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 int vrtc_set_mmss(unsigned long nowtime)
  89 {
  90         unsigned long flags;
  91         struct rtc_time tm;
  92         int year;
  93         int retval = 0;
  94
  95         rtc_time_to_tm(nowtime, &tm);
  96         if (!rtc_valid_tm(&tm) && tm.tm_year >= 72) {
  97                 /*
  98                  * tm.year is the number of years since 1900, and the
  99                  * vrtc need the years since 1972.
 100                  */
 101                 year = tm.tm_year - 72;
 102                 spin_lock_irqsave(&rtc_lock, flags);
 103                 vrtc_cmos_write(year, RTC_YEAR);
 104                 vrtc_cmos_write(tm.tm_mon, RTC_MONTH);
 105                 vrtc_cmos_write(tm.tm_mday, RTC_DAY_OF_MONTH);
 106                 vrtc_cmos_write(tm.tm_hour, RTC_HOURS);
 107                 vrtc_cmos_write(tm.tm_min, RTC_MINUTES);
 108                 vrtc_cmos_write(tm.tm_sec, RTC_SECONDS);
 109                 spin_unlock_irqrestore(&rtc_lock, flags);
 110         } else {
 111                 printk(KERN_ERR
 112                        "%s: Invalid vRTC value: write of %lx to vRTC failed\n",
 113                         __FUNCTION__, nowtime);
 114                 retval = -EINVAL;
 115         }
 116         return retval;
 117 }
 118
 119 void __init mrst_rtc_init(void)
 120 {
 121         unsigned long vrtc_paddr;
 122
 123         sfi_table_parse(SFI_SIG_MRTC, NULL, NULL, sfi_parse_mrtc);
 124
 125         vrtc_paddr = sfi_mrtc_array[0].phys_addr;
 126         if (!sfi_mrtc_num || !vrtc_paddr)
 127                 return;
 128
 129         vrtc_virt_base = (void __iomem *)set_fixmap_offset_nocache(FIX_LNW_VRTC,
 130                                                                 vrtc_paddr);
 131         x86_platform.get_wallclock = vrtc_get_time;
 132         x86_platform.set_wallclock = vrtc_set_mmss;
 133 }
 134
 135 /*
 136  * The Moorestown platform has a memory mapped virtual RTC device that emulates
 137  * the programming interface of the RTC.
 138  */
 139
 140 static struct resource vrtc_resources[] = {
 141         [0] = {
 142                 .flags  = IORESOURCE_MEM,
 143         },
 144         [1] = {
 145                 .flags  = IORESOURCE_IRQ,
 146         }
 147 };
 148
 149 static struct platform_device vrtc_device = {
 150         .name           = "rtc_mrst",
 151         .id             = -1,
 152         .resource       = vrtc_resources,
 153         .num_resources  = ARRAY_SIZE(vrtc_resources),
 154 };
 155
 156 /* Register the RTC device if appropriate */
 157 static int __init mrst_device_create(void)
 158 {
 159         /* No Moorestown, no device */
 160         if (!mrst_identify_cpu())
 161                 return -ENODEV;
 162         /* No timer, no device */
 163         if (!sfi_mrtc_num)
 164                 return -ENODEV;
 165
 166         /* iomem resource */
 167         vrtc_resources[0].start = sfi_mrtc_array[0].phys_addr;
 168         vrtc_resources[0].end = sfi_mrtc_array[0].phys_addr +
 169                                 MRST_VRTC_MAP_SZ;
 170         /* irq resource */
 171         vrtc_resources[1].start = sfi_mrtc_array[0].irq;
 172         vrtc_resources[1].end = sfi_mrtc_array[0].irq;
 173
 174         return platform_device_register(&vrtc_device);
 175 }
 176
 177 module_init(mrst_device_create);