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1 | /* |
2 | * Au1xxx counter0 (aka Time-Of-Year counter) RTC interface driver. |
3 | * |
4 | * Copyright (C) 2008 Manuel Lauss <mano@roarinelk.homelinux.net> |
5 | * |
6 | * This file is subject to the terms and conditions of the GNU General Public |
7 | * License. See the file "COPYING" in the main directory of this archive |
8 | * for more details. |
9 | */ |
10 | |
11 | /* All current Au1xxx SoCs have 2 counters fed by an external 32.768 kHz |
12 | * crystal. Counter 0, which keeps counting during sleep/powerdown, is |
13 | * used to count seconds since the beginning of the unix epoch. |
14 | * |
15 | * The counters must be configured and enabled by bootloader/board code; |
16 | * no checks as to whether they really get a proper 32.768kHz clock are |
17 | * made as this would take far too long. |
18 | */ |
19 | |
20 | #include <linux/module.h> |
21 | #include <linux/kernel.h> |
22 | #include <linux/rtc.h> |
23 | #include <linux/init.h> |
24 | #include <linux/platform_device.h> |
25 | #include <linux/io.h> |
26 | #include <asm/mach-au1x00/au1000.h> |
27 | |
28 | /* 32kHz clock enabled and detected */ |
29 | #define CNTR_OK (SYS_CNTRL_E0 | SYS_CNTRL_32S) |
30 | |
31 | static int au1xtoy_rtc_read_time(struct device *dev, struct rtc_time *tm) |
32 | { |
33 | unsigned long t; |
34 | |
35 | t = au_readl(SYS_TOYREAD); |
36 | |
37 | rtc_time_to_tm(t, tm); |
38 | |
39 | return rtc_valid_tm(tm); |
40 | } |
41 | |
42 | static int au1xtoy_rtc_set_time(struct device *dev, struct rtc_time *tm) |
43 | { |
44 | unsigned long t; |
45 | |
46 | rtc_tm_to_time(tm, &t); |
47 | |
48 | au_writel(t, SYS_TOYWRITE); |
49 | au_sync(); |
50 | |
51 | /* wait for the pending register write to succeed. This can |
52 | * take up to 6 seconds... |
53 | */ |
54 | while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C0S) |
55 | msleep(1); |
56 | |
57 | return 0; |
58 | } |
59 | |
60 | static struct rtc_class_ops au1xtoy_rtc_ops = { |
61 | .read_time = au1xtoy_rtc_read_time, |
62 | .set_time = au1xtoy_rtc_set_time, |
63 | }; |
64 | |
65 | static int au1xtoy_rtc_probe(struct platform_device *pdev) |
66 | { |
67 | struct rtc_device *rtcdev; |
68 | unsigned long t; |
69 | int ret; |
70 | |
71 | t = au_readl(SYS_COUNTER_CNTRL); |
72 | if (!(t & CNTR_OK)) { |
73 | dev_err(&pdev->dev, "counters not working; aborting.\n"); |
74 | ret = -ENODEV; |
75 | goto out_err; |
76 | } |
77 | |
78 | ret = -ETIMEDOUT; |
79 | |
80 | /* set counter0 tickrate to 1Hz if necessary */ |
81 | if (au_readl(SYS_TOYTRIM) != 32767) { |
82 | /* wait until hardware gives access to TRIM register */ |
83 | t = 0x00100000; |
84 | while ((au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T0S) && --t) |
85 | msleep(1); |
86 | |
87 | if (!t) { |
88 | /* timed out waiting for register access; assume |
89 | * counters are unusable. |
90 | */ |
91 | dev_err(&pdev->dev, "timeout waiting for access\n"); |
92 | goto out_err; |
93 | } |
94 | |
95 | /* set 1Hz TOY tick rate */ |
96 | au_writel(32767, SYS_TOYTRIM); |
97 | au_sync(); |
98 | } |
99 | |
100 | /* wait until the hardware allows writes to the counter reg */ |
101 | while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C0S) |
102 | msleep(1); |
103 | |
104 | rtcdev = rtc_device_register("rtc-au1xxx", &pdev->dev, |
105 | &au1xtoy_rtc_ops, THIS_MODULE); |
106 | if (IS_ERR(rtcdev)) { |
107 | ret = PTR_ERR(rtcdev); |
108 | goto out_err; |
109 | } |
110 | |
111 | platform_set_drvdata(pdev, rtcdev); |
112 | |
113 | return 0; |
114 | |
115 | out_err: |
116 | return ret; |
117 | } |
118 | |
119 | static int au1xtoy_rtc_remove(struct platform_device *pdev) |
120 | { |
121 | struct rtc_device *rtcdev = platform_get_drvdata(pdev); |
122 | |
123 | rtc_device_unregister(rtcdev); |
124 | platform_set_drvdata(pdev, NULL); |
125 | |
126 | return 0; |
127 | } |
128 | |
129 | static struct platform_driver au1xrtc_driver = { |
130 | .driver = { |
131 | .name = "rtc-au1xxx", |
132 | .owner = THIS_MODULE, |
133 | }, |
134 | .remove = au1xtoy_rtc_remove, |
135 | }; |
136 | |
137 | static int __init au1xtoy_rtc_init(void) |
138 | { |
139 | return platform_driver_probe(&au1xrtc_driver, au1xtoy_rtc_probe); |
140 | } |
141 | |
142 | static void __exit au1xtoy_rtc_exit(void) |
143 | { |
144 | platform_driver_unregister(&au1xrtc_driver); |
145 | } |
146 | |
147 | module_init(au1xtoy_rtc_init); |
148 | module_exit(au1xtoy_rtc_exit); |
149 | |
150 | MODULE_DESCRIPTION("Au1xxx TOY-counter-based RTC driver"); |
151 | MODULE_AUTHOR("Manuel Lauss <manuel.lauss@gmail.com>"); |
152 | MODULE_LICENSE("GPL"); |
153 | MODULE_ALIAS("platform:rtc-au1xxx"); |
154 |
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