x86 BIOS interface for RTC on SGI UV

Real-time code needs to know the number of cycles per second
on SGI UV.  The information is provided via a run time BIOS
call.  This patch provides the linux side of that interface.
This is the first of several run time BIOS calls to be defined
in uv/bios.h and bios_uv.c.

Note that BIOS_CALL() is just a stub for now.  The bios
side is being worked on.
Signed-off-by: Russ Anderson <rja@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/Makefile

@@ -102,6 +102,7 @@ obj-$(CONFIG_OLPC)		+= olpc.o
 # 64 bit specific files
 ifeq ($(CONFIG_X86_64),y)
         obj-y				+= genapic_64.o genapic_flat_64.o genx2apic_uv_x.o tlb_uv.o
+	obj-y				+= bios_uv.o
         obj-$(CONFIG_X86_PM_TIMER)	+= pmtimer_64.o
         obj-$(CONFIG_AUDIT)		+= audit_64.o
 

arch/x86/kernel/bios_uv.c

+/*
+ * BIOS run time interface routines.
+ *
+ *  Copyright (c) 2008 Silicon Graphics, Inc.  All Rights Reserved.
+ *
+ *  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.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <asm/uv/bios.h>
+
+const char *
+x86_bios_strerror(long status)
+{
+	const char *str;
+	switch (status) {
+	case  0: str = "Call completed without error"; break;
+	case -1: str = "Not implemented"; break;
+	case -2: str = "Invalid argument"; break;
+	case -3: str = "Call completed with error"; break;
+	default: str = "Unknown BIOS status code"; break;
+	}
+	return str;
+}
+
+long
+x86_bios_freq_base(unsigned long which, unsigned long *ticks_per_second,
+		   unsigned long *drift_info)
+{
+	struct uv_bios_retval isrv;
+
+	BIOS_CALL(isrv, BIOS_FREQ_BASE, which, 0, 0, 0, 0, 0, 0);
+	*ticks_per_second = isrv.v0;
+	*drift_info = isrv.v1;
+	return isrv.status;
+}
+EXPORT_SYMBOL_GPL(x86_bios_freq_base);

arch/x86/kernel/genx2apic_uv_x.c

@@ -24,6 +24,7 @@
 #include <asm/pgtable.h>
 #include <asm/uv/uv_mmrs.h>
 #include <asm/uv/uv_hub.h>
+#include <asm/uv/bios.h>
 
 DEFINE_PER_CPU(struct uv_hub_info_s, __uv_hub_info);
 EXPORT_PER_CPU_SYMBOL_GPL(__uv_hub_info);
@@ -40,6 +41,9 @@ EXPORT_SYMBOL_GPL(uv_cpu_to_blade);
 short uv_possible_blades;
 EXPORT_SYMBOL_GPL(uv_possible_blades);
 
+unsigned long sn_rtc_cycles_per_second;
+EXPORT_SYMBOL(sn_rtc_cycles_per_second);
+
 /* Start with all IRQs pointing to boot CPU.  IRQ balancing will shift them. */
 
 static cpumask_t uv_target_cpus(void)
@@ -272,6 +276,23 @@ static __init void map_mmioh_high(int max_pnode)
 		map_high("MMIOH", mmioh.s.base, shift, map_uc);
 }
 
+static __init void uv_rtc_init(void)
+{
+	long status, ticks_per_sec, drift;
+
+	status =
+	    x86_bios_freq_base(BIOS_FREQ_BASE_REALTIME_CLOCK, &ticks_per_sec,
+					&drift);
+	if (status != 0 || ticks_per_sec < 100000) {
+		printk(KERN_WARNING
+			"unable to determine platform RTC clock frequency, "
+			"guessing.\n");
+		/* BIOS gives wrong value for clock freq. so guess */
+		sn_rtc_cycles_per_second = 1000000000000UL / 30000UL;
+	} else
+		sn_rtc_cycles_per_second = ticks_per_sec;
+}
+
 static __init void uv_system_init(void)
 {
 	union uvh_si_addr_map_config_u m_n_config;
@@ -326,6 +347,8 @@ static __init void uv_system_init(void)
 	gnode_upper = (((unsigned long)node_id.s.node_id) &
 		       ~((1 << n_val) - 1)) << m_val;
 
+	uv_rtc_init();
+
 	for_each_present_cpu(cpu) {
 		nid = cpu_to_node(cpu);
 		pnode = uv_apicid_to_pnode(per_cpu(x86_cpu_to_apicid, cpu));

include/asm-x86/uv/bios.h

+#ifndef _ASM_X86_BIOS_H
+#define _ASM_X86_BIOS_H
+
+/*
+ * BIOS layer definitions.
+ *
+ *  Copyright (c) 2008 Silicon Graphics, Inc.  All Rights Reserved.
+ *
+ *  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.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/rtc.h>
+
+#define BIOS_FREQ_BASE			0x01000001
+
+enum {
+	BIOS_FREQ_BASE_PLATFORM = 0,
+	BIOS_FREQ_BASE_INTERVAL_TIMER = 1,
+	BIOS_FREQ_BASE_REALTIME_CLOCK = 2
+};
+
+# define BIOS_CALL(result, a0, a1, a2, a3, a4, a5, a6, a7)		\
+	do {								\
+		/* XXX - the real call goes here */			\
+		result.status = BIOS_STATUS_UNIMPLEMENTED;		\
+		isrv.v0 = 0;						\
+		isrv.v1 = 0;						\
+	} while (0)
+
+enum {
+	BIOS_STATUS_SUCCESS		=  0,
+	BIOS_STATUS_UNIMPLEMENTED	= -1,
+	BIOS_STATUS_EINVAL		= -2,
+	BIOS_STATUS_ERROR		= -3
+};
+
+struct uv_bios_retval {
+	/*
+	 * A zero status value indicates call completed without error.
+	 * A negative status value indicates reason of call failure.
+	 * A positive status value indicates success but an
+	 * informational value should be printed (e.g., "reboot for
+	 * change to take effect").
+	 */
+	s64 status;
+	u64 v0;
+	u64 v1;
+	u64 v2;
+};
+
+extern long
+x86_bios_freq_base(unsigned long which, unsigned long *ticks_per_second,
+		   unsigned long *drift_info);
+extern const char *x86_bios_strerror(long status);
+
+#endif /* _ASM_X86_BIOS_H */