x86: mrst: Add vrtc driver which serves as a wall clock device

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.

[ tglx: Changed the exports to _GPL ]

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
LKML-Reference: <20101110172837.3311.40483.stgit@localhost.localdomain>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 120 insertions, 0 deletions

diff --git a/arch/x86/platform/mrst/vrtc.c b/arch/x86/platform/mrst/vrtc.c
new file mode 100644
index 000000000000..4944bd521d2c
--- /dev/null
+++ b/arch/x86/platform/mrst/vrtc.c
@@ -0,0 +1,120 @@
+/*
+ * 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 <linux/init.h>
+#include <linux/sfi.h>
+
+#include <asm/mrst.h>
+#include <asm/mrst-vrtc.h>
+#include <asm/time.h>
+#include <asm/fixmap.h>
+
+static unsigned char __iomem *vrtc_virt_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_GPL(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_GPL(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;
+}
+
+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_virt_base = virt_base;
+
+	x86_platform.get_wallclock = vrtc_get_time;
+	x86_platform.set_wallclock = vrtc_set_mmss;
+}