rtc: class: support hctosys from modular RTC drivers

Due to distribution constraints it may not be possible to statically
compile the required RTC driver into the kernel.

Expand RTC_HCTOSYS support to cover all RTC devices (statically compiled
or not) by checking at the end of RTC device registration whether the
time should be synced.

Signed-off-by: Steve Muckle <smuckle@google.com>
Link: https://lore.kernel.org/r/20191106194625.116692-1-smuckle@google.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

1 files changed, 0 insertions, 69 deletions

diff --git a/drivers/rtc/hctosys.c b/drivers/rtc/hctosys.c
deleted file mode 100644
index a74d0d890600..000000000000
--- a/drivers/rtc/hctosys.c
+++ /dev/null
@@ -1,69 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * RTC subsystem, initialize system time on startup
- *
- * Copyright (C) 2005 Tower Technologies
- * Author: Alessandro Zummo <a.zummo@towertech.it>
- */
-
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
-#include <linux/rtc.h>
-
-/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary
- * whether it stores the most close value or the value with partial
- * seconds truncated. However, it is important that we use it to store
- * the truncated value. This is because otherwise it is necessary,
- * in an rtc sync function, to read both xtime.tv_sec and
- * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read
- * of >32bits is not possible. So storing the most close value would
- * slow down the sync API. So here we have the truncated value and
- * the best guess is to add 0.5s.
- */
-
-static int __init rtc_hctosys(void)
-{
-	int err = -ENODEV;
-	struct rtc_time tm;
-	struct timespec64 tv64 = {
-		.tv_nsec = NSEC_PER_SEC >> 1,
-	};
-	struct rtc_device *rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE);
-
-	if (!rtc) {
-		pr_info("unable to open rtc device (%s)\n",
-			CONFIG_RTC_HCTOSYS_DEVICE);
-		goto err_open;
-	}
-
-	err = rtc_read_time(rtc, &tm);
-	if (err) {
-		dev_err(rtc->dev.parent,
-			"hctosys: unable to read the hardware clock\n");
-		goto err_read;
-	}
-
-	tv64.tv_sec = rtc_tm_to_time64(&tm);
-
-#if BITS_PER_LONG == 32
-	if (tv64.tv_sec > INT_MAX) {
-		err = -ERANGE;
-		goto err_read;
-	}
-#endif
-
-	err = do_settimeofday64(&tv64);
-
-	dev_info(rtc->dev.parent, "setting system clock to %ptR UTC (%lld)\n",
-		 &tm, (long long)tv64.tv_sec);
-
-err_read:
-	rtc_class_close(rtc);
-
-err_open:
-	rtc_hctosys_ret = err;
-
-	return err;
-}
-
-late_initcall(rtc_hctosys);