1 // SPDX-License-Identifier: GPL-2.0-only
3 * intel_mid_vrtc.c: Driver for virtual RTC device on Intel MID platform
5 * (C) Copyright 2009 Intel Corporation
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
13 * This driver is based on RTC CMOS driver.
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>
23 #include <asm/intel-mid.h>
24 #include <asm/intel_mid_vrtc.h>
26 #include <asm/fixmap.h>
28 static unsigned char __iomem
*vrtc_virt_base
;
30 unsigned char vrtc_cmos_read(unsigned char reg
)
34 /* vRTC's registers range from 0x0 to 0xD */
35 if (reg
> 0xd || !vrtc_virt_base
)
38 lock_cmos_prefix(reg
);
39 retval
= __raw_readb(vrtc_virt_base
+ (reg
<< 2));
40 lock_cmos_suffix(reg
);
43 EXPORT_SYMBOL_GPL(vrtc_cmos_read
);
45 void vrtc_cmos_write(unsigned char val
, unsigned char reg
)
47 if (reg
> 0xd || !vrtc_virt_base
)
50 lock_cmos_prefix(reg
);
51 __raw_writeb(val
, vrtc_virt_base
+ (reg
<< 2));
52 lock_cmos_suffix(reg
);
54 EXPORT_SYMBOL_GPL(vrtc_cmos_write
);
56 void vrtc_get_time(struct timespec64
*now
)
58 u8 sec
, min
, hour
, mday
, mon
;
62 spin_lock_irqsave(&rtc_lock
, flags
);
64 while ((vrtc_cmos_read(RTC_FREQ_SELECT
) & RTC_UIP
))
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
);
74 spin_unlock_irqrestore(&rtc_lock
, flags
);
76 /* vRTC YEAR reg contains the offset to 1972 */
79 pr_info("vRTC: sec: %d min: %d hour: %d day: %d "
80 "mon: %d year: %d\n", sec
, min
, hour
, mday
, mon
, year
);
82 now
->tv_sec
= mktime64(year
, mon
, mday
, hour
, min
, sec
);
86 int vrtc_set_mmss(const struct timespec64
*now
)
93 rtc_time64_to_tm(now
->tv_sec
, &tm
);
94 if (!rtc_valid_tm(&tm
) && tm
.tm_year
>= 72) {
96 * tm.year is the number of years since 1900, and the
97 * vrtc need the years since 1972.
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
);
109 pr_err("%s: Invalid vRTC value: write of %llx to vRTC failed\n",
110 __func__
, (s64
)now
->tv_sec
);
116 void __init
intel_mid_rtc_init(void)
118 unsigned long vrtc_paddr
;
120 sfi_table_parse(SFI_SIG_MRTC
, NULL
, NULL
, sfi_parse_mrtc
);
122 vrtc_paddr
= sfi_mrtc_array
[0].phys_addr
;
123 if (!sfi_mrtc_num
|| !vrtc_paddr
)
126 vrtc_virt_base
= (void __iomem
*)set_fixmap_offset_nocache(FIX_LNW_VRTC
,
128 x86_platform
.get_wallclock
= vrtc_get_time
;
129 x86_platform
.set_wallclock
= vrtc_set_mmss
;
133 * The Moorestown platform has a memory mapped virtual RTC device that emulates
134 * the programming interface of the RTC.
137 static struct resource vrtc_resources
[] = {
139 .flags
= IORESOURCE_MEM
,
142 .flags
= IORESOURCE_IRQ
,
146 static struct platform_device vrtc_device
= {
149 .resource
= vrtc_resources
,
150 .num_resources
= ARRAY_SIZE(vrtc_resources
),
153 /* Register the RTC device if appropriate */
154 static int __init
intel_mid_device_create(void)
156 /* No Moorestown, no device */
157 if (!intel_mid_identify_cpu())
159 /* No timer, no device */
164 vrtc_resources
[0].start
= sfi_mrtc_array
[0].phys_addr
;
165 vrtc_resources
[0].end
= sfi_mrtc_array
[0].phys_addr
+
168 vrtc_resources
[1].start
= sfi_mrtc_array
[0].irq
;
169 vrtc_resources
[1].end
= sfi_mrtc_array
[0].irq
;
171 return platform_device_register(&vrtc_device
);
173 device_initcall(intel_mid_device_create
);