1 /* rtc-sun4v.c: Hypervisor based RTC for SUN4V systems. 2 * 3 * Author: David S. Miller 4 * License: GPL 5 * 6 * Copyright (C) 2008 David S. Miller <davem@davemloft.net> 7 */ 8 9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 10 11 #include <linux/kernel.h> 12 #include <linux/delay.h> 13 #include <linux/init.h> 14 #include <linux/rtc.h> 15 #include <linux/platform_device.h> 16 17 #include <asm/hypervisor.h> 18 19 static unsigned long hypervisor_get_time(void) 20 { 21 unsigned long ret, time; 22 int retries = 10000; 23 24 retry: 25 ret = sun4v_tod_get(&time); 26 if (ret == HV_EOK) 27 return time; 28 if (ret == HV_EWOULDBLOCK) { 29 if (--retries > 0) { 30 udelay(100); 31 goto retry; 32 } 33 pr_warn("tod_get() timed out.\n"); 34 return 0; 35 } 36 pr_warn("tod_get() not supported.\n"); 37 return 0; 38 } 39 40 static int sun4v_read_time(struct device *dev, struct rtc_time *tm) 41 { 42 rtc_time_to_tm(hypervisor_get_time(), tm); 43 return 0; 44 } 45 46 static int hypervisor_set_time(unsigned long secs) 47 { 48 unsigned long ret; 49 int retries = 10000; 50 51 retry: 52 ret = sun4v_tod_set(secs); 53 if (ret == HV_EOK) 54 return 0; 55 if (ret == HV_EWOULDBLOCK) { 56 if (--retries > 0) { 57 udelay(100); 58 goto retry; 59 } 60 pr_warn("tod_set() timed out.\n"); 61 return -EAGAIN; 62 } 63 pr_warn("tod_set() not supported.\n"); 64 return -EOPNOTSUPP; 65 } 66 67 static int sun4v_set_time(struct device *dev, struct rtc_time *tm) 68 { 69 unsigned long secs; 70 int err; 71 72 err = rtc_tm_to_time(tm, &secs); 73 if (err) 74 return err; 75 76 return hypervisor_set_time(secs); 77 } 78 79 static const struct rtc_class_ops sun4v_rtc_ops = { 80 .read_time = sun4v_read_time, 81 .set_time = sun4v_set_time, 82 }; 83 84 static int __init sun4v_rtc_probe(struct platform_device *pdev) 85 { 86 struct rtc_device *rtc; 87 88 rtc = devm_rtc_device_register(&pdev->dev, "sun4v", 89 &sun4v_rtc_ops, THIS_MODULE); 90 if (IS_ERR(rtc)) 91 return PTR_ERR(rtc); 92 93 platform_set_drvdata(pdev, rtc); 94 return 0; 95 } 96 97 static struct platform_driver sun4v_rtc_driver = { 98 .driver = { 99 .name = "rtc-sun4v", 100 }, 101 }; 102 103 builtin_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe); 104