[POWERPC] cell: Add oprofile support

Add PPU event-based and cycle-based profiling support to Oprofile for Cell.

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 a virtual
counter routine.  Initially, the counters are configured to collect data
on the even CPUs in the system, one CPU per node.  In order to capture
the PC for the virtual CPU when the performance counter interrupt occurs
(the specified number of events between samples has occurred), the even
processors are configured to handle the performance counter interrupts
for their node.  The virtual counter routine is called via a kernel
timer after the virtual sample time.  The routine stops the counters,
saves the current counts, loads the last counts for the other virtual
CPU on the node, sets interrupts to be handled by the other virtual CPU
and restarts the counters, the virtual timer routine is scheduled to run
again.  The virtual sample time is kept relatively small to make sure
sampling occurs on both CPUs on the node with a relatively small
granularity.  Whenever the counters overflow, the performance counter
interrupt is called to collect the PC for the CPU where data is being
collected.

The oprofile driver relies on a firmware RTAS call to setup the debug bus
to route the desired signals to the performance counter hardware to be
counted.  The RTAS call must set the routing registers appropriately in
each of the islands to pass the signals down the debug bus as well as
routing the signals from a particular island onto the bus.  There is a
second firmware RTAS call to reset the debug bus to the non pass thru
state when the counters are not in use.

Signed-off-by: Carl Love <carll@us.ibm.com>
Signed-off-by: Maynard Johnson <mpjohn@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 724 insertions, 0 deletions

diff --git a/arch/powerpc/oprofile/op_model_cell.c b/arch/powerpc/oprofile/op_model_cell.c
new file mode 100644
index 000000000000..2eb15f388103
--- /dev/null
+++ b/arch/powerpc/oprofile/op_model_cell.c
@@ -0,0 +1,724 @@
+/*
+ * 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 "../platforms/cell/interrupt.h"
+
+#define PPU_CYCLES_EVENT_NUM 1	/*  event number for CYCLES */
+#define CBE_COUNT_ALL_CYCLES 0x42800000	/* PPU cycle event specifier */
+
+#define NUM_THREADS 2
+#define VIRT_CNTR_SW_TIME_NS 100000000	// 0.5 seconds
+
+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) */
+	u16 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];
+
+/* Interpetation of hdw_thread:
+ * 0 - even virtual cpus 0, 2, 4,...
+ * 1 - odd virtual cpus 1, 3, 5, ...
+ */
+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;
+
+static u32 reset_value[NR_PHYS_CTRS];
+static int num_counters;
+static int oprofile_running;
+static spinlock_t virt_cntr_lock = SPIN_LOCK_UNLOCKED;
+
+static u32 ctr_enabled;
+
+static unsigned char trace_bus[4];
+static unsigned char input_bus[2];
+
+/*
+ * 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 (ret)
+		printk(KERN_WARNING "%s: rtas returned: %d\n",
+		       __FUNCTION__, ret);
+}
+
+static void pm_rtas_activate_signals(u32 node, u32 count)
+{
+	int ret;
+	int j;
+	struct pm_signal pm_signal_local[NR_PHYS_CTRS];
+
+	for (j = 0; j < count; j++) {
+		/* fw expects physical cpu # */
+		pm_signal_local[j].cpu = node;
+		pm_signal_local[j].signal_group = pm_signal[j].signal_group;
+		pm_signal_local[j].bus_word = pm_signal[j].bus_word;
+		pm_signal_local[j].sub_unit = pm_signal[j].sub_unit;
+		pm_signal_local[j].bit = pm_signal[j].bit;
+	}
+
+	ret = rtas_ibm_cbe_perftools(SUBFUNC_ACTIVATE, PASSTHRU_ENABLE,
+				     pm_signal_local,
+				     count * sizeof(struct pm_signal));
+
+	if (ret)
+		printk(KERN_WARNING "%s: rtas returned: %d\n",
+		       __FUNCTION__, ret);
+}
+
+/*
+ * 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 = 21;
+		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 = unit_mask & 0x0000f000;
+
+	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);
+
+	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 < 4; i++) {
+		if (bus_word & (1 << i)) {
+			pm_regs.debug_bus_control |=
+			    (bus_type << (31 - (2 * i) + 1));
+
+			for (j = 0; j < 2; j++) {
+				if (input_bus[j] == 0xff) {
+					input_bus[j] = i;
+					pm_regs.group_control |=
+					    (i << (31 - i));
+					break;
+				}
+			}
+		}
+	}
+out:
+	;
+}
+
+static void write_pm_cntrl(int cpu, struct pm_cntrl *pm_cntrl)
+{
+	/* Oprofile will use 32 bit counters, set bits 7:10 to 0 */
+	u32 val = 0;
+	if (pm_cntrl->enable == 1)
+		val |= CBE_PM_ENABLE_PERF_MON;
+
+	if (pm_cntrl->stop_at_max == 1)
+		val |= CBE_PM_STOP_AT_MAX;
+
+	if (pm_cntrl->trace_mode == 1)
+		val |= CBE_PM_TRACE_MODE_SET(pm_cntrl->trace_mode);
+
+	if (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_cntrl->count_mode);
+	cbe_write_pm(cpu, pm_control, val);
+}
+
+static inline void
+set_count_mode(u32 kernel, u32 user, struct pm_cntrl *pm_cntrl)
+{
+	/* The user must specify user and kernel if they want them. If
+	 *  neither is specified, OProfile will count in hypervisor mode
+	 */
+	if (kernel) {
+		if (user)
+			pm_cntrl->count_mode = CBE_COUNT_ALL_MODES;
+		else
+			pm_cntrl->count_mode = CBE_COUNT_SUPERVISOR_MODE;
+	} else {
+		if (user)
+			pm_cntrl->count_mode = CBE_COUNT_PROBLEM_MODE;
+		else
+			pm_cntrl->count_mode = CBE_COUNT_HYPERVISOR_MODE;
+	}
+}
+
+static inline void enable_ctr(u32 cpu, u32 ctr, u32 * pm07_cntrl)
+{
+
+	pm07_cntrl[ctr] |= PM07_CTR_ENABLE(1);
+	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.
+ */
+static void cell_virtual_cntr(unsigned long data)
+{
+	/* This routine will alternate loading the virtual counters for
+	 * virtual CPUs
+	 */
+	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(&virt_cntr_lock, flags);
+
+	prev_hdw_thread = hdw_thread;
+
+	/* switch the cpu handling the interrupts */
+	hdw_thread = 1 ^ hdw_thread;
+	next_hdw_thread = hdw_thread;
+
+	/* 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.
+				 */
+				set_pm_event(i,
+				     pmc_cntrl[next_hdw_thread][i].evnts,
+				     pmc_cntrl[next_hdw_thread][i].masks);
+				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(&virt_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);
+}
+
+/* This function is called once for all cpus combined */
+static void
+cell_reg_setup(struct op_counter_config *ctr,
+	       struct op_system_config *sys, int num_ctrs)
+{
+	int i, j, cpu;
+
+	pm_rtas_token = rtas_token("ibm,cbe-perftools");
+	if (pm_rtas_token == RTAS_UNKNOWN_SERVICE) {
+		printk(KERN_WARNING "%s: RTAS_UNKNOWN_SERVICE\n",
+		       __FUNCTION__);
+		goto out;
+	}
+
+	num_counters = num_ctrs;
+
+	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,
+		       &pm_regs.pm_cntrl);
+
+	/* 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 < 4; i++)
+		trace_bus[i] = 0xff;
+
+	for (i = 0; i < 2; 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];
+		}
+out:
+	;
+}
+
+/* This function is called once for each cpu */
+static void cell_cpu_setup(struct op_counter_config *cntr)
+{
+	u32 cpu = smp_processor_id();
+	u32 num_enabled = 0;
+	int i;
+
+	/* 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))
+		goto out;
+
+	if (pm_rtas_token == RTAS_UNKNOWN_SERVICE) {
+		printk(KERN_WARNING "%s: RTAS_UNKNOWN_SERVICE\n",
+		       __FUNCTION__);
+		goto out;
+	}
+
+	/* Stop all counters */
+	cbe_disable_pm(cpu);
+	cbe_disable_pm_interrupts(cpu);
+
+	cbe_write_pm(cpu, pm_interval, 0);
+	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, &pm_regs.pm_cntrl);
+
+	for (i = 0; i < num_counters; ++i) {
+		if (ctr_enabled & (1 << i)) {
+			pm_signal[num_enabled].cpu = cbe_cpu_to_node(cpu);
+			num_enabled++;
+		}
+	}
+
+	pm_rtas_activate_signals(cbe_cpu_to_node(cpu), num_enabled);
+out:
+	;
+}
+
+static void cell_global_start(struct op_counter_config *ctr)
+{
+	u32 cpu;
+	u32 interrupt_mask = 0;
+	u32 i;
+
+	/* 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_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();
+}
+
+static void cell_global_stop(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_handle_interrupt(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(&virt_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_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_pc(pc, is_kernel, i);
+				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 writting to the latches.  This is a
+		 * HW design issue.
+		 */
+		cbe_enable_pm(cpu);
+	}
+	spin_unlock_irqrestore(&virt_cntr_lock, flags);
+}
+
+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,
+	.handle_interrupt = cell_handle_interrupt,
+};