[CELL] oprofile: add support to OProfile for profiling CELL BE SPUs

From: Maynard Johnson <mpjohn@us.ibm.com>

This patch updates the existing arch/powerpc/oprofile/op_model_cell.c
to add in the SPU profiling capabilities.  In addition, a 'cell' subdirectory
was added to arch/powerpc/oprofile to hold Cell-specific SPU profiling code.
Exports spu_set_profile_private_kref and spu_get_profile_private_kref which
are used by OProfile to store private profile information in spufs data
structures.

Also incorporated several fixes from other patches (rrn).  Check pointer
returned from kzalloc.  Eliminated unnecessary cast.  Better error
handling and cleanup in the related area.  64-bit unsigned long parameter
was being demoted to 32-bit unsigned int and eventually promoted back to
unsigned long.

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

1 files changed, 527 insertions, 80 deletions

diff --git a/arch/powerpc/oprofile/op_model_cell.c b/arch/powerpc/oprofile/op_model_cell.c
index c29293befba9..d928b54f3a0f 100644
--- a/arch/powerpc/oprofile/op_model_cell.c
+++ b/arch/powerpc/oprofile/op_model_cell.c
@@ -5,8 +5,8 @@
  *
  * Author: David Erb (djerb@us.ibm.com)
  * Modifications:
- *         Carl Love <carll@us.ibm.com>
- *         Maynard Johnson <maynardj@us.ibm.com>
+ *         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
@@ -38,12 +38,25 @@
 
 #include "../platforms/cell/interrupt.h"
 #include "../platforms/cell/cbe_regs.h"
+#include "cell/pr_util.h"
+
+static void cell_global_stop_spu(void);
+
+/*
+ * 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;
+
+#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 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
@@ -51,6 +64,7 @@
 #define NUM_TRACE_BUS_WORDS 4
 #define NUM_INPUT_BUS_WORDS 2
 
+#define MAX_SPU_COUNT 0xFFFFFF  /* maximum 24 bit LFSR value */
 
 struct pmc_cntrl_data {
         unsigned long vcntr;
@@ -62,11 +76,10 @@ struct pmc_cntrl_data {
 /*
  * 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 */
+        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)
                                  */
@@ -112,21 +125,42 @@ 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:
+/*
+ * 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
+/*
+ * 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 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;
@@ -147,8 +181,8 @@ rtas_ibm_cbe_perftools(int subfunc, int passthru,
 {
         u64 paddr = __pa(address);
 
-        return rtas_call(pm_rtas_token, 5, 1, NULL, subfunc, passthru,
-                         paddr >> 32, paddr & 0xffffffff, length);
+        return rtas_call(pm_rtas_token, 5, 1, NULL, subfunc,
+                         passthru, paddr >> 32, paddr & 0xffffffff, length);
 }
 
 static void pm_rtas_reset_signals(u32 node)
@@ -156,12 +190,13 @@ 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.
+        /*
+         * 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 #. */
@@ -175,18 +210,24 @@ static void pm_rtas_reset_signals(u32 node)
                                      &pm_signal_local,
                                      sizeof(struct pm_signal));
 
-        if (ret)
+        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",
                        __FUNCTION__, ret);
 }
 
-static void pm_rtas_activate_signals(u32 node, u32 count)
+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.
+        /*
+         * 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
@@ -213,10 +254,14 @@ static void pm_rtas_activate_signals(u32 node, u32 count)
                                              pm_signal_local,
                                              i * sizeof(struct pm_signal));
 
-                if (ret)
+                if (unlikely(ret)) {
                         printk(KERN_WARNING "%s: rtas returned: %d\n",
                                __FUNCTION__, ret);
+                        return -EIO;
+                }
         }
+
+        return 0;
 }
 
 /*
@@ -260,11 +305,12 @@ static void set_pm_event(u32 ctr, int event, u32 unit_mask)
         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.
+        /*
+         * 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
+         * performance counter event selection.  See the CELL Performance
          * monitoring signals manual and the Perf cntr hardware descriptions
          * for the details.
          */
@@ -298,6 +344,7 @@ static void set_pm_event(u32 ctr, int event, u32 unit_mask)
                                         input_bus[j] = i;
                                         pm_regs.group_control |=
                                             (i << (31 - i));
+
                                         break;
                                 }
                         }
@@ -309,7 +356,8 @@ out:
 
 static void write_pm_cntrl(int cpu)
 {
-        /* Oprofile will use 32 bit counters, set bits 7:10 to 0
+        /*
+         * Oprofile will use 32 bit counters, set bits 7:10 to 0
          * pmregs.pm_cntrl is a global
          */
 
@@ -326,7 +374,8 @@ static void write_pm_cntrl(int cpu)
         if (pm_regs.pm_cntrl.freeze == 1)
                 val |= CBE_PM_FREEZE_ALL_CTRS;
 
-        /* Routine set_count_mode must be called previously to set
+        /*
+         * 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);
@@ -336,7 +385,8 @@ static void write_pm_cntrl(int cpu)
 static inline void
 set_count_mode(u32 kernel, u32 user)
 {
-        /* The user must specify user and kernel if they want them. If
+        /*
+         * 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
          */
@@ -364,7 +414,7 @@ static inline void enable_ctr(u32 cpu, u32 ctr, u32 * pm07_cntrl)
 
 /*
  * Oprofile is expected to collect data on all CPUs simultaneously.
- * However, there is one set of performance counters per node.  There are
+ * 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
@@ -377,19 +427,19 @@ static inline void enable_ctr(u32 cpu, u32 ctr, u32 * pm07_cntrl)
  * 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)
 {
-        /* 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.
+        /*
+         * 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);
@@ -400,22 +450,25 @@ static void cell_virtual_cntr(unsigned long data)
         hdw_thread = 1 ^ hdw_thread;
         next_hdw_thread = hdw_thread;
 
-        for (i = 0; i < num_counters; i++)
-        /* There are some per thread events.  Must do the
+        /*
+         * 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
+        /*
+         * 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
+                /*
+                 * stop counters, save counter values, restore counts
                  * for previous thread
                  */
                 cbe_disable_pm(cpu);
@@ -428,7 +481,7 @@ static void cell_virtual_cntr(unsigned long data)
                             == 0xFFFFFFFF)
                                 /* If the cntr value is 0xffffffff, we must
                                  * reset that to 0xfffffff0 when the current
-                                 * thread is restarted.  This will generate a
+                                 * 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,
@@ -444,13 +497,15 @@ static void cell_virtual_cntr(unsigned long data)
                                                       next_hdw_thread)[i]);
                 }
 
-                /* Switch to the other thread. Change the interrupt
+                /*
+                 * 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.
+                                /*
+                                 * There are some per thread events.
                                  * Must do the set event, enable_cntr
                                  * for each cpu.
                                  */
@@ -482,17 +537,42 @@ static void start_virt_cntrs(void)
 }
 
 /* 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)
+static int cell_reg_setup(struct op_counter_config *ctr,
+                        struct op_system_config *sys, int num_ctrs)
 {
         int i, j, cpu;
+        spu_cycle_reset = 0;
+
+        if (ctr[0].event == SPU_CYCLES_EVENT_NUM) {
+                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",
+                               __FUNCTION__);
+                        return -EIO;
+                }
+        }
 
         pm_rtas_token = rtas_token("ibm,cbe-perftools");
-        if (pm_rtas_token == RTAS_UNKNOWN_SERVICE) {
-                printk(KERN_WARNING "%s: RTAS_UNKNOWN_SERVICE\n",
+
+        /*
+         * For all events excetp 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.
+         */
+        if (unlikely(pm_rtas_token == RTAS_UNKNOWN_SERVICE)) {
+                printk(KERN_ERR
+                       "%s: rtas token ibm,cbe-perftools unknown\n",
                        __FUNCTION__);
-                goto out;
+                return -EIO;
         }
 
         num_counters = num_ctrs;
@@ -520,7 +600,8 @@ cell_reg_setup(struct op_counter_config *ctr,
                         per_cpu(pmc_values, j)[i] = 0;
         }
 
-        /* Setup the thread 1 events, map the thread 0 event to the
+        /*
+         * Setup the thread 1 events, map the thread 0 event to the
          * equivalent thread 1 event.
          */
         for (i = 0; i < num_ctrs; ++i) {
@@ -544,9 +625,10 @@ cell_reg_setup(struct op_counter_config *ctr,
         for (i = 0; i < NUM_INPUT_BUS_WORDS; i++)
                 input_bus[i] = 0xff;
 
-        /* Our counters count up, and "count" refers to
+        /*
+         * 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
+         * on overflow.  So we calculate the starting value
          * which will give us "count" until overflow.
          * Then we set the events on the enabled counters.
          */
@@ -569,28 +651,27 @@ cell_reg_setup(struct op_counter_config *ctr,
                 for (i = 0; i < num_counters; ++i) {
                         per_cpu(pmc_values, cpu)[i] = reset_value[i];
                 }
-out:
-        ;
+
+        return 0;
 }
 
+
+
 /* This function is called once for each cpu */
-static void cell_cpu_setup(struct op_counter_config *cntr)
+static int cell_cpu_setup(struct op_counter_config *cntr)
 {
         u32 cpu = smp_processor_id();
         u32 num_enabled = 0;
         int i;
 
+        if (spu_cycle_reset)
+                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))
-                goto out;
-
-        if (pm_rtas_token == RTAS_UNKNOWN_SERVICE) {
-                printk(KERN_WARNING "%s: RTAS_UNKNOWN_SERVICE\n",
-                       __FUNCTION__);
-                goto out;
-        }
+                return 0;
 
         /* Stop all counters */
         cbe_disable_pm(cpu);
@@ -609,16 +690,286 @@ static void cell_cpu_setup(struct op_counter_config *cntr)
                 }
         }
 
-        pm_rtas_activate_signals(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[NR_PHYS_CTRS];
+
+        /*
+         * 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 < NUM_SPUS_PER_NODE; 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,
+                                     (NUM_SPUS_PER_NODE
+                                      * sizeof(struct pm_signal)));
+
+        if (unlikely(ret)) {
+                printk(KERN_WARNING "%s: rtas returned: %d\n",
+                       __FUNCTION__, 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
+
+static int cell_global_start_spu(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",
+                               __FUNCTION__, ret);
+                        rtas_error = -EIO;
+                        goto out;
+                }
+        }
+
+        rtas_error = start_spu_profiling(spu_cycle_reset);
+        if (rtas_error)
+                goto out_stop;
+
+        oprofile_running = 1;
+        return 0;
+
+out_stop:
+        cell_global_stop_spu();         /* clean up the PMU/debug bus */
 out:
-        ;
+        return rtas_error;
 }
 
-static void cell_global_start(struct op_counter_config *ctr)
+static int cell_global_start_ppu(struct op_counter_config *ctr)
 {
-        u32 cpu;
+        u32 cpu, i;
         u32 interrupt_mask = 0;
-        u32 i;
 
         /* This routine gets called once for the system.
          * There is one performance monitor per node, so we
@@ -651,19 +1002,79 @@ static void cell_global_start(struct op_counter_config *ctr)
         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"
+        /*
+         * 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 void cell_global_stop(void)
+static int cell_global_start(struct op_counter_config *ctr)
+{
+        if (spu_cycle_reset)
+                return cell_global_start_spu(ctr);
+        else
+                return cell_global_start_ppu(ctr);
+}
+
+/*
+ * 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(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",
+                               __FUNCTION__, rtn_value);
+                }
+
+                /* Deactivate the signals */
+                pm_rtas_reset_signals(cbe_cpu_to_node(cpu));
+        }
+
+        stop_spu_profiling();
+}
+
+static void cell_global_stop_ppu(void)
 {
         int cpu;
 
-        /* This routine will be called once for the system.
+        /*
+         * 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.
          */
@@ -687,8 +1098,16 @@ static void cell_global_stop(void)
         }
 }
 
-static void
-cell_handle_interrupt(struct pt_regs *regs, struct op_counter_config *ctr)
+static void cell_global_stop(void)
+{
+        if (spu_cycle_reset)
+                cell_global_stop_spu();
+        else
+                cell_global_stop_ppu();
+}
+
+static void cell_handle_interrupt(struct pt_regs *regs,
+                                struct op_counter_config *ctr)
 {
         u32 cpu;
         u64 pc;
@@ -699,13 +1118,15 @@ cell_handle_interrupt(struct pt_regs *regs, struct op_counter_config *ctr)
 
         cpu = smp_processor_id();
 
-        /* Need to make sure the interrupt handler and the virt counter
+        /*
+         * 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
+        /*
+         * Need to disable and reenable the performance counters
          * to get the desired behavior from the hardware.  This
          * is hardware specific.
          */
@@ -714,7 +1135,8 @@ cell_handle_interrupt(struct pt_regs *regs, struct op_counter_config *ctr)
 
         interrupt_mask = cbe_get_and_clear_pm_interrupts(cpu);
 
-        /* If the interrupt mask has been cleared, then the virt cntr
+        /*
+         * 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.
@@ -732,18 +1154,20 @@ cell_handle_interrupt(struct pt_regs *regs, struct op_counter_config *ctr)
                         }
                 }
 
-                /* The counters were frozen by the interrupt.
+                /*
+                 * 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
+                 * 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
+                /*
+                 * 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
@@ -755,10 +1179,33 @@ cell_handle_interrupt(struct pt_regs *regs, struct op_counter_config *ctr)
         spin_unlock_irqrestore(&virt_cntr_lock, flags);
 }
 
+/*
+ * 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 (spu_cycle_reset)
+                return spu_sync_start();
+        else
+                return DO_GENERIC_SYNC;
+}
+
+static int cell_sync_stop(void)
+{
+        if (spu_cycle_reset)
+                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,
 };