ppc4xx_cpm.c

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/*
 * PowerPC 4xx Clock and Power Management
 *
 * Copyright (C) 2010, Applied Micro Circuits Corporation
 * Victor Gallardo ([email protected])
 *
 * Based on arch/powerpc/platforms/44x/idle.c:
 * Jerone Young <[email protected]>
 * Copyright 2008 IBM Corp.
 *
 * Based on arch/powerpc/sysdev/fsl_pmc.c:
 * Anton Vorontsov <[email protected]>
 * Copyright 2009  MontaVista Software, Inc.
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * 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 of
 * the License, 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., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <linux/kernel.h>
#include <linux/of_platform.h>
#include <linux/sysfs.h>
#include <linux/cpu.h>
#include <linux/suspend.h>
#include <asm/dcr.h>
#include <asm/dcr-native.h>
#include <asm/machdep.h>

#define CPM_ER  0
#define CPM_FR  1
#define CPM_SR  2

#define CPM_IDLE_WAIT   0
#define CPM_IDLE_DOZE   1

struct cpm {
    dcr_host_t  dcr_host;
    unsigned int    dcr_offset[3];
    unsigned int    powersave_off;
    unsigned int    unused;
    unsigned int    idle_doze;
    unsigned int    standby;
    unsigned int    suspend;
};

static struct cpm cpm;

struct cpm_idle_mode {
    unsigned int enabled;
    const char  *name;
};

static struct cpm_idle_mode idle_mode[] = {
    [CPM_IDLE_WAIT] = { 1, "wait" }, /* default */
    [CPM_IDLE_DOZE] = { 0, "doze" },
};

static unsigned int cpm_set(unsigned int cpm_reg, unsigned int mask)
{
    unsigned int value;

    /* CPM controller supports 3 different types of sleep interface
     * known as class 1, 2 and 3. For class 1 units, they are
     * unconditionally put to sleep when the corresponding CPM bit is
     * set. For class 2 and 3 units this is not case; if they can be
     * put to to sleep, they will. Here we do not verify, we just
     * set them and expect them to eventually go off when they can.
     */
    value = dcr_read(cpm.dcr_host, cpm.dcr_offset[cpm_reg]);
    dcr_write(cpm.dcr_host, cpm.dcr_offset[cpm_reg], value | mask);

    /* return old state, to restore later if needed */
    return value;
}

static void cpm_idle_wait(void)
{
    unsigned long msr_save;

    /* save off initial state */
    msr_save = mfmsr();
    /* sync required when CPM0_ER[CPU] is set */
    mb();
    /* set wait state MSR */
    mtmsr(msr_save|MSR_WE|MSR_EE|MSR_CE|MSR_DE);
    isync();
    /* return to initial state */
    mtmsr(msr_save);
    isync();
}

static void cpm_idle_sleep(unsigned int mask)
{
    unsigned int er_save;

    /* update CPM_ER state */
    er_save = cpm_set(CPM_ER, mask);

    /* go to wait state so that CPM0_ER[CPU] can take effect */
    cpm_idle_wait();

    /* restore CPM_ER state */
    dcr_write(cpm.dcr_host, cpm.dcr_offset[CPM_ER], er_save);
}

static void cpm_idle_doze(void)
{
    cpm_idle_sleep(cpm.idle_doze);
}

static void cpm_idle_config(int mode)
{
    int i;

    if (idle_mode[mode].enabled)
        return;

    for (i = 0; i < ARRAY_SIZE(idle_mode); i++)
        idle_mode[i].enabled = 0;

    idle_mode[mode].enabled = 1;
}

static ssize_t cpm_idle_show(struct kobject *kobj,
                 struct kobj_attribute *attr, char *buf)
{
    char *s = buf;
    int i;

    for (i = 0; i < ARRAY_SIZE(idle_mode); i++) {
        if (idle_mode[i].enabled)
            s += sprintf(s, "[%s] ", idle_mode[i].name);
        else
            s += sprintf(s, "%s ", idle_mode[i].name);
    }

    *(s-1) = '\n'; /* convert the last space to a newline */

    return s - buf;
}

static ssize_t cpm_idle_store(struct kobject *kobj,
                  struct kobj_attribute *attr,
                  const char *buf, size_t n)
{
    int i;
    char *p;
    int len;

    p = memchr(buf, '\n', n);
    len = p ? p - buf : n;

    for (i = 0; i < ARRAY_SIZE(idle_mode); i++) {
        if (strncmp(buf, idle_mode[i].name, len) == 0) {
            cpm_idle_config(i);
            return n;
        }
    }

    return -EINVAL;
}

static struct kobj_attribute cpm_idle_attr =
    __ATTR(idle, 0644, cpm_idle_show, cpm_idle_store);

static void cpm_idle_config_sysfs(void)
{
    struct device *dev;
    unsigned long ret;

    dev = get_cpu_device(0);

    ret = sysfs_create_file(&dev->kobj,
                &cpm_idle_attr.attr);
    if (ret)
        printk(KERN_WARNING
               "cpm: failed to create idle sysfs entry\n");
}

static void cpm_idle(void)
{
    if (idle_mode[CPM_IDLE_DOZE].enabled)
        cpm_idle_doze();
    else
        cpm_idle_wait();
}

static int cpm_suspend_valid(suspend_state_t state)
{
    switch (state) {
    case PM_SUSPEND_STANDBY:
        return !!cpm.standby;
    case PM_SUSPEND_MEM:
        return !!cpm.suspend;
    default:
        return 0;
    }
}

static void cpm_suspend_standby(unsigned int mask)
{
    unsigned long tcr_save;

    /* disable decrement interrupt */
    tcr_save = mfspr(SPRN_TCR);
    mtspr(SPRN_TCR, tcr_save & ~TCR_DIE);

    /* go to sleep state */
    cpm_idle_sleep(mask);

    /* restore decrement interrupt */
    mtspr(SPRN_TCR, tcr_save);
}

static int cpm_suspend_enter(suspend_state_t state)
{
    switch (state) {
    case PM_SUSPEND_STANDBY:
        cpm_suspend_standby(cpm.standby);
        break;
    case PM_SUSPEND_MEM:
        cpm_suspend_standby(cpm.suspend);
        break;
    }

    return 0;
}

static struct platform_suspend_ops cpm_suspend_ops = {
    .valid      = cpm_suspend_valid,
    .enter      = cpm_suspend_enter,
};

static int cpm_get_uint_property(struct device_node *np,
                 const char *name)
{
    int len;
    const unsigned int *prop = of_get_property(np, name, &len);

    if (prop == NULL || len < sizeof(u32))
        return 0;

    return *prop;
}

static int __init cpm_init(void)
{
    struct device_node *np;
    int dcr_base, dcr_len;
    int ret = 0;

    if (!cpm.powersave_off) {
        cpm_idle_config(CPM_IDLE_WAIT);
        ppc_md.power_save = &cpm_idle;
    }

    np = of_find_compatible_node(NULL, NULL, "ibm,cpm");
    if (!np) {
        ret = -EINVAL;
        goto out;
    }

    dcr_base = dcr_resource_start(np, 0);
    dcr_len = dcr_resource_len(np, 0);

    if (dcr_base == 0 || dcr_len == 0) {
        printk(KERN_ERR "cpm: could not parse dcr property for %s\n",
               np->full_name);
        ret = -EINVAL;
        goto out;
    }

    cpm.dcr_host = dcr_map(np, dcr_base, dcr_len);

    if (!DCR_MAP_OK(cpm.dcr_host)) {
        printk(KERN_ERR "cpm: failed to map dcr property for %s\n",
               np->full_name);
        ret = -EINVAL;
        goto out;
    }

    /* All 4xx SoCs with a CPM controller have one of two
     * different order for the CPM registers. Some have the
     * CPM registers in the following order (ER,FR,SR). The
     * others have them in the following order (SR,ER,FR).
     */

    if (cpm_get_uint_property(np, "er-offset") == 0) {
        cpm.dcr_offset[CPM_ER] = 0;
        cpm.dcr_offset[CPM_FR] = 1;
        cpm.dcr_offset[CPM_SR] = 2;
    } else {
        cpm.dcr_offset[CPM_ER] = 1;
        cpm.dcr_offset[CPM_FR] = 2;
        cpm.dcr_offset[CPM_SR] = 0;
    }

    /* Now let's see what IPs to turn off for the following modes */

    cpm.unused = cpm_get_uint_property(np, "unused-units");
    cpm.idle_doze = cpm_get_uint_property(np, "idle-doze");
    cpm.standby = cpm_get_uint_property(np, "standby");
    cpm.suspend = cpm_get_uint_property(np, "suspend");

    /* If some IPs are unused let's turn them off now */

    if (cpm.unused) {
        cpm_set(CPM_ER, cpm.unused);
        cpm_set(CPM_FR, cpm.unused);
    }

    /* Now let's export interfaces */

    if (!cpm.powersave_off && cpm.idle_doze)
        cpm_idle_config_sysfs();

    if (cpm.standby || cpm.suspend)
        suspend_set_ops(&cpm_suspend_ops);
out:
    if (np)
        of_node_put(np);
    return ret;
}

late_initcall(cpm_init);

static int __init cpm_powersave_off(char *arg)
{
    cpm.powersave_off = 1;
    return 0;
}
__setup("powersave=off", cpm_powersave_off);