dcdbas.c

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/*
 *  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) 1995-2006 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/platform_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 <linux/mutex.h>
#include <asm/io.h>
#include <asm/semaphore.h>

#include "dcdbas.h"

#define DRIVER_NAME		"dcdbas"
#define DRIVER_VERSION		"5.6.0-3.2"
#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 DEFINE_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 */
	mutex_lock(&smi_data_lock);
	ret = smi_data_buf_realloc(buf_size);
	mutex_unlock(&smi_data_lock);
	if (ret)
		return ret;

	return count;
}

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

	mutex_lock(&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:
	mutex_unlock(&smi_data_lock);
	return ret;
}

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

	if ((pos + count) > MAX_SMI_DATA_BUF_SIZE)
		return -EINVAL;

	mutex_lock(&smi_data_lock);

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

	memcpy(smi_data_buf + pos, buf, count);
	ret = count;
out:
	mutex_unlock(&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 */
	mutex_lock(&smi_data_lock);
	ret = smi_data_buf_realloc(sizeof(struct apm_cmd));
	mutex_unlock(&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;

	mutex_lock(&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;