Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha

d5bdaf4f · Linus Torvalds <[email protected]> · 2013-11-20 15:03:45 -08:00

Pull alpha updates from Matt Turner:
 "It contains a few fixes and some work from Richard to make alpha
  emulation under QEMU much more usable"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha:
  alpha: Prevent a NULL ptr dereference in csum_partial_copy.
  alpha: perf: fix out-of-bounds array access triggered from raw event
  alpha: Use qemu+cserve provided high-res clock and alarm.
  alpha: Switch to GENERIC_CLOCKEVENTS
  alpha: Enable the rpcc clocksource for single processor
  alpha: Reorganize rtc handling
  alpha: Primitive support for CPU power down.
  alpha: Allow HZ to be configured
  alpha: Notice if we're being run under QEMU
  alpha: Eliminate compiler warning from memset macro

Commit: d5bdaf4f68f0590fc481bca54bcaffeb27b75fca
Parents: dc6ec87d · 5cfe8f1b

Merge commit. Changes below are compared with the first parent: dc6ec87d.

Changes

24 files changed · +777 −388

File	Status	Add	Del	Content
arch/alpha/Kconfig	modified	+73	−3	View file
arch/alpha/include/asm/machvec.h	modified	+13	−9	View file
arch/alpha/include/asm/pal.h	modified	+71	−0	View file
arch/alpha/include/asm/rtc.h	modified	+0	−11	View file
arch/alpha/include/asm/string.h	modified	+18	−6	View file
arch/alpha/include/uapi/asm/pal.h	modified	+1	−0	View file
arch/alpha/kernel/Makefile	modified	+1	−0	View file
arch/alpha/kernel/alpha_ksyms.c	modified	+1	−0	View file
arch/alpha/kernel/irq_alpha.c	modified	+1	−15	View file
arch/alpha/kernel/machvec_impl.h	modified	+1	−4	View file
arch/alpha/kernel/perf_event.c	modified	+13	−2	View file
arch/alpha/kernel/process.c	modified	+17	−0	View file
arch/alpha/kernel/proto.h	modified	+2	−4	View file
arch/alpha/kernel/rtc.c	added	+323	−0	View file
arch/alpha/kernel/setup.c	modified	+20	−3	View file
arch/alpha/kernel/smp.c	modified	+3	−30	View file
arch/alpha/kernel/sys_jensen.c	modified	+0	−2	View file
arch/alpha/kernel/sys_marvel.c	modified	+1	−54	View file
arch/alpha/kernel/time.c	modified	+175	−230	View file
arch/alpha/kernel/traps.c	modified	+15	−0	View file
arch/alpha/lib/csum_partial_copy.c	modified	+5	−5	View file
arch/alpha/lib/ev6-memset.S	modified	+7	−5	View file
arch/alpha/lib/memset.S	modified	+7	−4	View file
drivers/rtc/Kconfig	modified	+9	−1	View file

Only the first 600 diff lines are shown. Download the complete patch.

arch/alpha/Kconfig

View file

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 135c674..d39dc9b 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -16,8 +16,8 @@ config ALPHA
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
+	select GENERIC_CLOCKEVENTS
 	select GENERIC_SMP_IDLE_THREAD
-	select GENERIC_CMOS_UPDATE
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER
 	select HAVE_MOD_ARCH_SPECIFIC
@@ -488,6 +488,20 @@ config VGA_HOSE
 	  which always have multiple hoses, and whose consoles support it.
 
 
+config ALPHA_QEMU
+	bool "Run under QEMU emulation"
+	depends on !ALPHA_GENERIC
+	---help---
+	  Assume the presence of special features supported by QEMU PALcode
+	  that reduce the overhead of system emulation.
+
+	  Generic kernels will auto-detect QEMU.  But when building a
+	  system-specific kernel, the assumption is that we want to
+	  elimiate as many runtime tests as possible.
+
+	  If unsure, say N.
+
+
 config ALPHA_SRM
 	bool "Use SRM as bootloader" if ALPHA_CABRIOLET || ALPHA_AVANTI_CH || ALPHA_EB64P || ALPHA_PC164 || ALPHA_TAKARA || ALPHA_EB164 || ALPHA_ALCOR || ALPHA_MIATA || ALPHA_LX164 || ALPHA_SX164 || ALPHA_NAUTILUS || ALPHA_NONAME
 	depends on TTY
@@ -572,6 +586,30 @@ config NUMA
 	  Access).  This option is for configuring high-end multiprocessor
 	  server machines.  If in doubt, say N.
 
+config ALPHA_WTINT
+	bool "Use WTINT" if ALPHA_SRM || ALPHA_GENERIC
+	default y if ALPHA_QEMU
+	default n if ALPHA_EV5 || ALPHA_EV56 || (ALPHA_EV4 && !ALPHA_LCA)
+	default n if !ALPHA_SRM && !ALPHA_GENERIC
+	default y if SMP
+	---help---
+	  The Wait for Interrupt (WTINT) PALcall attempts to place the CPU
+	  to sleep until the next interrupt.  This may reduce the power
+	  consumed, and the heat produced by the computer.  However, it has
+	  the side effect of making the cycle counter unreliable as a timing
+	  device across the sleep.
+
+	  For emulation under QEMU, definitely say Y here, as we have other
+	  mechanisms for measuring time than the cycle counter.
+
+	  For EV4 (but not LCA), EV5 and EV56 systems, or for systems running
+	  MILO, sleep mode is not supported so you might as well say N here.
+
+	  For SMP systems we cannot use the cycle counter for timing anyway,
+	  so you might as well say Y here.
+
+	  If unsure, say N.
+
 config NODES_SHIFT
 	int
 	default "7"
@@ -613,9 +651,41 @@ config VERBOSE_MCHECK_ON
 
 	  Take the default (1) unless you want more control or more info.
 
+choice
+	prompt "Timer interrupt frequency (HZ)?"
+	default HZ_128 if ALPHA_QEMU
+	default HZ_1200 if ALPHA_RAWHIDE
+	default HZ_1024
+	---help---
+	  The frequency at which timer interrupts occur.  A high frequency
+	  minimizes latency, whereas a low frequency minimizes overhead of
+	  process accounting.  The later effect is especially significant
+	  when being run under QEMU.
+
+	  Note that some Alpha hardware cannot change the interrupt frequency
+	  of the timer.  If unsure, say 1024 (or 1200 for Rawhide).
+
+	config HZ_32
+		bool "32 Hz"
+	config HZ_64
+		bool "64 Hz"
+	config HZ_128
+		bool "128 Hz"
+	config HZ_256
+		bool "256 Hz"
+	config HZ_1024
+		bool "1024 Hz"
+	config HZ_1200
+		bool "1200 Hz"
+endchoice
+
 config HZ
-	int
-	default 1200 if ALPHA_RAWHIDE
+	int 
+	default 32 if HZ_32
+	default 64 if HZ_64
+	default 128 if HZ_128
+	default 256 if HZ_256
+	default 1200 if HZ_1200
 	default 1024
 
 source "drivers/pci/Kconfig"

arch/alpha/include/asm/machvec.h

View file

diff --git a/arch/alpha/include/asm/machvec.h b/arch/alpha/include/asm/machvec.h
index 72dbf23..75cb364 100644
--- a/arch/alpha/include/asm/machvec.h
+++ b/arch/alpha/include/asm/machvec.h
@@ -33,6 +33,7 @@ struct alpha_machine_vector
 
 	int nr_irqs;
 	int rtc_port;
+	int rtc_boot_cpu_only;
 	unsigned int max_asn;
 	unsigned long max_isa_dma_address;
 	unsigned long irq_probe_mask;
@@ -95,9 +96,6 @@ struct alpha_machine_vector
 
 	struct _alpha_agp_info *(*agp_info)(void);
 
-	unsigned int (*rtc_get_time)(struct rtc_time *);
-	int (*rtc_set_time)(struct rtc_time *);
-
 	const char *vector_name;
 
 	/* NUMA information */
@@ -126,13 +124,19 @@ extern struct alpha_machine_vector alpha_mv;
 
 #ifdef CONFIG_ALPHA_GENERIC
 extern int alpha_using_srm;
+extern int alpha_using_qemu;
 #else
-#ifdef CONFIG_ALPHA_SRM
-#define alpha_using_srm 1
-#else
-#define alpha_using_srm 0
-#endif
+# ifdef CONFIG_ALPHA_SRM
+#  define alpha_using_srm 1
+# else
+#  define alpha_using_srm 0
+# endif
+# ifdef CONFIG_ALPHA_QEMU
+#  define alpha_using_qemu 1
+# else
+#  define alpha_using_qemu 0
+# endif
 #endif /* GENERIC */
 
-#endif
+#endif /* __KERNEL__ */
 #endif /* __ALPHA_MACHVEC_H */

arch/alpha/include/asm/pal.h

View file

diff --git a/arch/alpha/include/asm/pal.h b/arch/alpha/include/asm/pal.h
index 6fcd2b5..5422a47 100644
--- a/arch/alpha/include/asm/pal.h
+++ b/arch/alpha/include/asm/pal.h
@@ -89,6 +89,7 @@ __CALL_PAL_W1(wrmces, unsigned long);
 __CALL_PAL_RW2(wrperfmon, unsigned long, unsigned long, unsigned long);
 __CALL_PAL_W1(wrusp, unsigned long);
 __CALL_PAL_W1(wrvptptr, unsigned long);
+__CALL_PAL_RW1(wtint, unsigned long, unsigned long);
 
 /*
  * TB routines..
@@ -111,5 +112,75 @@ __CALL_PAL_W1(wrvptptr, unsigned long);
 #define tbiap()		__tbi(-1, /* no second argument */)
 #define tbia()		__tbi(-2, /* no second argument */)
 
+/*
+ * QEMU Cserv routines..
+ */
+
+static inline unsigned long
+qemu_get_walltime(void)
+{
+	register unsigned long v0 __asm__("$0");
+	register unsigned long a0 __asm__("$16") = 3;
+
+	asm("call_pal %2 # cserve get_time"
+	    : "=r"(v0), "+r"(a0)
+	    : "i"(PAL_cserve)
+	    : "$17", "$18", "$19", "$20", "$21");
+
+	return v0;
+}
+
+static inline unsigned long
+qemu_get_alarm(void)
+{
+	register unsigned long v0 __asm__("$0");
+	register unsigned long a0 __asm__("$16") = 4;
+
+	asm("call_pal %2 # cserve get_alarm"
+	    : "=r"(v0), "+r"(a0)
+	    : "i"(PAL_cserve)
+	    : "$17", "$18", "$19", "$20", "$21");
+
+	return v0;
+}
+
+static inline void
+qemu_set_alarm_rel(unsigned long expire)
+{
+	register unsigned long a0 __asm__("$16") = 5;
+	register unsigned long a1 __asm__("$17") = expire;
+
+	asm volatile("call_pal %2 # cserve set_alarm_rel"
+		     : "+r"(a0), "+r"(a1)
+		     : "i"(PAL_cserve)
+		     : "$0", "$18", "$19", "$20", "$21");
+}
+
+static inline void
+qemu_set_alarm_abs(unsigned long expire)
+{
+	register unsigned long a0 __asm__("$16") = 6;
+	register unsigned long a1 __asm__("$17") = expire;
+
+	asm volatile("call_pal %2 # cserve set_alarm_abs"
+		     : "+r"(a0), "+r"(a1)
+		     : "i"(PAL_cserve)
+		     : "$0", "$18", "$19", "$20", "$21");
+}
+
+static inline unsigned long
+qemu_get_vmtime(void)
+{
+	register unsigned long v0 __asm__("$0");
+	register unsigned long a0 __asm__("$16") = 7;
+
+	asm("call_pal %2 # cserve get_time"
+	    : "=r"(v0), "+r"(a0)
+	    : "i"(PAL_cserve)
+	    : "$17", "$18", "$19", "$20", "$21");
+
+	return v0;
+}
+
 #endif /* !__ASSEMBLY__ */
 #endif /* __ALPHA_PAL_H */

arch/alpha/include/asm/rtc.h

View file

diff --git a/arch/alpha/include/asm/rtc.h b/arch/alpha/include/asm/rtc.h
index d70408d..f71c3b0 100644
--- a/arch/alpha/include/asm/rtc.h
+++ b/arch/alpha/include/asm/rtc.h
@@ -1,12 +1 @@
-#ifndef _ALPHA_RTC_H
-#define _ALPHA_RTC_H
-
-#if defined(CONFIG_ALPHA_MARVEL) && defined(CONFIG_SMP) \
- || defined(CONFIG_ALPHA_GENERIC)
-# define get_rtc_time		alpha_mv.rtc_get_time
-# define set_rtc_time		alpha_mv.rtc_set_time
-#endif
-
 #include <asm-generic/rtc.h>
-
-#endif

arch/alpha/include/asm/string.h

View file

diff --git a/arch/alpha/include/asm/string.h b/arch/alpha/include/asm/string.h
index b02b8a2..c2911f5 100644
--- a/arch/alpha/include/asm/string.h
+++ b/arch/alpha/include/asm/string.h
@@ -22,15 +22,27 @@ extern void * __memcpy(void *, const void *, size_t);
 
 #define __HAVE_ARCH_MEMSET
 extern void * __constant_c_memset(void *, unsigned long, size_t);
+extern void * ___memset(void *, int, size_t);
 extern void * __memset(void *, int, size_t);
 extern void * memset(void *, int, size_t);
 
-#define memset(s, c, n)							    \
-(__builtin_constant_p(c)						    \
- ? (__builtin_constant_p(n) && (c) == 0					    \
-    ? __builtin_memset((s),0,(n)) 					    \
-    : __constant_c_memset((s),0x0101010101010101UL*(unsigned char)(c),(n))) \
- : __memset((s),(c),(n)))
+/* For gcc 3.x, we cannot have the inline function named "memset" because
+   the __builtin_memset will attempt to resolve to the inline as well,
+   leading to a "sorry" about unimplemented recursive inlining.  */
+extern inline void *__memset(void *s, int c, size_t n)
+{
+	if (__builtin_constant_p(c)) {
+		if (__builtin_constant_p(n)) {
+			return __builtin_memset(s, c, n);
+		} else {
+			unsigned long c8 = (c & 0xff) * 0x0101010101010101UL;
+			return __constant_c_memset(s, c8, n);
+		}
+	}
+	return ___memset(s, c, n);
+}
+
+#define memset __memset
 
 #define __HAVE_ARCH_STRCPY
 extern char * strcpy(char *,const char *);

arch/alpha/include/uapi/asm/pal.h

View file

diff --git a/arch/alpha/include/uapi/asm/pal.h b/arch/alpha/include/uapi/asm/pal.h
index 3c0ce08..dfc8140 100644
--- a/arch/alpha/include/uapi/asm/pal.h
+++ b/arch/alpha/include/uapi/asm/pal.h
@@ -46,6 +46,7 @@
 #define PAL_rdusp	58
 #define PAL_whami	60
 #define PAL_retsys	61
+#define PAL_wtint	62
 #define PAL_rti		63
 
 

arch/alpha/kernel/Makefile

View file

diff --git a/arch/alpha/kernel/Makefile b/arch/alpha/kernel/Makefile
index 84ec46b..0d54650 100644
--- a/arch/alpha/kernel/Makefile
+++ b/arch/alpha/kernel/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_PCI)	+= pci.o pci_iommu.o pci-sysfs.o
 obj-$(CONFIG_SRM_ENV)	+= srm_env.o
 obj-$(CONFIG_MODULES)	+= module.o
 obj-$(CONFIG_PERF_EVENTS) += perf_event.o
+obj-$(CONFIG_RTC_DRV_ALPHA) += rtc.o
 
 ifdef CONFIG_ALPHA_GENERIC
 

arch/alpha/kernel/alpha_ksyms.c

View file

diff --git a/arch/alpha/kernel/alpha_ksyms.c b/arch/alpha/kernel/alpha_ksyms.c
index 89566b3..f4c7ab6 100644
--- a/arch/alpha/kernel/alpha_ksyms.c
+++ b/arch/alpha/kernel/alpha_ksyms.c
@@ -40,6 +40,7 @@ EXPORT_SYMBOL(strrchr);
 EXPORT_SYMBOL(memmove);
 EXPORT_SYMBOL(__memcpy);
 EXPORT_SYMBOL(__memset);
+EXPORT_SYMBOL(___memset);
 EXPORT_SYMBOL(__memsetw);
 EXPORT_SYMBOL(__constant_c_memset);
 EXPORT_SYMBOL(copy_page);

arch/alpha/kernel/irq_alpha.c

View file

diff --git a/arch/alpha/kernel/irq_alpha.c b/arch/alpha/kernel/irq_alpha.c
index 28e4429..1c8625c 100644
--- a/arch/alpha/kernel/irq_alpha.c
+++ b/arch/alpha/kernel/irq_alpha.c
@@ -66,21 +66,7 @@ do_entInt(unsigned long type, unsigned long vector,
 		break;
 	case 1:
 		old_regs = set_irq_regs(regs);
-#ifdef CONFIG_SMP
-	  {
-		long cpu;
-
-		smp_percpu_timer_interrupt(regs);
-		cpu = smp_processor_id();
-		if (cpu != boot_cpuid) {
-		        kstat_incr_irqs_this_cpu(RTC_IRQ, irq_to_desc(RTC_IRQ));
-		} else {
-			handle_irq(RTC_IRQ);
-		}
-	  }
-#else
 		handle_irq(RTC_IRQ);
-#endif
 		set_irq_regs(old_regs);
 		return;
 	case 2:
@@ -228,7 +214,7 @@ process_mcheck_info(unsigned long vector, unsigned long la_ptr,
  */
 
 struct irqaction timer_irqaction = {
-	.handler	= timer_interrupt,
+	.handler	= rtc_timer_interrupt,
 	.name		= "timer",
 };
 

arch/alpha/kernel/machvec_impl.h

View file

diff --git a/arch/alpha/kernel/machvec_impl.h b/arch/alpha/kernel/machvec_impl.h
index 7fa6248..f54bdf6 100644
--- a/arch/alpha/kernel/machvec_impl.h
+++ b/arch/alpha/kernel/machvec_impl.h
@@ -43,10 +43,7 @@
 #define CAT1(x,y)  x##y
 #define CAT(x,y)   CAT1(x,y)
 
-#define DO_DEFAULT_RTC \
-	.rtc_port = 0x70, \
-	.rtc_get_time = common_get_rtc_time, \
-	.rtc_set_time = common_set_rtc_time
+#define DO_DEFAULT_RTC			.rtc_port = 0x70
 
 #define DO_EV4_MMU							\
 	.max_asn =			EV4_MAX_ASN,			\

arch/alpha/kernel/perf_event.c

View file

diff --git a/arch/alpha/kernel/perf_event.c b/arch/alpha/kernel/perf_event.c
index d821b17..c52e7f0 100644
--- a/arch/alpha/kernel/perf_event.c
+++ b/arch/alpha/kernel/perf_event.c
@@ -83,6 +83,8 @@ struct alpha_pmu_t {
 	long pmc_left[3];
 	 /* Subroutine for allocation of PMCs.  Enforces constraints. */
 	int (*check_constraints)(struct perf_event **, unsigned long *, int);
+	/* Subroutine for checking validity of a raw event for this PMU. */
+	int (*raw_event_valid)(u64 config);
 };
 
 /*
@@ -203,6 +205,12 @@ success:
 }
 
 
+static int ev67_raw_event_valid(u64 config)
+{
+	return config >= EV67_CYCLES && config < EV67_LAST_ET;
+};
+
+
 static const struct alpha_pmu_t ev67_pmu = {
 	.event_map = ev67_perfmon_event_map,
 	.max_events = ARRAY_SIZE(ev67_perfmon_event_map),
@@ -211,7 +219,8 @@ static const struct alpha_pmu_t ev67_pmu = {
 	.pmc_count_mask = {EV67_PCTR_0_COUNT_MASK,  EV67_PCTR_1_COUNT_MASK,  0},
 	.pmc_max_period = {(1UL<<20) - 1, (1UL<<20) - 1, 0},
 	.pmc_left = {16, 4, 0},
-	.check_constraints = ev67_check_constraints
+	.check_constraints = ev67_check_constraints,
+	.raw_event_valid = ev67_raw_event_valid,
 };
 
 
@@ -609,7 +618,9 @@ static int __hw_perf_event_init(struct perf_event *event)
 	} else if (attr->type == PERF_TYPE_HW_CACHE) {
 		return -EOPNOTSUPP;
 	} else if (attr->type == PERF_TYPE_RAW) {
-		ev = attr->config & 0xff;
+		if (!alpha_pmu->raw_event_valid(attr->config))
+			return -EINVAL;
+		ev = attr->config;
 	} else {
 		return -EOPNOTSUPP;
 	}

arch/alpha/kernel/process.c

View file

diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index f2360a7..1941a07 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -46,6 +46,23 @@
 void (*pm_power_off)(void) = machine_power_off;
 EXPORT_SYMBOL(pm_power_off);
 
+#ifdef CONFIG_ALPHA_WTINT
+/*
+ * Sleep the CPU.
+ * EV6, LCA45 and QEMU know how to power down, skipping N timer interrupts.
+ */
+void arch_cpu_idle(void)
+{
+	wtint(0);
+	local_irq_enable();
+}
+
+void arch_cpu_idle_dead(void)
+{
+	wtint(INT_MAX);
+}
+#endif /* ALPHA_WTINT */
+
 struct halt_info {
 	int mode;
 	char *restart_cmd;

arch/alpha/kernel/proto.h

View file

diff --git a/arch/alpha/kernel/proto.h b/arch/alpha/kernel/proto.h
index d3e52d3..da2d6ec 100644
--- a/arch/alpha/kernel/proto.h
+++ b/arch/alpha/kernel/proto.h
@@ -135,17 +135,15 @@ extern void unregister_srm_console(void);
 /* smp.c */
 extern void setup_smp(void);
 extern void handle_ipi(struct pt_regs *);
-extern void smp_percpu_timer_interrupt(struct pt_regs *);
 
 /* bios32.c */
 /* extern void reset_for_srm(void); */
 
 /* time.c */
-extern irqreturn_t timer_interrupt(int irq, void *dev);
+extern irqreturn_t rtc_timer_interrupt(int irq, void *dev);
+extern void init_clockevent(void);
 extern void common_init_rtc(void);
 extern unsigned long est_cycle_freq;
-extern unsigned int common_get_rtc_time(struct rtc_time *time);
-extern int common_set_rtc_time(struct rtc_time *time);
 
 /* smc37c93x.c */
 extern void SMC93x_Init(void);

arch/alpha/kernel/rtc.c

View file

diff --git a/arch/alpha/kernel/rtc.c b/arch/alpha/kernel/rtc.c
new file mode 100644
index 0000000..c8d284d
--- /dev/null
+++ b/arch/alpha/kernel/rtc.c
@@ -0,0 +1,323 @@
+/*
+ *  linux/arch/alpha/kernel/rtc.c
+ *
+ *  Copyright (C) 1991, 1992, 1995, 1999, 2000  Linus Torvalds
+ *
+ * This file contains date handling.
+ */
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/param.h>
+#include <linux/string.h>
+#include <linux/mc146818rtc.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/platform_device.h>
+
+#include <asm/rtc.h>
+
+#include "proto.h"
+
+
+/*
+ * Support for the RTC device.
+ *
+ * We don't want to use the rtc-cmos driver, because we don't want to support
+ * alarms, as that would be indistinguishable from timer interrupts.
+ *
+ * Further, generic code is really, really tied to a 1900 epoch.  This is
+ * true in __get_rtc_time as well as the users of struct rtc_time e.g.
+ * rtc_tm_to_time.  Thankfully all of the other epochs in use are later
+ * than 1900, and so it's easy to adjust.
+ */
+
+static unsigned long rtc_epoch;
+
+static int __init
+specifiy_epoch(char *str)
+{
+	unsigned long epoch = simple_strtoul(str, NULL, 0);
+	if (epoch < 1900)
+		printk("Ignoring invalid user specified epoch %lu\n", epoch);
+	else
+		rtc_epoch = epoch;
+	return 1;
+}
+__setup("epoch=", specifiy_epoch);
+
+static void __init
+init_rtc_epoch(void)
+{
+	int epoch, year, ctrl;
+
+	if (rtc_epoch != 0) {
+		/* The epoch was specified on the command-line.  */
+		return;
+	}
+
+	/* Detect the epoch in use on this computer.  */
+	ctrl = CMOS_READ(RTC_CONTROL);
+	year = CMOS_READ(RTC_YEAR);
+	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
+		year = bcd2bin(year);
+
+	/* PC-like is standard; used for year >= 70 */
+	epoch = 1900;
+	if (year < 20) {
+		epoch = 2000;
+	} else if (year >= 20 && year < 48) {
+		/* NT epoch */
+		epoch = 1980;
+	} else if (year >= 48 && year < 70) {
+		/* Digital UNIX epoch */
+		epoch = 1952;
+	}
+	rtc_epoch = epoch;
+
+	printk(KERN_INFO "Using epoch %d for rtc year %d\n", epoch, year);
+}
+
+static int
+alpha_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	__get_rtc_time(tm);
+
+	/* Adjust for non-default epochs.  It's easier to depend on the
+	   generic __get_rtc_time and adjust the epoch here than create
+	   a copy of __get_rtc_time with the edits we need.  */
+	if (rtc_epoch != 1900) {
+		int year = tm->tm_year;
+		/* Undo the century adjustment made in __get_rtc_time.  */
+		if (year >= 100)
+			year -= 100;
+		year += rtc_epoch - 1900;
+		/* Redo the century adjustment with the epoch in place.  */
+		if (year <= 69)
+			year += 100;
+		tm->tm_year = year;
+	}
+
+	return rtc_valid_tm(tm);
+}
+
+static int
+alpha_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtc_time xtm;