This patch add a clockevent/clocksource using PWM Timer for Loongson1B,
which is based on earlier work by Tang, Haifeng.
Signed-off-by: Kelvin Cheung <keguang.zhang@xxxxxxxxx>
---
arch/mips/loongson1/Kconfig | 41 ++++++-
arch/mips/loongson1/common/Makefile | 2 +-
arch/mips/loongson1/common/clock.c | 28 -----
arch/mips/loongson1/common/time.c | 226 ++++++++++++++++++++++++++++++++++++
4 files changed, 266 insertions(+), 31 deletions(-)
delete mode 100644 arch/mips/loongson1/common/clock.c
create mode 100644 arch/mips/loongson1/common/time.c
diff --git a/arch/mips/loongson1/Kconfig b/arch/mips/loongson1/Kconfig
index 4ed9744..a2b796e 100644
--- a/arch/mips/loongson1/Kconfig
+++ b/arch/mips/loongson1/Kconfig
@@ -5,8 +5,8 @@ choice
config LOONGSON1_LS1B
bool "Loongson LS1B board"
- select CEVT_R4K
- select CSRC_R4K
+ select CEVT_R4K if !MIPS_EXTERNAL_TIMER
+ select CSRC_R4K if !MIPS_EXTERNAL_TIMER
select SYS_HAS_CPU_LOONGSON1B
select DMA_NONCOHERENT
select BOOT_ELF32
@@ -21,4 +21,41 @@ config LOONGSON1_LS1B
endchoice
+menuconfig CEVT_CSRC_LS1X
+ bool "Use PWM Timer for clockevent/clocksource"
+ select MIPS_EXTERNAL_TIMER
+ depends on CPU_LOONGSON1
+ help
+ This option changes the default clockevent/clocksource to PWM Timer,
+ and is required by Loongson1 CPUFreq support.
+
+ If unsure, say N.
+
+choice
+ prompt "Select clockevent/clocksource"
+ depends on CEVT_CSRC_LS1X
+ default TIMER_USE_PWM0
+
+config TIMER_USE_PWM0
+ bool "Use PWM Timer 0"
+ help
+ Use PWM Timer 0 as the default clockevent/clocksourcer.
+
+config TIMER_USE_PWM1
+ bool "Use PWM Timer 1"
+ help
+ Use PWM Timer 1 as the default clockevent/clocksourcer.
+
+config TIMER_USE_PWM2
+ bool "Use PWM Timer 2"
+ help
+ Use PWM Timer 2 as the default clockevent/clocksourcer.
+
+config TIMER_USE_PWM3
+ bool "Use PWM Timer 3"
+ help
+ Use PWM Timer 3 as the default clockevent/clocksourcer.
+
+endchoice
+
endif # MACH_LOONGSON1
diff --git a/arch/mips/loongson1/common/Makefile b/arch/mips/loongson1/common/Makefile
index b279770..723b4ce 100644
--- a/arch/mips/loongson1/common/Makefile
+++ b/arch/mips/loongson1/common/Makefile
@@ -2,4 +2,4 @@
# Makefile for common code of loongson1 based machines.
#
-obj-y += clock.o irq.o platform.o prom.o reset.o setup.o
+obj-y += time.o irq.o platform.o prom.o reset.o setup.o
diff --git a/arch/mips/loongson1/common/clock.c b/arch/mips/loongson1/common/clock.c
deleted file mode 100644
index b4437f1..0000000
--- a/arch/mips/loongson1/common/clock.c
+++ /dev/null
@@ -1,28 +0,0 @@
-/*
- * Copyright (c) 2011 Zhang, Keguang <keguang.zhang@xxxxxxxxx>
- *
- * 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/clk.h>
-#include <linux/err.h>
-#include <asm/time.h>
-#include <platform.h>
-
-void __init plat_time_init(void)
-{
- struct clk *clk;
-
- /* Initialize LS1X clocks */
- ls1x_clk_init();
-
- /* setup mips r4k timer */
- clk = clk_get(NULL, "cpu");
- if (IS_ERR(clk))
- panic("unable to get cpu clock, err=%ld", PTR_ERR(clk));
-
- mips_hpt_frequency = clk_get_rate(clk) / 2;
-}
diff --git a/arch/mips/loongson1/common/time.c b/arch/mips/loongson1/common/time.c
new file mode 100644
index 0000000..df0f850
--- /dev/null
+++ b/arch/mips/loongson1/common/time.c
@@ -0,0 +1,226 @@
+/*
+ * Copyright (c) 2014 Zhang, Keguang <keguang.zhang@xxxxxxxxx>
+ *
+ * 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/clk.h>
+#include <linux/interrupt.h>
+#include <asm/time.h>
+
+#include <loongson1.h>
+#include <platform.h>
+
+#ifdef CONFIG_CEVT_CSRC_LS1X
+
+#if defined(CONFIG_TIMER_USE_PWM1)
+#define LS1X_TIMER_BASE LS1X_PWM1_BASE
+#define LS1X_TIMER_IRQ LS1X_PWM1_IRQ
+
+#elif defined(CONFIG_TIMER_USE_PWM2)
+#define LS1X_TIMER_BASE LS1X_PWM2_BASE
+#define LS1X_TIMER_IRQ LS1X_PWM2_IRQ
+
+#elif defined(CONFIG_TIMER_USE_PWM3)
+#define LS1X_TIMER_BASE LS1X_PWM3_BASE
+#define LS1X_TIMER_IRQ LS1X_PWM3_IRQ
+
+#else
+#define LS1X_TIMER_BASE LS1X_PWM0_BASE
+#define LS1X_TIMER_IRQ LS1X_PWM0_IRQ
+#endif
+
+DEFINE_RAW_SPINLOCK(ls1x_timer_lock);
+
+static void __iomem *timer_base;
+static uint32_t ls1x_jiffies_per_tick;
+
+static inline void ls1x_pwmtimer_set_period(uint32_t period)
+{
+ __raw_writel(period, timer_base + PWM_HRC);
+ __raw_writel(period, timer_base + PWM_LRC);
+}
+
+static inline void ls1x_pwmtimer_restart(void)
+{
+ __raw_writel(0x0, timer_base + PWM_CNT);
+ __raw_writel(INT_EN | CNT_EN, timer_base + PWM_CTRL);
+}
+
+void __init ls1x_pwmtimer_init(void)
+{
+ timer_base = ioremap(LS1X_TIMER_BASE, 0xf);
+ if (!timer_base)
+ panic("Failed to remap timer registers");
+
+ ls1x_jiffies_per_tick = DIV_ROUND_CLOSEST(mips_hpt_frequency, HZ);
+
+ ls1x_pwmtimer_set_period(ls1x_jiffies_per_tick);
+ ls1x_pwmtimer_restart();
+}
+
+static cycle_t ls1x_clocksource_read(struct clocksource *cs)
+{
+ unsigned long flags;
+ int count;
+ u32 jifs;
+ static int old_count;
+ static u32 old_jifs;
+
+ raw_spin_lock_irqsave(&ls1x_timer_lock, flags);
+ /*
+ * Although our caller may have the read side of xtime_lock,
+ * this is now a seqlock, and we are cheating in this routine
+ * by having side effects on state that we cannot undo if
+ * there is a collision on the seqlock and our caller has to
+ * retry. (Namely, old_jifs and old_count.) So we must treat
+ * jiffies as volatile despite the lock. We read jiffies
+ * before latching the timer count to guarantee that although
+ * the jiffies value might be older than the count (that is,
+ * the counter may underflow between the last point where
+ * jiffies was incremented and the point where we latch the
+ * count), it cannot be newer.
+ */
+ jifs = jiffies;
+ /* read the count */
+ count = __raw_readl(timer_base + PWM_CNT);
+
+ /*
+ * It's possible for count to appear to go the wrong way for this
+ * reason:
+ *
+ * The timer counter underflows, but we haven't handled the resulting
+ * interrupt and incremented jiffies yet.
+ *
+ * Previous attempts to handle these cases intelligently were buggy, so
+ * we just do the simple thing now.
+ */
+ if (count < old_count && jifs == old_jifs)
+ count = old_count;
+
+ old_count = count;
+ old_jifs = jifs;
+
+ raw_spin_unlock_irqrestore(&ls1x_timer_lock, flags);
+
+ return (cycle_t) (jifs * ls1x_jiffies_per_tick) + count;
+}
+
+static struct clocksource ls1x_clocksource = {
+ .name = "ls1x-pwmtimer",
+ .read = ls1x_clocksource_read,
+ .mask = CLOCKSOURCE_MASK(24),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static irqreturn_t ls1x_clockevent_isr(int irq, void *devid)
+{
+ struct clock_event_device *cd = devid;
+
+ ls1x_pwmtimer_restart();
+ cd->event_handler(cd);
+
+ return IRQ_HANDLED;
+}
+
+static void ls1x_clockevent_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *cd)
+{
+ raw_spin_lock(&ls1x_timer_lock);
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ ls1x_pwmtimer_set_period(ls1x_jiffies_per_tick);
+ ls1x_pwmtimer_restart();
+ case CLOCK_EVT_MODE_RESUME:
+ __raw_writel(INT_EN | CNT_EN, timer_base + PWM_CTRL);
+ break;
+ case CLOCK_EVT_MODE_ONESHOT:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ __raw_writel(__raw_readl(timer_base + PWM_CTRL) & ~CNT_EN,
+ timer_base + PWM_CTRL);
+ break;
+ default:
+ break;
+ }
+ raw_spin_unlock(&ls1x_timer_lock);
+}
+
+static int ls1x_clockevent_set_next(unsigned long evt,
+ struct clock_event_device *cd)
+{
+ raw_spin_lock(&ls1x_timer_lock);
+ ls1x_pwmtimer_set_period(evt);
+ ls1x_pwmtimer_restart();
+ raw_spin_unlock(&ls1x_timer_lock);
+
+ return 0;
+}
+
+static struct clock_event_device ls1x_clockevent = {
+ .name = "ls1x-pwmtimer",
+ .features = CLOCK_EVT_FEAT_PERIODIC,
+ .rating = 300,
+ .irq = LS1X_TIMER_IRQ,
+ .set_next_event = ls1x_clockevent_set_next,
+ .set_mode = ls1x_clockevent_set_mode,
+};
+
+static struct irqaction ls1x_pwmtimer_irqaction = {
+ .name = "ls1x-pwmtimer",
+ .handler = ls1x_clockevent_isr,
+ .dev_id = &ls1x_clockevent,
+ .flags = IRQF_PERCPU | IRQF_TIMER,
+};
+
+static void __init ls1x_time_init(void)
+{
+ struct clock_event_device *cd = &ls1x_clockevent;
+ int ret;
+
+ if (!mips_hpt_frequency)
+ panic("Invalid timer clock rate");
+
+ ls1x_pwmtimer_init();
+
+ clockevent_set_clock(cd, mips_hpt_frequency);
+ cd->max_delta_ns = clockevent_delta2ns(0xffffff, cd);
+ cd->min_delta_ns = clockevent_delta2ns(0x000300, cd);
+ cd->cpumask = cpumask_of(smp_processor_id());
+ clockevents_register_device(cd);
+
+ ls1x_clocksource.rating = 200 + mips_hpt_frequency / 10000000;
+ ret = clocksource_register_hz(&ls1x_clocksource, mips_hpt_frequency);
+ if (ret)
+ panic(KERN_ERR "Failed to register clocksource: %d\n", ret);
+
+ setup_irq(LS1X_TIMER_IRQ, &ls1x_pwmtimer_irqaction);
+}
+#endif /* CONFIG_CEVT_CSRC_LS1X */
+
+void __init plat_time_init(void)
+{
+ struct clk *clk = NULL;
+
+ /* initialize LS1X clocks */
+ ls1x_clk_init();
+
+#ifdef CONFIG_CEVT_CSRC_LS1X
+ /* setup LS1X PWM timer */
+ clk = clk_get(NULL, "ls1x_pwmtimer");
+ if (IS_ERR(clk))
+ panic("unable to get timer clock, err=%ld", PTR_ERR(clk));
+
+ mips_hpt_frequency = clk_get_rate(clk);
+ ls1x_time_init();
+#else
+ /* setup mips r4k timer */
+ clk = clk_get(NULL, "cpu_clk");
+ if (IS_ERR(clk))
+ panic("unable to get cpu clock, err=%ld", PTR_ERR(clk));
+
+ mips_hpt_frequency = clk_get_rate(clk) / 2;
+#endif /* CONFIG_CEVT_CSRC_LS1X */
+}
--
1.9.1
