/*
 * coretemp.c - Linux kernel module for hardware monitoring
 *
 * Copyright (C) 2007 Rudolf Marek <r.marek@assembler.cz>
 *
 * Inspired from many hwmon drivers
 *
 * 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 of the License.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301 USA.
 */

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/hwmon.h>
#include <linux/sysfs.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/platform_device.h>
#include <linux/cpu.h>
#include <asm/msr.h>
#include <asm/processor.h>

#define DRVNAME	"coretemp"

typedef enum { SHOW_TEMP, SHOW_TJMAX, SHOW_LABEL, SHOW_NAME } SHOW;

/*
 * Functions declaration
 */

static struct coretemp_data *coretemp_update_device(struct device *dev);

struct coretemp_data {
	struct device *hwmon_dev;
	struct mutex update_lock;
	const char *name;
	u32 id;
	char valid;		/* zero until following fields are valid */
	unsigned long last_updated;	/* in jiffies */
	int temp;
	int tjmax;
	u8 alarm;
};

/*
 * Sysfs stuff
 */

static ssize_t show_name(struct device *dev, struct device_attribute
			  *devattr, char *buf)
{
	int ret;
	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
	struct coretemp_data *data = dev_get_drvdata(dev);

	if (attr->index == SHOW_NAME)
		ret = sprintf(buf, "%s\n", data->name);
	else	/* show label */
		ret = sprintf(buf, "Core %d\n", data->id);
	return ret;
}

static ssize_t show_alarm(struct device *dev, struct device_attribute
			  *devattr, char *buf)
{
	struct coretemp_data *data = coretemp_update_device(dev);
	/* read the Out-of-spec log, never clear */
	return sprintf(buf, "%d\n", data->alarm);
}

static ssize_t show_temp(struct device *dev,
			 struct device_attribute *devattr, char *buf)
{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
	struct coretemp_data *data = coretemp_update_device(dev);
	int err;

	if (attr->index == SHOW_TEMP)
		err = data->valid ? sprintf(buf, "%d\n", data->temp) : -EAGAIN;
	else
		err = sprintf(buf, "%d\n", data->tjmax);

	return err;
}

static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL,
			  SHOW_TEMP);
static SENSOR_DEVICE_ATTR(temp1_crit, S_IRUGO, show_temp, NULL,
			  SHOW_TJMAX);
static DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL);
static SENSOR_DEVICE_ATTR(temp1_label, S_IRUGO, show_name, NULL, SHOW_LABEL);
static SENSOR_DEVICE_ATTR(name, S_IRUGO, show_name, NULL, SHOW_NAME);

static struct attribute *coretemp_attributes[] = {
	&sensor_dev_attr_name.dev_attr.attr,
	&sensor_dev_attr_temp1_label.dev_attr.attr,
	&dev_attr_temp1_crit_alarm.attr,
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	&sensor_dev_attr_temp1_crit.dev_attr.attr,
	NULL
};

static const struct attribute_group coretemp_group = {
	.attrs = coretemp_attributes,
};

static struct coretemp_data *coretemp_update_device(struct device *dev)
{
	struct coretemp_data *data = dev_get_drvdata(dev);

	mutex_lock(&data->update_lock);

	if (!data->valid || time_after(jiffies, data->last_updated + HZ)) {
		u32 eax, edx;

		data->valid = 0;
		rdmsr_on_cpu(data->id, MSR_IA32_THERM_STATUS, &eax, &edx);
		data->alarm = (eax >> 5) & 1;
		/* update only if data has been valid */
		if (eax & 0x80000000) {
			data->temp = data->tjmax - (((eax >> 16)
							& 0x7f) * 1000);
			data->valid = 1;
		} else {
			dev_dbg(dev, "Temperature data invalid (0x%x)\n", eax);
		}
		data->last_updated = jiffies;
	}

	mutex_unlock(&data->update_lock);
	return data;
}

static int __devinit coretemp_probe(struct platform_device *pdev)
{
	struct coretemp_data *data;
	struct cpuinfo_x86 *c = &cpu_data(pdev->id);
	int err;
	u32 eax, edx;

	if (!(data = kzalloc(sizeof(struct coretemp_data), GFP_KERNEL))) {
		err = -ENOMEM;
		dev_err(&pdev->dev, "Out of memory\n");
		goto exit;
	}

	data->id = pdev->id;
	data->name = "coretemp";
	mutex_init(&data->update_lock);
	/* Tjmax default is 100 degrees C */
	data->tjmax = 100000;

	/* test if we can access the THERM_STATUS MSR */
	err = rdmsr_safe_on_cpu(data->id, MSR_IA32_THERM_STATUS, &eax, &edx);
	if (err) {
		dev_err(&pdev->dev,
			"Unable to access THERM_STATUS MSR, giving up\n");
		goto exit_free;
	}

	/* Check if we have problem with errata AE18 of Core processors:
	   Readings might stop update when processor visited too deep sleep,
	   fixed for stepping D0 (6EC).
	*/

	if ((c->x86_model == 0xe) && (c->x86_mask < 0xc)) {
		/* check for microcode update */
		rdmsr_on_cpu(data->id, MSR_IA32_UCODE_REV, &eax, &edx);
		if (edx < 0x39) {
			err = -ENODEV;
			dev_err(&pdev->dev,
				"Errata AE18 not fixed, update BIOS or "
				"microcode of the CPU!\n");
			goto exit_free;
		}
	}

	/* Some processors have Tjmax 85 following magic should detect it
	   Intel won't disclose the information without signed NDA, but
	   individuals cannot sign it. Catch(ed) 22.
	*/

	if (((c->x86_model == 0xf) && (c->x86_mask > 3)) ||
		(c->x86_model == 0xe))  {
		err = rdmsr_safe_on_cpu(data->id, 0xee, &eax, &edx);
		if (err) {
			dev_warn(&pdev->dev,
				 "Unable to access MSR 0xEE, Tjmax left at %d "
				 "degrees C\n", data->tjmax/1000);
		} else if (eax & 0x40000000) {
			data->tjmax = 85000;
		}
	}

	/* Intel says that above should not work for desktop Core2 processors,
	   but it seems to work. There is no other way how get the absolute
	   readings. Warn the user about this. First check if are desktop,
	   bit 50 of MSR_IA32_PLATFORM_ID should be 0.
	*/

	rdmsr_safe_on_cpu(data->id, MSR_IA32_PLATFORM_ID, &eax, &edx);

	if ((c->x86_model == 0xf) && (!(edx & 0x00040000))) {
		dev_warn(&pdev->dev, "Using undocumented features, absolute "
			 "temperature might be wrong!\n");
	}

	platform_set_drvdata(pdev, data);

	if ((err = sysfs_create_group(&pdev->dev.kobj, &coretemp_group)))
		goto exit_free;

	data->hwmon_dev = hwmon_device_register(&pdev->dev);
	if (IS_ERR(data->hwmon_dev)) {
		err = PTR_ERR(data->hwmon_dev);
		dev_err(&pdev->dev, "Class registration failed (%d)\n",
			err);
		goto exit_class;
	}

	return 0;

exit_class:
	sysfs_remove_group(&pdev->dev.kobj, &coretemp_group);
exit_free:
	kfree(data);
exit:
	return err;
}

static int __devexit coretemp_remove(struct platform_device *pdev)
{
	struct coretemp_data *data = platform_get_drvdata(pdev);

	hwmon_device_unregister(data->hwmon_dev);
	sysfs_remove_group(&pdev->dev.kobj, &coretemp_group);
	platform_set_drvdata(pdev, NULL);
	kfree(data);
	return 0;
}

static struct platform_driver coretemp_driver = {
	.driver = {
		.owner = THIS_MODULE,
		.name = DRVNAME,
	},
	.probe = coretemp_probe,
	.remove = __devexit_p(coretemp_remove),
};

struct pdev_entry {
	struct list_head list;
	struct platform_device *pdev;
	unsigned int cpu;
};

static LIST_HEAD(pdev_list);
static DEFINE_MUTEX(pdev_list_mutex);

static int __cpuinit coretemp_device_add(unsigned int cpu)
{
	int err;
	struct platform_device *pdev;
	struct pdev_entry *pdev_entry;

	pdev = platform_device_alloc(DRVNAME, cpu);
	if (!pdev) {
		err = -ENOMEM;
		printk(KERN_ERR DRVNAME ": Device allocation failed\n");
		goto exit;
	}

	pdev_entry = kzalloc(sizeof(struct pdev_entry), GFP_KERNEL);
	if (!pdev_entry) {
		err = -ENOMEM;
		goto exit_device_put;
	}

	err = platform_device_add(pdev);
	if (err) {
		printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
		       err);
		goto exit_device_free;
	}

	pdev_entry->pdev = pdev;
	pdev_entry->cpu = cpu;
	mutex_lock(&pdev_list_mutex);
	list_add_tail(&pdev_entry->list, &pdev_list);
	mutex_unlock(&pdev_list_mutex);

	return 0;

exit_device_free:
	kfree(pdev_entry);
exit_device_put:
	platform_device_put(pdev);
exit:
	return err;
}

#ifdef CONFIG_HOTPLUG_CPU
static void coretemp_device_remove(unsigned int cpu)
{
	struct pdev_entry *p, *n;
	mutex_lock(&pdev_list_mutex);
	list_for_each_entry_safe(p, n, &pdev_list, list) {
		if (p->cpu == cpu) {
			platform_device_unregister(p->pdev);
			list_del(&p->list);
			kfree(p);
		}
	}
	mutex_unlock(&pdev_list_mutex);
}

static int coretemp_cpu_callback(struct notifier_block *nfb,
				 unsigned long action, void *hcpu)
{
	unsigned int cpu = (unsigned long) hcpu;

	switch (action) {
	case CPU_ONLINE:
	case CPU_ONLINE_FROZEN:
		coretemp_device_add(cpu);
		break;
	case CPU_DEAD:
	case CPU_DEAD_FROZEN:
		coretemp_device_remove(cpu);
		break;
	}
	return NOTIFY_OK;
}

static struct notifier_block coretemp_cpu_notifier = {
	.notifier_call = coretemp_cpu_callback,
};
#endif				/* !CONFIG_HOTPLUG_CPU */

static int __init coretemp_init(void)
{
	int i, err = -ENODEV;
	struct pdev_entry *p, *n;

	/* quick check if we run Intel */
	if (cpu_data(0).x86_vendor != X86_VENDOR_INTEL)
		goto exit;

	err = platform_driver_register(&coretemp_driver);
	if (err)
		goto exit;

	for_each_online_cpu(i) {
		struct cpuinfo_x86 *c = &cpu_data(i);

		/* check if family 6, models e, f, 16 */
		if ((c->cpuid_level < 0) || (c->x86 != 0x6) ||
		    !((c->x86_model == 0xe) || (c->x86_model == 0xf) ||
			(c->x86_model == 0x16))) {

			/* supported CPU not found, but report the unknown
			   family 6 CPU */
			if ((c->x86 == 0x6) && (c->x86_model > 0xf))
				printk(KERN_WARNING DRVNAME ": Unknown CPU "
					"model %x\n", c->x86_model);
			continue;
		}

		err = coretemp_device_add(i);
		if (err)
			goto exit_devices_unreg;
	}
	if (list_empty(&pdev_list)) {
		err = -ENODEV;
		goto exit_driver_unreg;
	}

#ifdef CONFIG_HOTPLUG_CPU
	register_hotcpu_notifier(&coretemp_cpu_notifier);
#endif
	return 0;

exit_devices_unreg:
	mutex_lock(&pdev_list_mutex);
	list_for_each_entry_safe(p, n, &pdev_list, list) {
		platform_device_unregister(p->pdev);
		list_del(&p->list);
		kfree(p);
	}
	mutex_unlock(&pdev_list_mutex);
exit_driver_unreg:
	platform_driver_unregister(&coretemp_driver);
exit:
	return err;
}

static void __exit coretemp_exit(void)
{
	struct pdev_entry *p, *n;
#ifdef CONFIG_HOTPLUG_CPU
	unregister_hotcpu_notifier(&coretemp_cpu_notifier);
#endif
	mutex_lock(&pdev_list_mutex);
	list_for_each_entry_safe(p, n, &pdev_list, list) {
		platform_device_unregister(p->pdev);
		list_del(&p->list);
		kfree(p);
	}
	mutex_unlock(&pdev_list_mutex);
	platform_driver_unregister(&coretemp_driver);
}

MODULE_AUTHOR("Rudolf Marek <r.marek@assembler.cz>");
MODULE_DESCRIPTION("Intel Core temperature monitor");
MODULE_LICENSE("GPL");

module_init(coretemp_init)
module_exit(coretemp_exit)