linux-kernel - [RFC PATCH 11/14] rtc: switch to get/set rtc time to efi functions if CMOS RTC Not Present git set.

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Date:	Thu, 19 Dec 2013 15:51:52 +0800
From:	"Lee, Chun-Yi" <joeyli.kernel@...il.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	"H. Peter Anvin" <hpa@...or.com>,
	Matt Fleming <matt@...sole-pimps.org>,
	Matthew Garrett <matthew.garrett@...ula.com>
Cc:	Elliott@...com, samer.el-haj-mahmoud@...com,
	Oliver Neukum <oneukum@...e.de>, werner@...e.com,
	trenn@...e.de, JBeulich@...e.com, linux-kernel@...r.kernel.org,
	rtc-linux@...glegroups.com, x86@...nel.org,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	linux-acpi@...r.kernel.org, "Lee, Chun-Yi" <jlee@...e.com>
Subject: [RFC PATCH 11/14] rtc: switch to get/set rtc time to efi functions if CMOS RTC Not Present git set.

When CMOS RTC Not Present git set in FADT, system should not access CMOS
interface for time. This patch move get/set rtc time function from CMOS
to EFI runtime on x86_64 machine. And, it also set the BUG_ON check in
rtc_cmos_read/write function to avoid access it.

Signed-off-by: Lee, Chun-Yi <jlee@...e.com>
---
 arch/x86/kernel/rtc.c     |    8 ++++++++
 include/asm-generic/rtc.h |   22 ++++++++++++++++++++++
 2 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index 9b6c568..a54cd09 100644
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -117,6 +117,10 @@ unsigned char rtc_cmos_read(unsigned char addr)
 {
 	unsigned char val;
 
+	BUG_ON(acpi_gbl_FADT.header.revision >= 5 &&
+	       acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC &&
+	       addr <= RTC_YEAR);
+
 	lock_cmos_prefix(addr);
 	outb(addr, RTC_PORT(0));
 	val = inb(RTC_PORT(1));
@@ -128,6 +132,10 @@ EXPORT_SYMBOL(rtc_cmos_read);
 
 void rtc_cmos_write(unsigned char val, unsigned char addr)
 {
+	BUG_ON(acpi_gbl_FADT.header.revision >= 5 &&
+	       acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC &&
+	       addr <= RTC_YEAR);
+
 	lock_cmos_prefix(addr);
 	outb(addr, RTC_PORT(0));
 	outb(val, RTC_PORT(1));
diff --git a/include/asm-generic/rtc.h b/include/asm-generic/rtc.h
index fa86f24..4ba8aa6 100644
--- a/include/asm-generic/rtc.h
+++ b/include/asm-generic/rtc.h
@@ -16,6 +16,8 @@
 #include <linux/rtc.h>
 #include <linux/bcd.h>
 #include <linux/delay.h>
+#include <linux/efi.h>
+#include <linux/acpi.h>
 
 #define RTC_PIE 0x40		/* periodic interrupt enable */
 #define RTC_AIE 0x20		/* alarm interrupt enable */
@@ -51,6 +53,16 @@ static inline unsigned int __get_rtc_time(struct rtc_time *time)
 	unsigned int real_year;
 #endif
 
+	if (acpi_gbl_FADT.header.revision >= 5 &&
+	    acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC) {
+#if defined(CONFIG_EFI) && defined(CONFIG_X86_64)
+		printk_once(KERN_INFO "efi: get rtc time by EFI\n");
+		return efi_read_time(time);
+#else
+		BUG();
+#endif
+	}
+
 	/*
 	 * read RTC once any update in progress is done. The update
 	 * can take just over 2ms. We wait 20ms. There is no need to
@@ -123,6 +135,16 @@ static inline int __set_rtc_time(struct rtc_time *time)
 	unsigned int real_yrs, leap_yr;
 #endif
 
+	if (acpi_gbl_FADT.header.revision >= 5 &&
+	    acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC) {
+#if defined(CONFIG_EFI) && defined(CONFIG_X86_64)
+		printk_once(KERN_INFO "efi: set rtc time by EFI\n");
+		return efi_set_time(time);
+#else
+		BUG();
+#endif
+	}
+
 	yrs = time->tm_year;
 	mon = time->tm_mon + 1;   /* tm_mon starts at zero */
 	day = time->tm_mday;
-- 
1.6.4.2

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