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[RFC PATCH 4/7] Alchemy: TOY counter clocksource / clockevent support.

To: linux-mips@linux-mips.org
Subject: [RFC PATCH 4/7] Alchemy: TOY counter clocksource / clockevent support.
From: Manuel Lauss <mano@roarinelk.homelinux.net>
Date: Tue, 24 Jun 2008 22:11:24 +0200
In-reply-to: <20080624200810.GA2463@roarinelk.homelinux.net>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20080624200810.GA2463@roarinelk.homelinux.net>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.16 (2007-06-09)
From: Manuel Lauss <mano@roarinelk.homelinux.net>

Add support for the TOY (32kHz) counter as clocksource / clockevent
device to enable use of the 'wait' instruction.
If the 32kHz clock supply is unstable/stopped during init, the CP0 counter
clocksource/event will be used instead.

Signed-off-by: Manuel Lauss <mano@roarinelk.homelinux.net>
---
 arch/mips/au1000/Kconfig        |    4 +-
 arch/mips/au1000/common/power.c |    7 +-
 arch/mips/au1000/common/setup.c |    6 -
 arch/mips/au1000/common/time.c  |  333 +++++++++++++++++++--------------------
 4 files changed, 170 insertions(+), 180 deletions(-)

diff --git a/arch/mips/au1000/Kconfig b/arch/mips/au1000/Kconfig
index 1fe97cc..c689cd6 100644
--- a/arch/mips/au1000/Kconfig
+++ b/arch/mips/au1000/Kconfig
@@ -128,8 +128,8 @@ config SOC_AU1200
 config SOC_AU1X00
        bool
        select 64BIT_PHYS_ADDR
-       select CEVT_R4K
-       select CSRC_R4K
+       select CEVT_R4K_LIB
+       select CSRC_R4K_LIB
        select IRQ_CPU
        select SYS_HAS_CPU_MIPS32_R1
        select SYS_SUPPORTS_32BIT_KERNEL
diff --git a/arch/mips/au1000/common/power.c b/arch/mips/au1000/common/power.c
index 2166b9e..751b4b3 100644
--- a/arch/mips/au1000/common/power.c
+++ b/arch/mips/au1000/common/power.c
@@ -87,7 +87,11 @@ static unsigned int  sleep_static_memctlr[4][3];
 #define SLEEP_TEST_TIMEOUT 1
 #ifdef SLEEP_TEST_TIMEOUT
 static int sleep_ticks;
-void wakeup_counter0_set(int ticks);
+static void wakeup_counter0_set(int ticks)
+{
+       au_writel(au_readl(SYS_TOYREAD) + ticks, SYS_TOYMATCH2);
+       au_sync();
+}
 #endif
 
 static void save_core_regs(void)
@@ -185,7 +189,6 @@ static void restore_core_regs(void)
        }
 
        restore_au1xxx_intctl();
-       wakeup_counter0_adjust();
 }
 
 unsigned long suspend_mode;
diff --git a/arch/mips/au1000/common/setup.c b/arch/mips/au1000/common/setup.c
index 0d78f50..66f4fd6 100644
--- a/arch/mips/au1000/common/setup.c
+++ b/arch/mips/au1000/common/setup.c
@@ -93,12 +93,6 @@ void __init plat_mem_setup(void)
        ioport_resource.end = IOPORT_RESOURCE_END;
        iomem_resource.start = IOMEM_RESOURCE_START;
        iomem_resource.end = IOMEM_RESOURCE_END;
-
-       while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_E0S);
-       au_writel(SYS_CNTRL_E0 | SYS_CNTRL_EN0, SYS_COUNTER_CNTRL);
-       au_sync();
-       while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T0S);
-       au_writel(0, SYS_TOYTRIM);
 }
 
 #if defined(CONFIG_64BIT_PHYS_ADDR)
diff --git a/arch/mips/au1000/common/time.c b/arch/mips/au1000/common/time.c
index 1518570..b6c7833 100644
--- a/arch/mips/au1000/common/time.c
+++ b/arch/mips/au1000/common/time.c
@@ -23,131 +23,29 @@
  *
  * ########################################################################
  *
- * Setting up the clock on the MIPS boards.
+ * Clocksource/event using the Au1000 TOY counter.
+ * compared to the C0 timer, the TOY is a very lousy clocksource and
+ * hrtimers are definitely unusable with it.  But it enables the use
+ * of the 'wait' instructions for some power-savings during idle times.
  *
- * We provide the clock interrupt processing and the timer offset compute
- * functions.  If CONFIG_PM is selected, we also ensure the 32KHz timer is
- * available.  -- Dan
+ * If the TOY is unusable, the CP0 counter will be installed instead,
+ * and use of 'wait' prohibited.
  */
 
-#include <linux/types.h>
+#include <linux/clocksource.h>
 #include <linux/init.h>
+#include <linux/interrupt.h>
 #include <linux/spinlock.h>
+#include <linux/types.h>
 
 #include <asm/mipsregs.h>
 #include <asm/time.h>
 #include <asm/mach-au1x00/au1000.h>
 
-static int no_au1xxx_32khz;
 extern int allow_au1k_wait; /* default off for CP0 Counter */
 
-#ifdef CONFIG_PM
-#if HZ < 100 || HZ > 1000
-#error "unsupported HZ value! Must be in [100,1000]"
-#endif
-#define MATCH20_INC (328 * 100 / HZ) /* magic number 328 is for HZ=100... */
-static unsigned long last_pc0, last_match20;
-#endif
-
 static DEFINE_SPINLOCK(time_lock);
 
-unsigned long wtimer;
-
-#ifdef CONFIG_PM
-static irqreturn_t counter0_irq(int irq, void *dev_id)
-{
-       unsigned long pc0;
-       int time_elapsed;
-       static int jiffie_drift;
-
-       if (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_M20) {
-               /* should never happen! */
-               printk(KERN_WARNING "counter 0 w status error\n");
-               return IRQ_NONE;
-       }
-
-       pc0 = au_readl(SYS_TOYREAD);
-       if (pc0 < last_match20)
-               /* counter overflowed */
-               time_elapsed = (0xffffffff - last_match20) + pc0;
-       else
-               time_elapsed = pc0 - last_match20;
-
-       while (time_elapsed > 0) {
-               do_timer(1);
-#ifndef CONFIG_SMP
-               update_process_times(user_mode(get_irq_regs()));
-#endif
-               time_elapsed -= MATCH20_INC;
-               last_match20 += MATCH20_INC;
-               jiffie_drift++;
-       }
-
-       last_pc0 = pc0;
-       au_writel(last_match20 + MATCH20_INC, SYS_TOYMATCH2);
-       au_sync();
-
-       /*
-        * Our counter ticks at 10.009765625 ms/tick, we we're running
-        * almost 10 uS too slow per tick.
-        */
-
-       if (jiffie_drift >= 999) {
-               jiffie_drift -= 999;
-               do_timer(1); /* increment jiffies by one */
-#ifndef CONFIG_SMP
-               update_process_times(user_mode(get_irq_regs()));
-#endif
-       }
-
-       return IRQ_HANDLED;
-}
-
-struct irqaction counter0_action = {
-       .handler        = counter0_irq,
-       .flags          = IRQF_DISABLED,
-       .name           = "alchemy-toy",
-       .dev_id         = NULL,
-};
-
-/* When we wakeup from sleep, we have to "catch up" on all of the
- * timer ticks we have missed.
- */
-void wakeup_counter0_adjust(void)
-{
-       unsigned long pc0;
-       int time_elapsed;
-
-       pc0 = au_readl(SYS_TOYREAD);
-       if (pc0 < last_match20)
-               /* counter overflowed */
-               time_elapsed = (0xffffffff - last_match20) + pc0;
-       else
-               time_elapsed = pc0 - last_match20;
-
-       while (time_elapsed > 0) {
-               time_elapsed -= MATCH20_INC;
-               last_match20 += MATCH20_INC;
-       }
-
-       last_pc0 = pc0;
-       au_writel(last_match20 + MATCH20_INC, SYS_TOYMATCH2);
-       au_sync();
-
-}
-
-/* This is just for debugging to set the timer for a sleep delay. */
-void wakeup_counter0_set(int ticks)
-{
-       unsigned long pc0;
-
-       pc0 = au_readl(SYS_TOYREAD);
-       last_pc0 = pc0;
-       au_writel(last_match20 + (MATCH20_INC * ticks), SYS_TOYMATCH2);
-       au_sync();
-}
-#endif
-
 /*
  * I haven't found anyone that doesn't use a 12 MHz source clock,
  * but just in case.....
@@ -162,37 +60,15 @@ void wakeup_counter0_set(int ticks)
  * this advertised speed will introduce error and sometimes not work
  * properly.  This function is futher convoluted to still allow configurations
  * to do that in case they have really, really old silicon with a
- * write-only PLL register, that we need the 32 KHz when power management
- * "wait" is enabled, and we need to detect if the 32 KHz isn't present
- * but requested......got it? :-)              -- Dan
+ * write-only PLL register.                    -- Dan
  */
 unsigned long calc_clock(void)
 {
        unsigned long cpu_speed;
        unsigned long flags;
-       unsigned long counter;
 
        spin_lock_irqsave(&time_lock, flags);
 
-       /* Power management cares if we don't have a 32 KHz counter. */
-       no_au1xxx_32khz = 0;
-       counter = au_readl(SYS_COUNTER_CNTRL);
-       if (counter & SYS_CNTRL_E0) {
-               int trim_divide = 16;
-
-               au_writel(counter | SYS_CNTRL_EN1, SYS_COUNTER_CNTRL);
-
-               while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T1S);
-               /* RTC now ticks at 32.768/16 kHz */
-               au_writel(trim_divide - 1, SYS_RTCTRIM);
-               while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T1S);
-
-               while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C1S);
-               au_writel(0, SYS_TOYWRITE);
-               while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C1S);
-       } else
-               no_au1xxx_32khz = 1;
-
        /*
         * On early Au1000, sys_cpupll was write-only. Since these
         * silicon versions of Au1000 are not sold by AMD, we don't bend
@@ -206,60 +82,177 @@ unsigned long calc_clock(void)
 #endif
        else
                cpu_speed = (au_readl(SYS_CPUPLL) & 0x0000003f) * 
AU1000_SRC_CLK;
+
        /* On Alchemy CPU:counter ratio is 1:1 */
        mips_hpt_frequency = cpu_speed;
        /* Equation: Baudrate = CPU / (SD * 2 * CLKDIV * 16) */
        set_au1x00_uart_baud_base(cpu_speed / (2 * 
((int)(au_readl(SYS_POWERCTRL)
                                                          & 0x03) + 2) * 16));
+
        spin_unlock_irqrestore(&time_lock, flags);
+
        return cpu_speed;
 }
 
+/* Test and initialize TOY/RTC counters.  It is assumed bootloader
+ * and/or platform init code have already configured the 32kHz input
+ * sources for each (GPIO or dedicated crystal input).
+ */
+static int au1x_init_toy(void)
+{
+       unsigned long i, j;
+
+       /* enable 32kHz input */
+       i = au_readl(SYS_COUNTER_CNTRL);
+       au_writel(i | SYS_CNTRL_E0, SYS_COUNTER_CNTRL);
+       au_sync();
+
+       /* wait a bit for clock to stabilize throughout TOY unit */
+       for (j = 0x000fffff; j; j--)
+               asm volatile ("nop");
+
+       /* check 32S flag: clock detected? */
+       if (!(au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_32S))
+               goto out_err;
+
+       /* The 32S bit is unrealiable -- it stays set even when clock
+        * is stopped.  Instead, read the TOY counter, it _should_ not
+        * increased without some sort of clock.
+        */
+       i = au_readl(SYS_TOYREAD);
+       for (j = 0x7ffff; j; j--)
+               asm volatile ("nop");
+       j = au_readl(SYS_TOYREAD);
+       if (i == j)
+               goto out_err;
+
+       /* setup counter 0 (TOY) */
+       while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T0S)
+               asm volatile ("nop");
+       au_writel(0, SYS_TOYTRIM);      /* keep ticking at 32kHz */
+       au_sync();
+       while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T0S)
+               asm volatile ("nop");
+
+       while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C0S)
+               asm volatile ("nop");
+       au_writel(0, SYS_TOYWRITE);
+       au_sync();
+       while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C0S)
+               asm volatile ("nop");
+
+       /* setup counter 1 (RTC) too */
+       while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T1S)
+               asm volatile ("nop");
+       /* RTC now ticks at 32.768/16 kHz */
+       au_writel(15, SYS_RTCTRIM);
+       au_sync();
+       while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T1S)
+               asm volatile ("nop");
+
+       while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C1S)
+               asm volatile ("nop");
+       au_writel(0, SYS_RTCWRITE);
+       au_sync();
+       while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C1S)
+               asm volatile ("nop");
+
+       return 0;
+
+out_err:
+       /* no fun in TOY land */
+       au_writel(i & ~SYS_CNTRL_E0, SYS_COUNTER_CNTRL);
+       au_sync();
+       return -ENXIO;
+}
+
+static cycle_t au1x_toy_read(void)
+{
+       return au_readl(SYS_TOYREAD);
+}
+
+static struct clocksource clocksource_toy = {
+       .name           = "Au1000-TOY",
+       .read           = au1x_toy_read,
+       .mask           = CLOCKSOURCE_MASK(32),
+       .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int toymatch2_set_next_event(unsigned long delta,
+                               struct clock_event_device *cd)
+{
+       au_writel(au_readl(SYS_TOYREAD) + delta, SYS_TOYMATCH2);
+       au_sync();
+       return 0;
+}
+
+static void toymatch2_set_mode(enum clock_event_mode mode,
+                               struct clock_event_device *cd)
+{
+}
+
+static irqreturn_t toymatch2_irq(int irq, void *dev_id)
+{
+       struct clock_event_device *cd = dev_id;
+       cd->event_handler(cd);
+       return IRQ_HANDLED;
+}
+
+static struct clock_event_device ced_toy_match2 = {
+       .name           = "Au1000-TOY2",
+       .features       = CLOCK_EVT_FEAT_ONESHOT,
+       .rating         = 100,
+       .irq            = AU1000_TOY_MATCH2_INT,
+       .set_next_event = toymatch2_set_next_event,
+       .set_mode       = toymatch2_set_mode,
+       .cpumask        = CPU_MASK_ALL,
+};
+
+struct irqaction toymatch2_action = {
+       .handler        = toymatch2_irq,
+       .flags          = IRQF_DISABLED,
+       .name           = "toymatch2",
+       .dev_id         = &ced_toy_match2,
+};
+
+static void toymatch2_clockevent_init(void)
+{
+       struct clock_event_device *cd = &ced_toy_match2;
+
+       cd->mult        = div_sc(32768, NSEC_PER_SEC, 32);
+       cd->shift       = 32;
+       cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);
+
+       /* 0x140 -- boots AND BogoMIPS detection is pretty accurate too */
+       cd->min_delta_ns = clockevent_delta2ns(0x140, cd);
+       clockevents_register_device(cd);
+       setup_irq(AU1000_TOY_MATCH2_INT, &toymatch2_action);
+}
+
 void __init plat_time_init(void)
 {
        unsigned int est_freq = calc_clock();
 
        est_freq += 5000;    /* round */
-       est_freq -= est_freq%10000;
+       est_freq -= est_freq % 10000;
        printk(KERN_INFO "(PRId %08x) @ %u.%02u MHz\n", read_c0_prid(),
               est_freq / 1000000, ((est_freq % 1000000) * 100) / 1000000);
        set_au1x00_speed(est_freq);
 
-#ifdef CONFIG_PM
-       /*
-        * setup counter 0, since it keeps ticking after a
-        * 'wait' instruction has been executed. The CP0 timer and
-        * counter 1 do NOT continue running after 'wait'
-        *
-        * It's too early to call request_irq() here, so we handle
-        * counter 0 interrupt as a special irq and it doesn't show
-        * up under /proc/interrupts.
-        *
-        * Check to ensure we really have a 32 KHz oscillator before
-        * we do this.
-        */
-       if (no_au1xxx_32khz)
-               printk(KERN_WARNING "WARNING: no 32KHz clock found.\n");
-       else {
-               while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C0S);
-               au_writel(0, SYS_TOYWRITE);
-               while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C0S);
-
-               au_writel(au_readl(SYS_WAKEMSK) | (1 << 8), SYS_WAKEMSK);
-               au_writel(~0, SYS_WAKESRC);
-               au_sync();
-               while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_M20);
-
-               /* Setup match20 to interrupt once every HZ */
-               last_pc0 = last_match20 = au_readl(SYS_TOYREAD);
-               au_writel(last_match20 + MATCH20_INC, SYS_TOYMATCH2);
-               au_sync();
-               while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_M20);
-               setup_irq(AU1000_TOY_MATCH2_INT, &counter0_action);
-
-               /* We can use the real 'wait' instruction. */
+       if (au1x_init_toy()) {
+               r4k_clockevent_init();
+               init_r4k_clocksource();
+
+               /* 'wait' stops the CP0 counter */
+               allow_au1k_wait = 0;
+       } else {
+               toymatch2_clockevent_init();
+
+               clocksource_toy.rating = 100;
+               clocksource_set_clock(&clocksource_toy, 32768);
+               clocksource_register(&clocksource_toy);
+               printk(KERN_INFO "Au1000 TOY clocksource installed\n");
+
                allow_au1k_wait = 1;
        }
-
-#endif
 }
-- 
1.5.5.4


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