1 files changed, 285 insertions, 0 deletions
diff --git a/arch/mips/loongson64/hpet.c b/arch/mips/loongson64/hpet.c
new file mode 100644
index 0000000000..e428259257
--- /dev/null
+++ b/arch/mips/loongson64/hpet.c
@@ -0,0 +1,285 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <linux/percpu.h>
+#include <linux/delay.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+
+#include <asm/hpet.h>
+#include <asm/time.h>
+
+#define SMBUS_CFG_BASE		(loongson_sysconf.ht_control_base + 0x0300a000)
+#define SMBUS_PCI_REG40		0x40
+#define SMBUS_PCI_REG64		0x64
+#define SMBUS_PCI_REGB4		0xb4
+
+#define HPET_MIN_CYCLES		16
+#define HPET_MIN_PROG_DELTA	(HPET_MIN_CYCLES * 12)
+
+static DEFINE_SPINLOCK(hpet_lock);
+DEFINE_PER_CPU(struct clock_event_device, hpet_clockevent_device);
+
+static unsigned int smbus_read(int offset)
+{
+	return *(volatile unsigned int *)(SMBUS_CFG_BASE + offset);
+}
+
+static void smbus_write(int offset, int data)
+{
+	*(volatile unsigned int *)(SMBUS_CFG_BASE + offset) = data;
+}
+
+static void smbus_enable(int offset, int bit)
+{
+	unsigned int cfg = smbus_read(offset);
+
+	cfg |= bit;
+	smbus_write(offset, cfg);
+}
+
+static int hpet_read(int offset)
+{
+	return *(volatile unsigned int *)(HPET_MMIO_ADDR + offset);
+}
+
+static void hpet_write(int offset, int data)
+{
+	*(volatile unsigned int *)(HPET_MMIO_ADDR + offset) = data;
+}
+
+static void hpet_start_counter(void)
+{
+	unsigned int cfg = hpet_read(HPET_CFG);
+
+	cfg |= HPET_CFG_ENABLE;
+	hpet_write(HPET_CFG, cfg);
+}
+
+static void hpet_stop_counter(void)
+{
+	unsigned int cfg = hpet_read(HPET_CFG);
+
+	cfg &= ~HPET_CFG_ENABLE;
+	hpet_write(HPET_CFG, cfg);
+}
+
+static void hpet_reset_counter(void)
+{
+	hpet_write(HPET_COUNTER, 0);
+	hpet_write(HPET_COUNTER + 4, 0);
+}
+
+static void hpet_restart_counter(void)
+{
+	hpet_stop_counter();
+	hpet_reset_counter();
+	hpet_start_counter();
+}
+
+static void hpet_enable_legacy_int(void)
+{
+	/* Do nothing on Loongson-3 */
+}
+
+static int hpet_set_state_periodic(struct clock_event_device *evt)
+{
+	int cfg;
+
+	spin_lock(&hpet_lock);
+
+	pr_info("set clock event to periodic mode!\n");
+	/* stop counter */
+	hpet_stop_counter();
+
+	/* enables the timer0 to generate a periodic interrupt */
+	cfg = hpet_read(HPET_T0_CFG);
+	cfg &= ~HPET_TN_LEVEL;
+	cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL |
+		HPET_TN_32BIT;
+	hpet_write(HPET_T0_CFG, cfg);
+
+	/* set the comparator */
+	hpet_write(HPET_T0_CMP, HPET_COMPARE_VAL);
+	udelay(1);
+	hpet_write(HPET_T0_CMP, HPET_COMPARE_VAL);
+
+	/* start counter */
+	hpet_start_counter();
+
+	spin_unlock(&hpet_lock);
+	return 0;
+}
+
+static int hpet_set_state_shutdown(struct clock_event_device *evt)
+{
+	int cfg;
+
+	spin_lock(&hpet_lock);
+
+	cfg = hpet_read(HPET_T0_CFG);
+	cfg &= ~HPET_TN_ENABLE;
+	hpet_write(HPET_T0_CFG, cfg);
+
+	spin_unlock(&hpet_lock);
+	return 0;
+}
+
+static int hpet_set_state_oneshot(struct clock_event_device *evt)
+{
+	int cfg;
+
+	spin_lock(&hpet_lock);
+
+	pr_info("set clock event to one shot mode!\n");
+	cfg = hpet_read(HPET_T0_CFG);
+	/*
+	 * set timer0 type
+	 * 1 : periodic interrupt
+	 * 0 : non-periodic(oneshot) interrupt
+	 */
+	cfg &= ~HPET_TN_PERIODIC;
+	cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
+	hpet_write(HPET_T0_CFG, cfg);
+
+	spin_unlock(&hpet_lock);
+	return 0;
+}
+
+static int hpet_tick_resume(struct clock_event_device *evt)
+{
+	spin_lock(&hpet_lock);
+	hpet_enable_legacy_int();
+	spin_unlock(&hpet_lock);
+
+	return 0;
+}
+
+static int hpet_next_event(unsigned long delta,
+		struct clock_event_device *evt)
+{
+	u32 cnt;
+	s32 res;
+
+	cnt = hpet_read(HPET_COUNTER);
+	cnt += (u32) delta;
+	hpet_write(HPET_T0_CMP, cnt);
+
+	res = (s32)(cnt - hpet_read(HPET_COUNTER));
+
+	return res < HPET_MIN_CYCLES ? -ETIME : 0;
+}
+
+static irqreturn_t hpet_irq_handler(int irq, void *data)
+{
+	int is_irq;
+	struct clock_event_device *cd;
+	unsigned int cpu = smp_processor_id();
+
+	is_irq = hpet_read(HPET_STATUS);
+	if (is_irq & HPET_T0_IRS) {
+		/* clear the TIMER0 irq status register */
+		hpet_write(HPET_STATUS, HPET_T0_IRS);
+		cd = &per_cpu(hpet_clockevent_device, cpu);
+		cd->event_handler(cd);
+		return IRQ_HANDLED;
+	}
+	return IRQ_NONE;
+}
+
+/*
+ * hpet address assignation and irq setting should be done in bios.
+ * but pmon don't do this, we just setup here directly.
+ * The operation under is normal. unfortunately, hpet_setup process
+ * is before pci initialize.
+ *
+ * {
+ *	struct pci_dev *pdev;
+ *
+ *	pdev = pci_get_device(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS, NULL);
+ *	pci_write_config_word(pdev, SMBUS_PCI_REGB4, HPET_ADDR);
+ *
+ *	...
+ * }
+ */
+static void hpet_setup(void)
+{
+	/* set hpet base address */
+	smbus_write(SMBUS_PCI_REGB4, HPET_ADDR);
+
+	/* enable decoding of access to HPET MMIO*/
+	smbus_enable(SMBUS_PCI_REG40, (1 << 28));
+
+	/* HPET irq enable */
+	smbus_enable(SMBUS_PCI_REG64, (1 << 10));
+
+	hpet_enable_legacy_int();
+}
+
+void __init setup_hpet_timer(void)
+{
+	unsigned long flags = IRQF_NOBALANCING | IRQF_TIMER;
+	unsigned int cpu = smp_processor_id();
+	struct clock_event_device *cd;
+
+	hpet_setup();
+
+	cd = &per_cpu(hpet_clockevent_device, cpu);
+	cd->name = "hpet";
+	cd->rating = 100;
+	cd->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+	cd->set_state_shutdown = hpet_set_state_shutdown;
+	cd->set_state_periodic = hpet_set_state_periodic;
+	cd->set_state_oneshot = hpet_set_state_oneshot;
+	cd->tick_resume = hpet_tick_resume;
+	cd->set_next_event = hpet_next_event;
+	cd->irq = HPET_T0_IRQ;
+	cd->cpumask = cpumask_of(cpu);
+	clockevent_set_clock(cd, HPET_FREQ);
+	cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);
+	cd->max_delta_ticks = 0x7fffffff;
+	cd->min_delta_ns = clockevent_delta2ns(HPET_MIN_PROG_DELTA, cd);
+	cd->min_delta_ticks = HPET_MIN_PROG_DELTA;
+
+	clockevents_register_device(cd);
+	if (request_irq(HPET_T0_IRQ, hpet_irq_handler, flags, "hpet", NULL))
+		pr_err("Failed to request irq %d (hpet)\n", HPET_T0_IRQ);
+	pr_info("hpet clock event device register\n");
+}
+
+static u64 hpet_read_counter(struct clocksource *cs)
+{
+	return (u64)hpet_read(HPET_COUNTER);
+}
+
+static void hpet_suspend(struct clocksource *cs)
+{
+}
+
+static void hpet_resume(struct clocksource *cs)
+{
+	hpet_setup();
+	hpet_restart_counter();
+}
+
+static struct clocksource csrc_hpet = {
+	.name = "hpet",
+	/* mips clocksource rating is less than 300, so hpet is better. */
+	.rating = 300,
+	.read = hpet_read_counter,
+	.mask = CLOCKSOURCE_MASK(32),
+	/* oneshot mode work normal with this flag */
+	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
+	.suspend = hpet_suspend,
+	.resume = hpet_resume,
+	.mult = 0,
+	.shift = 10,
+};
+
+int __init init_hpet_clocksource(void)
+{
+	csrc_hpet.mult = clocksource_hz2mult(HPET_FREQ, csrc_hpet.shift);
+	return clocksource_register_hz(&csrc_hpet, HPET_FREQ);
+}
+
+arch_initcall(init_hpet_clocksource);