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-rw-r--r--drivers/clocksource/renesas-ostm.c248
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 0000000000..8da972dc17
--- /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