1 files changed, 305 insertions, 0 deletions
diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
new file mode 100644
index 000000000000..17facda52605
--- /dev/null
+++ b/drivers/clocksource/tcb_clksrc.c
@@ -0,0 +1,305 @@
+#include <linux/init.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/atmel_tc.h>
+
+
+/*
+ * We're configured to use a specific TC block, one that's not hooked
+ * up to external hardware, to provide a time solution:
+ *
+ *   - Two channels combine to create a free-running 32 bit counter
+ *     with a base rate of 5+ MHz, packaged as a clocksource (with
+ *     resolution better than 200 nsec).
+ *
+ *   - The third channel may be used to provide a 16-bit clockevent
+ *     source, used in either periodic or oneshot mode.  This runs
+ *     at 32 KiHZ, and can handle delays of up to two seconds.
+ *
+ * A boot clocksource and clockevent source are also currently needed,
+ * unless the relevant platforms (ARM/AT91, AVR32/AT32) are changed so
+ * this code can be used when init_timers() is called, well before most
+ * devices are set up.  (Some low end AT91 parts, which can run uClinux,
+ * have only the timers in one TC block... they currently don't support
+ * the tclib code, because of that initialization issue.)
+ *
+ * REVISIT behavior during system suspend states... we should disable
+ * all clocks and save the power.  Easily done for clockevent devices,
+ * but clocksources won't necessarily get the needed notifications.
+ * For deeper system sleep states, this will be mandatory...
+ */
+
+static void __iomem *tcaddr;
+
+static cycle_t tc_get_cycles(void)
+{
+	unsigned long	flags;
+	u32		lower, upper;
+
+	raw_local_irq_save(flags);
+	do {
+		upper = __raw_readl(tcaddr + ATMEL_TC_REG(1, CV));
+		lower = __raw_readl(tcaddr + ATMEL_TC_REG(0, CV));
+	} while (upper != __raw_readl(tcaddr + ATMEL_TC_REG(1, CV)));
+
+	raw_local_irq_restore(flags);
+	return (upper << 16) | lower;
+}
+
+static struct clocksource clksrc = {
+	.name           = "tcb_clksrc",
+	.rating         = 200,
+	.read           = tc_get_cycles,
+	.mask           = CLOCKSOURCE_MASK(32),
+	.shift          = 18,
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+
+struct tc_clkevt_device {
+	struct clock_event_device	clkevt;
+	struct clk			*clk;
+	void __iomem			*regs;
+};
+
+static struct tc_clkevt_device *to_tc_clkevt(struct clock_event_device *clkevt)
+{
+	return container_of(clkevt, struct tc_clkevt_device, clkevt);
+}
+
+/* For now, we always use the 32K clock ... this optimizes for NO_HZ,
+ * because using one of the divided clocks would usually mean the
+ * tick rate can never be less than several dozen Hz (vs 0.5 Hz).
+ *
+ * A divided clock could be good for high resolution timers, since
+ * 30.5 usec resolution can seem "low".
+ */
+static u32 timer_clock;
+
+static void tc_mode(enum clock_event_mode m, struct clock_event_device *d)
+{
+	struct tc_clkevt_device *tcd = to_tc_clkevt(d);
+	void __iomem		*regs = tcd->regs;
+
+	if (tcd->clkevt.mode == CLOCK_EVT_MODE_PERIODIC
+			|| tcd->clkevt.mode == CLOCK_EVT_MODE_ONESHOT) {
+		__raw_writel(0xff, regs + ATMEL_TC_REG(2, IDR));
+		__raw_writel(ATMEL_TC_CLKDIS, regs + ATMEL_TC_REG(2, CCR));
+		clk_disable(tcd->clk);
+	}
+
+	switch (m) {
+
+	/* By not making the gentime core emulate periodic mode on top
+	 * of oneshot, we get lower overhead and improved accuracy.
+	 */
+	case CLOCK_EVT_MODE_PERIODIC:
+		clk_enable(tcd->clk);
+
+		/* slow clock, count up to RC, then irq and restart */
+		__raw_writel(timer_clock
+				| ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO,
+				regs + ATMEL_TC_REG(2, CMR));
+		__raw_writel((32768 + HZ/2) / HZ, tcaddr + ATMEL_TC_REG(2, RC));
+
+		/* Enable clock and interrupts on RC compare */
+		__raw_writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER));
+
+		/* go go gadget! */
+		__raw_writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG,
+				regs + ATMEL_TC_REG(2, CCR));
+		break;
+
+	case CLOCK_EVT_MODE_ONESHOT:
+		clk_enable(tcd->clk);
+
+		/* slow clock, count up to RC, then irq and stop */
+		__raw_writel(timer_clock | ATMEL_TC_CPCSTOP
+				| ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO,
+				regs + ATMEL_TC_REG(2, CMR));
+		__raw_writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER));
+
+		/* set_next_event() configures and starts the timer */
+		break;
+
+	default:
+		break;
+	}
+}
+
+static int tc_next_event(unsigned long delta, struct clock_event_device *d)
+{
+	__raw_writel(delta, tcaddr + ATMEL_TC_REG(2, RC));
+
+	/* go go gadget! */
+	__raw_writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG,
+			tcaddr + ATMEL_TC_REG(2, CCR));
+	return 0;
+}
+
+static struct tc_clkevt_device clkevt = {
+	.clkevt	= {
+		.name		= "tc_clkevt",
+		.features	= CLOCK_EVT_FEAT_PERIODIC
+					| CLOCK_EVT_FEAT_ONESHOT,
+		.shift		= 32,
+		/* Should be lower than at91rm9200's system timer */
+		.rating		= 125,
+		.cpumask	= CPU_MASK_CPU0,
+		.set_next_event	= tc_next_event,
+		.set_mode	= tc_mode,
+	},
+};
+
+static irqreturn_t ch2_irq(int irq, void *handle)
+{
+	struct tc_clkevt_device	*dev = handle;
+	unsigned int		sr;
+
+	sr = __raw_readl(dev->regs + ATMEL_TC_REG(2, SR));
+	if (sr & ATMEL_TC_CPCS) {
+		dev->clkevt.event_handler(&dev->clkevt);
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static struct irqaction tc_irqaction = {
+	.name		= "tc_clkevt",
+	.flags		= IRQF_TIMER | IRQF_DISABLED,
+	.handler	= ch2_irq,
+};
+
+static void __init setup_clkevents(struct atmel_tc *tc,
+		struct clk *t0_clk, int clk32k_divisor_idx)
+{
+	struct platform_device *pdev = tc->pdev;
+	struct clk *t2_clk = tc->clk[2];
+	int irq = tc->irq[2];
+
+	clkevt.regs = tc->regs;
+	clkevt.clk = t2_clk;
+	tc_irqaction.dev_id = &clkevt;
+
+	timer_clock = clk32k_divisor_idx;
+
+	clkevt.clkevt.mult = div_sc(32768, NSEC_PER_SEC, clkevt.clkevt.shift);
+	clkevt.clkevt.max_delta_ns
+		= clockevent_delta2ns(0xffff, &clkevt.clkevt);
+	clkevt.clkevt.min_delta_ns = clockevent_delta2ns(1, &clkevt.clkevt) + 1;
+
+	setup_irq(irq, &tc_irqaction);
+
+	clockevents_register_device(&clkevt.clkevt);
+}
+
+#else /* !CONFIG_GENERIC_CLOCKEVENTS */
+
+static void __init setup_clkevents(struct atmel_tc *tc,
+		struct clk *t0_clk, int clk32k_divisor_idx)
+{
+	/* NOTHING */
+}
+
+#endif
+
+static int __init tcb_clksrc_init(void)
+{
+	static char bootinfo[] __initdata
+		= KERN_DEBUG "%s: tc%d at %d.%03d MHz\n";
+
+	struct platform_device *pdev;
+	struct atmel_tc *tc;
+	struct clk *t0_clk, *t1_clk;
+	u32 rate, divided_rate = 0;
+	int best_divisor_idx = -1;
+	int clk32k_divisor_idx = -1;
+	int i;
+
+	tc = atmel_tc_alloc(CONFIG_ATMEL_TCB_CLKSRC_BLOCK, clksrc.name);
+	if (!tc) {
+		pr_debug("can't alloc TC for clocksource\n");
+		return -ENODEV;
+	}
+	tcaddr = tc->regs;
+	pdev = tc->pdev;
+
+	t0_clk = tc->clk[0];
+	clk_enable(t0_clk);
+
+	/* How fast will we be counting?  Pick something over 5 MHz.  */
+	rate = (u32) clk_get_rate(t0_clk);
+	for (i = 0; i < 5; i++) {
+		unsigned divisor = atmel_tc_divisors[i];
+		unsigned tmp;
+
+		/* remember 32 KiHz clock for later */
+		if (!divisor) {
+			clk32k_divisor_idx = i;
+			continue;
+		}
+
+		tmp = rate / divisor;
+		pr_debug("TC: %u / %-3u [%d] --> %u\n", rate, divisor, i, tmp);
+		if (best_divisor_idx > 0) {
+			if (tmp < 5 * 1000 * 1000)
+				continue;
+		}
+		divided_rate = tmp;
+		best_divisor_idx = i;
+	}
+
+	clksrc.mult = clocksource_hz2mult(divided_rate, clksrc.shift);
+
+	printk(bootinfo, clksrc.name, CONFIG_ATMEL_TCB_CLKSRC_BLOCK,
+			divided_rate / 1000000,
+			((divided_rate + 500000) % 1000000) / 1000);
+
+	/* tclib will give us three clocks no matter what the
+	 * underlying platform supports.
+	 */
+	clk_enable(tc->clk[1]);
+
+	/* channel 0:  waveform mode, input mclk/8, clock TIOA0 on overflow */
+	__raw_writel(best_divisor_idx			/* likely divide-by-8 */
+			| ATMEL_TC_WAVE
+			| ATMEL_TC_WAVESEL_UP		/* free-run */
+			| ATMEL_TC_ACPA_SET		/* TIOA0 rises at 0 */
+			| ATMEL_TC_ACPC_CLEAR,		/* (duty cycle 50%) */
+			tcaddr + ATMEL_TC_REG(0, CMR));
+	__raw_writel(0x0000, tcaddr + ATMEL_TC_REG(0, RA));
+	__raw_writel(0x8000, tcaddr + ATMEL_TC_REG(0, RC));
+	__raw_writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR));	/* no irqs */
+	__raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR));
+
+	/* channel 1:  waveform mode, input TIOA0 */
+	__raw_writel(ATMEL_TC_XC1			/* input: TIOA0 */
+			| ATMEL_TC_WAVE
+			| ATMEL_TC_WAVESEL_UP,		/* free-run */
+			tcaddr + ATMEL_TC_REG(1, CMR));
+	__raw_writel(0xff, tcaddr + ATMEL_TC_REG(1, IDR));	/* no irqs */
+	__raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(1, CCR));
+
+	/* chain channel 0 to channel 1, then reset all the timers */
+	__raw_writel(ATMEL_TC_TC1XC1S_TIOA0, tcaddr + ATMEL_TC_BMR);
+	__raw_writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR);
+
+	/* and away we go! */
+	clocksource_register(&clksrc);
+
+	/* channel 2:  periodic and oneshot timer support */
+	setup_clkevents(tc, t0_clk, clk32k_divisor_idx);
+
+	return 0;
+}
+arch_initcall(tcb_clksrc_init);