[PATCH] powerpc64: remove broken/bitrotted HMT support

HMT support is currently broken and needs to be reworked to play nicely
with the SMT scheduler. Remove the bit rotten bits for the time being.

I also updated an incorrect comment, we enter __secondary_hold with the
physical cpu id in r3.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

3 files changed, 4 insertions, 138 deletions

diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index bb845eed0e98..11f2cd5af7dc 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -139,7 +139,7 @@ _GLOBAL(__secondary_hold)
         ori     r24,r24,MSR_RI
         mtmsrd  r24                     /* RI on */
 
-        /* Grab our linux cpu number */
+        /* Grab our physical cpu number */
         mr      r24,r3
 
         /* Tell the master cpu we're here */
@@ -153,11 +153,7 @@ _GLOBAL(__secondary_hold)
         cmpdi   0,r4,1
         bne     100b
 
-#ifdef CONFIG_HMT
-        SET_REG_IMMEDIATE(r4, .hmt_init)
-        mtctr   r4
-        bctr
-#elif defined(CONFIG_SMP) || defined(CONFIG_KEXEC)
+#if defined(CONFIG_SMP) || defined(CONFIG_KEXEC)
         LOAD_REG_IMMEDIATE(r4, .pSeries_secondary_smp_init)
         mtctr   r4
         mr      r3,r24
@@ -1808,22 +1804,6 @@ _STATIC(start_here_multiplatform)
         ori     r6,r6,MSR_RI
         mtmsrd  r6                      /* RI on */
 
-#ifdef CONFIG_HMT
-        /* Start up the second thread on cpu 0 */
-        mfspr   r3,SPRN_PVR
-        srwi    r3,r3,16
-        cmpwi   r3,0x34                 /* Pulsar  */
-        beq     90f
-        cmpwi   r3,0x36                 /* Icestar */
-        beq     90f
-        cmpwi   r3,0x37                 /* SStar   */
-        beq     90f
-        b       91f                     /* HMT not supported */
-90:     li      r3,0
-        bl      .hmt_start_secondary
-91:
-#endif
-
         /* The following gets the stack and TOC set up with the regs */
         /* pointing to the real addr of the kernel stack.  This is   */
         /* all done to support the C function call below which sets  */
@@ -1937,77 +1917,8 @@ _STATIC(start_here_common)
 
         bl .start_kernel
 
-_GLOBAL(hmt_init)
-#ifdef CONFIG_HMT
-        LOAD_REG_IMMEDIATE(r5, hmt_thread_data)
-        mfspr   r7,SPRN_PVR
-        srwi    r7,r7,16
-        cmpwi   r7,0x34                 /* Pulsar  */
-        beq     90f
-        cmpwi   r7,0x36                 /* Icestar */
-        beq     91f
-        cmpwi   r7,0x37                 /* SStar   */
-        beq     91f
-        b       101f
-90:     mfspr   r6,SPRN_PIR
-        andi.   r6,r6,0x1f
-        b       92f
-91:     mfspr   r6,SPRN_PIR
-        andi.   r6,r6,0x3ff
-92:     sldi    r4,r24,3
-        stwx    r6,r5,r4
-        bl      .hmt_start_secondary
-        b       101f
-
-__hmt_secondary_hold:
-        LOAD_REG_IMMEDIATE(r5, hmt_thread_data)
-        clrldi  r5,r5,4
-        li      r7,0
-        mfspr   r6,SPRN_PIR
-        mfspr   r8,SPRN_PVR
-        srwi    r8,r8,16
-        cmpwi   r8,0x34
-        bne     93f
-        andi.   r6,r6,0x1f
-        b       103f
-93:     andi.   r6,r6,0x3f
-
-103:    lwzx    r8,r5,r7
-        cmpw    r8,r6
-        beq     104f
-        addi    r7,r7,8
-        b       103b
-
-104:    addi    r7,r7,4
-        lwzx    r9,r5,r7
-        mr      r24,r9
-101:
-#endif
-        mr      r3,r24
-        b       .pSeries_secondary_smp_init
-
-#ifdef CONFIG_HMT
-_GLOBAL(hmt_start_secondary)
-        LOAD_REG_IMMEDIATE(r4,__hmt_secondary_hold)
-        clrldi  r4,r4,4
-        mtspr   SPRN_NIADORM, r4
-        mfspr   r4, SPRN_MSRDORM
-        li      r5, -65
-        and     r4, r4, r5
-        mtspr   SPRN_MSRDORM, r4
-        lis     r4,0xffef
-        ori     r4,r4,0x7403
-        mtspr   SPRN_TSC, r4
-        li      r4,0x1f4
-        mtspr   SPRN_TST, r4
-        mfspr   r4, SPRN_HID0
-        ori     r4, r4, 0x1
-        mtspr   SPRN_HID0, r4
-        mfspr   r4, SPRN_CTRLF
-        oris    r4, r4, 0x40
-        mtspr   SPRN_CTRLT, r4
-        blr
-#endif
+        /* Not reached */
+        BUG_OPCODE
 
 /*
  * We put a few things here that have to be page-aligned.
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index ec7153f4d47c..d34fe537400e 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -205,14 +205,6 @@ static cell_t __initdata regbuf[1024];
 
 #define MAX_CPU_THREADS 2
 
-/* TO GO */
-#ifdef CONFIG_HMT
-struct {
-        unsigned int pir;
-        unsigned int threadid;
-} hmt_thread_data[NR_CPUS];
-#endif /* CONFIG_HMT */
-
 /*
  * Error results ... some OF calls will return "-1" on error, some
  * will return 0, some will return either. To simplify, here are
@@ -1319,10 +1311,6 @@ static void __init prom_hold_cpus(void)
          */
         *spinloop = 0;
 
-#ifdef CONFIG_HMT
-        for (i = 0; i < NR_CPUS; i++)
-                RELOC(hmt_thread_data)[i].pir = 0xdeadbeef;
-#endif
         /* look for cpus */
         for (node = 0; prom_next_node(&node); ) {
                 type[0] = 0;
@@ -1389,32 +1377,6 @@ static void __init prom_hold_cpus(void)
                 /* Reserve cpu #s for secondary threads.   They start later. */
                 cpuid += cpu_threads;
         }
-#ifdef CONFIG_HMT
-        /* Only enable HMT on processors that provide support. */
-        if (__is_processor(PV_PULSAR) || 
-            __is_processor(PV_ICESTAR) ||
-            __is_processor(PV_SSTAR)) {
-                prom_printf("    starting secondary threads\n");
-
-                for (i = 0; i < NR_CPUS; i += 2) {
-                        if (!cpu_online(i))
-                                continue;
-
-                        if (i == 0) {
-                                unsigned long pir = mfspr(SPRN_PIR);
-                                if (__is_processor(PV_PULSAR)) {
-                                        RELOC(hmt_thread_data)[i].pir = 
-                                                pir & 0x1f;
-                                } else {
-                                        RELOC(hmt_thread_data)[i].pir = 
-                                                pir & 0x3ff;
-                                }
-                        }
-                }
-        } else {
-                prom_printf("Processor is not HMT capable\n");
-        }
-#endif
 
         if (cpuid > NR_CPUS)
                 prom_printf("WARNING: maximum CPUs (" __stringify(NR_CPUS)
diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
index e3fc3407bb1f..4e5c8f8d869d 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -9,13 +9,6 @@ config PPC_SPLPAR
           processors, that is, which share physical processors between
           two or more partitions.
 
-config HMT
-        bool "Hardware multithreading"
-        depends on SMP && PPC_PSERIES && BROKEN
-        help
-          This option enables hardware multithreading on RS64 cpus.
-          pSeries systems p620 and p660 have such a cpu type.
-
 config EEH
         bool "PCI Extended Error Handling (EEH)" if EMBEDDED
         depends on PPC_PSERIES