xtensa patches for -rc5

xtensa patches for -rc5

[Johannes Weiner]

Hi Chris,

due to SPI and net driver not getting into .30, I was able to drop all
the controversial patches affecting xtensa IRQ code.  Also the DMA
engine support is now not pressing anymore.

What's left is pretty trivial.  Two fixes, one affecting stack trace
printing for generic xtensa.  Both bugs were introduced with this
merge window so it would be good to have the fixes in before the
release.

The other part is the boot-time clock calibration on s6000.

Please consider merging this before .30 gets released.  We can take
care about the rest for .31.

Thanks,

	Hannes

[patch 1/5] xtensa: always use correct stack pointer for stack traces

[Johannes Weiner]

Commit '28a0ce7 xtensa: use correct stack pointer for stack traces'
changed the stack tracer from always reading the stack pointer
register to always using the saved value in the task descriptor.

The author was too dense to consider the fact that the saved stack
value is stale for a running process und thus unusable for 'current'.

What we do now is to use the stack pointer register (a1) for when the
task is unknown - we can't help it then - or when the task is
'current'.  For everything else use the saved stack pointer value
contained in the task descriptor.

Signed-off-by: Johannes Weiner <jw@emlix.com>
---
 arch/xtensa/kernel/traps.c |   16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c
index 9f0b711..ba9ab93 100644
--- a/arch/xtensa/kernel/traps.c
+++ b/arch/xtensa/kernel/traps.c
@@ -369,6 +369,18 @@ void show_regs(struct pt_regs * regs)
 		       regs->syscall);
 }
 
+static __always_inline unsigned long *stack_pointer(struct task_struct *task)
+{
+	unsigned long *sp;
+
+	if (!task || task == current)
+		__asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp));
+	else
+		sp = (unsigned long *)task->thread.sp;
+
+	return sp;
+}
+
 void show_trace(struct task_struct *task, unsigned long *sp)
 {
 	unsigned long a0, a1, pc;
@@ -377,7 +389,7 @@ void show_trace(struct task_struct *task, unsigned long *sp)
 	if (sp)
 		a1 = (unsigned long)sp;
 	else
-		a1 = task->thread.sp;
+		a1 = (unsigned long)stack_pointer(task);
 
 	sp_start = a1 & ~(THREAD_SIZE-1);
 	sp_end = sp_start + THREAD_SIZE;
@@ -420,7 +432,7 @@ void show_stack(struct task_struct *task, unsigned long *sp)
 	unsigned long *stack;
 
 	if (!sp)
-		sp = (unsigned long *)task->thread.sp;
+		sp = stack_pointer(task);
  	stack = sp;
 
 	printk("\nStack: ");
-- 
1.6.3.rc3

[patch 2/5] xtensa: register gpio chip before use

[Johannes Weiner]

Platform initialization sets up the LED heartbeat that is controlled
via GPIO.  Requesting the GPIO pins fails, however, as the chip is
only initialized later by a device_initcall().

Fix this up by exporting the initialization function.  Let the
platform set up the chip before it starts using it.

Signed-off-by: Johannes Weiner <jw@emlix.com>
---
 arch/xtensa/platforms/s6105/setup.c               |    3 +++
 arch/xtensa/variants/s6000/gpio.c                 |    3 +--
 arch/xtensa/variants/s6000/include/variant/gpio.h |    6 ++++++
 3 files changed, 10 insertions(+), 2 deletions(-)
 create mode 100644 arch/xtensa/variants/s6000/include/variant/gpio.h

diff --git a/arch/xtensa/platforms/s6105/setup.c b/arch/xtensa/platforms/s6105/setup.c
index ae041d5..855ddea 100644
--- a/arch/xtensa/platforms/s6105/setup.c
+++ b/arch/xtensa/platforms/s6105/setup.c
@@ -10,6 +10,8 @@
 #include <asm/bootparam.h>
 
 #include <variant/hardware.h>
+#include <variant/gpio.h>
+
 #include <platform/gpio.h>
 
 void platform_halt(void)
@@ -47,6 +49,7 @@ void __init platform_setup(char **cmdline)
 
 void __init platform_init(bp_tag_t *first)
 {
+	s6_gpio_init();
 	gpio_request(GPIO_LED1_NGREEN, "led1_green");
 	gpio_request(GPIO_LED1_RED, "led1_red");
 	gpio_direction_output(GPIO_LED1_NGREEN, 1);
diff --git a/arch/xtensa/variants/s6000/gpio.c b/arch/xtensa/variants/s6000/gpio.c
index 33a8d95..79317fd 100644
--- a/arch/xtensa/variants/s6000/gpio.c
+++ b/arch/xtensa/variants/s6000/gpio.c
@@ -64,8 +64,7 @@ static struct gpio_chip gpiochip = {
 	.exported = 0, /* no exporting to userspace */
 };
 
-static int gpio_init(void)
+int s6_gpio_init(void)
 {
 	return gpiochip_add(&gpiochip);
 }
-device_initcall(gpio_init);
diff --git a/arch/xtensa/variants/s6000/include/variant/gpio.h b/arch/xtensa/variants/s6000/include/variant/gpio.h
new file mode 100644
index 0000000..8327f62
--- /dev/null
+++ b/arch/xtensa/variants/s6000/include/variant/gpio.h
@@ -0,0 +1,6 @@
+#ifndef _XTENSA_VARIANT_S6000_GPIO_H
+#define _XTENSA_VARIANT_S6000_GPIO_H
+
+extern int s6_gpio_init(void);
+
+#endif /* _XTENSA_VARIANT_S6000_GPIO_H */
-- 
1.6.3.rc3

[patch 3/5] xtensa: fix wrong extern declaration renamed in code using it

[Johannes Weiner]

From: Oskar Schirmer <os@emlix.com>

The variable ccount_nsec has been renamed to nsec_per_ccount
in arch/xtensa/kernel/time.c in 2b8aea74 (2007-08-05),
but the fix failed to rename the variable in
arch/xtensa/include/asm/timex.h as well.

Signed-off-by: Oskar Schirmer <os@emlix.com>
---
 arch/xtensa/include/asm/timex.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/xtensa/include/asm/timex.h b/arch/xtensa/include/asm/timex.h
index b83a818..053bc42 100644
--- a/arch/xtensa/include/asm/timex.h
+++ b/arch/xtensa/include/asm/timex.h
@@ -39,9 +39,9 @@
 
 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
 extern unsigned long ccount_per_jiffy;
-extern unsigned long ccount_nsec;
+extern unsigned long nsec_per_ccount;
 #define CCOUNT_PER_JIFFY ccount_per_jiffy
-#define NSEC_PER_CCOUNT  ccount_nsec
+#define NSEC_PER_CCOUNT  nsec_per_ccount
 #else
 #define CCOUNT_PER_JIFFY (CONFIG_XTENSA_CPU_CLOCK*(1000000UL/HZ))
 #define NSEC_PER_CCOUNT (1000UL / CONFIG_XTENSA_CPU_CLOCK)
-- 
1.6.3.rc3

[patch 4/5] xtensa: implement ccount calibration for s6000

[Johannes Weiner]

From: Oskar Schirmer <os@emlix.com>

Calculate core frequency from timers at boot time
instead of assuming a fixed frequency. This is
useful as the true frequency is set up by the
boot loader, thus variable.

Signed-off-by: Oskar Schirmer <os@emlix.com>
---
 arch/xtensa/Kconfig                 |    1 +
 arch/xtensa/variants/s6000/Makefile |    1 +
 arch/xtensa/variants/s6000/delay.c  |   27 +++++++++++++++++++++++++++
 3 files changed, 29 insertions(+), 0 deletions(-)
 create mode 100644 arch/xtensa/variants/s6000/delay.c

diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 30d21a9..ebe228d 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -80,6 +80,7 @@ config XTENSA_VARIANT_S6000
 	bool "s6000 - Stretch software configurable processor"
 	select VARIANT_IRQ_SWITCH
 	select ARCH_REQUIRE_GPIOLIB
+	select XTENSA_CALIBRATE_CCOUNT
 endchoice
 
 config XTENSA_UNALIGNED_USER
diff --git a/arch/xtensa/variants/s6000/Makefile b/arch/xtensa/variants/s6000/Makefile
index 03b3975..d83f380 100644
--- a/arch/xtensa/variants/s6000/Makefile
+++ b/arch/xtensa/variants/s6000/Makefile
@@ -1,3 +1,4 @@
 # s6000 Makefile
 
 obj-y		+= irq.o gpio.o
+obj-$(CONFIG_XTENSA_CALIBRATE_CCOUNT)	+= delay.o
diff --git a/arch/xtensa/variants/s6000/delay.c b/arch/xtensa/variants/s6000/delay.c
new file mode 100644
index 0000000..54b2b57
--- /dev/null
+++ b/arch/xtensa/variants/s6000/delay.c
@@ -0,0 +1,27 @@
+#include <asm/delay.h>
+#include <asm/timex.h>
+#include <asm/io.h>
+#include <variant/hardware.h>
+
+#define LOOPS 10
+void platform_calibrate_ccount(void)
+{
+	u32 uninitialized_var(a);
+	u32 uninitialized_var(u);
+	u32 b;
+	u32 tstamp = S6_REG_GREG1 + S6_GREG1_GLOBAL_TIMER;
+	int i = LOOPS+1;
+	do {
+		u32 t = u;
+		asm volatile(
+		"1:	l32i %0, %2, 0 ;"
+		"	beq %0, %1, 1b ;"
+		: "=&a"(u) : "a"(t), "a"(tstamp));
+		b = xtensa_get_ccount();
+		if (i == LOOPS)
+			a = b;
+	} while (--i >= 0);
+	b -= a;
+	nsec_per_ccount = (LOOPS * 10000) / b;
+	ccount_per_jiffy = b * (100000UL / (LOOPS * HZ));
+}
-- 
1.6.3.rc3

[patch 5/5] xtensa: update s6105_defconfig for ccount calibration

[Johannes Weiner]

From: Oskar Schirmer <os@emlix.com>

The previous patch enabled ccount calibration for the s6000 variant.
This patch updates the defconfig for the s6105 platform to reflect this
change.

Signed-off-by: Oskar Schirmer <os@emlix.com>
---
 arch/xtensa/configs/s6105_defconfig |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/arch/xtensa/configs/s6105_defconfig b/arch/xtensa/configs/s6105_defconfig
index 6e1deff..768bee0 100644
--- a/arch/xtensa/configs/s6105_defconfig
+++ b/arch/xtensa/configs/s6105_defconfig
@@ -115,7 +115,7 @@ CONFIG_XTENSA_VARIANT_S6000=y
 CONFIG_PREEMPT=y
 # CONFIG_MATH_EMULATION is not set
 # CONFIG_HIGHMEM is not set
-# CONFIG_XTENSA_CALIBRATE_CCOUNT is not set
+CONFIG_XTENSA_CALIBRATE_CCOUNT=y
 CONFIG_SERIAL_CONSOLE=y
 # CONFIG_XTENSA_ISS_NETWORK is not set
 
@@ -131,7 +131,6 @@ CONFIG_SERIAL_CONSOLE=y
 # CONFIG_XTENSA_PLATFORM_ISS is not set
 # CONFIG_XTENSA_PLATFORM_XT2000 is not set
 CONFIG_XTENSA_PLATFORM_S6105=y
-CONFIG_XTENSA_CPU_CLOCK=300
 CONFIG_GENERIC_CALIBRATE_DELAY=y
 CONFIG_CMDLINE_BOOL=y
 CONFIG_CMDLINE="console=ttyS1,38400 debug bootmem_debug loglevel=7"
-- 
1.6.3.rc3