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 a84e31e..0e3d9f9 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 39e7c5a..a59b71e 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
+}