parisc: hijack jump to start_kernel

Bang in our own start_parisc call, which initializes the PDC
width, and turns on the FPU.

Previously, if CONFIG_PRINTK_TIME was on, we'd attempt to use
the FPU before we had enabled it, resulting in a difficult
to diagnose panic.

This patch causes init_per_cpu to redundantly set these for
cpu0, but this is harmless.

2 files changed, 27 insertions, 2 deletions

diff --git a/arch/parisc/kernel/head.S b/arch/parisc/kernel/head.S
index a84e31e82876..0e3d9f9b9e33 100644
--- a/arch/parisc/kernel/head.S
+++ b/arch/parisc/kernel/head.S
@@ -121,7 +121,7 @@ $pgt_fill_loop:
         copy            %r0,%r2
 
         /* And the RFI Target address too */
-        load32          start_kernel,%r11
+        load32          start_parisc,%r11
 
         /* And the initial task pointer */
         load32          init_thread_union,%r6
diff --git a/arch/parisc/kernel/setup.c b/arch/parisc/kernel/setup.c
index 39e7c5a5946a..a59b71efdbe5 100644
--- a/arch/parisc/kernel/setup.c
+++ b/arch/parisc/kernel/setup.c
@@ -368,6 +368,31 @@ static int __init parisc_init(void)
 
         return 0;
 }
-
 arch_initcall(parisc_init);
 
+void start_parisc(void)
+{
+        extern void start_kernel(void);
+
+        int ret, cpunum;
+        struct pdc_coproc_cfg coproc_cfg;
+
+        cpunum = smp_processor_id();
+
+        set_firmware_width_unlocked();
+
+        ret = pdc_coproc_cfg_unlocked(&coproc_cfg);
+        if (ret >= 0 && coproc_cfg.ccr_functional) {
+                mtctl(coproc_cfg.ccr_functional, 10);
+
+                cpu_data[cpunum].fp_rev = coproc_cfg.revision;
+                cpu_data[cpunum].fp_model = coproc_cfg.model;
+
+                asm volatile ("fstd     %fr0,8(%sp)");
+        } else {
+                panic("must have an fpu to boot linux");
+        }
+
+        start_kernel();
+        // not reached
+}