LXR linux/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
  31static unsigned char __iomem *vrtc_virt_base;
  32
  33unsigned 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}
  46EXPORT_SYMBOL_GPL(vrtc_cmos_read);
  47
  48void 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}
  57EXPORT_SYMBOL_GPL(vrtc_cmos_write);
  58
  59unsigned 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 */
  89int 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
 111void __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
 132static struct resource vrtc_resources[] = {
 133        [0] = {
 134                .flags  = IORESOURCE_MEM,
 135        },
 136        [1] = {
 137                .flags  = IORESOURCE_IRQ,
 138        }
 139};
 140
 141static 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 */
 149static 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
 169module_init(mrst_device_create);
 170