[PATCH 1/2] RTC: rtc-cmos: drivers/char/rtc.c features for DECstation support

[PATCH 1/2] RTC: rtc-cmos: drivers/char/rtc.c features for DECstation support

[Maciej W. Rozycki]

This brings in drivers/char/rtc.c functionality required for DECstation 
and, should the maintainers decide to switch, Alpha systems to use 
rtc-cmos.

Specifically these features are made available:

* RTC iomem rather than x86/PCI port I/O mapping, controlled with the 
  RTC_IOMAPPED macro as with the original driver.  The DS1287A chip in all 
  DECstation systems is mapped in the host bus address space as a 
  contiguous block of 64 32-bit words of which the least significant byte 
  accesses the RTC chip for both reads and writes.  All the address and 
  data window register accesses are made transparently by the chipset glue 
  logic so that the device appears directly mapped on the host bus.

* A way to set the size of the address space explicitly with the 
  newly-added `address_space' member of the platform part of the RTC 
  device structure.  This avoids the unreliable heuristics that does not 
  work in a setup where the RTC is not explicitly accessed with the usual 
  address and data window register pair.

* The ability to use the RTC periodic interrupt as a system clock device,
  which is implemented by arch/mips/kernel/cevt-ds1287.c for DECstation 
  systems and takes the RTC interrupt away from the RTC driver.  
  Eventually hooking back to the clock device's interrupt handler should 
  be possible for the purpose of the alarm clock and possibly also 
  update-in-progress interrupt, but this is not done by this change.

  o To avoid interfering with the clock interrupt all the places where the 
    RTC interrupt mask is fiddled with are only executed if and IRQ has 
    been assigned to the RTC driver.

  o To avoid changing the clock setup Register A is not fiddled with if 
    CMOS_RTC_FLAGS_NOFREQ is set in the newly-added `flags' member of the 
    platform part of the RTC device structure.  Originally, in 
    drivers/char/rtc.c, this was keyed with the absence of the RTC 
    interrupt, just like the interrupt mask, but there only the periodic 
    interrupt frequency is set, whereas rtc-cmos also sets the divider 
    bits.  Therefore a new flag is introduced so that systems where the 
    RTC interrupt is not usable rather than used as a system clock device 
    can fully initialise the RTC.

* A small clean-up is made to the IRQ assignment code that makes the IRQ 
  number hardcoded to -1 rather than arbitrary -ENXIO (or whatever error 
  happens to be returned by platform_get_irq) where no IRQ has been 
  assigned to the RTC driver (NO_IRQ might be another candidate, but it 
  looks like this macro has inconsistent or missing definitions and 
  limited use and might therefore be unsafe).

Verified to work correctly with a DECstation 5000/240 system.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
---
Alessandro,

 Please apply or otherwise let me know if you have any issues with this 
proposal.

 Thanks,

  Maciej

linux-rtc-cmos-dec.patch
Index: linux-20140404-3maxp/drivers/rtc/rtc-cmos.c
===================================================================
--- linux-20140404-3maxp.orig/drivers/rtc/rtc-cmos.c
+++ linux-20140404-3maxp/drivers/rtc/rtc-cmos.c
@@ -647,6 +647,7 @@ cmos_do_probe(struct device *dev, struct
 	int				retval = 0;
 	unsigned char			rtc_control;
 	unsigned			address_space;
+	u32				flags = 0;
 
 	/* there can be only one ... */
 	if (cmos_rtc.dev)
@@ -660,9 +661,12 @@ cmos_do_probe(struct device *dev, struct
 	 * REVISIT non-x86 systems may instead use memory space resources
 	 * (needing ioremap etc), not i/o space resources like this ...
 	 */
-	ports = request_region(ports->start,
-			resource_size(ports),
-			driver_name);
+	if (RTC_IOMAPPED)
+		ports = request_region
+			(ports->start, resource_size(ports), driver_name);
+	else
+		ports = request_mem_region
+			(ports->start, resource_size(ports), driver_name);
 	if (!ports) {
 		dev_dbg(dev, "i/o registers already in use\n");
 		return -EBUSY;
@@ -699,6 +703,11 @@ cmos_do_probe(struct device *dev, struct
 	 * expect CMOS_READ and friends to handle.
 	 */
 	if (info) {
+		if (info->flags)
+			flags = info->flags;
+		if (info->address_space)
+			address_space = info->address_space;
+
 		if (info->rtc_day_alarm && info->rtc_day_alarm < 128)
 			cmos_rtc.day_alrm = info->rtc_day_alarm;
 		if (info->rtc_mon_alarm && info->rtc_mon_alarm < 128)
@@ -726,18 +735,21 @@ cmos_do_probe(struct device *dev, struct
 
 	spin_lock_irq(&rtc_lock);
 
-	/* force periodic irq to CMOS reset default of 1024Hz;
-	 *
-	 * REVISIT it's been reported that at least one x86_64 ALI mobo
-	 * doesn't use 32KHz here ... for portability we might need to
-	 * do something about other clock frequencies.
-	 */
-	cmos_rtc.rtc->irq_freq = 1024;
-	hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
-	CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
+	if (!(flags & CMOS_RTC_FLAGS_NOFREQ)) {
+		/* force periodic irq to CMOS reset default of 1024Hz;
+		 *
+		 * REVISIT it's been reported that at least one x86_64 ALI
+		 * mobo doesn't use 32KHz here ... for portability we might
+		 * need to do something about other clock frequencies.
+		 */
+		cmos_rtc.rtc->irq_freq = 1024;
+		hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
+		CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
+	}
 
 	/* disable irqs */
-	cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
+	if (is_valid_irq(rtc_irq))
+		cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);
 
 	rtc_control = CMOS_READ(RTC_CONTROL);
 
@@ -802,14 +814,18 @@ cmos_do_probe(struct device *dev, struct
 	cmos_rtc.dev = NULL;
 	rtc_device_unregister(cmos_rtc.rtc);
 cleanup0:
-	release_region(ports->start, resource_size(ports));
+	if (RTC_IOMAPPED)
+		release_region(ports->start, resource_size(ports));
+	else
+		release_mem_region(ports->start, resource_size(ports));
 	return retval;
 }
 
-static void cmos_do_shutdown(void)
+static void cmos_do_shutdown(int rtc_irq)
 {
 	spin_lock_irq(&rtc_lock);
-	cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
+	if (is_valid_irq(rtc_irq))
+		cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
 	spin_unlock_irq(&rtc_lock);
 }
 
@@ -818,7 +834,7 @@ static void __exit cmos_do_remove(struct
 	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
 	struct resource *ports;
 
-	cmos_do_shutdown();
+	cmos_do_shutdown(cmos->irq);
 
 	sysfs_remove_bin_file(&dev->kobj, &nvram);
 
@@ -831,7 +847,10 @@ static void __exit cmos_do_remove(struct
 	cmos->rtc = NULL;
 
 	ports = cmos->iomem;
-	release_region(ports->start, resource_size(ports));
+	if (RTC_IOMAPPED)
+		release_region(ports->start, resource_size(ports));
+	else
+		release_mem_region(ports->start, resource_size(ports));
 	cmos->iomem = NULL;
 
 	cmos->dev = NULL;
@@ -1065,10 +1084,13 @@ static void __exit cmos_pnp_remove(struc
 
 static void cmos_pnp_shutdown(struct pnp_dev *pnp)
 {
-	if (system_state == SYSTEM_POWER_OFF && !cmos_poweroff(&pnp->dev))
+	struct device *dev = &pnp->dev;
+	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
+
+	if (system_state == SYSTEM_POWER_OFF && !cmos_poweroff(dev))
 		return;
 
-	cmos_do_shutdown();
+	cmos_do_shutdown(cmos->irq);
 }
 
 static const struct pnp_device_id rtc_ids[] = {
@@ -1145,11 +1167,21 @@ static inline void cmos_of_init(struct p
 
 static int __init cmos_platform_probe(struct platform_device *pdev)
 {
+	struct resource *resource;
+	int irq;
+
 	cmos_of_init(pdev);
 	cmos_wake_setup(&pdev->dev);
-	return cmos_do_probe(&pdev->dev,
-			platform_get_resource(pdev, IORESOURCE_IO, 0),
-			platform_get_irq(pdev, 0));
+
+	if (RTC_IOMAPPED)
+		resource = platform_get_resource(pdev, IORESOURCE_IO, 0);
+	else
+		resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		irq = -1;
+
+	return cmos_do_probe(&pdev->dev, resource, irq);
 }
 
 static int __exit cmos_platform_remove(struct platform_device *pdev)
@@ -1160,10 +1192,13 @@ static int __exit cmos_platform_remove(s
 
 static void cmos_platform_shutdown(struct platform_device *pdev)
 {
-	if (system_state == SYSTEM_POWER_OFF && !cmos_poweroff(&pdev->dev))
+	struct device *dev = &pdev->dev;
+	struct cmos_rtc	*cmos = dev_get_drvdata(dev);
+
+	if (system_state == SYSTEM_POWER_OFF && !cmos_poweroff(dev))
 		return;
 
-	cmos_do_shutdown();
+	cmos_do_shutdown(cmos->irq);
 }
 
 /* work with hotplug and coldplug */
Index: linux-20140404-3maxp/include/linux/mc146818rtc.h
===================================================================
--- linux-20140404-3maxp.orig/include/linux/mc146818rtc.h
+++ linux-20140404-3maxp/include/linux/mc146818rtc.h
@@ -31,6 +31,10 @@ struct cmos_rtc_board_info {
 	void	(*wake_on)(struct device *dev);
 	void	(*wake_off)(struct device *dev);
 
+	u32	flags;
+#define CMOS_RTC_FLAGS_NOFREQ	(1 << 0)
+	int	address_space;
+
 	u8	rtc_day_alarm;		/* zero, or register index */
 	u8	rtc_mon_alarm;		/* zero, or register index */
 	u8	rtc_century;		/* zero, or register index */

[PATCH 2/2] DEC: Switch DECstation systems to rtc-cmos

[Maciej W. Rozycki]

This adds an RTC platform device for DECstation systems so that they can 
use the rtc-cmos driver for their RTC device.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
---
Ralf,

 This part requires the other change or it won't build at all, so it can't 
be pushed to the LMO tree by itself.  I'm not sure which route, either RTC 
or LMO, will be the best for upstreaming this patch pair, but surely the 
rtc-cmos part will have to be reviewed first.

  Maciej

linux-dec-rtc.patch
Index: linux-20140404-3maxp/arch/mips/dec/Makefile
===================================================================
--- linux-20140404-3maxp.orig/arch/mips/dec/Makefile
+++ linux-20140404-3maxp/arch/mips/dec/Makefile
@@ -3,7 +3,7 @@
 #
 
 obj-y		:= ecc-berr.o int-handler.o ioasic-irq.o kn01-berr.o \
-		   kn02-irq.o kn02xa-berr.o reset.o setup.o time.o
+		   kn02-irq.o kn02xa-berr.o platform.o reset.o setup.o time.o
 
 obj-$(CONFIG_TC)		+= tc.o
 obj-$(CONFIG_CPU_HAS_WB)	+= wbflush.o
Index: linux-20140404-3maxp/arch/mips/dec/platform.c
===================================================================
--- /dev/null
+++ linux-20140404-3maxp/arch/mips/dec/platform.c
@@ -0,0 +1,44 @@
+/*
+ *	DEC platform devices.
+ *
+ *	Copyright (c) 2014  Maciej W. Rozycki
+ *
+ *	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/ioport.h>
+#include <linux/kernel.h>
+#include <linux/mc146818rtc.h>
+#include <linux/platform_device.h>
+
+static struct resource dec_rtc_resources[] = {
+	{
+		.name = "rtc",
+		.flags = IORESOURCE_MEM,
+	},
+};
+
+static struct cmos_rtc_board_info dec_rtc_info = {
+	.flags = CMOS_RTC_FLAGS_NOFREQ,
+	.address_space = 64,
+};
+
+static struct platform_device dec_rtc_device = {
+	.name = "rtc_cmos",
+	.id = PLATFORM_DEVID_NONE,
+	.dev.platform_data = &dec_rtc_info,
+	.resource = dec_rtc_resources,
+	.num_resources = ARRAY_SIZE(dec_rtc_resources),
+};
+
+static int __init dec_add_devices(void)
+{
+	dec_rtc_resources[0].start = RTC_PORT(0);
+	dec_rtc_resources[0].end = RTC_PORT(0) + dec_kn_slot_size - 1;
+	return platform_device_register(&dec_rtc_device);
+}
+
+device_initcall(dec_add_devices);

Re: [PATCH 1/2] RTC: rtc-cmos: drivers/char/rtc.c features for DECstation support

[Joshua Kinard]

On 04/19/2014 18:58, Maciej W. Rozycki wrote:
> This brings in drivers/char/rtc.c functionality required for DECstation 
> and, should the maintainers decide to switch, Alpha systems to use 
> rtc-cmos.
> 
> Specifically these features are made available:
> 
[snip]
> * The ability to use the RTC periodic interrupt as a system clock device,
>   which is implemented by arch/mips/kernel/cevt-ds1287.c for DECstation 
>   systems and takes the RTC interrupt away from the RTC driver.  
>   Eventually hooking back to the clock device's interrupt handler should 
>   be possible for the purpose of the alarm clock and possibly also 
>   update-in-progress interrupt, but this is not done by this change.

I had this implemented myself in the DS1685 driver I've still yet to send in
(for SGI IP32).  But the upper-level RTC code for periodic and update
interrupts was removed sometime between 2.6.39 and 3.0 and uses the kernel's
hrtimers to replace it.  No idea if they'll ever re-add that code for RTC
drivers that can use the hardware implementation instead.

-- 
Joshua Kinard
Gentoo/MIPS
kumba@gentoo.org
4096R/D25D95E3 2011-03-28

"The past tempts us, the present confuses us, the future frightens us.  And
our lives slip away, moment by moment, lost in that vast, terrible in-between."

--Emperor Turhan, Centauri Republic

Re: [rtc-linux] [PATCH 1/2] RTC: rtc-cmos: drivers/char/rtc.c features for DECstation support

[Alessandro Zummo]

On Sat, 19 Apr 2014 23:58:20 +0100 (BST)
"Maciej W. Rozycki" <macro@linux-mips.org> wrote:

> This brings in drivers/char/rtc.c functionality required for DECstation 
> and, should the maintainers decide to switch, Alpha systems to use 
> rtc-cmos.

 Seems sane. We need to be sure it doesn't break anything
 on non-Alpha machines. Did you test it on x86? It would be fine if
 we can get a couple of Tested-by:
 

-- 

 Best regards,

 Alessandro Zummo,
  Tower Technologies - Torino, Italy

  http://www.towertech.it

Re: [rtc-linux] [PATCH 1/2] RTC: rtc-cmos: drivers/char/rtc.c features for DECstation support

[Maciej W. Rozycki]

On Tue, 6 May 2014, Alessandro Zummo wrote:

> > This brings in drivers/char/rtc.c functionality required for DECstation 
> > and, should the maintainers decide to switch, Alpha systems to use 
> > rtc-cmos.
> 
>  Seems sane. We need to be sure it doesn't break anything
>  on non-Alpha machines. Did you test it on x86? It would be fine if
>  we can get a couple of Tested-by:

 Thanks for your review.  I can't test x86 easily/immediately, but I'll 
see what I can do, and will also appreciate if people can check that this 
change didn't cause any regressions.  Also Andrew was kind enough to pull 
this patch into his -mm tree, so hopefully any breakage will show up soon.

  Maciej