[PATCH 1/2] rtc/ia64: remove legacy efirtc driver

[PATCH 1/2] rtc/ia64: remove legacy efirtc driver

[Arnd Bergmann]

There are two EFI RTC drivers, the original drivers/char/efirtc.c
driver and the more modern drivers/rtc/rtc-efi.c.

Both implement the same interface, but the new one does so
in a more portable way.

Move everything over to that one and remove the old one.

Cc: linux-ia64@vger.kernel.org
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Stephane Eranian <eranian@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
This was last discussed in early 2018 in
https://lore.kernel.org/lkml/CAK8P3a0QZNY+K+V1HG056xCerz=_L2jh5UfZ+2LWkDqkw5Zznw@mail.gmail.com/

Nobody ever replied there, so let's try this instead.
If there is any reason to keep the driver after all,
please let us know.
---
 arch/ia64/configs/bigsur_defconfig    |   3 +-
 arch/ia64/configs/generic_defconfig   |   3 +-
 arch/ia64/configs/gensparse_defconfig |   3 +-
 arch/ia64/configs/tiger_defconfig     |   3 +-
 arch/ia64/configs/zx1_defconfig       |   3 +-
 drivers/char/Kconfig                  |   4 -
 drivers/char/Makefile                 |   1 -
 drivers/char/efirtc.c                 | 366 --------------------------
 include/linux/miscdevice.h            |   2 +-
 9 files changed, 11 insertions(+), 377 deletions(-)
 delete mode 100644 drivers/char/efirtc.c

diff --git a/arch/ia64/configs/bigsur_defconfig b/arch/ia64/configs/bigsur_defconfig
index b630bd7351c4..f3ba813a5b80 100644
--- a/arch/ia64/configs/bigsur_defconfig
+++ b/arch/ia64/configs/bigsur_defconfig
@@ -57,7 +57,8 @@ CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_8250_EXTENDED=y
 CONFIG_SERIAL_8250_SHARE_IRQ=y
 # CONFIG_HW_RANDOM is not set
-CONFIG_EFI_RTC=y
+CONFIG_RTC_CLASS=y
+CONFIG_RTC_DRV_EFI=y
 CONFIG_I2C=y
 CONFIG_I2C_CHARDEV=y
 CONFIG_AGP=m
diff --git a/arch/ia64/configs/generic_defconfig b/arch/ia64/configs/generic_defconfig
index 661d90b3e148..cb267a07c57f 100644
--- a/arch/ia64/configs/generic_defconfig
+++ b/arch/ia64/configs/generic_defconfig
@@ -94,7 +94,8 @@ CONFIG_SERIAL_8250_NR_UARTS=6
 CONFIG_SERIAL_8250_EXTENDED=y
 CONFIG_SERIAL_8250_SHARE_IRQ=y
 # CONFIG_HW_RANDOM is not set
-CONFIG_EFI_RTC=y
+CONFIG_RTC_CLASS=y
+CONFIG_RTC_DRV_EFI=y
 CONFIG_RAW_DRIVER=m
 CONFIG_HPET=y
 CONFIG_AGP=m
diff --git a/arch/ia64/configs/gensparse_defconfig b/arch/ia64/configs/gensparse_defconfig
index 7844e6a956a4..7e25f2f031b6 100644
--- a/arch/ia64/configs/gensparse_defconfig
+++ b/arch/ia64/configs/gensparse_defconfig
@@ -82,7 +82,8 @@ CONFIG_SERIAL_8250_NR_UARTS=6
 CONFIG_SERIAL_8250_EXTENDED=y
 CONFIG_SERIAL_8250_SHARE_IRQ=y
 # CONFIG_HW_RANDOM is not set
-CONFIG_EFI_RTC=y
+CONFIG_RTC_CLASS=y
+CONFIG_RTC_DRV_EFI=y
 CONFIG_RAW_DRIVER=m
 CONFIG_HPET=y
 CONFIG_AGP=m
diff --git a/arch/ia64/configs/tiger_defconfig b/arch/ia64/configs/tiger_defconfig
index 1d6e2a01452b..3f486d5bdc2d 100644
--- a/arch/ia64/configs/tiger_defconfig
+++ b/arch/ia64/configs/tiger_defconfig
@@ -86,7 +86,8 @@ CONFIG_SERIAL_8250_NR_UARTS=6
 CONFIG_SERIAL_8250_EXTENDED=y
 CONFIG_SERIAL_8250_SHARE_IRQ=y
 # CONFIG_HW_RANDOM is not set
-CONFIG_EFI_RTC=y
+CONFIG_RTC_CLASS=y
+CONFIG_RTC_DRV_EFI=y
 CONFIG_RAW_DRIVER=m
 CONFIG_HPET=y
 CONFIG_AGP=m
diff --git a/arch/ia64/configs/zx1_defconfig b/arch/ia64/configs/zx1_defconfig
index 8c92e095f8bb..70788a500448 100644
--- a/arch/ia64/configs/zx1_defconfig
+++ b/arch/ia64/configs/zx1_defconfig
@@ -69,7 +69,8 @@ CONFIG_SERIAL_8250_NR_UARTS=8
 CONFIG_SERIAL_8250_EXTENDED=y
 CONFIG_SERIAL_8250_SHARE_IRQ=y
 # CONFIG_HW_RANDOM is not set
-CONFIG_EFI_RTC=y
+CONFIG_RTC_CLASS=y
+CONFIG_RTC_DRV_EFI=y
 CONFIG_I2C_CHARDEV=y
 CONFIG_AGP=y
 CONFIG_AGP_HP_ZX1=y
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index df0fc997dc3e..dabbf3f519c6 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -297,10 +297,6 @@ config JS_RTC
 	  To compile this driver as a module, choose M here: the
 	  module will be called js-rtc.
 
-config EFI_RTC
-	bool "EFI Real Time Clock Services"
-	depends on IA64
-
 endif # RTC_LIB
 
 config DTLK
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 7c5ea6f9df14..abe3138b1f5a 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -22,7 +22,6 @@ obj-$(CONFIG_APPLICOM)		+= applicom.o
 obj-$(CONFIG_SONYPI)		+= sonypi.o
 obj-$(CONFIG_RTC)		+= rtc.o
 obj-$(CONFIG_HPET)		+= hpet.o
-obj-$(CONFIG_EFI_RTC)		+= efirtc.o
 obj-$(CONFIG_XILINX_HWICAP)	+= xilinx_hwicap/
 obj-$(CONFIG_NVRAM)		+= nvram.o
 obj-$(CONFIG_TOSHIBA)		+= toshiba.o
diff --git a/drivers/char/efirtc.c b/drivers/char/efirtc.c
deleted file mode 100644
index 4f73064d0c6f..000000000000
--- a/drivers/char/efirtc.c
+++ /dev/null
@@ -1,366 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * EFI Time Services Driver for Linux
- *
- * Copyright (C) 1999 Hewlett-Packard Co
- * Copyright (C) 1999 Stephane Eranian <eranian@hpl.hp.com>
- *
- * Based on skeleton from the drivers/char/rtc.c driver by P. Gortmaker
- *
- * This code provides an architected & portable interface to the real time
- * clock by using EFI instead of direct bit fiddling. The functionalities are 
- * quite different from the rtc.c driver. The only way to talk to the device 
- * is by using ioctl(). There is a /proc interface which provides the raw 
- * information.
- *
- * Please note that we have kept the API as close as possible to the
- * legacy RTC. The standard /sbin/hwclock program should work normally 
- * when used to get/set the time.
- *
- * NOTES:
- *	- Locking is required for safe execution of EFI calls with regards
- *	  to interrupts and SMP.
- *
- * TODO (December 1999):
- * 	- provide the API to set/get the WakeUp Alarm (different from the
- *	  rtc.c alarm).
- *	- SMP testing
- * 	- Add module support
- */
-
-#include <linux/types.h>
-#include <linux/errno.h>
-#include <linux/miscdevice.h>
-#include <linux/init.h>
-#include <linux/rtc.h>
-#include <linux/proc_fs.h>
-#include <linux/seq_file.h>
-#include <linux/efi.h>
-#include <linux/uaccess.h>
-
-
-#define EFI_RTC_VERSION		"0.4"
-
-#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
-/*
- * EFI Epoch is 1/1/1998
- */
-#define EFI_RTC_EPOCH		1998
-
-static DEFINE_SPINLOCK(efi_rtc_lock);
-
-static long efi_rtc_ioctl(struct file *file, unsigned int cmd,
-							unsigned long arg);
-
-#define is_leap(year) \
-          ((year) % 4 = 0 && ((year) % 100 != 0 || (year) % 400 = 0))
-
-static const unsigned short int __mon_yday[2][13] -{
-	/* Normal years.  */
-	{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
-	/* Leap years.  */  
-	{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
-};
-
-/*
- * returns day of the year [0-365]
- */
-static inline int
-compute_yday(efi_time_t *eft)
-{
-	/* efi_time_t.month is in the [1-12] so, we need -1 */
-	return  __mon_yday[is_leap(eft->year)][eft->month-1]+ eft->day -1;
-}
-/*
- * returns day of the week [0-6] 0=Sunday
- *
- * Don't try to provide a year that's before 1998, please !
- */
-static int
-compute_wday(efi_time_t *eft)
-{
-	int y;
-	int ndays = 0;
-
-	if ( eft->year < 1998 ) {
-		printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
-		return -1;
-	}
-
-	for(yïI_RTC_EPOCH; y < eft->year; y++ ) {
-		ndays += 365 + (is_leap(y) ? 1 : 0);
-	}
-	ndays += compute_yday(eft);
-
-	/*
-	 * 4=1/1/1998 was a Thursday
-	 */
-	return (ndays + 4) % 7;
-}
-
-static void
-convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
-{
-
-	eft->year	= wtime->tm_year + 1900;
-	eft->month	= wtime->tm_mon + 1; 
-	eft->day	= wtime->tm_mday;
-	eft->hour	= wtime->tm_hour;
-	eft->minute	= wtime->tm_min;
-	eft->second 	= wtime->tm_sec;
-	eft->nanosecond = 0; 
-	eft->daylight	= wtime->tm_isdst ? EFI_ISDST: 0;
-	eft->timezone	= EFI_UNSPECIFIED_TIMEZONE;
-}
-
-static void
-convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
-{
-	memset(wtime, 0, sizeof(*wtime));
-	wtime->tm_sec  = eft->second;
-	wtime->tm_min  = eft->minute;
-	wtime->tm_hour = eft->hour;
-	wtime->tm_mday = eft->day;
-	wtime->tm_mon  = eft->month - 1;
-	wtime->tm_year = eft->year - 1900;
-
-	/* day of the week [0-6], Sunday=0 */
-	wtime->tm_wday = compute_wday(eft);
-
-	/* day in the year [1-365]*/
-	wtime->tm_yday = compute_yday(eft);
-
-
-	switch (eft->daylight & EFI_ISDST) {
-		case EFI_ISDST:
-			wtime->tm_isdst = 1;
-			break;
-		case EFI_TIME_ADJUST_DAYLIGHT:
-			wtime->tm_isdst = 0;
-			break;
-		default:
-			wtime->tm_isdst = -1;
-	}
-}
-
-static long efi_rtc_ioctl(struct file *file, unsigned int cmd,
-							unsigned long arg)
-{
-
-	efi_status_t	status;
-	unsigned long	flags;
-	efi_time_t	eft;
-	efi_time_cap_t	cap;
-	struct rtc_time	wtime;
-	struct rtc_wkalrm __user *ewp;
-	unsigned char	enabled, pending;
-
-	switch (cmd) {
-		case RTC_UIE_ON:
-		case RTC_UIE_OFF:
-		case RTC_PIE_ON:
-		case RTC_PIE_OFF:
-		case RTC_AIE_ON:
-		case RTC_AIE_OFF:
-		case RTC_ALM_SET:
-		case RTC_ALM_READ:
-		case RTC_IRQP_READ:
-		case RTC_IRQP_SET:
-		case RTC_EPOCH_READ:
-		case RTC_EPOCH_SET:
-			return -EINVAL;
-
-		case RTC_RD_TIME:
-			spin_lock_irqsave(&efi_rtc_lock, flags);
-
-			status = efi.get_time(&eft, &cap);
-
-			spin_unlock_irqrestore(&efi_rtc_lock,flags);
-
-			if (status != EFI_SUCCESS) {
-				/* should never happen */
-				printk(KERN_ERR "efitime: can't read time\n");
-				return -EINVAL;
-			}
-
-			convert_from_efi_time(&eft, &wtime);
-
- 			return copy_to_user((void __user *)arg, &wtime,
-					    sizeof (struct rtc_time)) ? - EFAULT : 0;
-
-		case RTC_SET_TIME:
-
-			if (!capable(CAP_SYS_TIME)) return -EACCES;
-
-			if (copy_from_user(&wtime, (struct rtc_time __user *)arg,
-					   sizeof(struct rtc_time)) )
-				return -EFAULT;
-
-			convert_to_efi_time(&wtime, &eft);
-
-			spin_lock_irqsave(&efi_rtc_lock, flags);
-
-			status = efi.set_time(&eft);
-
-			spin_unlock_irqrestore(&efi_rtc_lock,flags);
-
-			return status = EFI_SUCCESS ? 0 : -EINVAL;
-
-		case RTC_WKALM_SET:
-
-			if (!capable(CAP_SYS_TIME)) return -EACCES;
-
-			ewp = (struct rtc_wkalrm __user *)arg;
-
-			if (  get_user(enabled, &ewp->enabled)
-			   || copy_from_user(&wtime, &ewp->time, sizeof(struct rtc_time)) )
-				return -EFAULT;
-
-			convert_to_efi_time(&wtime, &eft);
-
-			spin_lock_irqsave(&efi_rtc_lock, flags);
-			/*
-			 * XXX Fixme:
-			 * As of EFI 0.92 with the firmware I have on my
-			 * machine this call does not seem to work quite
-			 * right
-			 */
-			status = efi.set_wakeup_time((efi_bool_t)enabled, &eft);
-
-			spin_unlock_irqrestore(&efi_rtc_lock,flags);
-
-			return status = EFI_SUCCESS ? 0 : -EINVAL;
-
-		case RTC_WKALM_RD:
-
-			spin_lock_irqsave(&efi_rtc_lock, flags);
-
-			status = efi.get_wakeup_time((efi_bool_t *)&enabled, (efi_bool_t *)&pending, &eft);
-
-			spin_unlock_irqrestore(&efi_rtc_lock,flags);
-
-			if (status != EFI_SUCCESS) return -EINVAL;
-
-			ewp = (struct rtc_wkalrm __user *)arg;
-
-			if (  put_user(enabled, &ewp->enabled)
-			   || put_user(pending, &ewp->pending)) return -EFAULT;
-
-			convert_from_efi_time(&eft, &wtime);
-
-			return copy_to_user(&ewp->time, &wtime,
-					    sizeof(struct rtc_time)) ? -EFAULT : 0;
-	}
-	return -ENOTTY;
-}
-
-/*
- *	The various file operations we support.
- */
-
-static const struct file_operations efi_rtc_fops = {
-	.owner		= THIS_MODULE,
-	.unlocked_ioctl	= efi_rtc_ioctl,
-	.llseek		= no_llseek,
-};
-
-static struct miscdevice efi_rtc_dev= {
-	EFI_RTC_MINOR,
-	"efirtc",
-	&efi_rtc_fops
-};
-
-/*
- *	We export RAW EFI information to /proc/driver/efirtc
- */
-static int efi_rtc_proc_show(struct seq_file *m, void *v)
-{
-	efi_time_t 	eft, alm;
-	efi_time_cap_t	cap;
-	efi_bool_t	enabled, pending;	
-	unsigned long	flags;
-
-	memset(&eft, 0, sizeof(eft));
-	memset(&alm, 0, sizeof(alm));
-	memset(&cap, 0, sizeof(cap));
-
-	spin_lock_irqsave(&efi_rtc_lock, flags);
-
-	efi.get_time(&eft, &cap);
-	efi.get_wakeup_time(&enabled, &pending, &alm);
-
-	spin_unlock_irqrestore(&efi_rtc_lock,flags);
-
-	seq_printf(m,
-		   "Time           : %u:%u:%u.%09u\n"
-		   "Date           : %u-%u-%u\n"
-		   "Daylight       : %u\n",
-		   eft.hour, eft.minute, eft.second, eft.nanosecond, 
-		   eft.year, eft.month, eft.day,
-		   eft.daylight);
-
-	if (eft.timezone = EFI_UNSPECIFIED_TIMEZONE)
-		seq_puts(m, "Timezone       : unspecified\n");
-	else
-		/* XXX fixme: convert to string? */
-		seq_printf(m, "Timezone       : %u\n", eft.timezone);
-		
-
-	seq_printf(m,
-		   "Alarm Time     : %u:%u:%u.%09u\n"
-		   "Alarm Date     : %u-%u-%u\n"
-		   "Alarm Daylight : %u\n"
-		   "Enabled        : %s\n"
-		   "Pending        : %s\n",
-		   alm.hour, alm.minute, alm.second, alm.nanosecond, 
-		   alm.year, alm.month, alm.day, 
-		   alm.daylight,
-		   enabled = 1 ? "yes" : "no",
-		   pending = 1 ? "yes" : "no");
-
-	if (eft.timezone = EFI_UNSPECIFIED_TIMEZONE)
-		seq_puts(m, "Timezone       : unspecified\n");
-	else
-		/* XXX fixme: convert to string? */
-		seq_printf(m, "Timezone       : %u\n", alm.timezone);
-
-	/*
-	 * now prints the capabilities
-	 */
-	seq_printf(m,
-		   "Resolution     : %u\n"
-		   "Accuracy       : %u\n"
-		   "SetstoZero     : %u\n",
-		   cap.resolution, cap.accuracy, cap.sets_to_zero);
-
-	return 0;
-}
-static int __init 
-efi_rtc_init(void)
-{
-	int ret;
-	struct proc_dir_entry *dir;
-
-	printk(KERN_INFO "EFI Time Services Driver v%s\n", EFI_RTC_VERSION);
-
-	ret = misc_register(&efi_rtc_dev);
-	if (ret) {
-		printk(KERN_ERR "efirtc: can't misc_register on minor=%d\n",
-				EFI_RTC_MINOR);
-		return ret;
-	}
-
-	dir = proc_create_single("driver/efirtc", 0, NULL, efi_rtc_proc_show);
-	if (dir = NULL) {
-		printk(KERN_ERR "efirtc: can't create /proc/driver/efirtc.\n");
-		misc_deregister(&efi_rtc_dev);
-		return -1;
-	}
-	return 0;
-}
-device_initcall(efi_rtc_init);
-
-/*
-MODULE_LICENSE("GPL");
-*/
diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h
index 3247a3dc7934..4ab05916046c 100644
--- a/include/linux/miscdevice.h
+++ b/include/linux/miscdevice.h
@@ -25,7 +25,7 @@
 #define TEMP_MINOR		131	/* Temperature Sensor */
 #define APM_MINOR_DEV		134
 #define RTC_MINOR		135
-#define EFI_RTC_MINOR		136	/* EFI Time services */
+/*#define EFI_RTC_MINOR		136	was EFI Time services */
 #define VHCI_MINOR		137
 #define SUN_OPENPROM_MINOR	139
 #define DMAPI_MINOR		140	/* unused */
-- 
2.20.0

Re: [PATCH 1/2] rtc/ia64: remove legacy efirtc driver

[Alexandre Belloni]

On 23/10/2019 17:01:58+0200, Arnd Bergmann wrote:
> There are two EFI RTC drivers, the original drivers/char/efirtc.c
> driver and the more modern drivers/rtc/rtc-efi.c.
> 
> Both implement the same interface, but the new one does so
> in a more portable way.
> 
> Move everything over to that one and remove the old one.
> 
> Cc: linux-ia64@vger.kernel.org
> Cc: Fenghua Yu <fenghua.yu@intel.com>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Stephane Eranian <eranian@google.com>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

> ---
> This was last discussed in early 2018 in
> https://lore.kernel.org/lkml/CAK8P3a0QZNY+K+V1HG056xCerz=_L2jh5UfZ+2LWkDqkw5Zznw@mail.gmail.com/
> 
> Nobody ever replied there, so let's try this instead.
> If there is any reason to keep the driver after all,
> please let us know.
> ---
>  arch/ia64/configs/bigsur_defconfig    |   3 +-
>  arch/ia64/configs/generic_defconfig   |   3 +-
>  arch/ia64/configs/gensparse_defconfig |   3 +-
>  arch/ia64/configs/tiger_defconfig     |   3 +-
>  arch/ia64/configs/zx1_defconfig       |   3 +-
>  drivers/char/Kconfig                  |   4 -
>  drivers/char/Makefile                 |   1 -
>  drivers/char/efirtc.c                 | 366 --------------------------
>  include/linux/miscdevice.h            |   2 +-
>  9 files changed, 11 insertions(+), 377 deletions(-)
>  delete mode 100644 drivers/char/efirtc.c
> 
> diff --git a/arch/ia64/configs/bigsur_defconfig b/arch/ia64/configs/bigsur_defconfig
> index b630bd7351c4..f3ba813a5b80 100644
> --- a/arch/ia64/configs/bigsur_defconfig
> +++ b/arch/ia64/configs/bigsur_defconfig
> @@ -57,7 +57,8 @@ CONFIG_SERIAL_8250_CONSOLE=y
>  CONFIG_SERIAL_8250_EXTENDED=y
>  CONFIG_SERIAL_8250_SHARE_IRQ=y
>  # CONFIG_HW_RANDOM is not set
> -CONFIG_EFI_RTC=y
> +CONFIG_RTC_CLASS=y
> +CONFIG_RTC_DRV_EFI=y
>  CONFIG_I2C=y
>  CONFIG_I2C_CHARDEV=y
>  CONFIG_AGP=m
> diff --git a/arch/ia64/configs/generic_defconfig b/arch/ia64/configs/generic_defconfig
> index 661d90b3e148..cb267a07c57f 100644
> --- a/arch/ia64/configs/generic_defconfig
> +++ b/arch/ia64/configs/generic_defconfig
> @@ -94,7 +94,8 @@ CONFIG_SERIAL_8250_NR_UARTS=6
>  CONFIG_SERIAL_8250_EXTENDED=y
>  CONFIG_SERIAL_8250_SHARE_IRQ=y
>  # CONFIG_HW_RANDOM is not set
> -CONFIG_EFI_RTC=y
> +CONFIG_RTC_CLASS=y
> +CONFIG_RTC_DRV_EFI=y
>  CONFIG_RAW_DRIVER=m
>  CONFIG_HPET=y
>  CONFIG_AGP=m
> diff --git a/arch/ia64/configs/gensparse_defconfig b/arch/ia64/configs/gensparse_defconfig
> index 7844e6a956a4..7e25f2f031b6 100644
> --- a/arch/ia64/configs/gensparse_defconfig
> +++ b/arch/ia64/configs/gensparse_defconfig
> @@ -82,7 +82,8 @@ CONFIG_SERIAL_8250_NR_UARTS=6
>  CONFIG_SERIAL_8250_EXTENDED=y
>  CONFIG_SERIAL_8250_SHARE_IRQ=y
>  # CONFIG_HW_RANDOM is not set
> -CONFIG_EFI_RTC=y
> +CONFIG_RTC_CLASS=y
> +CONFIG_RTC_DRV_EFI=y
>  CONFIG_RAW_DRIVER=m
>  CONFIG_HPET=y
>  CONFIG_AGP=m
> diff --git a/arch/ia64/configs/tiger_defconfig b/arch/ia64/configs/tiger_defconfig
> index 1d6e2a01452b..3f486d5bdc2d 100644
> --- a/arch/ia64/configs/tiger_defconfig
> +++ b/arch/ia64/configs/tiger_defconfig
> @@ -86,7 +86,8 @@ CONFIG_SERIAL_8250_NR_UARTS=6
>  CONFIG_SERIAL_8250_EXTENDED=y
>  CONFIG_SERIAL_8250_SHARE_IRQ=y
>  # CONFIG_HW_RANDOM is not set
> -CONFIG_EFI_RTC=y
> +CONFIG_RTC_CLASS=y
> +CONFIG_RTC_DRV_EFI=y
>  CONFIG_RAW_DRIVER=m
>  CONFIG_HPET=y
>  CONFIG_AGP=m
> diff --git a/arch/ia64/configs/zx1_defconfig b/arch/ia64/configs/zx1_defconfig
> index 8c92e095f8bb..70788a500448 100644
> --- a/arch/ia64/configs/zx1_defconfig
> +++ b/arch/ia64/configs/zx1_defconfig
> @@ -69,7 +69,8 @@ CONFIG_SERIAL_8250_NR_UARTS=8
>  CONFIG_SERIAL_8250_EXTENDED=y
>  CONFIG_SERIAL_8250_SHARE_IRQ=y
>  # CONFIG_HW_RANDOM is not set
> -CONFIG_EFI_RTC=y
> +CONFIG_RTC_CLASS=y
> +CONFIG_RTC_DRV_EFI=y
>  CONFIG_I2C_CHARDEV=y
>  CONFIG_AGP=y
>  CONFIG_AGP_HP_ZX1=y
> diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
> index df0fc997dc3e..dabbf3f519c6 100644
> --- a/drivers/char/Kconfig
> +++ b/drivers/char/Kconfig
> @@ -297,10 +297,6 @@ config JS_RTC
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called js-rtc.
>  
> -config EFI_RTC
> -	bool "EFI Real Time Clock Services"
> -	depends on IA64
> -
>  endif # RTC_LIB
>  
>  config DTLK
> diff --git a/drivers/char/Makefile b/drivers/char/Makefile
> index 7c5ea6f9df14..abe3138b1f5a 100644
> --- a/drivers/char/Makefile
> +++ b/drivers/char/Makefile
> @@ -22,7 +22,6 @@ obj-$(CONFIG_APPLICOM)		+= applicom.o
>  obj-$(CONFIG_SONYPI)		+= sonypi.o
>  obj-$(CONFIG_RTC)		+= rtc.o
>  obj-$(CONFIG_HPET)		+= hpet.o
> -obj-$(CONFIG_EFI_RTC)		+= efirtc.o
>  obj-$(CONFIG_XILINX_HWICAP)	+= xilinx_hwicap/
>  obj-$(CONFIG_NVRAM)		+= nvram.o
>  obj-$(CONFIG_TOSHIBA)		+= toshiba.o
> diff --git a/drivers/char/efirtc.c b/drivers/char/efirtc.c
> deleted file mode 100644
> index 4f73064d0c6f..000000000000
> --- a/drivers/char/efirtc.c
> +++ /dev/null
> @@ -1,366 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0-only
> -/*
> - * EFI Time Services Driver for Linux
> - *
> - * Copyright (C) 1999 Hewlett-Packard Co
> - * Copyright (C) 1999 Stephane Eranian <eranian@hpl.hp.com>
> - *
> - * Based on skeleton from the drivers/char/rtc.c driver by P. Gortmaker
> - *
> - * This code provides an architected & portable interface to the real time
> - * clock by using EFI instead of direct bit fiddling. The functionalities are 
> - * quite different from the rtc.c driver. The only way to talk to the device 
> - * is by using ioctl(). There is a /proc interface which provides the raw 
> - * information.
> - *
> - * Please note that we have kept the API as close as possible to the
> - * legacy RTC. The standard /sbin/hwclock program should work normally 
> - * when used to get/set the time.
> - *
> - * NOTES:
> - *	- Locking is required for safe execution of EFI calls with regards
> - *	  to interrupts and SMP.
> - *
> - * TODO (December 1999):
> - * 	- provide the API to set/get the WakeUp Alarm (different from the
> - *	  rtc.c alarm).
> - *	- SMP testing
> - * 	- Add module support
> - */
> -
> -#include <linux/types.h>
> -#include <linux/errno.h>
> -#include <linux/miscdevice.h>
> -#include <linux/init.h>
> -#include <linux/rtc.h>
> -#include <linux/proc_fs.h>
> -#include <linux/seq_file.h>
> -#include <linux/efi.h>
> -#include <linux/uaccess.h>
> -
> -
> -#define EFI_RTC_VERSION		"0.4"
> -
> -#define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
> -/*
> - * EFI Epoch is 1/1/1998
> - */
> -#define EFI_RTC_EPOCH		1998
> -
> -static DEFINE_SPINLOCK(efi_rtc_lock);
> -
> -static long efi_rtc_ioctl(struct file *file, unsigned int cmd,
> -							unsigned long arg);
> -
> -#define is_leap(year) \
> -          ((year) % 4 = 0 && ((year) % 100 != 0 || (year) % 400 = 0))
> -
> -static const unsigned short int __mon_yday[2][13] > -{
> -	/* Normal years.  */
> -	{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
> -	/* Leap years.  */  
> -	{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
> -};
> -
> -/*
> - * returns day of the year [0-365]
> - */
> -static inline int
> -compute_yday(efi_time_t *eft)
> -{
> -	/* efi_time_t.month is in the [1-12] so, we need -1 */
> -	return  __mon_yday[is_leap(eft->year)][eft->month-1]+ eft->day -1;
> -}
> -/*
> - * returns day of the week [0-6] 0=Sunday
> - *
> - * Don't try to provide a year that's before 1998, please !
> - */
> -static int
> -compute_wday(efi_time_t *eft)
> -{
> -	int y;
> -	int ndays = 0;
> -
> -	if ( eft->year < 1998 ) {
> -		printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
> -		return -1;
> -	}
> -
> -	for(yïI_RTC_EPOCH; y < eft->year; y++ ) {
> -		ndays += 365 + (is_leap(y) ? 1 : 0);
> -	}
> -	ndays += compute_yday(eft);
> -
> -	/*
> -	 * 4=1/1/1998 was a Thursday
> -	 */
> -	return (ndays + 4) % 7;
> -}
> -
> -static void
> -convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
> -{
> -
> -	eft->year	= wtime->tm_year + 1900;
> -	eft->month	= wtime->tm_mon + 1; 
> -	eft->day	= wtime->tm_mday;
> -	eft->hour	= wtime->tm_hour;
> -	eft->minute	= wtime->tm_min;
> -	eft->second 	= wtime->tm_sec;
> -	eft->nanosecond = 0; 
> -	eft->daylight	= wtime->tm_isdst ? EFI_ISDST: 0;
> -	eft->timezone	= EFI_UNSPECIFIED_TIMEZONE;
> -}
> -
> -static void
> -convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
> -{
> -	memset(wtime, 0, sizeof(*wtime));
> -	wtime->tm_sec  = eft->second;
> -	wtime->tm_min  = eft->minute;
> -	wtime->tm_hour = eft->hour;
> -	wtime->tm_mday = eft->day;
> -	wtime->tm_mon  = eft->month - 1;
> -	wtime->tm_year = eft->year - 1900;
> -
> -	/* day of the week [0-6], Sunday=0 */
> -	wtime->tm_wday = compute_wday(eft);
> -
> -	/* day in the year [1-365]*/
> -	wtime->tm_yday = compute_yday(eft);
> -
> -
> -	switch (eft->daylight & EFI_ISDST) {
> -		case EFI_ISDST:
> -			wtime->tm_isdst = 1;
> -			break;
> -		case EFI_TIME_ADJUST_DAYLIGHT:
> -			wtime->tm_isdst = 0;
> -			break;
> -		default:
> -			wtime->tm_isdst = -1;
> -	}
> -}
> -
> -static long efi_rtc_ioctl(struct file *file, unsigned int cmd,
> -							unsigned long arg)
> -{
> -
> -	efi_status_t	status;
> -	unsigned long	flags;
> -	efi_time_t	eft;
> -	efi_time_cap_t	cap;
> -	struct rtc_time	wtime;
> -	struct rtc_wkalrm __user *ewp;
> -	unsigned char	enabled, pending;
> -
> -	switch (cmd) {
> -		case RTC_UIE_ON:
> -		case RTC_UIE_OFF:
> -		case RTC_PIE_ON:
> -		case RTC_PIE_OFF:
> -		case RTC_AIE_ON:
> -		case RTC_AIE_OFF:
> -		case RTC_ALM_SET:
> -		case RTC_ALM_READ:
> -		case RTC_IRQP_READ:
> -		case RTC_IRQP_SET:
> -		case RTC_EPOCH_READ:
> -		case RTC_EPOCH_SET:
> -			return -EINVAL;
> -
> -		case RTC_RD_TIME:
> -			spin_lock_irqsave(&efi_rtc_lock, flags);
> -
> -			status = efi.get_time(&eft, &cap);
> -
> -			spin_unlock_irqrestore(&efi_rtc_lock,flags);
> -
> -			if (status != EFI_SUCCESS) {
> -				/* should never happen */
> -				printk(KERN_ERR "efitime: can't read time\n");
> -				return -EINVAL;
> -			}
> -
> -			convert_from_efi_time(&eft, &wtime);
> -
> - 			return copy_to_user((void __user *)arg, &wtime,
> -					    sizeof (struct rtc_time)) ? - EFAULT : 0;
> -
> -		case RTC_SET_TIME:
> -
> -			if (!capable(CAP_SYS_TIME)) return -EACCES;
> -
> -			if (copy_from_user(&wtime, (struct rtc_time __user *)arg,
> -					   sizeof(struct rtc_time)) )
> -				return -EFAULT;
> -
> -			convert_to_efi_time(&wtime, &eft);
> -
> -			spin_lock_irqsave(&efi_rtc_lock, flags);
> -
> -			status = efi.set_time(&eft);
> -
> -			spin_unlock_irqrestore(&efi_rtc_lock,flags);
> -
> -			return status = EFI_SUCCESS ? 0 : -EINVAL;
> -
> -		case RTC_WKALM_SET:
> -
> -			if (!capable(CAP_SYS_TIME)) return -EACCES;
> -
> -			ewp = (struct rtc_wkalrm __user *)arg;
> -
> -			if (  get_user(enabled, &ewp->enabled)
> -			   || copy_from_user(&wtime, &ewp->time, sizeof(struct rtc_time)) )
> -				return -EFAULT;
> -
> -			convert_to_efi_time(&wtime, &eft);
> -
> -			spin_lock_irqsave(&efi_rtc_lock, flags);
> -			/*
> -			 * XXX Fixme:
> -			 * As of EFI 0.92 with the firmware I have on my
> -			 * machine this call does not seem to work quite
> -			 * right
> -			 */
> -			status = efi.set_wakeup_time((efi_bool_t)enabled, &eft);
> -
> -			spin_unlock_irqrestore(&efi_rtc_lock,flags);
> -
> -			return status = EFI_SUCCESS ? 0 : -EINVAL;
> -
> -		case RTC_WKALM_RD:
> -
> -			spin_lock_irqsave(&efi_rtc_lock, flags);
> -
> -			status = efi.get_wakeup_time((efi_bool_t *)&enabled, (efi_bool_t *)&pending, &eft);
> -
> -			spin_unlock_irqrestore(&efi_rtc_lock,flags);
> -
> -			if (status != EFI_SUCCESS) return -EINVAL;
> -
> -			ewp = (struct rtc_wkalrm __user *)arg;
> -
> -			if (  put_user(enabled, &ewp->enabled)
> -			   || put_user(pending, &ewp->pending)) return -EFAULT;
> -
> -			convert_from_efi_time(&eft, &wtime);
> -
> -			return copy_to_user(&ewp->time, &wtime,
> -					    sizeof(struct rtc_time)) ? -EFAULT : 0;
> -	}
> -	return -ENOTTY;
> -}
> -
> -/*
> - *	The various file operations we support.
> - */
> -
> -static const struct file_operations efi_rtc_fops = {
> -	.owner		= THIS_MODULE,
> -	.unlocked_ioctl	= efi_rtc_ioctl,
> -	.llseek		= no_llseek,
> -};
> -
> -static struct miscdevice efi_rtc_dev= {
> -	EFI_RTC_MINOR,
> -	"efirtc",
> -	&efi_rtc_fops
> -};
> -
> -/*
> - *	We export RAW EFI information to /proc/driver/efirtc
> - */
> -static int efi_rtc_proc_show(struct seq_file *m, void *v)
> -{
> -	efi_time_t 	eft, alm;
> -	efi_time_cap_t	cap;
> -	efi_bool_t	enabled, pending;	
> -	unsigned long	flags;
> -
> -	memset(&eft, 0, sizeof(eft));
> -	memset(&alm, 0, sizeof(alm));
> -	memset(&cap, 0, sizeof(cap));
> -
> -	spin_lock_irqsave(&efi_rtc_lock, flags);
> -
> -	efi.get_time(&eft, &cap);
> -	efi.get_wakeup_time(&enabled, &pending, &alm);
> -
> -	spin_unlock_irqrestore(&efi_rtc_lock,flags);
> -
> -	seq_printf(m,
> -		   "Time           : %u:%u:%u.%09u\n"
> -		   "Date           : %u-%u-%u\n"
> -		   "Daylight       : %u\n",
> -		   eft.hour, eft.minute, eft.second, eft.nanosecond, 
> -		   eft.year, eft.month, eft.day,
> -		   eft.daylight);
> -
> -	if (eft.timezone = EFI_UNSPECIFIED_TIMEZONE)
> -		seq_puts(m, "Timezone       : unspecified\n");
> -	else
> -		/* XXX fixme: convert to string? */
> -		seq_printf(m, "Timezone       : %u\n", eft.timezone);
> -		
> -
> -	seq_printf(m,
> -		   "Alarm Time     : %u:%u:%u.%09u\n"
> -		   "Alarm Date     : %u-%u-%u\n"
> -		   "Alarm Daylight : %u\n"
> -		   "Enabled        : %s\n"
> -		   "Pending        : %s\n",
> -		   alm.hour, alm.minute, alm.second, alm.nanosecond, 
> -		   alm.year, alm.month, alm.day, 
> -		   alm.daylight,
> -		   enabled = 1 ? "yes" : "no",
> -		   pending = 1 ? "yes" : "no");
> -
> -	if (eft.timezone = EFI_UNSPECIFIED_TIMEZONE)
> -		seq_puts(m, "Timezone       : unspecified\n");
> -	else
> -		/* XXX fixme: convert to string? */
> -		seq_printf(m, "Timezone       : %u\n", alm.timezone);
> -
> -	/*
> -	 * now prints the capabilities
> -	 */
> -	seq_printf(m,
> -		   "Resolution     : %u\n"
> -		   "Accuracy       : %u\n"
> -		   "SetstoZero     : %u\n",
> -		   cap.resolution, cap.accuracy, cap.sets_to_zero);
> -
> -	return 0;
> -}
> -static int __init 
> -efi_rtc_init(void)
> -{
> -	int ret;
> -	struct proc_dir_entry *dir;
> -
> -	printk(KERN_INFO "EFI Time Services Driver v%s\n", EFI_RTC_VERSION);
> -
> -	ret = misc_register(&efi_rtc_dev);
> -	if (ret) {
> -		printk(KERN_ERR "efirtc: can't misc_register on minor=%d\n",
> -				EFI_RTC_MINOR);
> -		return ret;
> -	}
> -
> -	dir = proc_create_single("driver/efirtc", 0, NULL, efi_rtc_proc_show);
> -	if (dir = NULL) {
> -		printk(KERN_ERR "efirtc: can't create /proc/driver/efirtc.\n");
> -		misc_deregister(&efi_rtc_dev);
> -		return -1;
> -	}
> -	return 0;
> -}
> -device_initcall(efi_rtc_init);
> -
> -/*
> -MODULE_LICENSE("GPL");
> -*/
> diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h
> index 3247a3dc7934..4ab05916046c 100644
> --- a/include/linux/miscdevice.h
> +++ b/include/linux/miscdevice.h
> @@ -25,7 +25,7 @@
>  #define TEMP_MINOR		131	/* Temperature Sensor */
>  #define APM_MINOR_DEV		134
>  #define RTC_MINOR		135
> -#define EFI_RTC_MINOR		136	/* EFI Time services */
> +/*#define EFI_RTC_MINOR		136	was EFI Time services */
>  #define VHCI_MINOR		137
>  #define SUN_OPENPROM_MINOR	139
>  #define DMAPI_MINOR		140	/* unused */
> -- 
> 2.20.0
> 

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH 1/2] rtc/ia64: remove legacy efirtc driver

[Luck, Tony]

On Wed, Oct 23, 2019 at 05:01:58PM +0200, Arnd Bergmann wrote:
> There are two EFI RTC drivers, the original drivers/char/efirtc.c
> driver and the more modern drivers/rtc/rtc-efi.c.
> 
> Both implement the same interface, but the new one does so
> in a more portable way.
> 
> Move everything over to that one and remove the old one.

The new one is more talkative that the old one. I see this extra
line on the console when I boot ia64:

rtc-efi rtc-efi: setting system clock to 2019-10-23T18:30:23 UTC (1571855423)

That seems somewhat useful & informative (though the repeated "rtc-efi"
at the start of the line is redundant).

Acked-by: Tony Luck <tony.luck@intel.com>

-Tony

Re: [PATCH 1/2] rtc/ia64: remove legacy efirtc driver

[Alexandre Belloni]

On 23/10/2019 11:46:16-0700, Luck, Tony wrote:
> On Wed, Oct 23, 2019 at 05:01:58PM +0200, Arnd Bergmann wrote:
> > There are two EFI RTC drivers, the original drivers/char/efirtc.c
> > driver and the more modern drivers/rtc/rtc-efi.c.
> > 
> > Both implement the same interface, but the new one does so
> > in a more portable way.
> > 
> > Move everything over to that one and remove the old one.
> 
> The new one is more talkative that the old one. I see this extra
> line on the console when I boot ia64:
> 
> rtc-efi rtc-efi: setting system clock to 2019-10-23T18:30:23 UTC (1571855423)
> 
> That seems somewhat useful & informative (though the repeated "rtc-efi"
> at the start of the line is redundant).
> 

You can remove CONFIG_RTC_HCTOSYS, this line will disappear, systemd
will not like that but efirtc was not setting the system time anyway so
this shouldn't change the behaviour.

The redundancy in the log is kind of specific to this RTC. For CMOS,
this is: rtc_cmos 00:01, it should identify the RTC uniquely.

> Acked-by: Tony Luck <tony.luck@intel.com>
> 
> -Tony

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

RE: [PATCH 1/2] rtc/ia64: remove legacy efirtc driver

[Luck, Tony]

>> rtc-efi rtc-efi: setting system clock to 2019-10-23T18:30:23 UTC (1571855423)

> You can remove CONFIG_RTC_HCTOSYS, this line will disappear, systemd
> will not like that but efirtc was not setting the system time anyway so
> this shouldn't change the behaviour.


Wait ... that message says "setting system clock"

but then you say " efirtc was not setting the system time anyway".

So did the time get set, or not?

If it wasn't set, why does the message say that it was set?

-Tony

Re: [PATCH 1/2] rtc/ia64: remove legacy efirtc driver

[Alexandre Belloni]

On 23/10/2019 21:30:29+0000, Luck, Tony wrote:
> >> rtc-efi rtc-efi: setting system clock to 2019-10-23T18:30:23 UTC (1571855423)
> 
> > You can remove CONFIG_RTC_HCTOSYS, this line will disappear, systemd
> > will not like that but efirtc was not setting the system time anyway so
> > this shouldn't change the behaviour.
> 
> 
> Wait ... that message says "setting system clock"
> 
> but then you say " efirtc was not setting the system time anyway".
> 
> So did the time get set, or not?
> 
> If it wasn't set, why does the message say that it was set?
> 

What I meant was that drivers/char/efirtc.c was not setting the system
time but when using drivers/rtc/rtc-efi.c with CONFIG_RTC_HCTOSYS, the
kernel will use the rtc to set the system time.


-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH 1/2] rtc/ia64: remove legacy efirtc driver

[Arnd Bergmann]

On Thu, Oct 24, 2019 at 1:20 AM Alexandre Belloni
<alexandre.belloni@bootlin.com> wrote:
>
> On 23/10/2019 21:30:29+0000, Luck, Tony wrote:
> > >> rtc-efi rtc-efi: setting system clock to 2019-10-23T18:30:23 UTC (1571855423)
> >
> > > You can remove CONFIG_RTC_HCTOSYS, this line will disappear, systemd
> > > will not like that but efirtc was not setting the system time anyway so
> > > this shouldn't change the behaviour.
> >
> >
> > Wait ... that message says "setting system clock"
> >
> > but then you say " efirtc was not setting the system time anyway".
> >
> > So did the time get set, or not?
> >
> > If it wasn't set, why does the message say that it was set?
> >
>
> What I meant was that drivers/char/efirtc.c was not setting the system
> time but when using drivers/rtc/rtc-efi.c with CONFIG_RTC_HCTOSYS, the
> kernel will use the rtc to set the system time.

arch/ia64 has a read_persistent_clock64() function, so it ends up reading
the system time regardless of the RTC driver or CONFIG_RTC_HCTOSYS.

As ia64 sets neither ARCH_HIBERNATION_POSSIBLE nor
ARCH_SUSPEND_POSSIBLE, so we could just remove the
read_persistent_clock64() and efi_gettimeofday(), relying instead
on user space (/sbin/hwclock) or CONFIG_RTC_HCTOSYS.

         Arnd

RE: [PATCH 1/2] rtc/ia64: remove legacy efirtc driver

[Luck, Tony]

PiBhcmNoL2lhNjQgaGFzIGEgcmVhZF9wZXJzaXN0ZW50X2Nsb2NrNjQoKSBmdW5jdGlvbiwgc28g
aXQgZW5kcyB1cCByZWFkaW5nDQo+IHRoZSBzeXN0ZW0gdGltZSByZWdhcmRsZXNzIG9mIHRoZSBS
VEMgZHJpdmVyIG9yIENPTkZJR19SVENfSENUT1NZUy4NCj4NCj4gQXMgaWE2NCBzZXRzIG5laXRo
ZXIgQVJDSF9ISUJFUk5BVElPTl9QT1NTSUJMRSBub3INCj4gQVJDSF9TVVNQRU5EX1BPU1NJQkxF
LCBzbyB3ZSBjb3VsZCBqdXN0IHJlbW92ZSB0aGUNCj4gcmVhZF9wZXJzaXN0ZW50X2Nsb2NrNjQo
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Re: [PATCH 1/2] rtc/ia64: remove legacy efirtc driver

[Arnd Bergmann]

On Thu, Oct 24, 2019 at 6:57 PM Luck, Tony <tony.luck@intel.com> wrote:
>
> > arch/ia64 has a read_persistent_clock64() function, so it ends up reading
> > the system time regardless of the RTC driver or CONFIG_RTC_HCTOSYS.
> >
> > As ia64 sets neither ARCH_HIBERNATION_POSSIBLE nor
> > ARCH_SUSPEND_POSSIBLE, so we could just remove the
> > read_persistent_clock64() and efi_gettimeofday(), relying instead
> > on user space (/sbin/hwclock) or CONFIG_RTC_HCTOSYS.
>
> Seems weird. ia64 has always assumed from day 1 that it is running
> on a UEFI capable platorm (well at day 1 it was called "EFI", the "U"
> came later).
>
> So read_persistent_clock64() just calls EFI directly to get the time.
>
> Seems simpler than worrying about having the right drivers and CONFIG
> bits set.

It would just be a little more consistent. Most architectures cannot
implement  read_persistent_clock64()  or CONFIG_RTC_HCTOSYS
when the RTC driver is a loadable module, so distros normally have to
set the system time after loading modules already. If some architectures
have a reliable platform interface that allows setting the time at early
boot, that doesn't mean we have to rely on that.

       Arnd