powerpc/oprofile: IBM CELL: cleanup and restructuring

[safe/jmp/linux-2.6] / arch / powerpc / oprofile / op_model_cell.c

/*
 * Cell Broadband Engine OProfile Support
 *
 * (C) Copyright IBM Corporation 2006
 *
 * Author: David Erb (djerb@us.ibm.com)
 * Modifications:
 *         Carl Love <carll@us.ibm.com>
 *         Maynard Johnson <maynardj@us.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 of the License, or (at your option) any later version.
 */

#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kthread.h>
#include <linux/oprofile.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/timer.h>
#include <asm/cell-pmu.h>
#include <asm/cputable.h>
#include <asm/firmware.h>
#include <asm/io.h>
#include <asm/oprofile_impl.h>
#include <asm/processor.h>
#include <asm/prom.h>
#include <asm/ptrace.h>
#include <asm/reg.h>
#include <asm/rtas.h>
#include <asm/system.h>
#include <asm/cell-regs.h>

#include "../platforms/cell/interrupt.h"
#include "cell/pr_util.h"

#define PPU_PROFILING            0
#define SPU_PROFILING_CYCLES     1
#define SPU_PROFILING_EVENTS     2

#define NUM_SPUS_PER_NODE    8
#define SPU_CYCLES_EVENT_NUM 2  /*  event number for SPU_CYCLES */

#define PPU_CYCLES_EVENT_NUM 1  /*  event number for CYCLES */
#define PPU_CYCLES_GRP_NUM   1  /* special group number for identifying
                                 * PPU_CYCLES event
                                 */
#define CBE_COUNT_ALL_CYCLES 0x42800000 /* PPU cycle event specifier */

#define NUM_THREADS 2         /* number of physical threads in
                               * physical processor
                               */
#define NUM_DEBUG_BUS_WORDS 4
#define NUM_INPUT_BUS_WORDS 2

#define MAX_SPU_COUNT 0xFFFFFF  /* maximum 24 bit LFSR value */

/*
 * spu_cycle_reset is the number of cycles between samples.
 * This variable is used for SPU profiling and should ONLY be set
 * at the beginning of cell_reg_setup; otherwise, it's read-only.
 */
static unsigned int spu_cycle_reset;
static unsigned int profiling_mode;

struct pmc_cntrl_data {
        unsigned long vcntr;
        unsigned long evnts;
        unsigned long masks;
        unsigned long enabled;
};

/*
 * ibm,cbe-perftools rtas parameters
 */
struct pm_signal {
        u16 cpu;                /* Processor to modify */
        u16 sub_unit;           /* hw subunit this applies to (if applicable)*/
        short int signal_group; /* Signal Group to Enable/Disable */
        u8 bus_word;            /* Enable/Disable on this Trace/Trigger/Event
                                 * Bus Word(s) (bitmask)
                                 */
        u8 bit;                 /* Trigger/Event bit (if applicable) */
};

/*
 * rtas call arguments
 */
enum {
        SUBFUNC_RESET = 1,
        SUBFUNC_ACTIVATE = 2,
        SUBFUNC_DEACTIVATE = 3,

        PASSTHRU_IGNORE = 0,
        PASSTHRU_ENABLE = 1,
        PASSTHRU_DISABLE = 2,
};

struct pm_cntrl {
        u16 enable;
        u16 stop_at_max;
        u16 trace_mode;
        u16 freeze;
        u16 count_mode;
};

static struct {
        u32 group_control;
        u32 debug_bus_control;
        struct pm_cntrl pm_cntrl;
        u32 pm07_cntrl[NR_PHYS_CTRS];
} pm_regs;

#define GET_SUB_UNIT(x) ((x & 0x0000f000) >> 12)
#define GET_BUS_WORD(x) ((x & 0x000000f0) >> 4)
#define GET_BUS_TYPE(x) ((x & 0x00000300) >> 8)
#define GET_POLARITY(x) ((x & 0x00000002) >> 1)
#define GET_COUNT_CYCLES(x) (x & 0x00000001)
#define GET_INPUT_CONTROL(x) ((x & 0x00000004) >> 2)

static DEFINE_PER_CPU(unsigned long[NR_PHYS_CTRS], pmc_values);
static struct pmc_cntrl_data pmc_cntrl[NUM_THREADS][NR_PHYS_CTRS];

/*
 * The CELL profiling code makes rtas calls to setup the debug bus to
 * route the performance signals.  Additionally, SPU profiling requires
 * a second rtas call to setup the hardware to capture the SPU PCs.
 * The EIO error value is returned if the token lookups or the rtas
 * call fail.  The EIO error number is the best choice of the existing
 * error numbers.  The probability of rtas related error is very low.  But
 * by returning EIO and printing additional information to dmsg the user
 * will know that OProfile did not start and dmesg will tell them why.
 * OProfile does not support returning errors on Stop.  Not a huge issue
 * since failure to reset the debug bus or stop the SPU PC collection is
 * not a fatel issue.  Chances are if the Stop failed, Start doesn't work
 * either.
 */

/*
 * Interpetation of hdw_thread:
 * 0 - even virtual cpus 0, 2, 4,...
 * 1 - odd virtual cpus 1, 3, 5, ...
 *
 * FIXME: this is strictly wrong, we need to clean this up in a number
 * of places. It works for now. -arnd
 */
static u32 hdw_thread;

static u32 virt_cntr_inter_mask;
static struct timer_list timer_virt_cntr;

/*
 * pm_signal needs to be global since it is initialized in
 * cell_reg_setup at the time when the necessary information
 * is available.
 */
static struct pm_signal pm_signal[NR_PHYS_CTRS];
static int pm_rtas_token;    /* token for debug bus setup call */
static int spu_rtas_token;   /* token for SPU cycle profiling */

static u32 reset_value[NR_PHYS_CTRS];
static int num_counters;
static int oprofile_running;
static DEFINE_SPINLOCK(cntr_lock);

static u32 ctr_enabled;

static unsigned char input_bus[NUM_INPUT_BUS_WORDS];

/*
 * Firmware interface functions
 */
static int
rtas_ibm_cbe_perftools(int subfunc, int passthru,
                       void *address, unsigned long length)
{
        u64 paddr = __pa(address);

        return rtas_call(pm_rtas_token, 5, 1, NULL, subfunc,
                         passthru, paddr >> 32, paddr & 0xffffffff, length);
}

static void pm_rtas_reset_signals(u32 node)
{
        int ret;
        struct pm_signal pm_signal_local;

        /*
         * The debug bus is being set to the passthru disable state.
         * However, the FW still expects atleast one legal signal routing
         * entry or it will return an error on the arguments.   If we don't
         * supply a valid entry, we must ignore all return values.  Ignoring
         * all return values means we might miss an error we should be
         * concerned about.
         */

        /*  fw expects physical cpu #. */
        pm_signal_local.cpu = node;
        pm_signal_local.signal_group = 21;
        pm_signal_local.bus_word = 1;
        pm_signal_local.sub_unit = 0;
        pm_signal_local.bit = 0;

        ret = rtas_ibm_cbe_perftools(SUBFUNC_RESET, PASSTHRU_DISABLE,
                                     &pm_signal_local,
                                     sizeof(struct pm_signal));

        if (unlikely(ret))
                /*
                 * Not a fatal error. For Oprofile stop, the oprofile
                 * functions do not support returning an error for
                 * failure to stop OProfile.
                 */
                printk(KERN_WARNING "%s: rtas returned: %d\n",
                       __func__, ret);
}

static int pm_rtas_activate_signals(u32 node, u32 count)
{
        int ret;
        int i, j;
        struct pm_signal pm_signal_local[NR_PHYS_CTRS];

        /*
         * There is no debug setup required for the cycles event.
         * Note that only events in the same group can be used.
         * Otherwise, there will be conflicts in correctly routing
         * the signals on the debug bus.  It is the responsiblity
         * of the OProfile user tool to check the events are in
         * the same group.
         */
        i = 0;
        for (j = 0; j < count; j++) {
                if (pm_signal[j].signal_group != PPU_CYCLES_GRP_NUM) {

                        /* fw expects physical cpu # */
                        pm_signal_local[i].cpu = node;
                        pm_signal_local[i].signal_group
                                = pm_signal[j].signal_group;
                        pm_signal_local[i].bus_word = pm_signal[j].bus_word;
                        pm_signal_local[i].sub_unit = pm_signal[j].sub_unit;
                        pm_signal_local[i].bit = pm_signal[j].bit;
                        i++;
                }
        }

        if (i != 0) {
                ret = rtas_ibm_cbe_perftools(SUBFUNC_ACTIVATE, PASSTHRU_ENABLE,
                                             pm_signal_local,
                                             i * sizeof(struct pm_signal));

                if (unlikely(ret)) {
                        printk(KERN_WARNING "%s: rtas returned: %d\n",
                               __func__, ret);
                        return -EIO;
                }
        }

        return 0;
}

/*
 * PM Signal functions
 */
static void set_pm_event(u32 ctr, int event, u32 unit_mask)
{
        struct pm_signal *p;
        u32 signal_bit;
        u32 bus_word, bus_type, count_cycles, polarity, input_control;
        int j, i;

        if (event == PPU_CYCLES_EVENT_NUM) {
                /* Special Event: Count all cpu cycles */
                pm_regs.pm07_cntrl[ctr] = CBE_COUNT_ALL_CYCLES;
                p = &(pm_signal[ctr]);
                p->signal_group = PPU_CYCLES_GRP_NUM;
                p->bus_word = 1;
                p->sub_unit = 0;
                p->bit = 0;
                goto out;
        } else {
                pm_regs.pm07_cntrl[ctr] = 0;
        }

        bus_word = GET_BUS_WORD(unit_mask);
        bus_type = GET_BUS_TYPE(unit_mask);
        count_cycles = GET_COUNT_CYCLES(unit_mask);
        polarity = GET_POLARITY(unit_mask);
        input_control = GET_INPUT_CONTROL(unit_mask);
        signal_bit = (event % 100);

        p = &(pm_signal[ctr]);

        p->signal_group = event / 100;
        p->bus_word = bus_word;
        p->sub_unit = GET_SUB_UNIT(unit_mask);

        pm_regs.pm07_cntrl[ctr] = 0;
        pm_regs.pm07_cntrl[ctr] |= PM07_CTR_COUNT_CYCLES(count_cycles);
        pm_regs.pm07_cntrl[ctr] |= PM07_CTR_POLARITY(polarity);
        pm_regs.pm07_cntrl[ctr] |= PM07_CTR_INPUT_CONTROL(input_control);

        /*
         * Some of the islands signal selection is based on 64 bit words.
         * The debug bus words are 32 bits, the input words to the performance
         * counters are defined as 32 bits.  Need to convert the 64 bit island
         * specification to the appropriate 32 input bit and bus word for the
         * performance counter event selection.  See the CELL Performance
         * monitoring signals manual and the Perf cntr hardware descriptions
         * for the details.
         */
        if (input_control == 0) {
                if (signal_bit > 31) {
                        signal_bit -= 32;
                        if (bus_word == 0x3)
                                bus_word = 0x2;
                        else if (bus_word == 0xc)
                                bus_word = 0x8;
                }

                if ((bus_type == 0) && p->signal_group >= 60)
                        bus_type = 2;
                if ((bus_type == 1) && p->signal_group >= 50)
                        bus_type = 0;

                pm_regs.pm07_cntrl[ctr] |= PM07_CTR_INPUT_MUX(signal_bit);
        } else {
                pm_regs.pm07_cntrl[ctr] = 0;
                p->bit = signal_bit;
        }

        for (i = 0; i < NUM_DEBUG_BUS_WORDS; i++) {
                if (bus_word & (1 << i)) {
                        pm_regs.debug_bus_control |=
                            (bus_type << (30 - (2 * i)));

                        for (j = 0; j < NUM_INPUT_BUS_WORDS; j++) {
                                if (input_bus[j] == 0xff) {
                                        input_bus[j] = i;
                                        pm_regs.group_control |=
                                            (i << (30 - (2 * j)));

                                        break;
                                }
                        }
                }
        }
out:
        ;
}

static void write_pm_cntrl(int cpu)
{
        /*
         * Oprofile will use 32 bit counters, set bits 7:10 to 0
         * pmregs.pm_cntrl is a global
         */

        u32 val = 0;
        if (pm_regs.pm_cntrl.enable == 1)
                val |= CBE_PM_ENABLE_PERF_MON;

        if (pm_regs.pm_cntrl.stop_at_max == 1)
                val |= CBE_PM_STOP_AT_MAX;

        if (pm_regs.pm_cntrl.trace_mode != 0)
                val |= CBE_PM_TRACE_MODE_SET(pm_regs.pm_cntrl.trace_mode);

        if (pm_regs.pm_cntrl.freeze == 1)
                val |= CBE_PM_FREEZE_ALL_CTRS;

        /*
         * Routine set_count_mode must be called previously to set
         * the count mode based on the user selection of user and kernel.
         */
        val |= CBE_PM_COUNT_MODE_SET(pm_regs.pm_cntrl.count_mode);
        cbe_write_pm(cpu, pm_control, val);
}

static inline void
set_count_mode(u32 kernel, u32 user)
{
        /*
         * The user must specify user and kernel if they want them. If
         *  neither is specified, OProfile will count in hypervisor mode.
         *  pm_regs.pm_cntrl is a global
         */
        if (kernel) {
                if (user)
                        pm_regs.pm_cntrl.count_mode = CBE_COUNT_ALL_MODES;
                else
                        pm_regs.pm_cntrl.count_mode =
                                CBE_COUNT_SUPERVISOR_MODE;
        } else {
                if (user)
                        pm_regs.pm_cntrl.count_mode = CBE_COUNT_PROBLEM_MODE;
                else
                        pm_regs.pm_cntrl.count_mode =
                                CBE_COUNT_HYPERVISOR_MODE;
        }
}

static inline void enable_ctr(u32 cpu, u32 ctr, u32 *pm07_cntrl)
{

        pm07_cntrl[ctr] |= CBE_PM_CTR_ENABLE;
        cbe_write_pm07_control(cpu, ctr, pm07_cntrl[ctr]);
}

/*
 * Oprofile is expected to collect data on all CPUs simultaneously.
 * However, there is one set of performance counters per node.  There are
 * two hardware threads or virtual CPUs on each node.  Hence, OProfile must
 * multiplex in time the performance counter collection on the two virtual
 * CPUs.  The multiplexing of the performance counters is done by this
 * virtual counter routine.
 *
 * The pmc_values used below is defined as 'per-cpu' but its use is
 * more akin to 'per-node'.  We need to store two sets of counter
 * values per node -- one for the previous run and one for the next.
 * The per-cpu[NR_PHYS_CTRS] gives us the storage we need.  Each odd/even
 * pair of per-cpu arrays is used for storing the previous and next
 * pmc values for a given node.
 * NOTE: We use the per-cpu variable to improve cache performance.
 *
 * This routine will alternate loading the virtual counters for
 * virtual CPUs
 */
static void cell_virtual_cntr(unsigned long data)
{
        int i, prev_hdw_thread, next_hdw_thread;
        u32 cpu;
        unsigned long flags;

        /*
         * Make sure that the interrupt_hander and the virt counter are
         * not both playing with the counters on the same node.
         */

        spin_lock_irqsave(&cntr_lock, flags);

        prev_hdw_thread = hdw_thread;

        /* switch the cpu handling the interrupts */
        hdw_thread = 1 ^ hdw_thread;
        next_hdw_thread = hdw_thread;

        pm_regs.group_control = 0;
        pm_regs.debug_bus_control = 0;

        for (i = 0; i < NUM_INPUT_BUS_WORDS; i++)
                input_bus[i] = 0xff;

        /*
         * There are some per thread events.  Must do the
         * set event, for the thread that is being started
         */
        for (i = 0; i < num_counters; i++)
                set_pm_event(i,
                        pmc_cntrl[next_hdw_thread][i].evnts,
                        pmc_cntrl[next_hdw_thread][i].masks);

        /*
         * The following is done only once per each node, but
         * we need cpu #, not node #, to pass to the cbe_xxx functions.
         */
        for_each_online_cpu(cpu) {
                if (cbe_get_hw_thread_id(cpu))
                        continue;

                /*
                 * stop counters, save counter values, restore counts
                 * for previous thread
                 */
                cbe_disable_pm(cpu);
                cbe_disable_pm_interrupts(cpu);
                for (i = 0; i < num_counters; i++) {
                        per_cpu(pmc_values, cpu + prev_hdw_thread)[i]
                            = cbe_read_ctr(cpu, i);

                        if (per_cpu(pmc_values, cpu + next_hdw_thread)[i]
                            == 0xFFFFFFFF)
                                /* If the cntr value is 0xffffffff, we must
                                 * reset that to 0xfffffff0 when the current
                                 * thread is restarted.  This will generate a
                                 * new interrupt and make sure that we never
                                 * restore the counters to the max value.  If
                                 * the counters were restored to the max value,
                                 * they do not increment and no interrupts are
                                 * generated.  Hence no more samples will be
                                 * collected on that cpu.
                                 */
                                cbe_write_ctr(cpu, i, 0xFFFFFFF0);
                        else
                                cbe_write_ctr(cpu, i,
                                              per_cpu(pmc_values,
                                                      cpu +
                                                      next_hdw_thread)[i]);
                }

                /*
                 * Switch to the other thread. Change the interrupt
                 * and control regs to be scheduled on the CPU
                 * corresponding to the thread to execute.
                 */
                for (i = 0; i < num_counters; i++) {
                        if (pmc_cntrl[next_hdw_thread][i].enabled) {
                                /*
                                 * There are some per thread events.
                                 * Must do the set event, enable_cntr
                                 * for each cpu.
                                 */
                                enable_ctr(cpu, i,
                                           pm_regs.pm07_cntrl);
                        } else {
                                cbe_write_pm07_control(cpu, i, 0);
                        }
                }

                /* Enable interrupts on the CPU thread that is starting */
                cbe_enable_pm_interrupts(cpu, next_hdw_thread,
                                         virt_cntr_inter_mask);
                cbe_enable_pm(cpu);
        }

        spin_unlock_irqrestore(&cntr_lock, flags);

        mod_timer(&timer_virt_cntr, jiffies + HZ / 10);
}

static void start_virt_cntrs(void)
{
        init_timer(&timer_virt_cntr);
        timer_virt_cntr.function = cell_virtual_cntr;
        timer_virt_cntr.data = 0UL;
        timer_virt_cntr.expires = jiffies + HZ / 10;
        add_timer(&timer_virt_cntr);
}

static int cell_reg_setup_spu_cycles(struct op_counter_config *ctr,
                        struct op_system_config *sys, int num_ctrs)
{
        spu_cycle_reset = ctr[0].count;

        /*
         * Each node will need to make the rtas call to start
         * and stop SPU profiling.  Get the token once and store it.
         */
        spu_rtas_token = rtas_token("ibm,cbe-spu-perftools");

        if (unlikely(spu_rtas_token == RTAS_UNKNOWN_SERVICE)) {
                printk(KERN_ERR
                       "%s: rtas token ibm,cbe-spu-perftools unknown\n",
                       __func__);
                return -EIO;
        }
        return 0;
}

static int cell_reg_setup_ppu(struct op_counter_config *ctr,
                        struct op_system_config *sys, int num_ctrs)
{
        int i, j, cpu;

        num_counters = num_ctrs;

        if (unlikely(num_ctrs > NR_PHYS_CTRS)) {
                printk(KERN_ERR
                       "%s: Oprofile, number of specified events " \
                       "exceeds number of physical counters\n",
                       __func__);
                return -EIO;
        }
        pm_regs.group_control = 0;
        pm_regs.debug_bus_control = 0;

        /* setup the pm_control register */
        memset(&pm_regs.pm_cntrl, 0, sizeof(struct pm_cntrl));
        pm_regs.pm_cntrl.stop_at_max = 1;
        pm_regs.pm_cntrl.trace_mode = 0;
        pm_regs.pm_cntrl.freeze = 1;

        set_count_mode(sys->enable_kernel, sys->enable_user);

        /* Setup the thread 0 events */
        for (i = 0; i < num_ctrs; ++i) {

                pmc_cntrl[0][i].evnts = ctr[i].event;
                pmc_cntrl[0][i].masks = ctr[i].unit_mask;
                pmc_cntrl[0][i].enabled = ctr[i].enabled;
                pmc_cntrl[0][i].vcntr = i;

                for_each_possible_cpu(j)
                        per_cpu(pmc_values, j)[i] = 0;
        }

        /*
         * Setup the thread 1 events, map the thread 0 event to the
         * equivalent thread 1 event.
         */
        for (i = 0; i < num_ctrs; ++i) {
                if ((ctr[i].event >= 2100) && (ctr[i].event <= 2111))
                        pmc_cntrl[1][i].evnts = ctr[i].event + 19;
                else if (ctr[i].event == 2203)
                        pmc_cntrl[1][i].evnts = ctr[i].event;
                else if ((ctr[i].event >= 2200) && (ctr[i].event <= 2215))
                        pmc_cntrl[1][i].evnts = ctr[i].event + 16;
                else
                        pmc_cntrl[1][i].evnts = ctr[i].event;

                pmc_cntrl[1][i].masks = ctr[i].unit_mask;
                pmc_cntrl[1][i].enabled = ctr[i].enabled;
                pmc_cntrl[1][i].vcntr = i;
        }

        for (i = 0; i < NUM_INPUT_BUS_WORDS; i++)
                input_bus[i] = 0xff;

        /*
         * Our counters count up, and "count" refers to
         * how much before the next interrupt, and we interrupt
         * on overflow.  So we calculate the starting value
         * which will give us "count" until overflow.
         * Then we set the events on the enabled counters.
         */
        for (i = 0; i < num_counters; ++i) {
                /* start with virtual counter set 0 */
                if (pmc_cntrl[0][i].enabled) {
                        /* Using 32bit counters, reset max - count */
                        reset_value[i] = 0xFFFFFFFF - ctr[i].count;
                        set_pm_event(i,
                                     pmc_cntrl[0][i].evnts,
                                     pmc_cntrl[0][i].masks);

                        /* global, used by cell_cpu_setup */
                        ctr_enabled |= (1 << i);
                }
        }

        /* initialize the previous counts for the virtual cntrs */
        for_each_online_cpu(cpu)
                for (i = 0; i < num_counters; ++i) {
                        per_cpu(pmc_values, cpu)[i] = reset_value[i];
                }

        return 0;
}


/* This function is called once for all cpus combined */
static int cell_reg_setup(struct op_counter_config *ctr,
                        struct op_system_config *sys, int num_ctrs)
{
        int ret;

        spu_cycle_reset = 0;

        /*
         * For all events except PPU CYCLEs, each node will need to make
         * the rtas cbe-perftools call to setup and reset the debug bus.
         * Make the token lookup call once and store it in the global
         * variable pm_rtas_token.
         */
        pm_rtas_token = rtas_token("ibm,cbe-perftools");

        if (unlikely(pm_rtas_token == RTAS_UNKNOWN_SERVICE)) {
                printk(KERN_ERR
                       "%s: rtas token ibm,cbe-perftools unknown\n",
                       __func__);
                return -EIO;
        }

        if (ctr[0].event == SPU_CYCLES_EVENT_NUM) {
                profiling_mode = SPU_PROFILING_CYCLES;
                ret = cell_reg_setup_spu_cycles(ctr, sys, num_ctrs);
        } else {
                profiling_mode = PPU_PROFILING;
                ret = cell_reg_setup_ppu(ctr, sys, num_ctrs);
        }

        return ret;
}



/* This function is called once for each cpu */
static int cell_cpu_setup(struct op_counter_config *cntr)
{
        u32 cpu = smp_processor_id();
        u32 num_enabled = 0;
        int i;

        /* Cycle based SPU profiling does not use the performance
         * counters.  The trace array is configured to collect
         * the data.
         */
        if (profiling_mode == SPU_PROFILING_CYCLES)
                return 0;

        /* There is one performance monitor per processor chip (i.e. node),
         * so we only need to perform this function once per node.
         */
        if (cbe_get_hw_thread_id(cpu))
                return 0;

        /* Stop all counters */
        cbe_disable_pm(cpu);
        cbe_disable_pm_interrupts(cpu);

        cbe_write_pm(cpu, pm_start_stop, 0);
        cbe_write_pm(cpu, group_control, pm_regs.group_control);
        cbe_write_pm(cpu, debug_bus_control, pm_regs.debug_bus_control);
        write_pm_cntrl(cpu);

        for (i = 0; i < num_counters; ++i) {
                if (ctr_enabled & (1 << i)) {
                        pm_signal[num_enabled].cpu = cbe_cpu_to_node(cpu);
                        num_enabled++;
                }
        }

        /*
         * The pm_rtas_activate_signals will return -EIO if the FW
         * call failed.
         */
        return pm_rtas_activate_signals(cbe_cpu_to_node(cpu), num_enabled);
}

#define ENTRIES  303
#define MAXLFSR  0xFFFFFF

/* precomputed table of 24 bit LFSR values */
static int initial_lfsr[] = {
 8221349, 12579195, 5379618, 10097839, 7512963, 7519310, 3955098, 10753424,
 15507573, 7458917, 285419, 2641121, 9780088, 3915503, 6668768, 1548716,
 4885000, 8774424, 9650099, 2044357, 2304411, 9326253, 10332526, 4421547,
 3440748, 10179459, 13332843, 10375561, 1313462, 8375100, 5198480, 6071392,
 9341783, 1526887, 3985002, 1439429, 13923762, 7010104, 11969769, 4547026,
 2040072, 4025602, 3437678, 7939992, 11444177, 4496094, 9803157, 10745556,
 3671780, 4257846, 5662259, 13196905, 3237343, 12077182, 16222879, 7587769,
 14706824, 2184640, 12591135, 10420257, 7406075, 3648978, 11042541, 15906893,
 11914928, 4732944, 10695697, 12928164, 11980531, 4430912, 11939291, 2917017,
 6119256, 4172004, 9373765, 8410071, 14788383, 5047459, 5474428, 1737756,
 15967514, 13351758, 6691285, 8034329, 2856544, 14394753, 11310160, 12149558,
 7487528, 7542781, 15668898, 12525138, 12790975, 3707933, 9106617, 1965401,
 16219109, 12801644, 2443203, 4909502, 8762329, 3120803, 6360315, 9309720,
 15164599, 10844842, 4456529, 6667610, 14924259, 884312, 6234963, 3326042,
 15973422, 13919464, 5272099, 6414643, 3909029, 2764324, 5237926, 4774955,
 10445906, 4955302, 5203726, 10798229, 11443419, 2303395, 333836, 9646934,
 3464726, 4159182, 568492, 995747, 10318756, 13299332, 4836017, 8237783,
 3878992, 2581665, 11394667, 5672745, 14412947, 3159169, 9094251, 16467278,
 8671392, 15230076, 4843545, 7009238, 15504095, 1494895, 9627886, 14485051,
 8304291, 252817, 12421642, 16085736, 4774072, 2456177, 4160695, 15409741,
 4902868, 5793091, 13162925, 16039714, 782255, 11347835, 14884586, 366972,
 16308990, 11913488, 13390465, 2958444, 10340278, 1177858, 1319431, 10426302,
 2868597, 126119, 5784857, 5245324, 10903900, 16436004, 3389013, 1742384,
 14674502, 10279218, 8536112, 10364279, 6877778, 14051163, 1025130, 6072469,
 1988305, 8354440, 8216060, 16342977, 13112639, 3976679, 5913576, 8816697,
 6879995, 14043764, 3339515, 9364420, 15808858, 12261651, 2141560, 5636398,
 10345425, 10414756, 781725, 6155650, 4746914, 5078683, 7469001, 6799140,
 10156444, 9667150, 10116470, 4133858, 2121972, 1124204, 1003577, 1611214,
 14304602, 16221850, 13878465, 13577744, 3629235, 8772583, 10881308, 2410386,
 7300044, 5378855, 9301235, 12755149, 4977682, 8083074, 10327581, 6395087,
 9155434, 15501696, 7514362, 14520507, 15808945, 3244584, 4741962, 9658130,
 14336147, 8654727, 7969093, 15759799, 14029445, 5038459, 9894848, 8659300,
 13699287, 8834306, 10712885, 14753895, 10410465, 3373251, 309501, 9561475,
 5526688, 14647426, 14209836, 5339224, 207299, 14069911, 8722990, 2290950,
 3258216, 12505185, 6007317, 9218111, 14661019, 10537428, 11731949, 9027003,
 6641507, 9490160, 200241, 9720425, 16277895, 10816638, 1554761, 10431375,
 7467528, 6790302, 3429078, 14633753, 14428997, 11463204, 3576212, 2003426,
 6123687, 820520, 9992513, 15784513, 5778891, 6428165, 8388607
};

/*
 * The hardware uses an LFSR counting sequence to determine when to capture
 * the SPU PCs.  An LFSR sequence is like a puesdo random number sequence
 * where each number occurs once in the sequence but the sequence is not in
 * numerical order. The SPU PC capture is done when the LFSR sequence reaches
 * the last value in the sequence.  Hence the user specified value N
 * corresponds to the LFSR number that is N from the end of the sequence.
 *
 * To avoid the time to compute the LFSR, a lookup table is used.  The 24 bit
 * LFSR sequence is broken into four ranges.  The spacing of the precomputed
 * values is adjusted in each range so the error between the user specifed
 * number (N) of events between samples and the actual number of events based
 * on the precomputed value will be les then about 6.2%.  Note, if the user
 * specifies N < 2^16, the LFSR value that is 2^16 from the end will be used.
 * This is to prevent the loss of samples because the trace buffer is full.
 *
 *         User specified N                  Step between          Index in
 *                                       precomputed values      precomputed
 *                                                                  table
 * 0                to  2^16-1                  ----                  0
 * 2^16     to  2^16+2^19-1             2^12                1 to 128
 * 2^16+2^19        to  2^16+2^19+2^22-1        2^15              129 to 256
 * 2^16+2^19+2^22  to   2^24-1                  2^18              257 to 302
 *
 *
 * For example, the LFSR values in the second range are computed for 2^16,
 * 2^16+2^12, ... , 2^19-2^16, 2^19 and stored in the table at indicies
 * 1, 2,..., 127, 128.
 *
 * The 24 bit LFSR value for the nth number in the sequence can be
 * calculated using the following code:
 *
 * #define size 24
 * int calculate_lfsr(int n)
 * {
 *      int i;
 *      unsigned int newlfsr0;
 *      unsigned int lfsr = 0xFFFFFF;
 *      unsigned int howmany = n;
 *
 *      for (i = 2; i < howmany + 2; i++) {
 *              newlfsr0 = (((lfsr >> (size - 1 - 0)) & 1) ^
 *              ((lfsr >> (size - 1 - 1)) & 1) ^
 *              (((lfsr >> (size - 1 - 6)) & 1) ^
 *              ((lfsr >> (size - 1 - 23)) & 1)));
 *
 *              lfsr >>= 1;
 *              lfsr = lfsr | (newlfsr0 << (size - 1));
 *      }
 *      return lfsr;
 * }
 */

#define V2_16  (0x1 << 16)
#define V2_19  (0x1 << 19)
#define V2_22  (0x1 << 22)

static int calculate_lfsr(int n)
{
        /*
         * The ranges and steps are in powers of 2 so the calculations
         * can be done using shifts rather then divide.
         */
        int index;

        if ((n >> 16) == 0)
                index = 0;
        else if (((n - V2_16) >> 19) == 0)
                index = ((n - V2_16) >> 12) + 1;
        else if (((n - V2_16 - V2_19) >> 22) == 0)
                index = ((n - V2_16 - V2_19) >> 15 ) + 1 + 128;
        else if (((n - V2_16 - V2_19 - V2_22) >> 24) == 0)
                index = ((n - V2_16 - V2_19 - V2_22) >> 18 ) + 1 + 256;
        else
                index = ENTRIES-1;

        /* make sure index is valid */
        if ((index > ENTRIES) || (index < 0))
                index = ENTRIES-1;

        return initial_lfsr[index];
}

static int pm_rtas_activate_spu_profiling(u32 node)
{
        int ret, i;
        struct pm_signal pm_signal_local[NUM_SPUS_PER_NODE];

        /*
         * Set up the rtas call to configure the debug bus to
         * route the SPU PCs.  Setup the pm_signal for each SPU
         */
        for (i = 0; i < ARRAY_SIZE(pm_signal_local); i++) {
                pm_signal_local[i].cpu = node;
                pm_signal_local[i].signal_group = 41;
                /* spu i on word (i/2) */
                pm_signal_local[i].bus_word = 1 << i / 2;
                /* spu i */
                pm_signal_local[i].sub_unit = i;
                pm_signal_local[i].bit = 63;
        }

        ret = rtas_ibm_cbe_perftools(SUBFUNC_ACTIVATE,
                                     PASSTHRU_ENABLE, pm_signal_local,
                                     (ARRAY_SIZE(pm_signal_local)
                                      * sizeof(struct pm_signal)));

        if (unlikely(ret)) {
                printk(KERN_WARNING "%s: rtas returned: %d\n",
                       __func__, ret);
                return -EIO;
        }

        return 0;
}

#ifdef CONFIG_CPU_FREQ
static int
oprof_cpufreq_notify(struct notifier_block *nb, unsigned long val, void *data)
{
        int ret = 0;
        struct cpufreq_freqs *frq = data;
        if ((val == CPUFREQ_PRECHANGE && frq->old < frq->new) ||
            (val == CPUFREQ_POSTCHANGE && frq->old > frq->new) ||
            (val == CPUFREQ_RESUMECHANGE || val == CPUFREQ_SUSPENDCHANGE))
                set_spu_profiling_frequency(frq->new, spu_cycle_reset);
        return ret;
}

static struct notifier_block cpu_freq_notifier_block = {
        .notifier_call  = oprof_cpufreq_notify
};
#endif

/*
 * Note the generic OProfile stop calls do not support returning
 * an error on stop.  Hence, will not return an error if the FW
 * calls fail on stop.  Failure to reset the debug bus is not an issue.
 * Failure to disable the SPU profiling is not an issue.  The FW calls
 * to enable the performance counters and debug bus will work even if
 * the hardware was not cleanly reset.
 */
static void cell_global_stop_spu_cycles(void)
{
        int subfunc, rtn_value;
        unsigned int lfsr_value;
        int cpu;

        oprofile_running = 0;

#ifdef CONFIG_CPU_FREQ
        cpufreq_unregister_notifier(&cpu_freq_notifier_block,
                                    CPUFREQ_TRANSITION_NOTIFIER);
#endif

        for_each_online_cpu(cpu) {
                if (cbe_get_hw_thread_id(cpu))
                        continue;

                subfunc = 3;    /*
                                 * 2 - activate SPU tracing,
                                 * 3 - deactivate
                                 */
                lfsr_value = 0x8f100000;

                rtn_value = rtas_call(spu_rtas_token, 3, 1, NULL,
                                      subfunc, cbe_cpu_to_node(cpu),
                                      lfsr_value);

                if (unlikely(rtn_value != 0)) {
                        printk(KERN_ERR
                               "%s: rtas call ibm,cbe-spu-perftools " \
                               "failed, return = %d\n",
                               __func__, rtn_value);
                }

                /* Deactivate the signals */
                pm_rtas_reset_signals(cbe_cpu_to_node(cpu));
        }

        if (profiling_mode == SPU_PROFILING_CYCLES)
                stop_spu_profiling_cycles();
}

static void cell_global_stop_ppu(void)
{
        int cpu;

        /*
         * This routine will be called once for the system.
         * There is one performance monitor per node, so we
         * only need to perform this function once per node.
         */
        del_timer_sync(&timer_virt_cntr);
        oprofile_running = 0;
        smp_wmb();

        for_each_online_cpu(cpu) {
                if (cbe_get_hw_thread_id(cpu))
                        continue;

                cbe_sync_irq(cbe_cpu_to_node(cpu));
                /* Stop the counters */
                cbe_disable_pm(cpu);

                /* Deactivate the signals */
                pm_rtas_reset_signals(cbe_cpu_to_node(cpu));

                /* Deactivate interrupts */
                cbe_disable_pm_interrupts(cpu);
        }
}

static void cell_global_stop(void)
{
        if (profiling_mode == PPU_PROFILING)
                cell_global_stop_ppu();
        else
                cell_global_stop_spu_cycles();
}

static int cell_global_start_spu_cycles(struct op_counter_config *ctr)
{
        int subfunc;
        unsigned int lfsr_value;
        int cpu;
        int ret;
        int rtas_error;
        unsigned int cpu_khzfreq = 0;

        /* The SPU profiling uses time-based profiling based on
         * cpu frequency, so if configured with the CPU_FREQ
         * option, we should detect frequency changes and react
         * accordingly.
         */
#ifdef CONFIG_CPU_FREQ
        ret = cpufreq_register_notifier(&cpu_freq_notifier_block,
                                        CPUFREQ_TRANSITION_NOTIFIER);
        if (ret < 0)
                /* this is not a fatal error */
                printk(KERN_ERR "CPU freq change registration failed: %d\n",
                       ret);

        else
                cpu_khzfreq = cpufreq_quick_get(smp_processor_id());
#endif

        set_spu_profiling_frequency(cpu_khzfreq, spu_cycle_reset);

        for_each_online_cpu(cpu) {
                if (cbe_get_hw_thread_id(cpu))
                        continue;

                /*
                 * Setup SPU cycle-based profiling.
                 * Set perf_mon_control bit 0 to a zero before
                 * enabling spu collection hardware.
                 */
                cbe_write_pm(cpu, pm_control, 0);

                if (spu_cycle_reset > MAX_SPU_COUNT)
                        /* use largest possible value */
                        lfsr_value = calculate_lfsr(MAX_SPU_COUNT-1);
                else
                        lfsr_value = calculate_lfsr(spu_cycle_reset);

                /* must use a non zero value. Zero disables data collection. */
                if (lfsr_value == 0)
                        lfsr_value = calculate_lfsr(1);

                lfsr_value = lfsr_value << 8; /* shift lfsr to correct
                                                * register location
                                                */

                /* debug bus setup */
                ret = pm_rtas_activate_spu_profiling(cbe_cpu_to_node(cpu));

                if (unlikely(ret)) {
                        rtas_error = ret;
                        goto out;
                }


                subfunc = 2;    /* 2 - activate SPU tracing, 3 - deactivate */

                /* start profiling */
                ret = rtas_call(spu_rtas_token, 3, 1, NULL, subfunc,
                  cbe_cpu_to_node(cpu), lfsr_value);

                if (unlikely(ret != 0)) {
                        printk(KERN_ERR
                               "%s: rtas call ibm,cbe-spu-perftools failed, " \
                               "return = %d\n", __func__, ret);
                        rtas_error = -EIO;
                        goto out;
                }
        }

        rtas_error = start_spu_profiling_cycles(spu_cycle_reset);
        if (rtas_error)
                goto out_stop;

        oprofile_running = 1;
        return 0;

out_stop:
        cell_global_stop_spu_cycles();  /* clean up the PMU/debug bus */
out:
        return rtas_error;
}

static int cell_global_start_ppu(struct op_counter_config *ctr)
{
        u32 cpu, i;
        u32 interrupt_mask = 0;

        /* This routine gets called once for the system.
         * There is one performance monitor per node, so we
         * only need to perform this function once per node.
         */
        for_each_online_cpu(cpu) {
                if (cbe_get_hw_thread_id(cpu))
                        continue;

                interrupt_mask = 0;

                for (i = 0; i < num_counters; ++i) {
                        if (ctr_enabled & (1 << i)) {
                                cbe_write_ctr(cpu, i, reset_value[i]);
                                enable_ctr(cpu, i, pm_regs.pm07_cntrl);
                                interrupt_mask |=
                                    CBE_PM_CTR_OVERFLOW_INTR(i);
                        } else {
                                /* Disable counter */
                                cbe_write_pm07_control(cpu, i, 0);
                        }
                }

                cbe_get_and_clear_pm_interrupts(cpu);
                cbe_enable_pm_interrupts(cpu, hdw_thread, interrupt_mask);
                cbe_enable_pm(cpu);
        }

        virt_cntr_inter_mask = interrupt_mask;
        oprofile_running = 1;
        smp_wmb();

        /*
         * NOTE: start_virt_cntrs will result in cell_virtual_cntr() being
         * executed which manipulates the PMU.  We start the "virtual counter"
         * here so that we do not need to synchronize access to the PMU in
         * the above for-loop.
         */
        start_virt_cntrs();

        return 0;
}

static int cell_global_start(struct op_counter_config *ctr)
{
        if (profiling_mode == SPU_PROFILING_CYCLES)
                return cell_global_start_spu_cycles(ctr);
        else
                return cell_global_start_ppu(ctr);
}


static void cell_handle_interrupt_ppu(struct pt_regs *regs,
                                      struct op_counter_config *ctr)
{
        u32 cpu;
        u64 pc;
        int is_kernel;
        unsigned long flags = 0;
        u32 interrupt_mask;
        int i;

        cpu = smp_processor_id();

        /*
         * Need to make sure the interrupt handler and the virt counter
         * routine are not running at the same time. See the
         * cell_virtual_cntr() routine for additional comments.
         */
        spin_lock_irqsave(&cntr_lock, flags);

        /*
         * Need to disable and reenable the performance counters
         * to get the desired behavior from the hardware.  This
         * is hardware specific.
         */

        cbe_disable_pm(cpu);

        interrupt_mask = cbe_get_and_clear_pm_interrupts(cpu);

        /*
         * If the interrupt mask has been cleared, then the virt cntr
         * has cleared the interrupt.  When the thread that generated
         * the interrupt is restored, the data count will be restored to
         * 0xffffff0 to cause the interrupt to be regenerated.
         */

        if ((oprofile_running == 1) && (interrupt_mask != 0)) {
                pc = regs->nip;
                is_kernel = is_kernel_addr(pc);

                for (i = 0; i < num_counters; ++i) {
                        if ((interrupt_mask & CBE_PM_CTR_OVERFLOW_INTR(i))
                            && ctr[i].enabled) {
                                oprofile_add_ext_sample(pc, regs, i, is_kernel);
                                cbe_write_ctr(cpu, i, reset_value[i]);
                        }
                }

                /*
                 * The counters were frozen by the interrupt.
                 * Reenable the interrupt and restart the counters.
                 * If there was a race between the interrupt handler and
                 * the virtual counter routine.  The virutal counter
                 * routine may have cleared the interrupts.  Hence must
                 * use the virt_cntr_inter_mask to re-enable the interrupts.
                 */
                cbe_enable_pm_interrupts(cpu, hdw_thread,
                                         virt_cntr_inter_mask);

                /*
                 * The writes to the various performance counters only writes
                 * to a latch.  The new values (interrupt setting bits, reset
                 * counter value etc.) are not copied to the actual registers
                 * until the performance monitor is enabled.  In order to get
                 * this to work as desired, the permormance monitor needs to
                 * be disabled while writing to the latches.  This is a
                 * HW design issue.
                 */
                cbe_enable_pm(cpu);
        }
        spin_unlock_irqrestore(&cntr_lock, flags);
}

static void cell_handle_interrupt(struct pt_regs *regs,
                                  struct op_counter_config *ctr)
{
        if (profiling_mode == PPU_PROFILING)
                cell_handle_interrupt_ppu(regs, ctr);
}

/*
 * This function is called from the generic OProfile
 * driver.  When profiling PPUs, we need to do the
 * generic sync start; otherwise, do spu_sync_start.
 */
static int cell_sync_start(void)
{
        if ((profiling_mode == SPU_PROFILING_CYCLES) ||
            (profiling_mode == SPU_PROFILING_EVENTS))
                return spu_sync_start();
        else
                return DO_GENERIC_SYNC;
}

static int cell_sync_stop(void)
{
        if ((profiling_mode == SPU_PROFILING_CYCLES) ||
            (profiling_mode == SPU_PROFILING_EVENTS))
                return spu_sync_stop();
        else
                return 1;
}

struct op_powerpc_model op_model_cell = {
        .reg_setup = cell_reg_setup,
        .cpu_setup = cell_cpu_setup,
        .global_start = cell_global_start,
        .global_stop = cell_global_stop,
        .sync_start = cell_sync_start,
        .sync_stop = cell_sync_stop,
        .handle_interrupt = cell_handle_interrupt,
};