cbe_thermal.c

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/*
 * thermal support for the cell processor
 *
 * This module adds some sysfs attributes to cpu and spu nodes.
 * Base for measurements are the digital thermal sensors (DTS)
 * located on the chip.
 * The accuracy is 2 degrees, starting from 65 up to 125 degrees celsius
 * The attributes can be found under
 * /sys/devices/system/cpu/cpuX/thermal
 * /sys/devices/system/spu/spuX/thermal
 *
 * The following attributes are added for each node:
 * temperature:
 *  contains the current temperature measured by the DTS
 * throttle_begin:
 *  throttling begins when temperature is greater or equal to
 *  throttle_begin. Setting this value to 125 prevents throttling.
 * throttle_end:
 *  throttling is being ceased, if the temperature is lower than
 *  throttle_end. Due to a delay between applying throttling and
 *  a reduced temperature this value should be less than throttle_begin.
 *  A value equal to throttle_begin provides only a very little hysteresis.
 * throttle_full_stop:
 *  If the temperatrue is greater or equal to throttle_full_stop,
 *  full throttling is applied to the cpu or spu. This value should be
 *  greater than throttle_begin and throttle_end. Setting this value to
 *  65 prevents the unit from running code at all.
 *
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
 *
 * Author: Christian Krafft <[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, 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/cpu.h>
#include <asm/spu.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/cell-regs.h>

#include "spu_priv1_mmio.h"

#define TEMP_MIN 65
#define TEMP_MAX 125

#define DEVICE_PREFIX_ATTR(_prefix,_name,_mode)         \
struct device_attribute attr_ ## _prefix ## _ ## _name = {  \
    .attr = { .name = __stringify(_name), .mode = _mode },  \
    .show   = _prefix ## _show_ ## _name,           \
    .store  = _prefix ## _store_ ## _name,          \
};

static inline u8 reg_to_temp(u8 reg_value)
{
    return ((reg_value & 0x3f) << 1) + TEMP_MIN;
}

static inline u8 temp_to_reg(u8 temp)
{
    return ((temp - TEMP_MIN) >> 1) & 0x3f;
}

static struct cbe_pmd_regs __iomem *get_pmd_regs(struct device *dev)
{
    struct spu *spu;

    spu = container_of(dev, struct spu, dev);

    return cbe_get_pmd_regs(spu_devnode(spu));
}

/* returns the value for a given spu in a given register */
static u8 spu_read_register_value(struct device *dev, union spe_reg __iomem *reg)
{
    union spe_reg value;
    struct spu *spu;

    spu = container_of(dev, struct spu, dev);
    value.val = in_be64(&reg->val);

    return value.spe[spu->spe_id];
}

static ssize_t spu_show_temp(struct device *dev, struct device_attribute *attr,
            char *buf)
{
    u8 value;
    struct cbe_pmd_regs __iomem *pmd_regs;

    pmd_regs = get_pmd_regs(dev);

    value = spu_read_register_value(dev, &pmd_regs->ts_ctsr1);

    return sprintf(buf, "%d\n", reg_to_temp(value));
}

static ssize_t show_throttle(struct cbe_pmd_regs __iomem *pmd_regs, char *buf, int pos)
{
    u64 value;

    value = in_be64(&pmd_regs->tm_tpr.val);
    /* access the corresponding byte */
    value >>= pos;
    value &= 0x3F;

    return sprintf(buf, "%d\n", reg_to_temp(value));
}

static ssize_t store_throttle(struct cbe_pmd_regs __iomem *pmd_regs, const char *buf, size_t size, int pos)
{
    u64 reg_value;
    int temp;
    u64 new_value;
    int ret;

    ret = sscanf(buf, "%u", &temp);

    if (ret != 1 || temp < TEMP_MIN || temp > TEMP_MAX)
        return -EINVAL;

    new_value = temp_to_reg(temp);

    reg_value = in_be64(&pmd_regs->tm_tpr.val);

    /* zero out bits for new value */
    reg_value &= ~(0xffull << pos);
    /* set bits to new value */
    reg_value |= new_value << pos;

    out_be64(&pmd_regs->tm_tpr.val, reg_value);
    return size;
}

static ssize_t spu_show_throttle_end(struct device *dev,
            struct device_attribute *attr, char *buf)
{
    return show_throttle(get_pmd_regs(dev), buf, 0);
}

static ssize_t spu_show_throttle_begin(struct device *dev,
            struct device_attribute *attr, char *buf)
{
    return show_throttle(get_pmd_regs(dev), buf, 8);
}

static ssize_t spu_show_throttle_full_stop(struct device *dev,
            struct device_attribute *attr, char *buf)
{
    return show_throttle(get_pmd_regs(dev), buf, 16);
}

static ssize_t spu_store_throttle_end(struct device *dev,
            struct device_attribute *attr, const char *buf, size_t size)
{
    return store_throttle(get_pmd_regs(dev), buf, size, 0);
}

static ssize_t spu_store_throttle_begin(struct device *dev,
            struct device_attribute *attr, const char *buf, size_t size)
{
    return store_throttle(get_pmd_regs(dev), buf, size, 8);
}

static ssize_t spu_store_throttle_full_stop(struct device *dev,
            struct device_attribute *attr, const char *buf, size_t size)
{
    return store_throttle(get_pmd_regs(dev), buf, size, 16);
}

static ssize_t ppe_show_temp(struct device *dev, char *buf, int pos)
{
    struct cbe_pmd_regs __iomem *pmd_regs;
    u64 value;

    pmd_regs = cbe_get_cpu_pmd_regs(dev->id);
    value = in_be64(&pmd_regs->ts_ctsr2);

    value = (value >> pos) & 0x3f;

    return sprintf(buf, "%d\n", reg_to_temp(value));
}


/* shows the temperature of the DTS on the PPE,
 * located near the linear thermal sensor */
static ssize_t ppe_show_temp0(struct device *dev,
            struct device_attribute *attr, char *buf)
{
    return ppe_show_temp(dev, buf, 32);
}

/* shows the temperature of the second DTS on the PPE */
static ssize_t ppe_show_temp1(struct device *dev,
            struct device_attribute *attr, char *buf)
{
    return ppe_show_temp(dev, buf, 0);
}

static ssize_t ppe_show_throttle_end(struct device *dev,
            struct device_attribute *attr, char *buf)
{
    return show_throttle(cbe_get_cpu_pmd_regs(dev->id), buf, 32);
}

static ssize_t ppe_show_throttle_begin(struct device *dev,
            struct device_attribute *attr, char *buf)
{
    return show_throttle(cbe_get_cpu_pmd_regs(dev->id), buf, 40);
}

static ssize_t ppe_show_throttle_full_stop(struct device *dev,
            struct device_attribute *attr, char *buf)
{
    return show_throttle(cbe_get_cpu_pmd_regs(dev->id), buf, 48);
}

static ssize_t ppe_store_throttle_end(struct device *dev,
            struct device_attribute *attr, const char *buf, size_t size)
{
    return store_throttle(cbe_get_cpu_pmd_regs(dev->id), buf, size, 32);
}

static ssize_t ppe_store_throttle_begin(struct device *dev,
            struct device_attribute *attr, const char *buf, size_t size)
{
    return store_throttle(cbe_get_cpu_pmd_regs(dev->id), buf, size, 40);
}

static ssize_t ppe_store_throttle_full_stop(struct device *dev,
            struct device_attribute *attr, const char *buf, size_t size)
{
    return store_throttle(cbe_get_cpu_pmd_regs(dev->id), buf, size, 48);
}


static struct device_attribute attr_spu_temperature = {
    .attr = {.name = "temperature", .mode = 0400 },
    .show = spu_show_temp,
};

static DEVICE_PREFIX_ATTR(spu, throttle_end, 0600);
static DEVICE_PREFIX_ATTR(spu, throttle_begin, 0600);
static DEVICE_PREFIX_ATTR(spu, throttle_full_stop, 0600);


static struct attribute *spu_attributes[] = {
    &attr_spu_temperature.attr,
    &attr_spu_throttle_end.attr,
    &attr_spu_throttle_begin.attr,
    &attr_spu_throttle_full_stop.attr,
    NULL,
};

static struct attribute_group spu_attribute_group = {
    .name   = "thermal",
    .attrs  = spu_attributes,
};

static struct device_attribute attr_ppe_temperature0 = {
    .attr = {.name = "temperature0", .mode = 0400 },
    .show = ppe_show_temp0,
};

static struct device_attribute attr_ppe_temperature1 = {
    .attr = {.name = "temperature1", .mode = 0400 },
    .show = ppe_show_temp1,
};

static DEVICE_PREFIX_ATTR(ppe, throttle_end, 0600);
static DEVICE_PREFIX_ATTR(ppe, throttle_begin, 0600);
static DEVICE_PREFIX_ATTR(ppe, throttle_full_stop, 0600);

static struct attribute *ppe_attributes[] = {
    &attr_ppe_temperature0.attr,
    &attr_ppe_temperature1.attr,
    &attr_ppe_throttle_end.attr,
    &attr_ppe_throttle_begin.attr,
    &attr_ppe_throttle_full_stop.attr,
    NULL,
};

static struct attribute_group ppe_attribute_group = {
    .name   = "thermal",
    .attrs  = ppe_attributes,
};

/*
 * initialize throttling with default values
 */
static int __init init_default_values(void)
{
    int cpu;
    struct cbe_pmd_regs __iomem *pmd_regs;
    struct device *dev;
    union ppe_spe_reg tpr;
    union spe_reg str1;
    u64 str2;
    union spe_reg cr1;
    u64 cr2;

    /* TPR defaults */
    /* ppe
     *  1F - no full stop
     *  08 - dynamic throttling starts if over 80 degrees
     *  03 - dynamic throttling ceases if below 70 degrees */
    tpr.ppe = 0x1F0803;
    /* spe
     *  10 - full stopped when over 96 degrees
     *  08 - dynamic throttling starts if over 80 degrees
     *  03 - dynamic throttling ceases if below 70 degrees
     */
    tpr.spe = 0x100803;

    /* STR defaults */
    /* str1
     *  10 - stop 16 of 32 cycles
     */
    str1.val = 0x1010101010101010ull;
    /* str2
     *  10 - stop 16 of 32 cycles
     */
    str2 = 0x10;

    /* CR defaults */
    /* cr1
     *  4 - normal operation
     */
    cr1.val = 0x0404040404040404ull;
    /* cr2
     *  4 - normal operation
     */
    cr2 = 0x04;

    for_each_possible_cpu (cpu) {
        pr_debug("processing cpu %d\n", cpu);
        dev = get_cpu_device(cpu);

        if (!dev) {
            pr_info("invalid dev pointer for cbe_thermal\n");
            return -EINVAL;
        }

        pmd_regs = cbe_get_cpu_pmd_regs(dev->id);

        if (!pmd_regs) {
            pr_info("invalid CBE regs pointer for cbe_thermal\n");
            return -EINVAL;
        }

        out_be64(&pmd_regs->tm_str2, str2);
        out_be64(&pmd_regs->tm_str1.val, str1.val);
        out_be64(&pmd_regs->tm_tpr.val, tpr.val);
        out_be64(&pmd_regs->tm_cr1.val, cr1.val);
        out_be64(&pmd_regs->tm_cr2, cr2);
    }

    return 0;
}


static int __init thermal_init(void)
{
    int rc = init_default_values();

    if (rc == 0) {
        spu_add_dev_attr_group(&spu_attribute_group);
        cpu_add_dev_attr_group(&ppe_attribute_group);
    }

    return rc;
}
module_init(thermal_init);

static void __exit thermal_exit(void)
{
    spu_remove_dev_attr_group(&spu_attribute_group);
    cpu_remove_dev_attr_group(&ppe_attribute_group);
}
module_exit(thermal_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Krafft <[email protected]>");