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cbe_thermal.c

/*
 * 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 <krafft@de.ibm.com>
 *
 * 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/sysdev.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 SYSDEV_PREFIX_ATTR(_prefix,_name,_mode)             \
struct sysdev_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 sys_device *sysdev)
{
      struct spu *spu;

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

      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 sys_device *sysdev, union spe_reg __iomem *reg)
{
      union spe_reg value;
      struct spu *spu;

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

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

static ssize_t spu_show_temp(struct sys_device *sysdev, char *buf)
{
      u8 value;
      struct cbe_pmd_regs __iomem *pmd_regs;

      pmd_regs = get_pmd_regs(sysdev);

      value = spu_read_register_value(sysdev, &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 sys_device *sysdev, char *buf)
{
      return show_throttle(get_pmd_regs(sysdev), buf, 0);
}

static ssize_t spu_show_throttle_begin(struct sys_device *sysdev, char *buf)
{
      return show_throttle(get_pmd_regs(sysdev), buf, 8);
}

static ssize_t spu_show_throttle_full_stop(struct sys_device *sysdev, char *buf)
{
      return show_throttle(get_pmd_regs(sysdev), buf, 16);
}

static ssize_t spu_store_throttle_end(struct sys_device *sysdev, const char *buf, size_t size)
{
      return store_throttle(get_pmd_regs(sysdev), buf, size, 0);
}

static ssize_t spu_store_throttle_begin(struct sys_device *sysdev, const char *buf, size_t size)
{
      return store_throttle(get_pmd_regs(sysdev), buf, size, 8);
}

static ssize_t spu_store_throttle_full_stop(struct sys_device *sysdev, const char *buf, size_t size)
{
      return store_throttle(get_pmd_regs(sysdev), buf, size, 16);
}

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

      pmd_regs = cbe_get_cpu_pmd_regs(sysdev->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 sys_device *sysdev, char *buf)
{
      return ppe_show_temp(sysdev, buf, 32);
}

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

static ssize_t ppe_show_throttle_end(struct sys_device *sysdev, char *buf)
{
      return show_throttle(cbe_get_cpu_pmd_regs(sysdev->id), buf, 32);
}

static ssize_t ppe_show_throttle_begin(struct sys_device *sysdev, char *buf)
{
      return show_throttle(cbe_get_cpu_pmd_regs(sysdev->id), buf, 40);
}

static ssize_t ppe_show_throttle_full_stop(struct sys_device *sysdev, char *buf)
{
      return show_throttle(cbe_get_cpu_pmd_regs(sysdev->id), buf, 48);
}

static ssize_t ppe_store_throttle_end(struct sys_device *sysdev, const char *buf, size_t size)
{
      return store_throttle(cbe_get_cpu_pmd_regs(sysdev->id), buf, size, 32);
}

static ssize_t ppe_store_throttle_begin(struct sys_device *sysdev, const char *buf, size_t size)
{
      return store_throttle(cbe_get_cpu_pmd_regs(sysdev->id), buf, size, 40);
}

static ssize_t ppe_store_throttle_full_stop(struct sys_device *sysdev, const char *buf, size_t size)
{
      return store_throttle(cbe_get_cpu_pmd_regs(sysdev->id), buf, size, 48);
}


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

static SYSDEV_PREFIX_ATTR(spu, throttle_end, 0600);
static SYSDEV_PREFIX_ATTR(spu, throttle_begin, 0600);
static SYSDEV_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 sysdev_attribute attr_ppe_temperature0 = {
      .attr = {.name = "temperature0", .mode = 0400 },
      .show = ppe_show_temp0,
};

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

static SYSDEV_PREFIX_ATTR(ppe, throttle_end, 0600);
static SYSDEV_PREFIX_ATTR(ppe, throttle_begin, 0600);
static SYSDEV_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 sys_device *sysdev;
      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);
            sysdev = get_cpu_sysdev(cpu);

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

            pmd_regs = cbe_get_cpu_pmd_regs(sysdev->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_sysdev_attr_group(&spu_attribute_group);
            cpu_add_sysdev_attr_group(&ppe_attribute_group);
      }

      return rc;
}
module_init(thermal_init);

static void __exit thermal_exit(void)
{
      spu_remove_sysdev_attr_group(&spu_attribute_group);
      cpu_remove_sysdev_attr_group(&ppe_attribute_group);
}
module_exit(thermal_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");


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