Enable RTC for Ebony and Walnut

Enable RTC for Ebony and Walnut

[David Gibson]

This patch extends the Ebony and Walnut platform code to instantiate
the existing ds1742 RTC class driver for the DS1743 RTC/NVRAM chip
found on both those boards.  The patch uses a helper function to scan
the device tree and instantiate the appropriate platform_device based
on it, so it should be easy to extend for other boards which have mmio
mapped RTC chips.

Along with this, the device tree binding for the ds1743 chips is
tweaked, based on the existing DS1385 OF binding found at:
	http://playground.sun.com/1275/proposals/Closed/Remanded/Accepted/346-it.txt
Although that document covers the NVRAM portion of the chip, whereas
here we're interested in the RTC portion, so it's not entirely clear
if that's a good model.

This implements only RTC class driver support - that is /dev/rtc0, not
/dev/rtc, and the low-level get/set time callbacks remain
unimplemented.  That means in order to get at the clock you will
either need a modified version of hwclock which will look at
/dev/rtc0, or you'll need to configure udev to symlink rtc0 to rtc.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Index: working-2.6/arch/powerpc/boot/dts/ebony.dts
===================================================================
--- working-2.6.orig/arch/powerpc/boot/dts/ebony.dts	2007-10-22 13:55:49.000000000 +1000
+++ working-2.6/arch/powerpc/boot/dts/ebony.dts	2007-12-21 13:11:34.000000000 +1100
@@ -150,9 +150,10 @@
 					};
 				};
 
-				ds1743@1,0 {
+				nvram@1,0 {
 					/* NVRAM & RTC */
-					compatible = "ds1743";
+					compatible = "ds1743-nvram";
+					#bytes = <2000>;
 					reg = <1 0 2000>;
 				};
 
Index: working-2.6/arch/powerpc/platforms/44x/ebony.c
===================================================================
--- working-2.6.orig/arch/powerpc/platforms/44x/ebony.c	2007-12-10 10:52:44.000000000 +1100
+++ working-2.6/arch/powerpc/platforms/44x/ebony.c	2007-12-21 13:11:34.000000000 +1100
@@ -18,6 +18,7 @@
 
 #include <linux/init.h>
 #include <linux/of_platform.h>
+#include <linux/rtc.h>
 
 #include <asm/machdep.h>
 #include <asm/prom.h>
@@ -40,6 +41,7 @@ static int __init ebony_device_probe(voi
 		return 0;
 
 	of_platform_bus_probe(NULL, ebony_of_bus, NULL);
+	of_instantiate_rtc();
 
 	return 0;
 }
Index: working-2.6/arch/powerpc/platforms/Kconfig
===================================================================
--- working-2.6.orig/arch/powerpc/platforms/Kconfig	2007-12-10 10:52:44.000000000 +1100
+++ working-2.6/arch/powerpc/platforms/Kconfig	2007-12-21 13:11:34.000000000 +1100
@@ -315,6 +315,9 @@ config FSL_ULI1575
 config CPM
 	bool
 
+config OF_RTC
+	bool
+
 source "arch/powerpc/sysdev/bestcomm/Kconfig"
 
 endmenu
Index: working-2.6/arch/powerpc/sysdev/Makefile
===================================================================
--- working-2.6.orig/arch/powerpc/sysdev/Makefile	2007-12-21 13:11:32.000000000 +1100
+++ working-2.6/arch/powerpc/sysdev/Makefile	2007-12-21 13:11:34.000000000 +1100
@@ -27,6 +27,7 @@ obj-$(CONFIG_PPC_I8259)		+= i8259.o
 obj-$(CONFIG_PPC_83xx)		+= ipic.o
 obj-$(CONFIG_4xx)		+= uic.o
 obj-$(CONFIG_XILINX_VIRTEX)	+= xilinx_intc.o
+obj-$(CONFIG_OF_RTC)		+= of_rtc.o
 endif
 
 # Temporary hack until we have migrated to asm-powerpc
Index: working-2.6/arch/powerpc/sysdev/of_rtc.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ working-2.6/arch/powerpc/sysdev/of_rtc.c	2007-12-21 13:11:34.000000000 +1100
@@ -0,0 +1,59 @@
+/*
+ * Instantiate mmio-mapped RTC chips based on device tree information
+ *
+ * Copyright 2007 David Gibson <dwg@au1.ibm.com>, IBM Corporation.
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/init.h>
+#include <asm/of_platform.h>
+
+static struct {
+	char *compatible;
+	char *plat_name;
+} of_rtc_table[] = {
+	{ "ds1743-nvram", "rtc-ds1742" },
+};
+
+void __init of_instantiate_rtc(void)
+{
+	struct device_node *node;
+	int err;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(of_rtc_table); i++) {
+		char *compatible = of_rtc_table[i].compatible;
+		char *plat_name = of_rtc_table[i].plat_name;
+
+		for_each_compatible_node(node, NULL, compatible) {
+			struct resource *res;
+
+			res = kmalloc(sizeof(*res), GFP_KERNEL);
+			if (!res) {
+				printk(KERN_ERR "OF RTC: Out of memory "
+				       "allocating resource structure for %s\n",
+				       node->full_name);
+				continue;
+			}
+
+			err = of_address_to_resource(node, 0, res);
+			if (err) {
+				printk(KERN_ERR "OF RTC: Error "
+				       "translating resources for %s\n",
+				       node->full_name);
+				continue;
+			}
+
+			printk(KERN_INFO "OF_RTC: %s is a %s @ 0x%llx-0x%llx\n",
+			       node->full_name, plat_name,
+			       (unsigned long long)res->start,
+			       (unsigned long long)res->end);
+			platform_device_register_simple(plat_name, -1, res, 1);
+		}
+	}
+}
Index: working-2.6/arch/powerpc/platforms/44x/Kconfig
===================================================================
--- working-2.6.orig/arch/powerpc/platforms/44x/Kconfig	2007-12-10 10:52:44.000000000 +1100
+++ working-2.6/arch/powerpc/platforms/44x/Kconfig	2007-12-21 13:11:34.000000000 +1100
@@ -11,6 +11,7 @@ config EBONY
 	depends on 44x
 	default y
 	select 440GP
+	select OF_RTC
 	help
 	  This option enables support for the IBM PPC440GP evaluation board.
 
Index: working-2.6/include/asm-powerpc/of_platform.h
===================================================================
--- working-2.6.orig/include/asm-powerpc/of_platform.h	2007-12-21 13:11:32.000000000 +1100
+++ working-2.6/include/asm-powerpc/of_platform.h	2007-12-21 13:11:34.000000000 +1100
@@ -37,4 +37,6 @@ extern int of_platform_bus_probe(struct 
 
 extern struct of_device *of_find_device_by_phandle(phandle ph);
 
+extern void of_instantiate_rtc(void);
+
 #endif	/* _ASM_POWERPC_OF_PLATFORM_H */
Index: working-2.6/arch/powerpc/boot/dts/walnut.dts
===================================================================
--- working-2.6.orig/arch/powerpc/boot/dts/walnut.dts	2007-12-10 10:52:43.000000000 +1100
+++ working-2.6/arch/powerpc/boot/dts/walnut.dts	2007-12-21 13:11:34.000000000 +1100
@@ -168,9 +168,10 @@
 				};
 			};
 
-			ds1743@1,0 {
+			nvram@1,0 {
 				/* NVRAM and RTC */
-				compatible = "ds1743";
+				compatible = "ds1743-nvram";
+				#bytes = <2000>;
 				reg = <1 0 2000>;
 			};
 
Index: working-2.6/arch/powerpc/platforms/40x/walnut.c
===================================================================
--- working-2.6.orig/arch/powerpc/platforms/40x/walnut.c	2007-12-21 13:14:53.000000000 +1100
+++ working-2.6/arch/powerpc/platforms/40x/walnut.c	2007-12-21 13:15:05.000000000 +1100
@@ -39,6 +39,7 @@ static int __init walnut_device_probe(vo
 
 	/* FIXME: do bus probe here */
 	of_platform_bus_probe(NULL, walnut_of_bus, NULL);
+	of_instantiate_rtc();
 
 	return 0;
 }

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Re: Enable RTC for Ebony and Walnut

[Stephen Rothwell]

[-- Attachment #1: Type: text/plain, Size: 912 bytes --]

On Fri, 21 Dec 2007 13:21:30 +1100 David Gibson <david@gibson.dropbear.id.au> wrote:
>
> +++ working-2.6/arch/powerpc/sysdev/of_rtc.c	2007-12-21 13:11:34.000000000 +1100
> +#include <asm/of_platform.h>

Use linux/of_platform.h, please.

> +
> +static struct {

const or __initdata

> +	char *compatible;

const

> +	char *plat_name;

const (ok, no, thanks to platform_device_register_simple()).

> +} of_rtc_table[] = {
> +	{ "ds1743-nvram", "rtc-ds1742" },
> +};
> +
> +void __init of_instantiate_rtc(void)
> +{
> +	struct device_node *node;
> +	int err;
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(of_rtc_table); i++) {
> +		char *compatible = of_rtc_table[i].compatible;

const (or maybe just use of_rtc_table[i].compatible directly in the one
place it is used).

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

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Re: Enable RTC for Ebony and Walnut

[Olof Johansson]

Hi,

On Fri, Dec 21, 2007 at 01:21:30PM +1100, David Gibson wrote:
> Index: working-2.6/arch/powerpc/platforms/Kconfig
> ===================================================================
> --- working-2.6.orig/arch/powerpc/platforms/Kconfig	2007-12-10 10:52:44.000000000 +1100
> +++ working-2.6/arch/powerpc/platforms/Kconfig	2007-12-21 13:11:34.000000000 +1100
> @@ -315,6 +315,9 @@ config FSL_ULI1575
>  config CPM
>  	bool
>  
> +config OF_RTC
> +	bool
> +

New config options should have descriptions, even if they're silent
ones.


Thanks,

-Olof

Re: Enable RTC for Ebony and Walnut

[David Gibson]

On Fri, Dec 21, 2007 at 03:29:22PM -0600, Olof Johansson wrote:
> Hi,
> 
> On Fri, Dec 21, 2007 at 01:21:30PM +1100, David Gibson wrote:
> > Index: working-2.6/arch/powerpc/platforms/Kconfig
> > ===================================================================
> > --- working-2.6.orig/arch/powerpc/platforms/Kconfig	2007-12-10 10:52:44.000000000 +1100
> > +++ working-2.6/arch/powerpc/platforms/Kconfig	2007-12-21 13:11:34.000000000 +1100
> > @@ -315,6 +315,9 @@ config FSL_ULI1575
> >  config CPM
> >  	bool
> >  
> > +config OF_RTC
> > +	bool
> > +
> 
> New config options should have descriptions, even if they're silent
> ones.

Uh.. but if there's a description, won't kconfig prompt for the
option?  This one should only ever be selected by the platform
options.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Re: Enable RTC for Ebony and Walnut

[Olof Johansson]

On Wed, Jan 02, 2008 at 10:42:08PM +1100, David Gibson wrote:
> On Fri, Dec 21, 2007 at 03:29:22PM -0600, Olof Johansson wrote:
> > Hi,
> > 
> > On Fri, Dec 21, 2007 at 01:21:30PM +1100, David Gibson wrote:
> > > Index: working-2.6/arch/powerpc/platforms/Kconfig
> > > ===================================================================
> > > --- working-2.6.orig/arch/powerpc/platforms/Kconfig	2007-12-10 10:52:44.000000000 +1100
> > > +++ working-2.6/arch/powerpc/platforms/Kconfig	2007-12-21 13:11:34.000000000 +1100
> > > @@ -315,6 +315,9 @@ config FSL_ULI1575
> > >  config CPM
> > >  	bool
> > >  
> > > +config OF_RTC
> > > +	bool
> > > +
> > 
> > New config options should have descriptions, even if they're silent
> > ones.
> 
> Uh.. but if there's a description, won't kconfig prompt for the
> option?  This one should only ever be selected by the platform
> options.

Sorry, should have said "should have help texts to describe them". Yes,
the one-line description will trigger a question, but adding a short
help text describing what the config option is for does not.


-Olof

Enable RTC for Ebony and Walnut (v2)

[David Gibson]

This patch extends the Ebony and Walnut platform code to instantiate
the existing ds1742 RTC class driver for the DS1743 RTC/NVRAM chip
found on both those boards.  The patch uses a helper function to scan
the device tree and instantiate the appropriate platform_device based
on it, so it should be easy to extend for other boards which have mmio
mapped RTC chips.

Along with this, the device tree binding for the ds1743 chips is
tweaked, based on the existing DS1385 OF binding found at:
	http://playground.sun.com/1275/proposals/Closed/Remanded/Accepted/346-it.txt
Although that document covers the NVRAM portion of the chip, whereas
here we're interested in the RTC portion, so it's not entirely clear
if that's a good model.

This implements only RTC class driver support - that is /dev/rtc0, not
/dev/rtc, and the low-level get/set time callbacks remain
unimplemented.  That means in order to get at the clock you will
either need a modified version of hwclock which will look at
/dev/rtc0, or you'll need to configure udev to symlink rtc0 to rtc.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---

Updated for kernel changes and feedback.

Index: working-2.6/arch/powerpc/boot/dts/ebony.dts
===================================================================
--- working-2.6.orig/arch/powerpc/boot/dts/ebony.dts	2008-01-11 11:45:27.000000000 +1100
+++ working-2.6/arch/powerpc/boot/dts/ebony.dts	2008-01-11 14:17:03.000000000 +1100
@@ -158,9 +158,10 @@
 					};
 				};
 
-				ds1743@1,0 {
+				nvram@1,0 {
 					/* NVRAM & RTC */
-					compatible = "ds1743";
+					compatible = "ds1743-nvram";
+					#bytes = <2000>;
 					reg = <1 0 2000>;
 				};
 
Index: working-2.6/arch/powerpc/platforms/44x/ebony.c
===================================================================
--- working-2.6.orig/arch/powerpc/platforms/44x/ebony.c	2008-01-11 11:45:27.000000000 +1100
+++ working-2.6/arch/powerpc/platforms/44x/ebony.c	2008-01-11 14:17:03.000000000 +1100
@@ -18,6 +18,7 @@
 
 #include <linux/init.h>
 #include <linux/of_platform.h>
+#include <linux/rtc.h>
 
 #include <asm/machdep.h>
 #include <asm/prom.h>
@@ -38,6 +39,7 @@ static __initdata struct of_device_id eb
 static int __init ebony_device_probe(void)
 {
 	of_platform_bus_probe(NULL, ebony_of_bus, NULL);
+	of_instantiate_rtc();
 
 	return 0;
 }
Index: working-2.6/arch/powerpc/platforms/Kconfig
===================================================================
--- working-2.6.orig/arch/powerpc/platforms/Kconfig	2007-12-10 10:52:44.000000000 +1100
+++ working-2.6/arch/powerpc/platforms/Kconfig	2008-01-11 14:17:03.000000000 +1100
@@ -315,6 +315,12 @@ config FSL_ULI1575
 config CPM
 	bool
 
+config OF_RTC
+	bool
+	help
+	  Uses information from the OF or flattened device tree to instatiate
+	  platform devices for direct mapped RTC chips like the DS1742 or DS1743.
+
 source "arch/powerpc/sysdev/bestcomm/Kconfig"
 
 endmenu
Index: working-2.6/arch/powerpc/sysdev/Makefile
===================================================================
--- working-2.6.orig/arch/powerpc/sysdev/Makefile	2008-01-11 11:45:27.000000000 +1100
+++ working-2.6/arch/powerpc/sysdev/Makefile	2008-01-11 14:17:03.000000000 +1100
@@ -27,6 +27,7 @@ obj-$(CONFIG_PPC_I8259)		+= i8259.o
 obj-$(CONFIG_PPC_83xx)		+= ipic.o
 obj-$(CONFIG_4xx)		+= uic.o
 obj-$(CONFIG_XILINX_VIRTEX)	+= xilinx_intc.o
+obj-$(CONFIG_OF_RTC)		+= of_rtc.o
 ifeq ($(CONFIG_PCI),y)
 obj-$(CONFIG_4xx)		+= ppc4xx_pci.o
 endif
Index: working-2.6/arch/powerpc/sysdev/of_rtc.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ working-2.6/arch/powerpc/sysdev/of_rtc.c	2008-01-11 14:17:03.000000000 +1100
@@ -0,0 +1,59 @@
+/*
+ * Instantiate mmio-mapped RTC chips based on device tree information
+ *
+ * Copyright 2007 David Gibson <dwg@au1.ibm.com>, IBM Corporation.
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/init.h>
+#include <linux/of_platform.h>
+
+static __initdata struct {
+	const char *compatible;
+	char *plat_name;
+} of_rtc_table[] = {
+	{ "ds1743-nvram", "rtc-ds1742" },
+};
+
+void __init of_instantiate_rtc(void)
+{
+	struct device_node *node;
+	int err;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(of_rtc_table); i++) {
+		char *plat_name = of_rtc_table[i].plat_name;
+
+		for_each_compatible_node(node, NULL,
+					 of_rtc_table[i].compatible) {
+			struct resource *res;
+
+			res = kmalloc(sizeof(*res), GFP_KERNEL);
+			if (!res) {
+				printk(KERN_ERR "OF RTC: Out of memory "
+				       "allocating resource structure for %s\n",
+				       node->full_name);
+				continue;
+			}
+
+			err = of_address_to_resource(node, 0, res);
+			if (err) {
+				printk(KERN_ERR "OF RTC: Error "
+				       "translating resources for %s\n",
+				       node->full_name);
+				continue;
+			}
+
+			printk(KERN_INFO "OF_RTC: %s is a %s @ 0x%llx-0x%llx\n",
+			       node->full_name, plat_name,
+			       (unsigned long long)res->start,
+			       (unsigned long long)res->end);
+			platform_device_register_simple(plat_name, -1, res, 1);
+		}
+	}
+}
Index: working-2.6/arch/powerpc/platforms/44x/Kconfig
===================================================================
--- working-2.6.orig/arch/powerpc/platforms/44x/Kconfig	2008-01-11 11:45:27.000000000 +1100
+++ working-2.6/arch/powerpc/platforms/44x/Kconfig	2008-01-11 14:17:03.000000000 +1100
@@ -13,6 +13,7 @@ config EBONY
 	default y
 	select 440GP
 	select PCI
+	select OF_RTC
 	help
 	  This option enables support for the IBM PPC440GP evaluation board.
 
Index: working-2.6/include/asm-powerpc/of_platform.h
===================================================================
--- working-2.6.orig/include/asm-powerpc/of_platform.h	2008-01-11 11:45:29.000000000 +1100
+++ working-2.6/include/asm-powerpc/of_platform.h	2008-01-11 14:17:03.000000000 +1100
@@ -37,4 +37,6 @@ extern int of_platform_bus_probe(struct 
 
 extern struct of_device *of_find_device_by_phandle(phandle ph);
 
+extern void of_instantiate_rtc(void);
+
 #endif	/* _ASM_POWERPC_OF_PLATFORM_H */
Index: working-2.6/arch/powerpc/boot/dts/walnut.dts
===================================================================
--- working-2.6.orig/arch/powerpc/boot/dts/walnut.dts	2008-01-11 11:45:27.000000000 +1100
+++ working-2.6/arch/powerpc/boot/dts/walnut.dts	2008-01-11 14:17:03.000000000 +1100
@@ -175,9 +175,10 @@
 				};
 			};
 
-			ds1743@1,0 {
+			nvram@1,0 {
 				/* NVRAM and RTC */
-				compatible = "ds1743";
+				compatible = "ds1743-nvram";
+				#bytes = <2000>;
 				reg = <1 0 2000>;
 			};
 
Index: working-2.6/arch/powerpc/platforms/40x/walnut.c
===================================================================
--- working-2.6.orig/arch/powerpc/platforms/40x/walnut.c	2008-01-11 11:45:27.000000000 +1100
+++ working-2.6/arch/powerpc/platforms/40x/walnut.c	2008-01-11 14:17:03.000000000 +1100
@@ -36,6 +36,7 @@ static __initdata struct of_device_id wa
 static int __init walnut_device_probe(void)
 {
 	of_platform_bus_probe(NULL, walnut_of_bus, NULL);
+	of_instantiate_rtc();
 
 	return 0;
 }

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Re: Enable RTC for Ebony and Walnut (v2)

[Stephen Rothwell]

[-- Attachment #1: Type: text/plain, Size: 599 bytes --]

On Fri, 11 Jan 2008 14:25:34 +1100 David Gibson <dwg@au1.ibm.com> wrote:
>
> +++ working-2.6/arch/powerpc/sysdev/of_rtc.c	2008-01-11 14:17:03.000000000 +1100

> +static __initdata struct {
> +	const char *compatible;

If you make this an array, then the string will become __initdata as well.

> +	char *plat_name;
> +} of_rtc_table[] = {
> +	{ "ds1743-nvram", "rtc-ds1742" },
> +};

> +			platform_device_register_simple(plat_name, -1, res, 1);

Do we care if this fails?

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

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Re: Enable RTC for Ebony and Walnut (v2)

[David Gibson]

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On Fri, Jan 11, 2008 at 05:29:57PM +1100, Stephen Rothwell wrote:
> On Fri, 11 Jan 2008 14:25:34 +1100 David Gibson <dwg@au1.ibm.com> wrote:
> >
> > +++ working-2.6/arch/powerpc/sysdev/of_rtc.c	2008-01-11 14:17:03.000000000 +1100
> 
> > +static __initdata struct {
> > +	const char *compatible;
> 
> If you make this an array, then the string will become __initdata as well.

Well, yes, but then I'd have to pick a specific size for the string.
Since this is supposed to be a stopgap until I can build a more
general constructor mechanism..

> > +	char *plat_name;
> > +} of_rtc_table[] = {
> > +	{ "ds1743-nvram", "rtc-ds1742" },
> > +};
> 
> > +			platform_device_register_simple(plat_name, -1, res, 1);
> 
> Do we care if this fails?

Well.. sort of, but there's not really any sane way of reporting it.
This will be called from early platform init code, failures shouldn't
cause us not to boot, and failure to register one rtc shouldn't cause
us not to attempt to register others if they're present.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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