1 files changed, 248 insertions, 0 deletions
diff --git a/drivers/clocksource/renesas-ostm.c b/drivers/clocksource/renesas-ostm.c
new file mode 100644
index 000000000..8da972dc1
--- /dev/null
+++ b/drivers/clocksource/renesas-ostm.c
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Renesas Timer Support - OSTM
+ *
+ * Copyright (C) 2017 Renesas Electronics America, Inc.
+ * Copyright (C) 2017 Chris Brandt
+ */
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.h>
+
+#include "timer-of.h"
+
+/*
+ * The OSTM contains independent channels.
+ * The first OSTM channel probed will be set up as a free running
+ * clocksource. Additionally we will use this clocksource for the system
+ * schedule timer sched_clock().
+ *
+ * The second (or more) channel probed will be set up as an interrupt
+ * driven clock event.
+ */
+
+static void __iomem *system_clock;	/* For sched_clock() */
+
+/* OSTM REGISTERS */
+#define	OSTM_CMP		0x000	/* RW,32 */
+#define	OSTM_CNT		0x004	/* R,32 */
+#define	OSTM_TE			0x010	/* R,8 */
+#define	OSTM_TS			0x014	/* W,8 */
+#define	OSTM_TT			0x018	/* W,8 */
+#define	OSTM_CTL		0x020	/* RW,8 */
+
+#define	TE			0x01
+#define	TS			0x01
+#define	TT			0x01
+#define	CTL_PERIODIC		0x00
+#define	CTL_ONESHOT		0x02
+#define	CTL_FREERUN		0x02
+
+static void ostm_timer_stop(struct timer_of *to)
+{
+	if (readb(timer_of_base(to) + OSTM_TE) & TE) {
+		writeb(TT, timer_of_base(to) + OSTM_TT);
+
+		/*
+		 * Read back the register simply to confirm the write operation
+		 * has completed since I/O writes can sometimes get queued by
+		 * the bus architecture.
+		 */
+		while (readb(timer_of_base(to) + OSTM_TE) & TE)
+			;
+	}
+}
+
+static int __init ostm_init_clksrc(struct timer_of *to)
+{
+	ostm_timer_stop(to);
+
+	writel(0, timer_of_base(to) + OSTM_CMP);
+	writeb(CTL_FREERUN, timer_of_base(to) + OSTM_CTL);
+	writeb(TS, timer_of_base(to) + OSTM_TS);
+
+	return clocksource_mmio_init(timer_of_base(to) + OSTM_CNT,
+				     to->np->full_name, timer_of_rate(to), 300,
+				     32, clocksource_mmio_readl_up);
+}
+
+static u64 notrace ostm_read_sched_clock(void)
+{
+	return readl(system_clock);
+}
+
+static void __init ostm_init_sched_clock(struct timer_of *to)
+{
+	system_clock = timer_of_base(to) + OSTM_CNT;
+	sched_clock_register(ostm_read_sched_clock, 32, timer_of_rate(to));
+}
+
+static int ostm_clock_event_next(unsigned long delta,
+				 struct clock_event_device *ced)
+{
+	struct timer_of *to = to_timer_of(ced);
+
+	ostm_timer_stop(to);
+
+	writel(delta, timer_of_base(to) + OSTM_CMP);
+	writeb(CTL_ONESHOT, timer_of_base(to) + OSTM_CTL);
+	writeb(TS, timer_of_base(to) + OSTM_TS);
+
+	return 0;
+}
+
+static int ostm_shutdown(struct clock_event_device *ced)
+{
+	struct timer_of *to = to_timer_of(ced);
+
+	ostm_timer_stop(to);
+
+	return 0;
+}
+static int ostm_set_periodic(struct clock_event_device *ced)
+{
+	struct timer_of *to = to_timer_of(ced);
+
+	if (clockevent_state_oneshot(ced) || clockevent_state_periodic(ced))
+		ostm_timer_stop(to);
+
+	writel(timer_of_period(to) - 1, timer_of_base(to) + OSTM_CMP);
+	writeb(CTL_PERIODIC, timer_of_base(to) + OSTM_CTL);
+	writeb(TS, timer_of_base(to) + OSTM_TS);
+
+	return 0;
+}
+
+static int ostm_set_oneshot(struct clock_event_device *ced)
+{
+	struct timer_of *to = to_timer_of(ced);
+
+	ostm_timer_stop(to);
+
+	return 0;
+}
+
+static irqreturn_t ostm_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *ced = dev_id;
+
+	if (clockevent_state_oneshot(ced))
+		ostm_timer_stop(to_timer_of(ced));
+
+	/* notify clockevent layer */
+	if (ced->event_handler)
+		ced->event_handler(ced);
+
+	return IRQ_HANDLED;
+}
+
+static int __init ostm_init_clkevt(struct timer_of *to)
+{
+	struct clock_event_device *ced = &to->clkevt;
+
+	ced->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC;
+	ced->set_state_shutdown = ostm_shutdown;
+	ced->set_state_periodic = ostm_set_periodic;
+	ced->set_state_oneshot = ostm_set_oneshot;
+	ced->set_next_event = ostm_clock_event_next;
+	ced->shift = 32;
+	ced->rating = 300;
+	ced->cpumask = cpumask_of(0);
+	clockevents_config_and_register(ced, timer_of_rate(to), 0xf,
+					0xffffffff);
+
+	return 0;
+}
+
+static int __init ostm_init(struct device_node *np)
+{
+	struct reset_control *rstc;
+	struct timer_of *to;
+	int ret;
+
+	to = kzalloc(sizeof(*to), GFP_KERNEL);
+	if (!to)
+		return -ENOMEM;
+
+	rstc = of_reset_control_get_optional_exclusive(np, NULL);
+	if (IS_ERR(rstc)) {
+		ret = PTR_ERR(rstc);
+		goto err_free;
+	}
+
+	reset_control_deassert(rstc);
+
+	to->flags = TIMER_OF_BASE | TIMER_OF_CLOCK;
+	if (system_clock) {
+		/*
+		 * clock sources don't use interrupts, clock events do
+		 */
+		to->flags |= TIMER_OF_IRQ;
+		to->of_irq.flags = IRQF_TIMER | IRQF_IRQPOLL;
+		to->of_irq.handler = ostm_timer_interrupt;
+	}
+
+	ret = timer_of_init(np, to);
+	if (ret)
+		goto err_reset;
+
+	/*
+	 * First probed device will be used as system clocksource. Any
+	 * additional devices will be used as clock events.
+	 */
+	if (!system_clock) {
+		ret = ostm_init_clksrc(to);
+		if (ret)
+			goto err_cleanup;
+
+		ostm_init_sched_clock(to);
+		pr_info("%pOF: used for clocksource\n", np);
+	} else {
+		ret = ostm_init_clkevt(to);
+		if (ret)
+			goto err_cleanup;
+
+		pr_info("%pOF: used for clock events\n", np);
+	}
+
+	return 0;
+
+err_cleanup:
+	timer_of_cleanup(to);
+err_reset:
+	reset_control_assert(rstc);
+	reset_control_put(rstc);
+err_free:
+	kfree(to);
+	return ret;
+}
+
+TIMER_OF_DECLARE(ostm, "renesas,ostm", ostm_init);
+
+#ifdef CONFIG_ARCH_RZG2L
+static int __init ostm_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+
+	return ostm_init(dev->of_node);
+}
+
+static const struct of_device_id ostm_of_table[] = {
+	{ .compatible = "renesas,ostm", },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver ostm_device_driver = {
+	.driver = {
+		.name = "renesas_ostm",
+		.of_match_table = of_match_ptr(ostm_of_table),
+		.suppress_bind_attrs = true,
+	},
+};
+builtin_platform_driver_probe(ostm_device_driver, ostm_probe);
+#endif