1 // SPDX-License-Identifier: GPL-2.0 2 /* rtc-sun4v.c: Hypervisor based RTC for SUN4V systems. 3 * 4 * Author: David S. Miller 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_time64_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 return hypervisor_set_time(rtc_tm_to_time64(tm)); 70 } 71 72 static const struct rtc_class_ops sun4v_rtc_ops = { 73 .read_time = sun4v_read_time, 74 .set_time = sun4v_set_time, 75 }; 76 77 static int __init sun4v_rtc_probe(struct platform_device *pdev) 78 { 79 struct rtc_device *rtc; 80 81 rtc = devm_rtc_allocate_device(&pdev->dev); 82 if (IS_ERR(rtc)) 83 return PTR_ERR(rtc); 84 85 rtc->ops = &sun4v_rtc_ops; 86 rtc->range_max = U64_MAX; 87 platform_set_drvdata(pdev, rtc); 88 89 return rtc_register_device(rtc); 90 } 91 92 static struct platform_driver sun4v_rtc_driver = { 93 .driver = { 94 .name = "rtc-sun4v", 95 }, 96 }; 97 98 builtin_platform_driver_probe(sun4v_rtc_driver, sun4v_rtc_probe); 99