m68k/atari: Implement arch_nvram_ops methods and enable CONFIG_HAVE_ARCH_NVRAM_OPS

This change “m68k/atari: Implement arch_nvram_ops methods and enable CONFIG_HAVE_ARCH_NVRAM_OPS” in Linux kernel is authored by Finn Thain <fthain [at] telegraphics.com.au> on Tue Jan 15 15:18:56 2019 +1100.

m68k/atari: Implement arch_nvram_ops methods and enable CONFIG_HAVE_ARCH_NVRAM_OPS

Atari RTC NVRAM uses a checksum so implement the remaining arch_nvram_ops
methods for the set_checksum and initialize ioctls. Enable
CONFIG_HAVE_ARCH_NVRAM_OPS.

Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This Linux change may have been applied to various maintained Linux releases and you can find Linux releases including commit 666047f.

There are 31 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 arch/Kconfig              |  3 +++
 arch/m68k/Kconfig.machine |  1 +
 arch/m68k/atari/nvram.c   | 24 ++++++++++++++++++++++++
 drivers/char/Kconfig      |  3 ++-
 4 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 4cfb6de..87393fb 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -701,6 +701,9 @@ config HAVE_ARCH_HASH
 	  file which provides platform-specific implementations of some
 	  functions in <linux/hash.h> or fs/namei.c.
 
+config HAVE_ARCH_NVRAM_OPS
+	bool
+
 config ISA_BUS_API
 	def_bool ISA
 
diff --git a/arch/m68k/Kconfig.machine b/arch/m68k/Kconfig.machine
index 328ba83..ad584e3 100644
--- a/arch/m68k/Kconfig.machine
+++ b/arch/m68k/Kconfig.machine
@@ -16,6 +16,7 @@ config ATARI
 	bool "Atari support"
 	depends on MMU
 	select MMU_MOTOROLA if MMU
+	select HAVE_ARCH_NVRAM_OPS
 	help
 	  This option enables support for the 68000-based Atari series of
 	  computers (including the TT, Falcon and Medusa). If you plan to use
diff --git a/arch/m68k/atari/nvram.c b/arch/m68k/atari/nvram.c
index e75adebe..c347fd2 100644
--- a/arch/m68k/atari/nvram.c
+++ b/arch/m68k/atari/nvram.c
@@ -74,6 +74,26 @@ static void __nvram_set_checksum(void)
 	__nvram_write_byte(sum, ATARI_CKS_LOC + 1);
 }
 
+static long atari_nvram_set_checksum(void)
+{
+	spin_lock_irq(&rtc_lock);
+	__nvram_set_checksum();
+	spin_unlock_irq(&rtc_lock);
+	return 0;
+}
+
+static long atari_nvram_initialize(void)
+{
+	loff_t i;
+
+	spin_lock_irq(&rtc_lock);
+	for (i = 0; i < NVRAM_BYTES; ++i)
+		__nvram_write_byte(0, i);
+	__nvram_set_checksum();
+	spin_unlock_irq(&rtc_lock);
+	return 0;
+}
+
 static ssize_t atari_nvram_read(char *buf, size_t count, loff_t *ppos)
 {
 	char *p = buf;
@@ -113,6 +133,8 @@ static ssize_t atari_nvram_write(char *buf, size_t count, loff_t *ppos)
 
 static ssize_t atari_nvram_get_size(void)
 {
+	if (!MACH_IS_ATARI)
+		return -ENODEV;
 	return NVRAM_BYTES;
 }
 
@@ -120,6 +142,8 @@ static ssize_t atari_nvram_get_size(void)
 	.read           = atari_nvram_read,
 	.write          = atari_nvram_write,
 	.get_size       = atari_nvram_get_size,
+	.set_checksum   = atari_nvram_set_checksum,
+	.initialize     = atari_nvram_initialize,
 };
 EXPORT_SYMBOL(arch_nvram_ops);
 
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index a8cac68..ce99795 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -244,7 +244,8 @@ source "drivers/char/hw_random/Kconfig"
 
 config NVRAM
 	tristate "/dev/nvram support"
-	depends on X86 || GENERIC_NVRAM
+	depends on X86 || GENERIC_NVRAM || HAVE_ARCH_NVRAM_OPS
+	default M68K
 	---help---
 	  If you say Y here and create a character special file /dev/nvram
 	  with major number 10 and minor number 144 using mknod ("man mknod"),

The commit for this change in Linux stable tree is 666047f (patch).

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