[PATCH] g_file_storage: fix obscure race condition

[linux/fpc-iii.git] / drivers / firmware / dcdbas.c

/*
 *  dcdbas.c: Dell Systems Management Base Driver
 *
 *  The Dell Systems Management Base Driver provides a sysfs interface for
 *  systems management software to perform System Management Interrupts (SMIs)
 *  and Host Control Actions (power cycle or power off after OS shutdown) on
 *  Dell systems.
 *
 *  See Documentation/dcdbas.txt for more information.
 *
 *  Copyright (C) 1995-2005 Dell Inc.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License v2.0 as published by
 *  the Free Software Foundation.
 *
 *  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.
 */

#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mc146818rtc.h>
#include <linux/module.h>
#include <linux/reboot.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/types.h>
#include <asm/io.h>
#include <asm/semaphore.h>

#include "dcdbas.h"

#define DRIVER_NAME             "dcdbas"
#define DRIVER_VERSION          "5.6.0-1"
#define DRIVER_DESCRIPTION      "Dell Systems Management Base Driver"

static struct platform_device *dcdbas_pdev;

static u8 *smi_data_buf;
static dma_addr_t smi_data_buf_handle;
static unsigned long smi_data_buf_size;
static u32 smi_data_buf_phys_addr;
static DECLARE_MUTEX(smi_data_lock);

static unsigned int host_control_action;
static unsigned int host_control_smi_type;
static unsigned int host_control_on_shutdown;

/**
 * smi_data_buf_free: free SMI data buffer
 */
static void smi_data_buf_free(void)
{
        if (!smi_data_buf)
                return;

        dev_dbg(&dcdbas_pdev->dev, "%s: phys: %x size: %lu\n",
                __FUNCTION__, smi_data_buf_phys_addr, smi_data_buf_size);

        dma_free_coherent(&dcdbas_pdev->dev, smi_data_buf_size, smi_data_buf,
                          smi_data_buf_handle);
        smi_data_buf = NULL;
        smi_data_buf_handle = 0;
        smi_data_buf_phys_addr = 0;
        smi_data_buf_size = 0;
}

/**
 * smi_data_buf_realloc: grow SMI data buffer if needed
 */
static int smi_data_buf_realloc(unsigned long size)
{
        void *buf;
        dma_addr_t handle;

        if (smi_data_buf_size >= size)
                return 0;

        if (size > MAX_SMI_DATA_BUF_SIZE)
                return -EINVAL;

        /* new buffer is needed */
        buf = dma_alloc_coherent(&dcdbas_pdev->dev, size, &handle, GFP_KERNEL);
        if (!buf) {
                dev_dbg(&dcdbas_pdev->dev,
                        "%s: failed to allocate memory size %lu\n",
                        __FUNCTION__, size);
                return -ENOMEM;
        }
        /* memory zeroed by dma_alloc_coherent */

        if (smi_data_buf)
                memcpy(buf, smi_data_buf, smi_data_buf_size);

        /* free any existing buffer */
        smi_data_buf_free();

        /* set up new buffer for use */
        smi_data_buf = buf;
        smi_data_buf_handle = handle;
        smi_data_buf_phys_addr = (u32) virt_to_phys(buf);
        smi_data_buf_size = size;

        dev_dbg(&dcdbas_pdev->dev, "%s: phys: %x size: %lu\n",
                __FUNCTION__, smi_data_buf_phys_addr, smi_data_buf_size);

        return 0;
}

static ssize_t smi_data_buf_phys_addr_show(struct device *dev,
                                           struct device_attribute *attr,
                                           char *buf)
{
        return sprintf(buf, "%x\n", smi_data_buf_phys_addr);
}

static ssize_t smi_data_buf_size_show(struct device *dev,
                                      struct device_attribute *attr,
                                      char *buf)
{
        return sprintf(buf, "%lu\n", smi_data_buf_size);
}

static ssize_t smi_data_buf_size_store(struct device *dev,
                                       struct device_attribute *attr,
                                       const char *buf, size_t count)
{
        unsigned long buf_size;
        ssize_t ret;

        buf_size = simple_strtoul(buf, NULL, 10);

        /* make sure SMI data buffer is at least buf_size */
        down(&smi_data_lock);
        ret = smi_data_buf_realloc(buf_size);
        up(&smi_data_lock);
        if (ret)
                return ret;

        return count;
}

static ssize_t smi_data_read(struct kobject *kobj, char *buf, loff_t pos,
                             size_t count)
{
        size_t max_read;
        ssize_t ret;

        down(&smi_data_lock);

        if (pos >= smi_data_buf_size) {
                ret = 0;
                goto out;
        }

        max_read = smi_data_buf_size - pos;
        ret = min(max_read, count);
        memcpy(buf, smi_data_buf + pos, ret);
out:
        up(&smi_data_lock);
        return ret;
}

static ssize_t smi_data_write(struct kobject *kobj, char *buf, loff_t pos,
                              size_t count)
{
        ssize_t ret;

        down(&smi_data_lock);

        ret = smi_data_buf_realloc(pos + count);
        if (ret)
                goto out;

        memcpy(smi_data_buf + pos, buf, count);
        ret = count;
out:
        up(&smi_data_lock);
        return ret;
}

static ssize_t host_control_action_show(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        return sprintf(buf, "%u\n", host_control_action);
}

static ssize_t host_control_action_store(struct device *dev,
                                         struct device_attribute *attr,
                                         const char *buf, size_t count)
{
        ssize_t ret;

        /* make sure buffer is available for host control command */
        down(&smi_data_lock);
        ret = smi_data_buf_realloc(sizeof(struct apm_cmd));
        up(&smi_data_lock);
        if (ret)
                return ret;

        host_control_action = simple_strtoul(buf, NULL, 10);
        return count;
}

static ssize_t host_control_smi_type_show(struct device *dev,
                                          struct device_attribute *attr,
                                          char *buf)
{
        return sprintf(buf, "%u\n", host_control_smi_type);
}

static ssize_t host_control_smi_type_store(struct device *dev,
                                           struct device_attribute *attr,
                                           const char *buf, size_t count)
{
        host_control_smi_type = simple_strtoul(buf, NULL, 10);
        return count;
}

static ssize_t host_control_on_shutdown_show(struct device *dev,
                                             struct device_attribute *attr,
                                             char *buf)
{
        return sprintf(buf, "%u\n", host_control_on_shutdown);
}

static ssize_t host_control_on_shutdown_store(struct device *dev,
                                              struct device_attribute *attr,
                                              const char *buf, size_t count)
{
        host_control_on_shutdown = simple_strtoul(buf, NULL, 10);
        return count;
}

/**
 * smi_request: generate SMI request
 *
 * Called with smi_data_lock.
 */
static int smi_request(struct smi_cmd *smi_cmd)
{
        cpumask_t old_mask;
        int ret = 0;

        if (smi_cmd->magic != SMI_CMD_MAGIC) {
                dev_info(&dcdbas_pdev->dev, "%s: invalid magic value\n",
                         __FUNCTION__);
                return -EBADR;
        }

        /* SMI requires CPU 0 */
        old_mask = current->cpus_allowed;
        set_cpus_allowed(current, cpumask_of_cpu(0));
        if (smp_processor_id() != 0) {
                dev_dbg(&dcdbas_pdev->dev, "%s: failed to get CPU 0\n",
                        __FUNCTION__);
                ret = -EBUSY;
                goto out;
        }

        /* generate SMI */
        asm volatile (
                "outb %b0,%w1"
                : /* no output args */
                : "a" (smi_cmd->command_code),
                  "d" (smi_cmd->command_address),
                  "b" (smi_cmd->ebx),
                  "c" (smi_cmd->ecx)
                : "memory"
        );

out:
        set_cpus_allowed(current, old_mask);
        return ret;
}

/**
 * smi_request_store:
 *
 * The valid values are:
 * 0: zero SMI data buffer
 * 1: generate calling interface SMI
 * 2: generate raw SMI
 *
 * User application writes smi_cmd to smi_data before telling driver
 * to generate SMI.
 */
static ssize_t smi_request_store(struct device *dev,
                                 struct device_attribute *attr,
                                 const char *buf, size_t count)
{
        struct smi_cmd *smi_cmd;
        unsigned long val = simple_strtoul(buf, NULL, 10);
        ssize_t ret;

        down(&smi_data_lock);

        if (smi_data_buf_size < sizeof(struct smi_cmd)) {
                ret = -ENODEV;
                goto out;
        }
        smi_cmd = (struct smi_cmd *)smi_data_buf;

        switch (val) {
        case 2:
                /* Raw SMI */
                ret = smi_request(smi_cmd);
                if (!ret)
                        ret = count;
                break;
        case 1:
                /* Calling Interface SMI */
                smi_cmd->ebx = (u32) virt_to_phys(smi_cmd->command_buffer);
                ret = smi_request(smi_cmd);
                if (!ret)
                        ret = count;
                break;
        case 0:
                memset(smi_data_buf, 0, smi_data_buf_size);
                ret = count;
                break;
        default:
                ret = -EINVAL;
                break;
        }

out:
        up(&smi_data_lock);
        return ret;
}

/**
 * host_control_smi: generate host control SMI
 *
 * Caller must set up the host control command in smi_data_buf.
 */
static int host_control_smi(void)
{
        struct apm_cmd *apm_cmd;
        u8 *data;
        unsigned long flags;
        u32 num_ticks;
        s8 cmd_status;
        u8 index;

        apm_cmd = (struct apm_cmd *)smi_data_buf;
        apm_cmd->status = ESM_STATUS_CMD_UNSUCCESSFUL;

        switch (host_control_smi_type) {
        case HC_SMITYPE_TYPE1:
                spin_lock_irqsave(&rtc_lock, flags);
                /* write SMI data buffer physical address */
                data = (u8 *)&smi_data_buf_phys_addr;
                for (index = PE1300_CMOS_CMD_STRUCT_PTR;
                     index < (PE1300_CMOS_CMD_STRUCT_PTR + 4);
                     index++, data++) {
                        outb(index,
                             (CMOS_BASE_PORT + CMOS_PAGE2_INDEX_PORT_PIIX4));
                        outb(*data,
                             (CMOS_BASE_PORT + CMOS_PAGE2_DATA_PORT_PIIX4));
                }

                /* first set status to -1 as called by spec */
                cmd_status = ESM_STATUS_CMD_UNSUCCESSFUL;
                outb((u8) cmd_status, PCAT_APM_STATUS_PORT);

                /* generate SMM call */
                outb(ESM_APM_CMD, PCAT_APM_CONTROL_PORT);
                spin_unlock_irqrestore(&rtc_lock, flags);

                /* wait a few to see if it executed */
                num_ticks = TIMEOUT_USEC_SHORT_SEMA_BLOCKING;
                while ((cmd_status = inb(PCAT_APM_STATUS_PORT))
                       == ESM_STATUS_CMD_UNSUCCESSFUL) {
                        num_ticks--;
                        if (num_ticks == EXPIRED_TIMER)
                                return -ETIME;
                }
                break;

        case HC_SMITYPE_TYPE2:
        case HC_SMITYPE_TYPE3:
                spin_lock_irqsave(&rtc_lock, flags);
                /* write SMI data buffer physical address */
                data = (u8 *)&smi_data_buf_phys_addr;
                for (index = PE1400_CMOS_CMD_STRUCT_PTR;
                     index < (PE1400_CMOS_CMD_STRUCT_PTR + 4);
                     index++, data++) {
                        outb(index, (CMOS_BASE_PORT + CMOS_PAGE1_INDEX_PORT));
                        outb(*data, (CMOS_BASE_PORT + CMOS_PAGE1_DATA_PORT));
                }

                /* generate SMM call */
                if (host_control_smi_type == HC_SMITYPE_TYPE3)
                        outb(ESM_APM_CMD, PCAT_APM_CONTROL_PORT);
                else
                        outb(ESM_APM_CMD, PE1400_APM_CONTROL_PORT);

                /* restore RTC index pointer since it was written to above */
                CMOS_READ(RTC_REG_C);
                spin_unlock_irqrestore(&rtc_lock, flags);

                /* read control port back to serialize write */
                cmd_status = inb(PE1400_APM_CONTROL_PORT);

                /* wait a few to see if it executed */
                num_ticks = TIMEOUT_USEC_SHORT_SEMA_BLOCKING;
                while (apm_cmd->status == ESM_STATUS_CMD_UNSUCCESSFUL) {
                        num_ticks--;
                        if (num_ticks == EXPIRED_TIMER)
                                return -ETIME;
                }
                break;

        default:
                dev_dbg(&dcdbas_pdev->dev, "%s: invalid SMI type %u\n",
                        __FUNCTION__, host_control_smi_type);
                return -ENOSYS;
        }

        return 0;
}

/**
 * dcdbas_host_control: initiate host control
 *
 * This function is called by the driver after the system has
 * finished shutting down if the user application specified a
 * host control action to perform on shutdown.  It is safe to
 * use smi_data_buf at this point because the system has finished
 * shutting down and no userspace apps are running.
 */
static void dcdbas_host_control(void)
{
        struct apm_cmd *apm_cmd;
        u8 action;

        if (host_control_action == HC_ACTION_NONE)
                return;

        action = host_control_action;
        host_control_action = HC_ACTION_NONE;

        if (!smi_data_buf) {
                dev_dbg(&dcdbas_pdev->dev, "%s: no SMI buffer\n", __FUNCTION__);
                return;
        }

        if (smi_data_buf_size < sizeof(struct apm_cmd)) {
                dev_dbg(&dcdbas_pdev->dev, "%s: SMI buffer too small\n",
                        __FUNCTION__);
                return;
        }

        apm_cmd = (struct apm_cmd *)smi_data_buf;

        /* power off takes precedence */
        if (action & HC_ACTION_HOST_CONTROL_POWEROFF) {
                apm_cmd->command = ESM_APM_POWER_CYCLE;
                apm_cmd->reserved = 0;
                *((s16 *)&apm_cmd->parameters.shortreq.parm[0]) = (s16) 0;
                host_control_smi();
        } else if (action & HC_ACTION_HOST_CONTROL_POWERCYCLE) {
                apm_cmd->command = ESM_APM_POWER_CYCLE;
                apm_cmd->reserved = 0;
                *((s16 *)&apm_cmd->parameters.shortreq.parm[0]) = (s16) 20;
                host_control_smi();
        }
}

/**
 * dcdbas_reboot_notify: handle reboot notification for host control
 */
static int dcdbas_reboot_notify(struct notifier_block *nb, unsigned long code,
                                void *unused)
{
        static unsigned int notify_cnt = 0;

        switch (code) {
        case SYS_DOWN:
        case SYS_HALT:
        case SYS_POWER_OFF:
                if (host_control_on_shutdown) {
                        /* firmware is going to perform host control action */
                        if (++notify_cnt == 2) {
                                printk(KERN_WARNING
                                       "Please wait for shutdown "
                                       "action to complete...\n");
                                dcdbas_host_control();
                        }
                        /*
                         * register again and initiate the host control
                         * action on the second notification to allow
                         * everyone that registered to be notified
                         */
                        register_reboot_notifier(nb);
                }
                break;
        }

        return NOTIFY_DONE;
}

static struct notifier_block dcdbas_reboot_nb = {
        .notifier_call = dcdbas_reboot_notify,
        .next = NULL,
        .priority = 0
};

static DCDBAS_BIN_ATTR_RW(smi_data);

static struct bin_attribute *dcdbas_bin_attrs[] = {
        &bin_attr_smi_data,
        NULL
};

static DCDBAS_DEV_ATTR_RW(smi_data_buf_size);
static DCDBAS_DEV_ATTR_RO(smi_data_buf_phys_addr);
static DCDBAS_DEV_ATTR_WO(smi_request);
static DCDBAS_DEV_ATTR_RW(host_control_action);
static DCDBAS_DEV_ATTR_RW(host_control_smi_type);
static DCDBAS_DEV_ATTR_RW(host_control_on_shutdown);

static struct device_attribute *dcdbas_dev_attrs[] = {
        &dev_attr_smi_data_buf_size,
        &dev_attr_smi_data_buf_phys_addr,
        &dev_attr_smi_request,
        &dev_attr_host_control_action,
        &dev_attr_host_control_smi_type,
        &dev_attr_host_control_on_shutdown,
        NULL
};

/**
 * dcdbas_init: initialize driver
 */
static int __init dcdbas_init(void)
{
        int i;

        host_control_action = HC_ACTION_NONE;
        host_control_smi_type = HC_SMITYPE_NONE;

        dcdbas_pdev = platform_device_register_simple(DRIVER_NAME, -1, NULL, 0);
        if (IS_ERR(dcdbas_pdev))
                return PTR_ERR(dcdbas_pdev);

        /*
         * BIOS SMI calls require buffer addresses be in 32-bit address space.
         * This is done by setting the DMA mask below.
         */
        dcdbas_pdev->dev.coherent_dma_mask = DMA_32BIT_MASK;
        dcdbas_pdev->dev.dma_mask = &dcdbas_pdev->dev.coherent_dma_mask;

        register_reboot_notifier(&dcdbas_reboot_nb);

        for (i = 0; dcdbas_bin_attrs[i]; i++)
                sysfs_create_bin_file(&dcdbas_pdev->dev.kobj,
                                      dcdbas_bin_attrs[i]);

        for (i = 0; dcdbas_dev_attrs[i]; i++)
                device_create_file(&dcdbas_pdev->dev, dcdbas_dev_attrs[i]);

        dev_info(&dcdbas_pdev->dev, "%s (version %s)\n",
                 DRIVER_DESCRIPTION, DRIVER_VERSION);

        return 0;
}

/**
 * dcdbas_exit: perform driver cleanup
 */
static void __exit dcdbas_exit(void)
{
        platform_device_unregister(dcdbas_pdev);
        unregister_reboot_notifier(&dcdbas_reboot_nb);
        smi_data_buf_free();
}

module_init(dcdbas_init);
module_exit(dcdbas_exit);

MODULE_DESCRIPTION(DRIVER_DESCRIPTION " (version " DRIVER_VERSION ")");
MODULE_VERSION(DRIVER_VERSION);
MODULE_AUTHOR("Dell Inc.");
MODULE_LICENSE("GPL");