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Date: Tue, 16 Jul 2013 10:34:15 -0700
From: Richard Henderson <rth@...ddle.net>
To: linux-kernel@...r.kernel.org
Cc: ink@...assic.park.msu.ru, mattst88@...il.com,
linux-alpha@...r.kernel.org
Subject: [RFC PATCH 07/10] alpha: Add an rtc driver for the qemu wallclock PALcall
In the normal case, one wants the guest to follow the host time.
QEMU has a cserve call that retrieves the wall clock.
Signed-off-by: Richard Henderson <rth@...ddle.net>
---
arch/alpha/include/asm/pal.h | 56 ++++++++++++++++++++++++++++++++++++++
arch/alpha/kernel/Makefile | 3 +-
arch/alpha/kernel/rtc.c | 65 +++++++++++++++++++++++++++++++++++++++-----
drivers/rtc/Kconfig | 7 +++++
4 files changed, 122 insertions(+), 9 deletions(-)
diff --git a/arch/alpha/include/asm/pal.h b/arch/alpha/include/asm/pal.h
index e78ec9b..ccaa49a 100644
--- a/arch/alpha/include/asm/pal.h
+++ b/arch/alpha/include/asm/pal.h
@@ -112,5 +112,61 @@ __CALL_PAL_RW1(wtint, unsigned long, 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", "$21");
+}
+
#endif /* !__ASSEMBLY__ */
#endif /* __ALPHA_PAL_H */
diff --git a/arch/alpha/kernel/Makefile b/arch/alpha/kernel/Makefile
index 0d54650..bf04ee8 100644
--- a/arch/alpha/kernel/Makefile
+++ b/arch/alpha/kernel/Makefile
@@ -8,7 +8,7 @@ ccflags-y := -Wno-sign-compare
obj-y := entry.o traps.o process.o osf_sys.o irq.o \
irq_alpha.o signal.o setup.o ptrace.o time.o \
- alpha_ksyms.o systbls.o err_common.o io.o
+ alpha_ksyms.o systbls.o err_common.o io.o rtc.o
obj-$(CONFIG_VGA_HOSE) += console.o
obj-$(CONFIG_SMP) += smp.o
@@ -16,7 +16,6 @@ obj-$(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
diff --git a/arch/alpha/kernel/rtc.c b/arch/alpha/kernel/rtc.c
index c8d284d..fd910ff 100644
--- a/arch/alpha/kernel/rtc.c
+++ b/arch/alpha/kernel/rtc.c
@@ -16,10 +16,12 @@
#include <linux/platform_device.h>
#include <asm/rtc.h>
+#include <asm/pal.h>
#include "proto.h"
+#ifdef CONFIG_RTC_DRV_ALPHA
/*
* Support for the RTC device.
*
@@ -293,20 +295,68 @@ static const struct rtc_class_ops remote_rtc_ops = {
.set_mmss = remote_set_mmss,
.ioctl = alpha_rtc_ioctl,
};
-#endif
+#endif /* HAVE_REMOTE_RTC */
+#endif /* CONFIG_RTC_DRV_ALPHA */
+
+#ifdef CONFIG_RTC_DRV_ALPHA_QEMU
+/*
+ * Support for the QEMU wall clock as an RTC device.
+ */
+
+static int
+qemu_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ unsigned long nsec = qemu_get_walltime();
+ unsigned long sec = nsec / NSEC_PER_SEC;
+ rtc_time_to_tm(sec, tm);
+ return 0;
+}
+
+static int
+qemu_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ return -EOPNOTSUPP;
+}
+
+static int
+qemu_rtc_set_mmss(struct device *dev, unsigned long sec)
+{
+ return -EOPNOTSUPP;
+}
+
+static const struct rtc_class_ops qemu_rtc_ops = {
+ .read_time = qemu_rtc_read_time,
+ .set_time = qemu_rtc_set_time,
+ .set_mmss = qemu_rtc_set_mmss,
+};
+#endif /* CONFIG_RTC_DRV_ALPHA_QEMU */
+
+#if defined(CONFIG_RTC_DRV_ALPHA) || defined(CONFIG_RTC_DRV_ALPHA_QEMU)
static int __init
-alpha_rtc_init(void)
+rtc_init(void)
{
const struct rtc_class_ops *ops;
struct platform_device *pdev;
struct rtc_device *rtc;
const char *name;
+#ifdef CONFIG_RTC_DRV_ALPHA_QEMU
+ if (alpha_using_qemu) {
+ name = "rtc-qemu";
+ ops = &qemu_rtc_ops;
+
+ pdev = platform_device_register_simple(name, -1, NULL, 0);
+ rtc = devm_rtc_device_register(&pdev->dev, name, ops, NULL);
+ if (!IS_ERR(rtc))
+ platform_set_drvdata(pdev, rtc);
+ }
+#endif /* ALPHA_QEMU */
+
+#ifdef CONFIG_RTC_DRV_ALPHA
init_rtc_epoch();
name = "rtc-alpha";
ops = &alpha_rtc_ops;
-
#ifdef HAVE_REMOTE_RTC
if (alpha_mv.rtc_boot_cpu_only)
ops = &remote_rtc_ops;
@@ -314,10 +364,11 @@ alpha_rtc_init(void)
pdev = platform_device_register_simple(name, -1, NULL, 0);
rtc = devm_rtc_device_register(&pdev->dev, name, ops, THIS_MODULE);
- if (IS_ERR(rtc))
- return PTR_ERR(rtc);
+ if (!IS_ERR(rtc))
+ platform_set_drvdata(pdev, rtc);
+#endif /* ALPHA */
- platform_set_drvdata(pdev, rtc);
return 0;
}
-device_initcall(alpha_rtc_init);
+device_initcall(rtc_init);
+#endif
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index a4d3f9a..1884ca4 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -631,6 +631,13 @@ config RTC_DRV_ALPHA
Direct support for the real-time clock found on every Alpha
system, specifically MC146818 compatibles. If in doubt, say Y.
+config RTC_DRV_ALPHA_QEMU
+ bool "Alpha QEMU paravirtual RTC"
+ depends on ALPHA
+ default y if ALPHA_QEMU
+ help
+ Support for the paravirtual real-time clock found in QEMU.
+
config RTC_DRV_VRTC
tristate "Virtual RTC for Intel MID platforms"
depends on X86_INTEL_MID
--
1.8.1.4
--
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