smbus_write_byte_data(client, command,
                                        gsb->bdata);
                }
                break;

        case ACPI_GSB_ACCESS_ATTRIB_WORD:
                if (action == ACPI_READ) {
                        status = i2c_smbus_read_word_data(client, command);
                        if (status >= 0) {
                                gsb->wdata = status;
                                status = 0;
                        }
                } else {
                        status = i2c_smbus_write_word_data(client, command,
                                        gsb->wdata);
                }
                break;

        case ACPI_GSB_ACCESS_ATTRIB_BLOCK:
                if (action == ACPI_READ) {
                        status = i2c_smbus_read_block_data(client, command,
                                        gsb->data);
                        if (status >= 0) {
                                gsb->len = status;
                                status = 0;
                        }
                } else {
                        status = i2c_smbus_write_block_data(client, command,
                                        gsb->len, gsb->data);
                }
                break;

        case ACPI_GSB_ACCESS_ATTRIB_MULTIBYTE:
                if (action == ACPI_READ) {
                        status = acpi_gsb_i2c_read_bytes(client, command,
                                        gsb->data, info->access_length);
                } else {
                        status = acpi_gsb_i2c_write_bytes(client, command,
                                        gsb->data, info->access_length);
                }
                break;

        default:
                dev_warn(&adapter->dev, "protocol 0x%02x not supported for client 0x%02x\n",
                         accessor_type, client->addr);
                ret = AE_BAD_PARAMETER;
                goto err;
        }

        gsb->status = status;

 err:
        kfree(client);
        ACPI_FREE(ares);
        return ret;
}


int i2c_acpi_install_space_handler(struct i2c_adapter *adapter)
{
        acpi_handle handle;
        struct i2c_acpi_handler_data *data;
        acpi_status status;

        if (!adapter->dev.parent)
                return -ENODEV;

        handle = ACPI_HANDLE(adapter->dev.parent);

        if (!handle)
                return -ENODEV;

        data = kzalloc(sizeof(struct i2c_acpi_handler_data),
                            GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->adapter = adapter;
        status = acpi_bus_attach_private_data(handle, (void *)data);
        if (ACPI_FAILURE(status)) {
                kfree(data);
                return -ENOMEM;
        }

        status = acpi_install_address_space_handler(handle,
                                ACPI_ADR_SPACE_GSBUS,
                                &i2c_acpi_space_handler,
                                NULL,
                                data);
        if (ACPI_FAILURE(status)) {
                dev_err(&adapter->dev, "Error installing i2c space handler\n");
                acpi_bus_detach_private_data(handle);
                kfree(data);
                return -ENOMEM;
        }

        return 0;
}

void i2c_acpi_remove_space_handler(struct i2c_adapter *adapter)
{
        acpi_handle handle;
        struct i2c_acpi_handler_data *data;
        acpi_status status;

        if (!adapter->dev.parent)
                return;

        handle = ACPI_HANDLE(adapter->dev.parent);

        if (!handle)
                return;

        acpi_remove_address_space_handler(handle,
                                ACPI_ADR_SPACE_GSBUS,
                                &i2c_acpi_space_handler);

        status = acpi_bus_get_private_data(handle, (void **)&data);
        if (ACPI_SUCCESS(status))
                kfree(data);

        acpi_bus_detach_private_data(handle);
}
#endif /* CONFIG_ACPI_I2C_OPREGION */