sch56xx-common.c

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/***************************************************************************
 *   Copyright (C) 2010-2012 Hans de Goede <[email protected]>           *
 *                                                                         *
 *   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; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/acpi.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/watchdog.h>
#include <linux/miscdevice.h>
#include <linux/uaccess.h>
#include <linux/kref.h>
#include <linux/slab.h>
#include "sch56xx-common.h"

/* Insmod parameters */
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

#define SIO_SCH56XX_LD_EM   0x0C    /* Embedded uController Logical Dev */
#define SIO_UNLOCK_KEY      0x55    /* Key to enable Super-I/O */
#define SIO_LOCK_KEY        0xAA    /* Key to disable Super-I/O */

#define SIO_REG_LDSEL       0x07    /* Logical device select */
#define SIO_REG_DEVID       0x20    /* Device ID */
#define SIO_REG_ENABLE      0x30    /* Logical device enable */
#define SIO_REG_ADDR        0x66    /* Logical device address (2 bytes) */

#define SIO_SCH5627_ID      0xC6    /* Chipset ID */
#define SIO_SCH5636_ID      0xC7    /* Chipset ID */

#define REGION_LENGTH       10

#define SCH56XX_CMD_READ    0x02
#define SCH56XX_CMD_WRITE   0x03

/* Watchdog registers */
#define SCH56XX_REG_WDOG_PRESET     0x58B
#define SCH56XX_REG_WDOG_CONTROL    0x58C
#define SCH56XX_WDOG_TIME_BASE_SEC  0x01
#define SCH56XX_REG_WDOG_OUTPUT_ENABLE  0x58E
#define SCH56XX_WDOG_OUTPUT_ENABLE  0x02

struct sch56xx_watchdog_data {
    u16 addr;
    struct mutex *io_lock;
    struct kref kref;
    struct watchdog_info wdinfo;
    struct watchdog_device wddev;
    u8 watchdog_preset;
    u8 watchdog_control;
    u8 watchdog_output_enable;
};

static struct platform_device *sch56xx_pdev;

/* Super I/O functions */
static inline int superio_inb(int base, int reg)
{
    outb(reg, base);
    return inb(base + 1);
}

static inline int superio_enter(int base)
{
    /* Don't step on other drivers' I/O space by accident */
    if (!request_muxed_region(base, 2, "sch56xx")) {
        pr_err("I/O address 0x%04x already in use\n", base);
        return -EBUSY;
    }

    outb(SIO_UNLOCK_KEY, base);

    return 0;
}

static inline void superio_select(int base, int ld)
{
    outb(SIO_REG_LDSEL, base);
    outb(ld, base + 1);
}

static inline void superio_exit(int base)
{
    outb(SIO_LOCK_KEY, base);
    release_region(base, 2);
}

static int sch56xx_send_cmd(u16 addr, u8 cmd, u16 reg, u8 v)
{
    u8 val;
    int i;
    /*
     * According to SMSC for the commands we use the maximum time for
     * the EM to respond is 15 ms, but testing shows in practice it
     * responds within 15-32 reads, so we first busy poll, and if
     * that fails sleep a bit and try again until we are way past
     * the 15 ms maximum response time.
     */
    const int max_busy_polls = 64;
    const int max_lazy_polls = 32;

    /* (Optional) Write-Clear the EC to Host Mailbox Register */
    val = inb(addr + 1);
    outb(val, addr + 1);

    /* Set Mailbox Address Pointer to first location in Region 1 */
    outb(0x00, addr + 2);
    outb(0x80, addr + 3);

    /* Write Request Packet Header */
    outb(cmd, addr + 4); /* VREG Access Type read:0x02 write:0x03 */
    outb(0x01, addr + 5); /* # of Entries: 1 Byte (8-bit) */
    outb(0x04, addr + 2); /* Mailbox AP to first data entry loc. */

    /* Write Value field */
    if (cmd == SCH56XX_CMD_WRITE)
        outb(v, addr + 4);

    /* Write Address field */
    outb(reg & 0xff, addr + 6);
    outb(reg >> 8, addr + 7);

    /* Execute the Random Access Command */
    outb(0x01, addr); /* Write 01h to the Host-to-EC register */

    /* EM Interface Polling "Algorithm" */
    for (i = 0; i < max_busy_polls + max_lazy_polls; i++) {
        if (i >= max_busy_polls)
            msleep(1);
        /* Read Interrupt source Register */
        val = inb(addr + 8);
        /* Write Clear the interrupt source bits */
        if (val)
            outb(val, addr + 8);
        /* Command Completed ? */
        if (val & 0x01)
            break;
    }
    if (i == max_busy_polls + max_lazy_polls) {
        pr_err("Max retries exceeded reading virtual "
               "register 0x%04hx (%d)\n", reg, 1);
        return -EIO;
    }

    /*
     * According to SMSC we may need to retry this, but sofar I've always
     * seen this succeed in 1 try.
     */
    for (i = 0; i < max_busy_polls; i++) {
        /* Read EC-to-Host Register */
        val = inb(addr + 1);
        /* Command Completed ? */
        if (val == 0x01)
            break;

        if (i == 0)
            pr_warn("EC reports: 0x%02x reading virtual register "
                "0x%04hx\n", (unsigned int)val, reg);
    }
    if (i == max_busy_polls) {
        pr_err("Max retries exceeded reading virtual "
               "register 0x%04hx (%d)\n", reg, 2);
        return -EIO;
    }

    /*
     * According to the SMSC app note we should now do:
     *
     * Set Mailbox Address Pointer to first location in Region 1 *
     * outb(0x00, addr + 2);
     * outb(0x80, addr + 3);
     *
     * But if we do that things don't work, so let's not.
     */

    /* Read Value field */
    if (cmd == SCH56XX_CMD_READ)
        return inb(addr + 4);

    return 0;
}

int sch56xx_read_virtual_reg(u16 addr, u16 reg)
{
    return sch56xx_send_cmd(addr, SCH56XX_CMD_READ, reg, 0);
}
EXPORT_SYMBOL(sch56xx_read_virtual_reg);

int sch56xx_write_virtual_reg(u16 addr, u16 reg, u8 val)
{
    return sch56xx_send_cmd(addr, SCH56XX_CMD_WRITE, reg, val);
}
EXPORT_SYMBOL(sch56xx_write_virtual_reg);

int sch56xx_read_virtual_reg16(u16 addr, u16 reg)
{
    int lsb, msb;

    /* Read LSB first, this will cause the matching MSB to be latched */
    lsb = sch56xx_read_virtual_reg(addr, reg);
    if (lsb < 0)
        return lsb;

    msb = sch56xx_read_virtual_reg(addr, reg + 1);
    if (msb < 0)
        return msb;

    return lsb | (msb << 8);
}
EXPORT_SYMBOL(sch56xx_read_virtual_reg16);

int sch56xx_read_virtual_reg12(u16 addr, u16 msb_reg, u16 lsn_reg,
                   int high_nibble)
{
    int msb, lsn;

    /* Read MSB first, this will cause the matching LSN to be latched */
    msb = sch56xx_read_virtual_reg(addr, msb_reg);
    if (msb < 0)
        return msb;

    lsn = sch56xx_read_virtual_reg(addr, lsn_reg);
    if (lsn < 0)
        return lsn;

    if (high_nibble)
        return (msb << 4) | (lsn >> 4);
    else
        return (msb << 4) | (lsn & 0x0f);
}
EXPORT_SYMBOL(sch56xx_read_virtual_reg12);

/*
 * Watchdog routines
 */

/* Release our data struct when we're unregistered *and*
   all references to our watchdog device are released */
static void watchdog_release_resources(struct kref *r)
{
    struct sch56xx_watchdog_data *data =
        container_of(r, struct sch56xx_watchdog_data, kref);
    kfree(data);
}

static int watchdog_set_timeout(struct watchdog_device *wddev,
                unsigned int timeout)
{
    struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
    unsigned int resolution;
    u8 control;
    int ret;

    /* 1 second or 60 second resolution? */
    if (timeout <= 255)
        resolution = 1;
    else
        resolution = 60;

    if (timeout < resolution || timeout > (resolution * 255))
        return -EINVAL;

    if (resolution == 1)
        control = data->watchdog_control | SCH56XX_WDOG_TIME_BASE_SEC;
    else
        control = data->watchdog_control & ~SCH56XX_WDOG_TIME_BASE_SEC;

    if (data->watchdog_control != control) {
        mutex_lock(data->io_lock);
        ret = sch56xx_write_virtual_reg(data->addr,
                        SCH56XX_REG_WDOG_CONTROL,
                        control);
        mutex_unlock(data->io_lock);
        if (ret)
            return ret;

        data->watchdog_control = control;
    }

    /*
     * Remember new timeout value, but do not write as that (re)starts
     * the watchdog countdown.
     */
    data->watchdog_preset = DIV_ROUND_UP(timeout, resolution);
    wddev->timeout = data->watchdog_preset * resolution;

    return 0;
}

static int watchdog_start(struct watchdog_device *wddev)
{
    struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
    int ret;
    u8 val;

    /*
     * The sch56xx's watchdog cannot really be started / stopped
     * it is always running, but we can avoid the timer expiring
     * from causing a system reset by clearing the output enable bit.
     *
     * The sch56xx's watchdog will set the watchdog event bit, bit 0
     * of the second interrupt source register (at base-address + 9),
     * when the timer expires.
     *
     * This will only cause a system reset if the 0-1 flank happens when
     * output enable is true. Setting output enable after the flank will
     * not cause a reset, nor will the timer expiring a second time.
     * This means we must clear the watchdog event bit in case it is set.
     *
     * The timer may still be running (after a recent watchdog_stop) and
     * mere milliseconds away from expiring, so the timer must be reset
     * first!
     */

    mutex_lock(data->io_lock);

    /* 1. Reset the watchdog countdown counter */
    ret = sch56xx_write_virtual_reg(data->addr, SCH56XX_REG_WDOG_PRESET,
                    data->watchdog_preset);
    if (ret)
        goto leave;

    /* 2. Enable output */
    val = data->watchdog_output_enable | SCH56XX_WDOG_OUTPUT_ENABLE;
    ret = sch56xx_write_virtual_reg(data->addr,
                    SCH56XX_REG_WDOG_OUTPUT_ENABLE, val);
    if (ret)
        goto leave;

    data->watchdog_output_enable = val;

    /* 3. Clear the watchdog event bit if set */
    val = inb(data->addr + 9);
    if (val & 0x01)
        outb(0x01, data->addr + 9);

leave:
    mutex_unlock(data->io_lock);
    return ret;
}

static int watchdog_trigger(struct watchdog_device *wddev)
{
    struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
    int ret;

    /* Reset the watchdog countdown counter */
    mutex_lock(data->io_lock);
    ret = sch56xx_write_virtual_reg(data->addr, SCH56XX_REG_WDOG_PRESET,
                    data->watchdog_preset);
    mutex_unlock(data->io_lock);

    return ret;
}

static int watchdog_stop(struct watchdog_device *wddev)
{
    struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);
    int ret = 0;
    u8 val;

    val = data->watchdog_output_enable & ~SCH56XX_WDOG_OUTPUT_ENABLE;
    mutex_lock(data->io_lock);
    ret = sch56xx_write_virtual_reg(data->addr,
                    SCH56XX_REG_WDOG_OUTPUT_ENABLE, val);
    mutex_unlock(data->io_lock);
    if (ret)
        return ret;

    data->watchdog_output_enable = val;
    return 0;
}

static void watchdog_ref(struct watchdog_device *wddev)
{
    struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);

    kref_get(&data->kref);
}

static void watchdog_unref(struct watchdog_device *wddev)
{
    struct sch56xx_watchdog_data *data = watchdog_get_drvdata(wddev);

    kref_put(&data->kref, watchdog_release_resources);
}

static const struct watchdog_ops watchdog_ops = {
    .owner      = THIS_MODULE,
    .start      = watchdog_start,
    .stop       = watchdog_stop,
    .ping       = watchdog_trigger,
    .set_timeout    = watchdog_set_timeout,
    .ref        = watchdog_ref,
    .unref      = watchdog_unref,
};

struct sch56xx_watchdog_data *sch56xx_watchdog_register(struct device *parent,
    u16 addr, u32 revision, struct mutex *io_lock, int check_enabled)
{
    struct sch56xx_watchdog_data *data;
    int err, control, output_enable;

    /* Cache the watchdog registers */
    mutex_lock(io_lock);
    control =
        sch56xx_read_virtual_reg(addr, SCH56XX_REG_WDOG_CONTROL);
    output_enable =
        sch56xx_read_virtual_reg(addr, SCH56XX_REG_WDOG_OUTPUT_ENABLE);
    mutex_unlock(io_lock);

    if (control < 0)
        return NULL;
    if (output_enable < 0)
        return NULL;
    if (check_enabled && !(output_enable & SCH56XX_WDOG_OUTPUT_ENABLE)) {
        pr_warn("Watchdog not enabled by BIOS, not registering\n");
        return NULL;
    }

    data = kzalloc(sizeof(struct sch56xx_watchdog_data), GFP_KERNEL);
    if (!data)
        return NULL;

    data->addr = addr;
    data->io_lock = io_lock;
    kref_init(&data->kref);

    strlcpy(data->wdinfo.identity, "sch56xx watchdog",
        sizeof(data->wdinfo.identity));
    data->wdinfo.firmware_version = revision;
    data->wdinfo.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT;
    if (!nowayout)
        data->wdinfo.options |= WDIOF_MAGICCLOSE;

    data->wddev.info = &data->wdinfo;
    data->wddev.ops = &watchdog_ops;
    data->wddev.parent = parent;
    data->wddev.timeout = 60;
    data->wddev.min_timeout = 1;
    data->wddev.max_timeout = 255 * 60;
    if (nowayout)
        set_bit(WDOG_NO_WAY_OUT, &data->wddev.status);
    if (output_enable & SCH56XX_WDOG_OUTPUT_ENABLE)
        set_bit(WDOG_ACTIVE, &data->wddev.status);

    /* Since the watchdog uses a downcounter there is no register to read
       the BIOS set timeout from (if any was set at all) ->
       Choose a preset which will give us a 1 minute timeout */
    if (control & SCH56XX_WDOG_TIME_BASE_SEC)
        data->watchdog_preset = 60; /* seconds */
    else
        data->watchdog_preset = 1; /* minute */

    data->watchdog_control = control;
    data->watchdog_output_enable = output_enable;

    watchdog_set_drvdata(&data->wddev, data);
    err = watchdog_register_device(&data->wddev);
    if (err) {
        pr_err("Registering watchdog chardev: %d\n", err);
        kfree(data);
        return NULL;
    }

    return data;
}
EXPORT_SYMBOL(sch56xx_watchdog_register);

void sch56xx_watchdog_unregister(struct sch56xx_watchdog_data *data)
{
    watchdog_unregister_device(&data->wddev);
    kref_put(&data->kref, watchdog_release_resources);
    /* Don't touch data after this it may have been free-ed! */
}
EXPORT_SYMBOL(sch56xx_watchdog_unregister);

/*
 * platform dev find, add and remove functions
 */

static int __init sch56xx_find(int sioaddr, const char **name)
{
    u8 devid;
    unsigned short address;
    int err;

    err = superio_enter(sioaddr);
    if (err)
        return err;

    devid = superio_inb(sioaddr, SIO_REG_DEVID);
    switch (devid) {
    case SIO_SCH5627_ID:
        *name = "sch5627";
        break;
    case SIO_SCH5636_ID:
        *name = "sch5636";
        break;
    default:
        pr_debug("Unsupported device id: 0x%02x\n",
             (unsigned int)devid);
        err = -ENODEV;
        goto exit;
    }

    superio_select(sioaddr, SIO_SCH56XX_LD_EM);

    if (!(superio_inb(sioaddr, SIO_REG_ENABLE) & 0x01)) {
        pr_warn("Device not activated\n");
        err = -ENODEV;
        goto exit;
    }

    /*
     * Warning the order of the low / high byte is the other way around
     * as on most other superio devices!!
     */
    address = superio_inb(sioaddr, SIO_REG_ADDR) |
           superio_inb(sioaddr, SIO_REG_ADDR + 1) << 8;
    if (address == 0) {
        pr_warn("Base address not set\n");
        err = -ENODEV;
        goto exit;
    }
    err = address;

exit:
    superio_exit(sioaddr);
    return err;
}

static int __init sch56xx_device_add(int address, const char *name)
{
    struct resource res = {
        .start  = address,
        .end    = address + REGION_LENGTH - 1,
        .flags  = IORESOURCE_IO,
    };
    int err;

    sch56xx_pdev = platform_device_alloc(name, address);
    if (!sch56xx_pdev)
        return -ENOMEM;

    res.name = sch56xx_pdev->name;
    err = acpi_check_resource_conflict(&res);
    if (err)
        goto exit_device_put;

    err = platform_device_add_resources(sch56xx_pdev, &res, 1);
    if (err) {
        pr_err("Device resource addition failed\n");
        goto exit_device_put;
    }

    err = platform_device_add(sch56xx_pdev);
    if (err) {
        pr_err("Device addition failed\n");
        goto exit_device_put;
    }

    return 0;

exit_device_put:
    platform_device_put(sch56xx_pdev);

    return err;
}

static int __init sch56xx_init(void)
{
    int address;
    const char *name = NULL;

    address = sch56xx_find(0x4e, &name);
    if (address < 0)
        address = sch56xx_find(0x2e, &name);
    if (address < 0)
        return address;

    return sch56xx_device_add(address, name);
}

static void __exit sch56xx_exit(void)
{
    platform_device_unregister(sch56xx_pdev);
}

MODULE_DESCRIPTION("SMSC SCH56xx Hardware Monitoring Common Code");
MODULE_AUTHOR("Hans de Goede <[email protected]>");
MODULE_LICENSE("GPL");

module_init(sch56xx_init);
module_exit(sch56xx_exit);