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
vrtc_cmos_read(unsigned char reg)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
vrtc_cmos_write(unsigned char val,unsigned char reg)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
vrtc_get_time(void)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 */
vrtc_set_mmss(unsigned long nowtime)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
mrst_rtc_init(void)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 */
mrst_device_create(void)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);
170