// SPDX-License-Identifier: GPL-2.0-only
/*
 * SMBus driver for ACPI Embedded Controller (v0.1)
 *
 * Copyright (c) 2007 Alexey Starikovskiy
 */

#define pr_fmt(fmt) "ACPI: " fmt

#include <linux/acpi.h>
#include <linux/wait.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>

#include "sbshc.h"
#include "internal.h"

#define ACPI_SMB_HC_CLASS       "smbus_host_ctl"
#define ACPI_SMB_HC_DEVICE_NAME "ACPI SMBus HC"

struct acpi_smb_hc {
        struct acpi_ec *ec;
        struct mutex lock;
        wait_queue_head_t wait;
        u8 offset;
        u8 query_bit;
        smbus_alarm_callback callback;
        void *context;
        bool done;
};

static int acpi_smbus_hc_probe(struct platform_device *pdev);
static void acpi_smbus_hc_remove(struct platform_device *pdev);

static const struct acpi_device_id sbs_device_ids[] = {
        {"ACPI0001", 0},
        {"ACPI0005", 0},
        {"", 0},
};

MODULE_DEVICE_TABLE(acpi, sbs_device_ids);

static struct platform_driver acpi_smb_hc_driver = {
        .probe = acpi_smbus_hc_probe,
        .remove = acpi_smbus_hc_remove,
        .driver = {
                .name = "acpi-smbus-hc",
                .acpi_match_table = sbs_device_ids,
        },
};

union acpi_smb_status {
        u8 raw;
        struct {
                u8 status:5;
                u8 reserved:1;
                u8 alarm:1;
                u8 done:1;
        } fields;
};

enum acpi_smb_status_codes {
        SMBUS_OK = 0,
        SMBUS_UNKNOWN_FAILURE = 0x07,
        SMBUS_DEVICE_ADDRESS_NACK = 0x10,
        SMBUS_DEVICE_ERROR = 0x11,
        SMBUS_DEVICE_COMMAND_ACCESS_DENIED = 0x12,
        SMBUS_UNKNOWN_ERROR = 0x13,
        SMBUS_DEVICE_ACCESS_DENIED = 0x17,
        SMBUS_TIMEOUT = 0x18,
        SMBUS_HOST_UNSUPPORTED_PROTOCOL = 0x19,
        SMBUS_BUSY = 0x1a,
        SMBUS_PEC_ERROR = 0x1f,
};

enum acpi_smb_offset {
        ACPI_SMB_PROTOCOL = 0,  /* protocol, PEC */
        ACPI_SMB_STATUS = 1,    /* status */
        ACPI_SMB_ADDRESS = 2,   /* address */
        ACPI_SMB_COMMAND = 3,   /* command */
        ACPI_SMB_DATA = 4,      /* 32 data registers */
        ACPI_SMB_BLOCK_COUNT = 0x24,    /* number of data bytes */
        ACPI_SMB_ALARM_ADDRESS = 0x25,  /* alarm address */
        ACPI_SMB_ALARM_DATA = 0x26,     /* 2 bytes alarm data */
};

static inline int smb_hc_read(struct acpi_smb_hc *hc, u8 address, u8 *data)
{
        return ec_read(hc->offset + address, data);
}

static inline int smb_hc_write(struct acpi_smb_hc *hc, u8 address, u8 data)
{
        return ec_write(hc->offset + address, data);
}

static int wait_transaction_complete(struct acpi_smb_hc *hc, int timeout)
{
        if (wait_event_timeout(hc->wait, hc->done, msecs_to_jiffies(timeout)))
                return 0;
        return -ETIME;
}

static int acpi_smbus_transaction(struct acpi_smb_hc *hc, u8 protocol,
                                  u8 address, u8 command, u8 *data, u8 length)
{
        int ret = -EFAULT, i;
        u8 temp, sz = 0;

        if (!hc) {
                pr_err("host controller is not configured\n");
                return ret;
        }

        mutex_lock(&hc->lock);
        hc->done = false;
        if (smb_hc_read(hc, ACPI_SMB_PROTOCOL, &temp))
                goto end;
        if (temp) {
                ret = -EBUSY;
                goto end;
        }
        smb_hc_write(hc, ACPI_SMB_COMMAND, command);
        if (!(protocol & 0x01)) {
                smb_hc_write(hc, ACPI_SMB_BLOCK_COUNT, length);
                for (i = 0; i < length; ++i)
                        smb_hc_write(hc, ACPI_SMB_DATA + i, data[i]);
        }
        smb_hc_write(hc, ACPI_SMB_ADDRESS, address << 1);
        smb_hc_write(hc, ACPI_SMB_PROTOCOL, protocol);
        /*
         * Wait for completion. Save the status code, data size,
         * and data into the return package (if required by the protocol).
         */
        ret = wait_transaction_complete(hc, 1000);
        if (ret || !(protocol & 0x01))
                goto end;
        switch (protocol) {
        case SMBUS_RECEIVE_BYTE:
        case SMBUS_READ_BYTE:
                sz = 1;
                break;
        case SMBUS_READ_WORD:
                sz = 2;
                break;
        case SMBUS_READ_BLOCK:
                if (smb_hc_read(hc, ACPI_SMB_BLOCK_COUNT, &sz)) {
                        ret = -EFAULT;
                        goto end;
                }
                sz &= 0x1f;
                break;
        }
        for (i = 0; i < sz; ++i)
                smb_hc_read(hc, ACPI_SMB_DATA + i, &data[i]);
      end:
        mutex_unlock(&hc->lock);
        return ret;
}

int acpi_smbus_read(struct acpi_smb_hc *hc, u8 protocol, u8 address,
                    u8 command, u8 *data)
{
        return acpi_smbus_transaction(hc, protocol, address, command, data, 0);
}

EXPORT_SYMBOL_GPL(acpi_smbus_read);

int acpi_smbus_write(struct acpi_smb_hc *hc, u8 protocol, u8 address,
                     u8 command, u8 *data, u8 length)
{
        return acpi_smbus_transaction(hc, protocol, address, command, data, length);
}

EXPORT_SYMBOL_GPL(acpi_smbus_write);

int acpi_smbus_register_callback(struct acpi_smb_hc *hc,
                                 smbus_alarm_callback callback, void *context)
{
        mutex_lock(&hc->lock);
        hc->callback = callback;
        hc->context = context;
        mutex_unlock(&hc->lock);
        return 0;
}

EXPORT_SYMBOL_GPL(acpi_smbus_register_callback);

int acpi_smbus_unregister_callback(struct acpi_smb_hc *hc)
{
        mutex_lock(&hc->lock);
        hc->callback = NULL;
        hc->context = NULL;
        mutex_unlock(&hc->lock);
        acpi_os_wait_events_complete();
        return 0;
}

EXPORT_SYMBOL_GPL(acpi_smbus_unregister_callback);

static inline void acpi_smbus_callback(void *context)
{
        struct acpi_smb_hc *hc = context;
        if (hc->callback)
                hc->callback(hc->context);
}

static int smbus_alarm(void *context)
{
        struct acpi_smb_hc *hc = context;
        union acpi_smb_status status;
        u8 address;
        if (smb_hc_read(hc, ACPI_SMB_STATUS, &status.raw))
                return 0;
        /* Check if it is only a completion notify */
        if (status.fields.done && status.fields.status == SMBUS_OK) {
                hc->done = true;
                wake_up(&hc->wait);
        }
        if (!status.fields.alarm)
                return 0;
        mutex_lock(&hc->lock);
        smb_hc_read(hc, ACPI_SMB_ALARM_ADDRESS, &address);
        status.fields.alarm = 0;
        smb_hc_write(hc, ACPI_SMB_STATUS, status.raw);
        /* We are only interested in events coming from known devices */
        switch (address >> 1) {
                case ACPI_SBS_CHARGER:
                case ACPI_SBS_MANAGER:
                case ACPI_SBS_BATTERY:
                        acpi_os_execute(OSL_NOTIFY_HANDLER,
                                        acpi_smbus_callback, hc);
        }
        mutex_unlock(&hc->lock);
        return 0;
}

static int acpi_smbus_hc_probe(struct platform_device *pdev)
{
        struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
        int status;
        unsigned long long val;
        struct acpi_smb_hc *hc;

        status = acpi_evaluate_integer(device->handle, "_EC", NULL, &val);
        if (ACPI_FAILURE(status)) {
                pr_err("error obtaining _EC.\n");
                return -EIO;
        }

        strscpy(acpi_device_name(device), ACPI_SMB_HC_DEVICE_NAME);
        strscpy(acpi_device_class(device), ACPI_SMB_HC_CLASS);

        hc = kzalloc_obj(struct acpi_smb_hc);
        if (!hc)
                return -ENOMEM;
        mutex_init(&hc->lock);
        init_waitqueue_head(&hc->wait);

        platform_set_drvdata(pdev, hc);

        hc->ec = dev_get_drvdata(pdev->dev.parent);
        hc->offset = (val >> 8) & 0xff;
        hc->query_bit = val & 0xff;

        acpi_ec_add_query_handler(hc->ec, hc->query_bit, NULL, smbus_alarm, hc);
        dev_info(&device->dev, "SBS HC: offset = 0x%0x, query_bit = 0x%0x\n",
                 hc->offset, hc->query_bit);

        return 0;
}

static void acpi_smbus_hc_remove(struct platform_device *pdev)
{
        struct acpi_smb_hc *hc = platform_get_drvdata(pdev);

        acpi_ec_remove_query_handler(hc->ec, hc->query_bit);
        acpi_os_wait_events_complete();
        kfree(hc);
}

module_platform_driver(acpi_smb_hc_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alexey Starikovskiy");
MODULE_DESCRIPTION("ACPI SMBus HC driver");