[PATCH 7/8] x86/mrst: add vrtc driver which serves as a wall clock device

Jacob Pan
2010-05-07T17:47:51Z

From: Feng Tang <feng.tang@intel.com>

Moorestown platform doesn't have a m146818 RTC device like traditional
x86 PC, but a firmware emulated virtual RTC device(vrtc), which provides
some basic RTC functions like get/set time. vrtc serves as the only
wall clock device on Moorestown platform.

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
arch/x86/include/asm/fixmap.h | 4 ++
arch/x86/include/asm/vrtc.h | 27 +++++++++++
arch/x86/kernel/Makefile | 2 +-
arch/x86/kernel/mrst.c | 20 ++++++++
arch/x86/kernel/vrtc.c | 100 +++++++++++++++++++++++++++++++++++++++++
5 files changed, 152 insertions(+), 1 deletions(-)
create mode 100644 arch/x86/include/asm/vrtc.h
create mode 100644 arch/x86/kernel/vrtc.c

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index d07b44f..c4ba8d9 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -117,6 +117,10 @@ enum fixed_addresses {
FIX_TEXT_POKE1, /* reserve 2 pages for text_poke() */
FIX_TEXT_POKE0, /* first page is last, because allocation is backward */
__end_of_permanent_fixed_addresses,
+
+#ifdef CONFIG_X86_MRST
+ FIX_LNW_VRTC,
+#endif
/*
* 256 temporary boot-time mappings, used by early_ioremap(),
* before ioremap() is functional.
diff --git a/arch/x86/include/asm/vrtc.h b/arch/x86/include/asm/vrtc.h
new file mode 100644
index 0000000..4e40129
--- /dev/null
+++ b/arch/x86/include/asm/vrtc.h
@@ -0,0 +1,27 @@
+#ifndef _MRST_VRTC_H
+#define _MRST_VRTC_H
+
+#ifdef CONFIG_X86_MRST
+extern unsigned char vrtc_cmos_read(unsigned char reg);
+extern void vrtc_cmos_write(unsigned char val, unsigned char reg);
+extern unsigned long vrtc_get_time(void);
+extern int vrtc_set_mmss(unsigned long nowtime);
+extern void vrtc_set_base(void __iomem *base);
+
+#define MRST_VRTC_PGOFFSET (0xc00)
+
+#else
+static inline unsigned char vrtc_cmos_read(unsigned char reg)
+{
+ return 0xff;
+}
+
+static inline void vrtc_cmos_write(unsigned char val, unsigned char reg)
+{
+ return;
+}
+#endif
+
+#define MRST_VRTC_MAP_SZ (1024)
+
+#endif
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index e77b220..f3fdcbe 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -104,7 +104,7 @@ obj-$(CONFIG_SCx200) += scx200.o
scx200-y += scx200_32.o

obj-$(CONFIG_OLPC) += olpc.o
-obj-$(CONFIG_X86_MRST) += mrst.o
+obj-$(CONFIG_X86_MRST) += mrst.o vrtc.o

microcode-y := microcode_core.o
microcode-$(CONFIG_MICROCODE_INTEL) += microcode_intel.o
diff --git a/arch/x86/kernel/mrst.c b/arch/x86/kernel/mrst.c
index 9e14e7f..0b3ef9f 100644
--- a/arch/x86/kernel/mrst.c
+++ b/arch/x86/kernel/mrst.c
@@ -24,6 +24,7 @@
#include <asm/io.h>
#include <asm/i8259.h>
#include <asm/apb_timer.h>
+#include <asm/vrtc.h>

/**
* the clockevent devices on Moorestown/Medfield can be APBT or LAPIC clock,
@@ -268,7 +269,24 @@ void __init mrst_time_init(void)

void __init mrst_rtc_init(void)
{
+ unsigned long rtc_paddr;
+ void __iomem *virt_base;
+
sfi_table_parse(SFI_SIG_MRTC, NULL, NULL, sfi_parse_mrtc);
+ if (!sfi_mrtc_num)
+ return;
+
+ rtc_paddr = sfi_mrtc_array[0].phys_addr;
+
+ /* vRTC's register address may not be page aligned */
+ set_fixmap_nocache(FIX_LNW_VRTC, rtc_paddr);
+
+ virt_base = (void __iomem *)__fix_to_virt(FIX_LNW_VRTC);
+ virt_base += rtc_paddr & ~PAGE_MASK;
+ vrtc_set_base(virt_base);
+
+ x86_platform.get_wallclock = vrtc_get_time;
+ x86_platform.set_wallclock = vrtc_set_mmss;
}

/*
@@ -326,6 +344,8 @@ void __init x86_mrst_early_setup(void)
x86_cpuinit.setup_percpu_clockev = mrst_setup_secondary_clock;

x86_platform.calibrate_tsc = mrst_calibrate_tsc;
+ x86_platform.wallclock_init = mrst_rtc_init;
+
x86_init.pci.init = pci_mrst_init;
x86_init.pci.fixup_irqs = x86_init_noop;

diff --git a/arch/x86/kernel/vrtc.c b/arch/x86/kernel/vrtc.c
new file mode 100644
index 0000000..fa1eb63
--- /dev/null
+++ b/arch/x86/kernel/vrtc.c
@@ -0,0 +1,100 @@
+/*
+ * vrtc.c: Driver for virtual RTC device on Intel MID platform
+ *
+ * (C) Copyright 2009 Intel Corporation
+ *
+ * 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; version 2
+ * of the License.
+ *
+ * Note:
+ * VRTC is emulated by system controller firmware, the real HW
+ * RTC is located in the PMIC device. SCU FW shadows PMIC RTC
+ * in a memory mapped IO space that is visible to the host IA
+ * processor.
+ *
+ * This driver is based on RTC CMOS driver.
+ */
+
+#include <linux/kernel.h>
+
+#include <asm/vrtc.h>
+#include <asm/time.h>
+#include <asm/fixmap.h>
+
+static unsigned char __iomem *vrtc_virt_base;
+
+void vrtc_set_base(void __iomem *base)
+{
+ vrtc_virt_base = base;
+}
+
+unsigned char vrtc_cmos_read(unsigned char reg)
+{
+ unsigned char retval;
+
+ /* vRTC's registers range from 0x0 to 0xD */
+ if (reg > 0xd || !vrtc_virt_base)
+ return 0xff;
+
+ lock_cmos_prefix(reg);
+ retval = __raw_readb(vrtc_virt_base + (reg << 2));
+ lock_cmos_suffix(reg);
+ return retval;
+}
+EXPORT_SYMBOL(vrtc_cmos_read);
+
+void vrtc_cmos_write(unsigned char val, unsigned char reg)
+{
+ if (reg > 0xd || !vrtc_virt_base)
+ return;
+
+ lock_cmos_prefix(reg);
+ __raw_writeb(val, vrtc_virt_base + (reg << 2));
+ lock_cmos_suffix(reg);
+}
+EXPORT_SYMBOL(vrtc_cmos_write);
+
+unsigned long vrtc_get_time(void)
+{
+ u8 sec, min, hour, mday, mon;
+ u32 year;
+
+ while ((vrtc_cmos_read(RTC_FREQ_SELECT) & RTC_UIP))
+ cpu_relax();
+
+ sec = vrtc_cmos_read(RTC_SECONDS);
+ min = vrtc_cmos_read(RTC_MINUTES);
+ hour = vrtc_cmos_read(RTC_HOURS);
+ mday = vrtc_cmos_read(RTC_DAY_OF_MONTH);
+ mon = vrtc_cmos_read(RTC_MONTH);
+ year = vrtc_cmos_read(RTC_YEAR);
+
+ /* vRTC YEAR reg contains the offset to 1960 */
+ year += 1960;
+
+ printk(KERN_INFO "vRTC: sec: %d min: %d hour: %d day: %d "
+ "mon: %d year: %d\n", sec, min, hour, mday, mon, year);
+
+ return mktime(year, mon, mday, hour, min, sec);
+}
+
+/* Only care about the minutes and seconds */
+int vrtc_set_mmss(unsigned long nowtime)
+{
+ int real_sec, real_min;
+ int vrtc_min;
+
+ vrtc_min = vrtc_cmos_read(RTC_MINUTES);
+
+ real_sec = nowtime % 60;
+ real_min = nowtime / 60;
+ if (((abs(real_min - vrtc_min) + 15)/30) & 1)
+ real_min += 30;
+ real_min %= 60;
+
+ vrtc_cmos_write(real_sec, RTC_SECONDS);
+ vrtc_cmos_write(real_min, RTC_MINUTES);
+ return 0;
+}
--
1.6.3.3