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/*

 * SMBus driver for ACPI Embedded Controller (v0.1)

 *

 * Copyright (c) 2007 Alexey Starikovskiy

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation version 2.

 */

#include <acpi/acpi_bus.h>

#include <acpi/acpi_drivers.h>

#include <acpi/actypes.h>

#include <linux/wait.h>

#include <linux/delay.h>

#include <linux/interrupt.h>

#include "sbshc.h"

#define ACPI_SMB_HC_CLASS       "smbus_host_controller"

#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;

};

static int acpi_smbus_hc_add(struct acpi_device *device);

static int acpi_smbus_hc_remove(struct acpi_device *device, int type);

static const struct acpi_device_id sbs_device_ids[] = {

        {"ACPI0001", 0},

        {"ACPI0005", 0},

        {"", 0},

};

MODULE_DEVICE_TABLE(acpi, sbs_device_ids);

static struct acpi_driver acpi_smb_hc_driver = {

        .name = "smbus_hc",

        .class = ACPI_SMB_HC_CLASS,

        .ids = sbs_device_ids,

        .ops = {

                .add = acpi_smbus_hc_add,

                .remove = acpi_smbus_hc_remove,

                },

};

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 inline int smb_check_done(struct acpi_smb_hc *hc)

{

        union acpi_smb_status status = {.raw = 0};

        smb_hc_read(hc, ACPI_SMB_STATUS, &status.raw);

        return status.fields.done && (status.fields.status == SMBUS_OK);

}

static int wait_transaction_complete(struct acpi_smb_hc *hc, int timeout)

{

        if (wait_event_timeout(hc->wait, smb_check_done(hc),

                               msecs_to_jiffies(timeout)))

                return 0;

        else

                return -ETIME;

}

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;

        mutex_lock(&hc->lock);

        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);

        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);

        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)

                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_GPE_HANDLER,

                                        acpi_smbus_callback, hc);

                default:;

        }

        mutex_unlock(&hc->lock);

        return 0;

}

typedef int (*acpi_ec_query_func) (void *data);

extern int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,

                              acpi_handle handle, acpi_ec_query_func func,

                              void *data);

static int acpi_smbus_hc_add(struct acpi_device *device)

{

        int status;

        unsigned long val;

        struct acpi_smb_hc *hc;

        if (!device)

                return -EINVAL;

        status = acpi_evaluate_integer(device->handle, "_EC", NULL, &val);

        if (ACPI_FAILURE(status)) {

                printk(KERN_ERR PREFIX "error obtaining _EC.\n");

                return -EIO;

        }

        strcpy(acpi_device_name(device), ACPI_SMB_HC_DEVICE_NAME);

        strcpy(acpi_device_class(device), ACPI_SMB_HC_CLASS);

        hc = kzalloc(sizeof(struct acpi_smb_hc), GFP_KERNEL);

        if (!hc)

                return -ENOMEM;

        mutex_init(&hc->lock);

        init_waitqueue_head(&hc->wait);

        hc->ec = acpi_driver_data(device->parent);

        hc->offset = (val >> 8) & 0xff;

        hc->query_bit = val & 0xff;

        acpi_driver_data(device) = hc;

        acpi_ec_add_query_handler(hc->ec, hc->query_bit, NULL, smbus_alarm, hc);

        printk(KERN_INFO PREFIX "SBS HC: EC = 0x%p, offset = 0x%0x, query_bit = 0x%0x\n",

                hc->ec, hc->offset, hc->query_bit);

        return 0;

}

extern void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit);

static int acpi_smbus_hc_remove(struct acpi_device *device, int type)

{

        struct acpi_smb_hc *hc;

        if (!device)

                return -EINVAL;

        hc = acpi_driver_data(device);

        acpi_ec_remove_query_handler(hc->ec, hc->query_bit);

        kfree(hc);

        return 0;

}

static int __init acpi_smb_hc_init(void)

{

        int result;

        result = acpi_bus_register_driver(&acpi_smb_hc_driver);

        if (result < 0)

                return -ENODEV;

        return 0;

}

static void __exit acpi_smb_hc_exit(void)

{

        acpi_bus_unregister_driver(&acpi_smb_hc_driver);

}

module_init(acpi_smb_hc_init);

module_exit(acpi_smb_hc_exit);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("Alexey Starikovskiy");

MODULE_DESCRIPTION("ACPI SMBus HC driver");