arch/x86/platform/intel-mid/intel_mid_vrtc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * intel_mid_vrtc.c: Driver for virtual RTC device on Intel MID platform
   4  *
   5  * (C) Copyright 2009 Intel Corporation
   6  *
   7  * Note:
   8  * VRTC is emulated by system controller firmware, the real HW
   9  * RTC is located in the PMIC device. SCU FW shadows PMIC RTC
  10  * in a memory mapped IO space that is visible to the host IA
  11  * processor.
  12  *
  13  * This driver is based on RTC CMOS driver.
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/export.h>
  18 #include <linux/init.h>
  19 #include <linux/sfi.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/mc146818rtc.h>
  22
  23 #include <asm/intel-mid.h>
  24 #include <asm/intel_mid_vrtc.h>
  25 #include <asm/time.h>
  26 #include <asm/fixmap.h>
  27
  28 static unsigned char __iomem *vrtc_virt_base;
  29
  30 unsigned char vrtc_cmos_read(unsigned char reg)
  31 {
  32         unsigned char retval;
  33
  34         /* vRTC's registers range from 0x0 to 0xD */
  35         if (reg > 0xd || !vrtc_virt_base)
  36                 return 0xff;
  37
  38         lock_cmos_prefix(reg);
  39         retval = __raw_readb(vrtc_virt_base + (reg << 2));
  40         lock_cmos_suffix(reg);
  41         return retval;
  42 }
  43 EXPORT_SYMBOL_GPL(vrtc_cmos_read);
  44
  45 void vrtc_cmos_write(unsigned char val, unsigned char reg)
  46 {
  47         if (reg > 0xd || !vrtc_virt_base)
  48                 return;
  49
  50         lock_cmos_prefix(reg);
  51         __raw_writeb(val, vrtc_virt_base + (reg << 2));
  52         lock_cmos_suffix(reg);
  53 }
  54 EXPORT_SYMBOL_GPL(vrtc_cmos_write);
  55
  56 void vrtc_get_time(struct timespec64 *now)
  57 {
  58         u8 sec, min, hour, mday, mon;
  59         unsigned long flags;
  60         u32 year;
  61
  62         spin_lock_irqsave(&rtc_lock, flags);
  63
  64         while ((vrtc_cmos_read(RTC_FREQ_SELECT) & RTC_UIP))
  65                 cpu_relax();
  66
  67         sec = vrtc_cmos_read(RTC_SECONDS);
  68         min = vrtc_cmos_read(RTC_MINUTES);
  69         hour = vrtc_cmos_read(RTC_HOURS);
  70         mday = vrtc_cmos_read(RTC_DAY_OF_MONTH);
  71         mon = vrtc_cmos_read(RTC_MONTH);
  72         year = vrtc_cmos_read(RTC_YEAR);
  73
  74         spin_unlock_irqrestore(&rtc_lock, flags);
  75
  76         /* vRTC YEAR reg contains the offset to 1972 */
  77         year += 1972;
  78
  79         pr_info("vRTC: sec: %d min: %d hour: %d day: %d "
  80                 "mon: %d year: %d\n", sec, min, hour, mday, mon, year);
  81
  82         now->tv_sec = mktime64(year, mon, mday, hour, min, sec);
  83         now->tv_nsec = 0;
  84 }
  85
  86 int vrtc_set_mmss(const struct timespec64 *now)
  87 {
  88         unsigned long flags;
  89         struct rtc_time tm;
  90         int year;
  91         int retval = 0;
  92
  93         rtc_time64_to_tm(now->tv_sec, &tm);
  94         if (!rtc_valid_tm(&tm) && tm.tm_year >= 72) {
  95                 /*
  96                  * tm.year is the number of years since 1900, and the
  97                  * vrtc need the years since 1972.
  98                  */
  99                 year = tm.tm_year - 72;
 100                 spin_lock_irqsave(&rtc_lock, flags);
 101                 vrtc_cmos_write(year, RTC_YEAR);
 102                 vrtc_cmos_write(tm.tm_mon, RTC_MONTH);
 103                 vrtc_cmos_write(tm.tm_mday, RTC_DAY_OF_MONTH);
 104                 vrtc_cmos_write(tm.tm_hour, RTC_HOURS);
 105                 vrtc_cmos_write(tm.tm_min, RTC_MINUTES);
 106                 vrtc_cmos_write(tm.tm_sec, RTC_SECONDS);
 107                 spin_unlock_irqrestore(&rtc_lock, flags);
 108         } else {
 109                 pr_err("%s: Invalid vRTC value: write of %llx to vRTC failed\n",
 110                         __func__, (s64)now->tv_sec);
 111                 retval = -EINVAL;
 112         }
 113         return retval;
 114 }
 115
 116 void __init intel_mid_rtc_init(void)
 117 {
 118         unsigned long vrtc_paddr;
 119
 120         sfi_table_parse(SFI_SIG_MRTC, NULL, NULL, sfi_parse_mrtc);
 121
 122         vrtc_paddr = sfi_mrtc_array[0].phys_addr;
 123         if (!sfi_mrtc_num || !vrtc_paddr)
 124                 return;
 125
 126         vrtc_virt_base = (void __iomem *)set_fixmap_offset_nocache(FIX_LNW_VRTC,
 127                                                                 vrtc_paddr);
 128         x86_platform.get_wallclock = vrtc_get_time;
 129         x86_platform.set_wallclock = vrtc_set_mmss;
 130 }
 131
 132 /*
 133  * The Moorestown platform has a memory mapped virtual RTC device that emulates
 134  * the programming interface of the RTC.
 135  */
 136
 137 static struct resource vrtc_resources[] = {
 138         [0] = {
 139                 .flags  = IORESOURCE_MEM,
 140         },
 141         [1] = {
 142                 .flags  = IORESOURCE_IRQ,
 143         }
 144 };
 145
 146 static struct platform_device vrtc_device = {
 147         .name           = "rtc_mrst",
 148         .id             = -1,
 149         .resource       = vrtc_resources,
 150         .num_resources  = ARRAY_SIZE(vrtc_resources),
 151 };
 152
 153 /* Register the RTC device if appropriate */
 154 static int __init intel_mid_device_create(void)
 155 {
 156         /* No Moorestown, no device */
 157         if (!intel_mid_identify_cpu())
 158                 return -ENODEV;
 159         /* No timer, no device */
 160         if (!sfi_mrtc_num)
 161                 return -ENODEV;
 162
 163         /* iomem resource */
 164         vrtc_resources[0].start = sfi_mrtc_array[0].phys_addr;
 165         vrtc_resources[0].end = sfi_mrtc_array[0].phys_addr +
 166                                 MRST_VRTC_MAP_SZ;
 167         /* irq resource */
 168         vrtc_resources[1].start = sfi_mrtc_array[0].irq;
 169         vrtc_resources[1].end = sfi_mrtc_array[0].irq;
 170
 171         return platform_device_register(&vrtc_device);
 172 }
 173 device_initcall(intel_mid_device_create);