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 __devinit 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 __devexit 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 = __devexit_p(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