sparc32: generic clockevent support

The kernel uses l14 timers as clockevents. l10 timer is used
as clocksource if platform master_l10_counter isn't constantly
zero. The clocksource is continuous, so it's possible to use
high resolution timers. l10 timer is also used as clockevent
on UP configurations.

This realization is for sun4m, sun4d, sun4c, microsparc-IIep
and LEON platforms. The appropriate LEON changes was made by
Konrad Eisele.

In case of sun4m's oneshot mode, profile irq is zeroed in
smp4m_percpu_timer_interrupt(). It is maybe
needless (double, triple etc overflow does nothing).

sun4d is able to have oneshot mode too, but I haven't
any way to test it. So code of its percpu timer handler
is made as much equal to the current code as possible.

The patch is tested on sun4m box in SMP mode by me,
and tested by Konrad on leon in up mode (leon smp
is broken atm - due to other reasons).

Signed-off-by: Tkhai Kirill <tkhai@yandex.ru>
Tested-by: Konrad Eisele <konrad@gaisler.com> [leon up]
[sam: revised patch to provide generic support for leon]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/Kconfig

@@ -73,17 +73,12 @@ config BITS
 	default 32 if SPARC32
 	default 64 if SPARC64
 
-config ARCH_USES_GETTIMEOFFSET
-	bool
-	default y if SPARC32
-
 config GENERIC_CMOS_UPDATE
 	bool
 	default y
 
 config GENERIC_CLOCKEVENTS
-	bool
-	default y if SPARC64
+	def_bool y
 
 config IOMMU_HELPER
 	bool

arch/sparc/include/asm/cpudata_32.h

@@ -14,7 +14,6 @@
 typedef struct {
 	unsigned long udelay_val;
 	unsigned long clock_tick;
-	unsigned int multiplier;
 	unsigned int counter;
 #ifdef CONFIG_SMP
 	unsigned int irq_resched_count;

arch/sparc/include/asm/leon.h

@@ -323,7 +323,7 @@ extern void leon_update_virq_handling(unsigned int virq,
 			      const char *name, int do_ack);
 extern void leon_clear_clock_irq(void);
 extern void leon_load_profile_irq(int cpu, unsigned int limit);
-extern void leon_init_timers(irq_handler_t counter_fn);
+extern void leon_init_timers(void);
 extern void leon_clear_clock_irq(void);
 extern void leon_load_profile_irq(int cpu, unsigned int limit);
 extern void leon_trans_init(struct device_node *dp);

arch/sparc/include/asm/timer_32.h

@@ -8,11 +8,40 @@
 #ifndef _SPARC_TIMER_H
 #define _SPARC_TIMER_H
 
+#include <linux/clocksource.h>
+#include <linux/irqreturn.h>
+
+#include <asm-generic/percpu.h>
+
 #include <asm/cpu_type.h>  /* For SUN4M_NCPUS */
 #include <asm/btfixup.h>
 
+#define SBUS_CLOCK_RATE   2000000 /* 2MHz */
+#define TIMER_VALUE_SHIFT 9
+#define TIMER_VALUE_MASK  0x3fffff
+#define TIMER_LIMIT_BIT   (1 << 31)  /* Bit 31 in Counter-Timer register */
+
+/* The counter timer register has the value offset by 9 bits.
+ * From sun4m manual:
+ * When a counter reaches the value in the corresponding limit register,
+ * the Limit bit is set and the counter is set to 500 nS (i.e. 0x00000200).
+ *
+ * To compensate for this add one to the value.
+ */
+static inline unsigned int timer_value(unsigned int value)
+{
+	return (value + 1) << TIMER_VALUE_SHIFT;
+}
+
 extern __volatile__ unsigned int *master_l10_counter;
 
+extern irqreturn_t notrace timer_interrupt(int dummy, void *dev_id);
+
+#ifdef CONFIG_SMP
+DECLARE_PER_CPU(struct clock_event_device, sparc32_clockevent);
+extern void register_percpu_ce(int cpu);
+#endif
+
 /* FIXME: Make do_[gs]ettimeofday btfixup calls */
 struct timespec;
 BTFIXUPDEF_CALL(int, bus_do_settimeofday, struct timespec *tv)

arch/sparc/include/asm/timex_32.h

@@ -12,5 +12,4 @@
 typedef unsigned long cycles_t;
 #define get_cycles()	(0)
 
-extern u32 (*do_arch_gettimeoffset)(void);
 #endif

arch/sparc/kernel/irq.h

@@ -41,15 +41,32 @@ struct sun4m_irq_global {
 extern struct sun4m_irq_percpu __iomem *sun4m_irq_percpu[SUN4M_NCPUS];
 extern struct sun4m_irq_global __iomem *sun4m_irq_global;
 
+/* The following definitions describe the individual platform features: */
+#define FEAT_L10_CLOCKSOURCE (1 << 0) /* L10 timer is used as a clocksource */
+#define FEAT_L10_CLOCKEVENT  (1 << 1) /* L10 timer is used as a clockevent */
+#define FEAT_L14_ONESHOT     (1 << 2) /* L14 timer clockevent can oneshot */
+
 /*
  * Platform specific configuration
  * The individual platforms assign their platform
  * specifics in their init functions.
  */
 struct sparc_config {
-	void (*init_timers)(irq_handler_t);
+	void (*init_timers)(void);
 	unsigned int (*build_device_irq)(struct platform_device *op,
 	                                 unsigned int real_irq);
+
+	/* generic clockevent features - see FEAT_* above */
+	int features;
+
+	/* clock rate used for clock event timer */
+	int clock_rate;
+
+	/* one period for clock source timer */
+	unsigned int cs_period;
+
+	/* function to obtain offsett for cs period */
+	unsigned int (*get_cycles_offset)(void);
 };
 extern struct sparc_config sparc_config;
 

arch/sparc/kernel/kernel.h

@@ -47,8 +47,6 @@ extern void init_IRQ(void);
 extern void sun4c_init_IRQ(void);
 
 /* sun4m_irq.c */
-extern unsigned int lvl14_resolution;
-
 extern void sun4m_init_IRQ(void);
 extern void sun4m_unmask_profile_irq(void);
 extern void sun4m_clear_profile_irq(int cpu);

arch/sparc/kernel/leon_kernel.c

@@ -10,6 +10,8 @@
 #include <linux/of_platform.h>
 #include <linux/interrupt.h>
 #include <linux/of_device.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
 
 #include <asm/oplib.h>
 #include <asm/timer.h>
@@ -250,7 +252,38 @@ void leon_update_virq_handling(unsigned int virq,
 	irq_set_chip_data(virq, (void *)mask);
 }
 
-void __init leon_init_timers(irq_handler_t counter_fn)
+static u32 leon_cycles_offset(void)
+{
+	u32 rld, val, off;
+	rld = LEON3_BYPASS_LOAD_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].rld);
+	val = LEON3_BYPASS_LOAD_PA(&leon3_gptimer_regs->e[leon3_gptimer_idx].val);
+	off = rld - val;
+	return rld - val;
+}
+
+#ifdef CONFIG_SMP
+
+/* smp clockevent irq */
+irqreturn_t leon_percpu_timer_ce_interrupt(int irq, void *unused)
+{
+	struct clock_event_device *ce;
+	int cpu = smp_processor_id();
+
+	leon_clear_profile_irq(cpu);
+
+	ce = &per_cpu(sparc32_clockevent, cpu);
+
+	irq_enter();
+	if (ce->event_handler)
+		ce->event_handler(ce);
+	irq_exit();
+
+	return IRQ_HANDLED;
+}
+
+#endif /* CONFIG_SMP */
+
+void __init leon_init_timers(void)
 {
 	int irq, eirq;
 	struct device_node *rootnp, *np, *nnp;
@@ -260,6 +293,14 @@ void __init leon_init_timers(irq_handler_t counter_fn)
 	int ampopts;
 	int err;
 
+	sparc_config.get_cycles_offset = leon_cycles_offset;
+	sparc_config.cs_period = 1000000 / HZ;
+	sparc_config.features |= FEAT_L10_CLOCKSOURCE;
+
+#ifndef CONFIG_SMP
+	sparc_config.features |= FEAT_L10_CLOCKEVENT;
+#endif
+
 	leondebug_irq_disable = 0;
 	leon_debug_irqout = 0;
 	master_l10_counter = (unsigned int *)&dummy_master_l10_counter;
@@ -369,7 +410,7 @@ void __init leon_init_timers(irq_handler_t counter_fn)
 		leon_eirq_setup(eirq);
 
 	irq = _leon_build_device_irq(NULL, leon3_gptimer_irq+leon3_gptimer_idx);
-	err = request_irq(irq, counter_fn, IRQF_TIMER, "timer", NULL);
+	err = request_irq(irq, timer_interrupt, IRQF_TIMER, "timer", NULL);
 	if (err) {
 		printk(KERN_ERR "unable to attach timer IRQ%d\n", irq);
 		prom_halt();
@@ -401,7 +442,7 @@ void __init leon_init_timers(irq_handler_t counter_fn)
 	/* Install per-cpu IRQ handler for broadcasted ticker */
 	irq = leon_build_device_irq(leon3_ticker_irq, handle_percpu_irq,
 				    "per-cpu", 0);
-	err = request_irq(irq, leon_percpu_timer_interrupt,
+	err = request_irq(irq, leon_percpu_timer_ce_interrupt,
 			  IRQF_PERCPU | IRQF_TIMER, "ticker",
 			  NULL);
 	if (err) {
@@ -428,7 +469,6 @@ void leon_clear_clock_irq(void)
 
 void leon_load_profile_irq(int cpu, unsigned int limit)
 {
-	BUG();
 }
 
 void __init leon_trans_init(struct device_node *dp)
@@ -496,6 +536,7 @@ void __init leon_init_IRQ(void)
 {
 	sparc_config.init_timers      = leon_init_timers;
 	sparc_config.build_device_irq = _leon_build_device_irq;
+	sparc_config.clock_rate = 1000000;
 
 	BTFIXUPSET_CALL(clear_clock_irq, leon_clear_clock_irq,
 			BTFIXUPCALL_NORM);

arch/sparc/kernel/leon_smp.c

@@ -23,6 +23,8 @@
 #include <linux/pm.h>
 #include <linux/delay.h>
 #include <linux/gfp.h>
+#include <linux/cpu.h>
+#include <linux/clockchips.h>
 
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
@@ -42,6 +44,7 @@
 #include <asm/asi.h>
 #include <asm/leon.h>
 #include <asm/leon_amba.h>
+#include <asm/timer.h>
 
 #include "kernel.h"
 
@@ -68,8 +71,6 @@ static inline unsigned long do_swap(volatile unsigned long *ptr,
 	return val;
 }
 
-static void smp_setup_percpu_timer(void);
-
 void __cpuinit leon_callin(void)
 {
 	int cpuid = hard_smpleon_processor_id();
@@ -79,7 +80,7 @@ void __cpuinit leon_callin(void)
 	leon_configure_cache_smp();
 
 	/* Get our local ticker going. */
-	smp_setup_percpu_timer();
+	register_percpu_ce(cpuid);
 
 	calibrate_delay();
 	smp_store_cpu_info(cpuid);
@@ -196,7 +197,6 @@ void __init leon_boot_cpus(void)
 	leon_smp_setbroadcast(1 << LEON3_IRQ_TICKER);
 
 	leon_configure_cache_smp();
-	smp_setup_percpu_timer();
 	local_flush_cache_all();
 
 }
@@ -489,32 +489,6 @@ void leon_cross_call_irq(void)
 	ccall_info.processors_out[i] = 1;
 }
 
-irqreturn_t leon_percpu_timer_interrupt(int irq, void *unused)
-{
-	int cpu = smp_processor_id();
-
-	leon_clear_profile_irq(cpu);
-
-	profile_tick(CPU_PROFILING);
-
-	if (!--prof_counter(cpu)) {
-		int user = user_mode(get_irq_regs());
-
-		update_process_times(user);
-
-		prof_counter(cpu) = prof_multiplier(cpu);
-	}
-
-	return IRQ_HANDLED;
-}
-
-static void __init smp_setup_percpu_timer(void)
-{
-	int cpu = smp_processor_id();
-
-	prof_counter(cpu) = prof_multiplier(cpu) = 1;
-}
-
 void __init leon_blackbox_id(unsigned *addr)
 {
 	int rd = *addr & 0x3e000000;

arch/sparc/kernel/pcic.c

@@ -703,31 +703,28 @@ static void pcic_clear_clock_irq(void)
 	pcic_timer_dummy = readl(pcic0.pcic_regs+PCI_SYS_LIMIT);
 }
 
-static irqreturn_t pcic_timer_handler (int irq, void *h)
+/* CPU frequency is 100 MHz, timer increments every 4 CPU clocks */
+#define USECS_PER_JIFFY  (1000000 / HZ)
+#define TICK_TIMER_LIMIT ((100 * 1000000 / 4) / HZ)
+
+static unsigned int pcic_cycles_offset(void)
 {
-	pcic_clear_clock_irq();
-	xtime_update(1);
-#ifndef CONFIG_SMP
-	update_process_times(user_mode(get_irq_regs()));
-#endif
-	return IRQ_HANDLED;
-}
+	u32 value, count;
 
-#define USECS_PER_JIFFY  10000  /* We have 100HZ "standard" timer for sparc */
-#define TICK_TIMER_LIMIT ((100*1000000/4)/100)
+	value = readl(pcic0.pcic_regs + PCI_SYS_COUNTER);
+	count = value & ~PCI_SYS_COUNTER_OVERFLOW;
 
-u32 pci_gettimeoffset(void)
-{
+	if (value & PCI_SYS_COUNTER_OVERFLOW)
+		count += TICK_TIMER_LIMIT;
 	/*
-	 * We divide all by 100
+	 * We divide all by HZ
 	 * to have microsecond resolution and to avoid overflow
 	 */
-	unsigned long count =
-	    readl(pcic0.pcic_regs+PCI_SYS_COUNTER) & ~PCI_SYS_COUNTER_OVERFLOW;
-	count = ((count/100)*USECS_PER_JIFFY) / (TICK_TIMER_LIMIT/100);
-	return count * 1000;
-}
+	count = ((count / HZ) * USECS_PER_JIFFY) / (TICK_TIMER_LIMIT / HZ);
 
+	/* Coordinate with the fact that timer_cs rate is 2MHz */
+	return count * 2;
+}
 
 void __init pci_time_init(void)
 {
@@ -736,9 +733,16 @@ void __init pci_time_init(void)
 	int timer_irq, irq;
 	int err;
 
-	do_arch_gettimeoffset = pci_gettimeoffset;
-
-	btfixup();
+#ifndef CONFIG_SMP
+	/*
+	 * It's in SBUS dimension, because timer_cs is in this dimension.
+	 * We take into account this in pcic_cycles_offset()
+	 */
+	timer_cs_period = SBUS_CLOCK_RATE / HZ;
+	sparc_config.features |= FEAT_L10_CLOCKEVENT;
+#endif
+	sparc_config.features |= FEAT_L10_CLOCKSOURCE;
+	sparc_config.get_cycles_offset = pcic_cycles_offset;
 
 	writel (TICK_TIMER_LIMIT, pcic->pcic_regs+PCI_SYS_LIMIT);
 	/* PROM should set appropriate irq */
@@ -747,7 +751,7 @@ void __init pci_time_init(void)
 	writel (PCI_COUNTER_IRQ_SET(timer_irq, 0),
 		pcic->pcic_regs+PCI_COUNTER_IRQ);
 	irq = pcic_build_device_irq(NULL, timer_irq);
-	err = request_irq(irq, pcic_timer_handler,
+	err = request_irq(irq, timer_interrupt,
 			  IRQF_TIMER, "timer", NULL);
 	if (err) {
 		prom_printf("time_init: unable to attach IRQ%d\n", timer_irq);