--- /dev/null
+/*
+ * Renesas Timer Support - OSTM
+ *
+ * Copyright (C) 2017 Renesas Electronics America, Inc.
+ * Copyright (C) 2017 Chris Brandt
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.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.
+ */
+
+struct ostm_device {
+ void __iomem *base;
+ unsigned long ticks_per_jiffy;
+ struct clock_event_device ced;
+};
+
+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 struct ostm_device *ced_to_ostm(struct clock_event_device *ced)
+{
+ return container_of(ced, struct ostm_device, ced);
+}
+
+static void ostm_timer_stop(struct ostm_device *ostm)
+{
+ if (readb(ostm->base + OSTM_TE) & TE) {
+ writeb(TT, ostm->base + 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(ostm->base + OSTM_TE) & TE)
+ ;
+ }
+}
+
+static int __init ostm_init_clksrc(struct ostm_device *ostm, unsigned long rate)
+{
+ /*
+ * irq not used (clock sources don't use interrupts)
+ */
+
+ ostm_timer_stop(ostm);
+
+ writel(0, ostm->base + OSTM_CMP);
+ writeb(CTL_FREERUN, ostm->base + OSTM_CTL);
+ writeb(TS, ostm->base + OSTM_TS);
+
+ return clocksource_mmio_init(ostm->base + OSTM_CNT,
+ "ostm", rate,
+ 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 ostm_device *ostm,
+ unsigned long rate)
+{
+ system_clock = ostm->base + OSTM_CNT;
+ sched_clock_register(ostm_read_sched_clock, 32, rate);
+}
+
+static int ostm_clock_event_next(unsigned long delta,
+ struct clock_event_device *ced)
+{
+ struct ostm_device *ostm = ced_to_ostm(ced);
+
+ ostm_timer_stop(ostm);
+
+ writel(delta, ostm->base + OSTM_CMP);
+ writeb(CTL_ONESHOT, ostm->base + OSTM_CTL);
+ writeb(TS, ostm->base + OSTM_TS);
+
+ return 0;
+}
+
+static int ostm_shutdown(struct clock_event_device *ced)
+{
+ struct ostm_device *ostm = ced_to_ostm(ced);
+
+ ostm_timer_stop(ostm);
+
+ return 0;
+}
+static int ostm_set_periodic(struct clock_event_device *ced)
+{
+ struct ostm_device *ostm = ced_to_ostm(ced);
+
+ if (clockevent_state_oneshot(ced) || clockevent_state_periodic(ced))
+ ostm_timer_stop(ostm);
+
+ writel(ostm->ticks_per_jiffy - 1, ostm->base + OSTM_CMP);
+ writeb(CTL_PERIODIC, ostm->base + OSTM_CTL);
+ writeb(TS, ostm->base + OSTM_TS);
+
+ return 0;
+}
+
+static int ostm_set_oneshot(struct clock_event_device *ced)
+{
+ struct ostm_device *ostm = ced_to_ostm(ced);
+
+ ostm_timer_stop(ostm);
+
+ return 0;
+}
+
+static irqreturn_t ostm_timer_interrupt(int irq, void *dev_id)
+{
+ struct ostm_device *ostm = dev_id;
+
+ if (clockevent_state_oneshot(&ostm->ced))
+ ostm_timer_stop(ostm);
+
+ /* notify clockevent layer */
+ if (ostm->ced.event_handler)
+ ostm->ced.event_handler(&ostm->ced);
+
+ return IRQ_HANDLED;
+}
+
+static int __init ostm_init_clkevt(struct ostm_device *ostm, int irq,
+ unsigned long rate)
+{
+ struct clock_event_device *ced = &ostm->ced;
+ int ret = -ENXIO;
+
+ ret = request_irq(irq, ostm_timer_interrupt,
+ IRQF_TIMER | IRQF_IRQPOLL,
+ "ostm", ostm);
+ if (ret) {
+ pr_err("ostm: failed to request irq\n");
+ return ret;
+ }
+
+ ced->name = "ostm";
+ 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, rate, 0xf, 0xffffffff);
+
+ return 0;
+}
+
+static int __init ostm_init(struct device_node *np)
+{
+ struct ostm_device *ostm;
+ int ret = -EFAULT;
+ struct clk *ostm_clk = NULL;
+ int irq;
+ unsigned long rate;
+
+ ostm = kzalloc(sizeof(*ostm), GFP_KERNEL);
+ if (!ostm)
+ return -ENOMEM;
+
+ ostm->base = of_iomap(np, 0);
+ if (!ostm->base) {
+ pr_err("ostm: failed to remap I/O memory\n");
+ goto err;
+ }
+
+ irq = irq_of_parse_and_map(np, 0);
+ if (irq < 0) {
+ pr_err("ostm: Failed to get irq\n");
+ goto err;
+ }
+
+ ostm_clk = of_clk_get(np, 0);
+ if (IS_ERR(ostm_clk)) {
+ pr_err("ostm: Failed to get clock\n");
+ ostm_clk = NULL;
+ goto err;
+ }
+
+ ret = clk_prepare_enable(ostm_clk);
+ if (ret) {
+ pr_err("ostm: Failed to enable clock\n");
+ goto err;
+ }
+
+ rate = clk_get_rate(ostm_clk);
+ ostm->ticks_per_jiffy = (rate + HZ / 2) / HZ;
+
+ /*
+ * 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(ostm, rate);
+
+ if (!ret) {
+ ostm_init_sched_clock(ostm, rate);
+ pr_info("ostm: used for clocksource\n");
+ }
+
+ } else {
+ ret = ostm_init_clkevt(ostm, irq, rate);
+
+ if (!ret)
+ pr_info("ostm: used for clock events\n");
+ }
+
+err:
+ if (ret) {
+ clk_disable_unprepare(ostm_clk);
+ iounmap(ostm->base);
+ kfree(ostm);
+ return ret;
+ }
+
+ return 0;
+}
+
+CLOCKSOURCE_OF_DECLARE(ostm, "renesas,ostm", ostm_init);
projects / kernel.git / commitdiff