2 * vrtc.c: Driver for virtual RTC device on Intel MID platform
4 * (C) Copyright 2009 Intel Corporation
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; version 2
12 * VRTC is emulated by system controller firmware, the real HW
13 * RTC is located in the PMIC device. SCU FW shadows PMIC RTC
14 * in a memory mapped IO space that is visible to the host IA
17 * This driver is based on RTC CMOS driver.
20 #include <linux/kernel.h>
21 #include <linux/init.h>
22 #include <linux/sfi.h>
23 #include <linux/platform_device.h>
26 #include <asm/mrst-vrtc.h>
28 #include <asm/fixmap.h>
30 static unsigned char __iomem *vrtc_virt_base;
32 unsigned char vrtc_cmos_read(unsigned char reg)
36 /* vRTC's registers range from 0x0 to 0xD */
37 if (reg > 0xd || !vrtc_virt_base)
40 lock_cmos_prefix(reg);
41 retval = __raw_readb(vrtc_virt_base + (reg << 2));
42 lock_cmos_suffix(reg);
45 EXPORT_SYMBOL_GPL(vrtc_cmos_read);
47 void vrtc_cmos_write(unsigned char val, unsigned char reg)
49 if (reg > 0xd || !vrtc_virt_base)
52 lock_cmos_prefix(reg);
53 __raw_writeb(val, vrtc_virt_base + (reg << 2));
54 lock_cmos_suffix(reg);
56 EXPORT_SYMBOL_GPL(vrtc_cmos_write);
58 unsigned long vrtc_get_time(void)
60 u8 sec, min, hour, mday, mon;
64 spin_lock_irqsave(&rtc_lock, flags);
66 while ((vrtc_cmos_read(RTC_FREQ_SELECT) & RTC_UIP))
69 sec = vrtc_cmos_read(RTC_SECONDS);
70 min = vrtc_cmos_read(RTC_MINUTES);
71 hour = vrtc_cmos_read(RTC_HOURS);
72 mday = vrtc_cmos_read(RTC_DAY_OF_MONTH);
73 mon = vrtc_cmos_read(RTC_MONTH);
74 year = vrtc_cmos_read(RTC_YEAR);
76 spin_unlock_irqrestore(&rtc_lock, flags);
78 /* vRTC YEAR reg contains the offset to 1960 */
81 printk(KERN_INFO "vRTC: sec: %d min: %d hour: %d day: %d "
82 "mon: %d year: %d\n", sec, min, hour, mday, mon, year);
84 return mktime(year, mon, mday, hour, min, sec);
87 /* Only care about the minutes and seconds */
88 int vrtc_set_mmss(unsigned long nowtime)
90 int real_sec, real_min;
94 spin_lock_irqsave(&rtc_lock, flags);
95 vrtc_min = vrtc_cmos_read(RTC_MINUTES);
97 real_sec = nowtime % 60;
98 real_min = nowtime / 60;
99 if (((abs(real_min - vrtc_min) + 15)/30) & 1)
103 vrtc_cmos_write(real_sec, RTC_SECONDS);
104 vrtc_cmos_write(real_min, RTC_MINUTES);
105 spin_unlock_irqrestore(&rtc_lock, flags);
110 void __init mrst_rtc_init(void)
112 unsigned long vrtc_paddr;
114 sfi_table_parse(SFI_SIG_MRTC, NULL, NULL, sfi_parse_mrtc);
116 vrtc_paddr = sfi_mrtc_array[0].phys_addr;
117 if (!sfi_mrtc_num || !vrtc_paddr)
120 vrtc_virt_base = (void __iomem *)set_fixmap_offset_nocache(FIX_LNW_VRTC,
122 x86_platform.get_wallclock = vrtc_get_time;
123 x86_platform.set_wallclock = vrtc_set_mmss;
127 * The Moorestown platform has a memory mapped virtual RTC device that emulates
128 * the programming interface of the RTC.
131 static struct resource vrtc_resources[] = {
133 .flags = IORESOURCE_MEM,
136 .flags = IORESOURCE_IRQ,
140 static struct platform_device vrtc_device = {
143 .resource = vrtc_resources,
144 .num_resources = ARRAY_SIZE(vrtc_resources),
147 /* Register the RTC device if appropriate */
148 static int __init mrst_device_create(void)
150 /* No Moorestown, no device */
151 if (!mrst_identify_cpu())
153 /* No timer, no device */
158 vrtc_resources[0].start = sfi_mrtc_array[0].phys_addr;
159 vrtc_resources[0].end = sfi_mrtc_array[0].phys_addr +
162 vrtc_resources[1].start = sfi_mrtc_array[0].irq;
163 vrtc_resources[1].end = sfi_mrtc_array[0].irq;
165 return platform_device_register(&vrtc_device);
168 module_init(mrst_device_create);