--- /dev/null
+#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);
projects / openwrt / staging / blogic.git / commitdiff