sbshc.c

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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 <linux/wait.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include "sbshc.h"

#define PREFIX "ACPI: "

#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;
};

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;
    /*
     * After the timeout happens, OS will try to check the status of SMbus.
     * If the status is what OS expected, it will be regarded as the bogus
     * timeout.
     */
    if (smb_check_done(hc))
        return 0;
    else
        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) {
        printk(KERN_ERR PREFIX "host controller is not configured\n");
        return ret;
    }

    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);
    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_NOTIFY_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 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;
    device->driver_data = 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);
    device->driver_data = NULL;
    return 0;
}

module_acpi_driver(acpi_smb_hc_driver);

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