arch/x86/platform/mrst/vrtc.c

   1 /*
   2  * vrtc.c: Driver for virtual RTC device on Intel MID platform
   3  *
   4  * (C) Copyright 2009 Intel Corporation
   5  *
   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
   9  * of the License.
  10  *
  11  * Note:
  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
  15  * processor.
  16  *
  17  * This driver is based on RTC CMOS driver.
  18  */
  19
  20 #include <linux/kernel.h>
  21 #include <linux/export.h>
  22 #include <linux/init.h>
  23 #include <linux/sfi.h>
  24 #include <linux/platform_device.h>
  25
  26 #include <asm/mrst.h>
  27 #include <asm/mrst-vrtc.h>
  28 #include <asm/time.h>
  29 #include <asm/fixmap.h>
  30
  31 static unsigned char __iomem *vrtc_virt_base;
  32
  33 unsigned char vrtc_cmos_read(unsigned char reg)
  34 {
  35         unsigned char retval;
  36
  37         /* vRTC's registers range from 0x0 to 0xD */
  38         if (reg > 0xd || !vrtc_virt_base)
  39                 return 0xff;
  40
  41         lock_cmos_prefix(reg);
  42         retval = __raw_readb(vrtc_virt_base + (reg << 2));
  43         lock_cmos_suffix(reg);
  44         return retval;
  45 }
  46 EXPORT_SYMBOL_GPL(vrtc_cmos_read);
  47
  48 void vrtc_cmos_write(unsigned char val, unsigned char reg)
  49 {
  50         if (reg > 0xd || !vrtc_virt_base)
  51                 return;
  52
  53         lock_cmos_prefix(reg);
  54         __raw_writeb(val, vrtc_virt_base + (reg << 2));
  55         lock_cmos_suffix(reg);
  56 }
  57 EXPORT_SYMBOL_GPL(vrtc_cmos_write);
  58
  59 unsigned long vrtc_get_time(void)
  60 {
  61         u8 sec, min, hour, mday, mon;
  62         unsigned long flags;
  63         u32 year;
  64
  65         spin_lock_irqsave(&rtc_lock, flags);
  66
  67         while ((vrtc_cmos_read(RTC_FREQ_SELECT) & RTC_UIP))
  68                 cpu_relax();
  69
  70         sec = vrtc_cmos_read(RTC_SECONDS);
  71         min = vrtc_cmos_read(RTC_MINUTES);
  72         hour = vrtc_cmos_read(RTC_HOURS);
  73         mday = vrtc_cmos_read(RTC_DAY_OF_MONTH);
  74         mon = vrtc_cmos_read(RTC_MONTH);
  75         year = vrtc_cmos_read(RTC_YEAR);
  76
  77         spin_unlock_irqrestore(&rtc_lock, flags);
  78
  79         /* vRTC YEAR reg contains the offset to 1972 */
  80         year += 1972;
  81
  82         printk(KERN_INFO "vRTC: sec: %d min: %d hour: %d day: %d "
  83                 "mon: %d year: %d\n", sec, min, hour, mday, mon, year);
  84
  85         return mktime(year, mon, mday, hour, min, sec);
  86 }
  87
  88 /* Only care about the minutes and seconds */
  89 int vrtc_set_mmss(unsigned long nowtime)
  90 {
  91         int real_sec, real_min;
  92         unsigned long flags;
  93         int vrtc_min;
  94
  95         spin_lock_irqsave(&rtc_lock, flags);
  96         vrtc_min = vrtc_cmos_read(RTC_MINUTES);
  97
  98         real_sec = nowtime % 60;
  99         real_min = nowtime / 60;
 100         if (((abs(real_min - vrtc_min) + 15)/30) & 1)
 101                 real_min += 30;
 102         real_min %= 60;
 103
 104         vrtc_cmos_write(real_sec, RTC_SECONDS);
 105         vrtc_cmos_write(real_min, RTC_MINUTES);
 106         spin_unlock_irqrestore(&rtc_lock, flags);
 107
 108         return 0;
 109 }
 110
 111 void __init mrst_rtc_init(void)
 112 {
 113         unsigned long vrtc_paddr;
 114
 115         sfi_table_parse(SFI_SIG_MRTC, NULL, NULL, sfi_parse_mrtc);
 116
 117         vrtc_paddr = sfi_mrtc_array[0].phys_addr;
 118         if (!sfi_mrtc_num || !vrtc_paddr)
 119                 return;
 120
 121         vrtc_virt_base = (void __iomem *)set_fixmap_offset_nocache(FIX_LNW_VRTC,
 122                                                                 vrtc_paddr);
 123         x86_platform.get_wallclock = vrtc_get_time;
 124         x86_platform.set_wallclock = vrtc_set_mmss;
 125 }
 126
 127 /*
 128  * The Moorestown platform has a memory mapped virtual RTC device that emulates
 129  * the programming interface of the RTC.
 130  */
 131
 132 static struct resource vrtc_resources[] = {
 133         [0] = {
 134                 .flags  = IORESOURCE_MEM,
 135         },
 136         [1] = {
 137                 .flags  = IORESOURCE_IRQ,
 138         }
 139 };
 140
 141 static struct platform_device vrtc_device = {
 142         .name           = "rtc_mrst",
 143         .id             = -1,
 144         .resource       = vrtc_resources,
 145         .num_resources  = ARRAY_SIZE(vrtc_resources),
 146 };
 147
 148 /* Register the RTC device if appropriate */
 149 static int __init mrst_device_create(void)
 150 {
 151         /* No Moorestown, no device */
 152         if (!mrst_identify_cpu())
 153                 return -ENODEV;
 154         /* No timer, no device */
 155         if (!sfi_mrtc_num)
 156                 return -ENODEV;
 157
 158         /* iomem resource */
 159         vrtc_resources[0].start = sfi_mrtc_array[0].phys_addr;
 160         vrtc_resources[0].end = sfi_mrtc_array[0].phys_addr +
 161                                 MRST_VRTC_MAP_SZ;
 162         /* irq resource */
 163         vrtc_resources[1].start = sfi_mrtc_array[0].irq;
 164         vrtc_resources[1].end = sfi_mrtc_array[0].irq;
 165
 166         return platform_device_register(&vrtc_device);
 167 }
 168
 169 module_init(mrst_device_create);