1 files changed, 371 insertions, 0 deletions
diff --git a/drivers/clocksource/em_sti.c b/drivers/clocksource/em_sti.c
new file mode 100644
index 000000000..ab190dffb
--- /dev/null
+++ b/drivers/clocksource/em_sti.c
@@ -0,0 +1,371 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Emma Mobile Timer Support - STI
+ *
+ *  Copyright (C) 2012 Magnus Damm
+ */
+
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/irq.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+
+enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR };
+
+struct em_sti_priv {
+	void __iomem *base;
+	struct clk *clk;
+	struct platform_device *pdev;
+	unsigned int active[USER_NR];
+	unsigned long rate;
+	raw_spinlock_t lock;
+	struct clock_event_device ced;
+	struct clocksource cs;
+};
+
+#define STI_CONTROL 0x00
+#define STI_COMPA_H 0x10
+#define STI_COMPA_L 0x14
+#define STI_COMPB_H 0x18
+#define STI_COMPB_L 0x1c
+#define STI_COUNT_H 0x20
+#define STI_COUNT_L 0x24
+#define STI_COUNT_RAW_H 0x28
+#define STI_COUNT_RAW_L 0x2c
+#define STI_SET_H 0x30
+#define STI_SET_L 0x34
+#define STI_INTSTATUS 0x40
+#define STI_INTRAWSTATUS 0x44
+#define STI_INTENSET 0x48
+#define STI_INTENCLR 0x4c
+#define STI_INTFFCLR 0x50
+
+static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs)
+{
+	return ioread32(p->base + offs);
+}
+
+static inline void em_sti_write(struct em_sti_priv *p, int offs,
+				unsigned long value)
+{
+	iowrite32(value, p->base + offs);
+}
+
+static int em_sti_enable(struct em_sti_priv *p)
+{
+	int ret;
+
+	/* enable clock */
+	ret = clk_enable(p->clk);
+	if (ret) {
+		dev_err(&p->pdev->dev, "cannot enable clock\n");
+		return ret;
+	}
+
+	/* reset the counter */
+	em_sti_write(p, STI_SET_H, 0x40000000);
+	em_sti_write(p, STI_SET_L, 0x00000000);
+
+	/* mask and clear pending interrupts */
+	em_sti_write(p, STI_INTENCLR, 3);
+	em_sti_write(p, STI_INTFFCLR, 3);
+
+	/* enable updates of counter registers */
+	em_sti_write(p, STI_CONTROL, 1);
+
+	return 0;
+}
+
+static void em_sti_disable(struct em_sti_priv *p)
+{
+	/* mask interrupts */
+	em_sti_write(p, STI_INTENCLR, 3);
+
+	/* stop clock */
+	clk_disable(p->clk);
+}
+
+static u64 em_sti_count(struct em_sti_priv *p)
+{
+	u64 ticks;
+	unsigned long flags;
+
+	/* the STI hardware buffers the 48-bit count, but to
+	 * break it out into two 32-bit access the registers
+	 * must be accessed in a certain order.
+	 * Always read STI_COUNT_H before STI_COUNT_L.
+	 */
+	raw_spin_lock_irqsave(&p->lock, flags);
+	ticks = (u64)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32;
+	ticks |= em_sti_read(p, STI_COUNT_L);
+	raw_spin_unlock_irqrestore(&p->lock, flags);
+
+	return ticks;
+}
+
+static u64 em_sti_set_next(struct em_sti_priv *p, u64 next)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&p->lock, flags);
+
+	/* mask compare A interrupt */
+	em_sti_write(p, STI_INTENCLR, 1);
+
+	/* update compare A value */
+	em_sti_write(p, STI_COMPA_H, next >> 32);
+	em_sti_write(p, STI_COMPA_L, next & 0xffffffff);
+
+	/* clear compare A interrupt source */
+	em_sti_write(p, STI_INTFFCLR, 1);
+
+	/* unmask compare A interrupt */
+	em_sti_write(p, STI_INTENSET, 1);
+
+	raw_spin_unlock_irqrestore(&p->lock, flags);
+
+	return next;
+}
+
+static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
+{
+	struct em_sti_priv *p = dev_id;
+
+	p->ced.event_handler(&p->ced);
+	return IRQ_HANDLED;
+}
+
+static int em_sti_start(struct em_sti_priv *p, unsigned int user)
+{
+	unsigned long flags;
+	int used_before;
+	int ret = 0;
+
+	raw_spin_lock_irqsave(&p->lock, flags);
+	used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
+	if (!used_before)
+		ret = em_sti_enable(p);
+
+	if (!ret)
+		p->active[user] = 1;
+	raw_spin_unlock_irqrestore(&p->lock, flags);
+
+	return ret;
+}
+
+static void em_sti_stop(struct em_sti_priv *p, unsigned int user)
+{
+	unsigned long flags;
+	int used_before, used_after;
+
+	raw_spin_lock_irqsave(&p->lock, flags);
+	used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
+	p->active[user] = 0;
+	used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
+
+	if (used_before && !used_after)
+		em_sti_disable(p);
+	raw_spin_unlock_irqrestore(&p->lock, flags);
+}
+
+static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
+{
+	return container_of(cs, struct em_sti_priv, cs);
+}
+
+static u64 em_sti_clocksource_read(struct clocksource *cs)
+{
+	return em_sti_count(cs_to_em_sti(cs));
+}
+
+static int em_sti_clocksource_enable(struct clocksource *cs)
+{
+	struct em_sti_priv *p = cs_to_em_sti(cs);
+
+	return em_sti_start(p, USER_CLOCKSOURCE);
+}
+
+static void em_sti_clocksource_disable(struct clocksource *cs)
+{
+	em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
+}
+
+static void em_sti_clocksource_resume(struct clocksource *cs)
+{
+	em_sti_clocksource_enable(cs);
+}
+
+static int em_sti_register_clocksource(struct em_sti_priv *p)
+{
+	struct clocksource *cs = &p->cs;
+
+	cs->name = dev_name(&p->pdev->dev);
+	cs->rating = 200;
+	cs->read = em_sti_clocksource_read;
+	cs->enable = em_sti_clocksource_enable;
+	cs->disable = em_sti_clocksource_disable;
+	cs->suspend = em_sti_clocksource_disable;
+	cs->resume = em_sti_clocksource_resume;
+	cs->mask = CLOCKSOURCE_MASK(48);
+	cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
+
+	dev_info(&p->pdev->dev, "used as clock source\n");
+
+	clocksource_register_hz(cs, p->rate);
+	return 0;
+}
+
+static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
+{
+	return container_of(ced, struct em_sti_priv, ced);
+}
+
+static int em_sti_clock_event_shutdown(struct clock_event_device *ced)
+{
+	struct em_sti_priv *p = ced_to_em_sti(ced);
+	em_sti_stop(p, USER_CLOCKEVENT);
+	return 0;
+}
+
+static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced)
+{
+	struct em_sti_priv *p = ced_to_em_sti(ced);
+
+	dev_info(&p->pdev->dev, "used for oneshot clock events\n");
+	em_sti_start(p, USER_CLOCKEVENT);
+	return 0;
+}
+
+static int em_sti_clock_event_next(unsigned long delta,
+				   struct clock_event_device *ced)
+{
+	struct em_sti_priv *p = ced_to_em_sti(ced);
+	u64 next;
+	int safe;
+
+	next = em_sti_set_next(p, em_sti_count(p) + delta);
+	safe = em_sti_count(p) < (next - 1);
+
+	return !safe;
+}
+
+static void em_sti_register_clockevent(struct em_sti_priv *p)
+{
+	struct clock_event_device *ced = &p->ced;
+
+	ced->name = dev_name(&p->pdev->dev);
+	ced->features = CLOCK_EVT_FEAT_ONESHOT;
+	ced->rating = 200;
+	ced->cpumask = cpu_possible_mask;
+	ced->set_next_event = em_sti_clock_event_next;
+	ced->set_state_shutdown = em_sti_clock_event_shutdown;
+	ced->set_state_oneshot = em_sti_clock_event_set_oneshot;
+
+	dev_info(&p->pdev->dev, "used for clock events\n");
+
+	clockevents_config_and_register(ced, p->rate, 2, 0xffffffff);
+}
+
+static int em_sti_probe(struct platform_device *pdev)
+{
+	struct em_sti_priv *p;
+	int irq, ret;
+
+	p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
+	if (p == NULL)
+		return -ENOMEM;
+
+	p->pdev = pdev;
+	platform_set_drvdata(pdev, p);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	/* map memory, let base point to the STI instance */
+	p->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(p->base))
+		return PTR_ERR(p->base);
+
+	ret = devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
+			       IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
+			       dev_name(&pdev->dev), p);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to request low IRQ\n");
+		return ret;
+	}
+
+	/* get hold of clock */
+	p->clk = devm_clk_get(&pdev->dev, "sclk");
+	if (IS_ERR(p->clk)) {
+		dev_err(&pdev->dev, "cannot get clock\n");
+		return PTR_ERR(p->clk);
+	}
+
+	ret = clk_prepare(p->clk);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "cannot prepare clock\n");
+		return ret;
+	}
+
+	ret = clk_enable(p->clk);
+	if (ret < 0) {
+		dev_err(&p->pdev->dev, "cannot enable clock\n");
+		clk_unprepare(p->clk);
+		return ret;
+	}
+	p->rate = clk_get_rate(p->clk);
+	clk_disable(p->clk);
+
+	raw_spin_lock_init(&p->lock);
+	em_sti_register_clockevent(p);
+	em_sti_register_clocksource(p);
+	return 0;
+}
+
+static int em_sti_remove(struct platform_device *pdev)
+{
+	return -EBUSY; /* cannot unregister clockevent and clocksource */
+}
+
+static const struct of_device_id em_sti_dt_ids[] = {
+	{ .compatible = "renesas,em-sti", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
+
+static struct platform_driver em_sti_device_driver = {
+	.probe		= em_sti_probe,
+	.remove		= em_sti_remove,
+	.driver		= {
+		.name	= "em_sti",
+		.of_match_table = em_sti_dt_ids,
+	}
+};
+
+static int __init em_sti_init(void)
+{
+	return platform_driver_register(&em_sti_device_driver);
+}
+
+static void __exit em_sti_exit(void)
+{
+	platform_driver_unregister(&em_sti_device_driver);
+}
+
+subsys_initcall(em_sti_init);
+module_exit(em_sti_exit);
+
+MODULE_AUTHOR("Magnus Damm");
+MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
+MODULE_LICENSE("GPL v2");