clocksource: Add Owl timer

The Actions Semi S500 SoC provides four timers, 2Hz0/1 and 32-bit TIMER0/1.

Use TIMER0 as clocksource and TIMER1 as clockevents.

Based on LeMaker linux-actions tree.

An S500 datasheet can be found on the LeMaker Guitar pages:
http://www.lemaker.org/product-guitar-download-29.html

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Andreas Färber <afaerber@suse.de>

1 files changed, 171 insertions, 0 deletions

diff --git a/drivers/clocksource/owl-timer.c b/drivers/clocksource/owl-timer.c
new file mode 100644
index 000000000000..4609363a79a6
--- /dev/null
+++ b/drivers/clocksource/owl-timer.c
@@ -0,0 +1,171 @@
+/*
+ * Actions Semi Owl timer
+ *
+ * Copyright 2012 Actions Semi Inc.
+ * Author: Actions Semi, Inc.
+ *
+ * Copyright (c) 2017 SUSE Linux GmbH
+ * Author: Andreas Färber
+ *
+ * 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, or (at your
+ * option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqreturn.h>
+#include <linux/sched_clock.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+#define OWL_Tx_CTL              0x0
+#define OWL_Tx_CMP              0x4
+#define OWL_Tx_VAL              0x8
+
+#define OWL_Tx_CTL_PD           BIT(0)
+#define OWL_Tx_CTL_INTEN        BIT(1)
+#define OWL_Tx_CTL_EN           BIT(2)
+
+static void __iomem *owl_timer_base;
+static void __iomem *owl_clksrc_base;
+static void __iomem *owl_clkevt_base;
+
+static inline void owl_timer_reset(void __iomem *base)
+{
+        writel(0, base + OWL_Tx_CTL);
+        writel(0, base + OWL_Tx_VAL);
+        writel(0, base + OWL_Tx_CMP);
+}
+
+static inline void owl_timer_set_enabled(void __iomem *base, bool enabled)
+{
+        u32 ctl = readl(base + OWL_Tx_CTL);
+
+        /* PD bit is cleared when set */
+        ctl &= ~OWL_Tx_CTL_PD;
+
+        if (enabled)
+                ctl |= OWL_Tx_CTL_EN;
+        else
+                ctl &= ~OWL_Tx_CTL_EN;
+
+        writel(ctl, base + OWL_Tx_CTL);
+}
+
+static u64 notrace owl_timer_sched_read(void)
+{
+        return (u64)readl(owl_clksrc_base + OWL_Tx_VAL);
+}
+
+static int owl_timer_set_state_shutdown(struct clock_event_device *evt)
+{
+        owl_timer_set_enabled(owl_clkevt_base, false);
+
+        return 0;
+}
+
+static int owl_timer_set_state_oneshot(struct clock_event_device *evt)
+{
+        owl_timer_reset(owl_clkevt_base);
+
+        return 0;
+}
+
+static int owl_timer_tick_resume(struct clock_event_device *evt)
+{
+        return 0;
+}
+
+static int owl_timer_set_next_event(unsigned long evt,
+                                    struct clock_event_device *ev)
+{
+        void __iomem *base = owl_clkevt_base;
+
+        owl_timer_set_enabled(base, false);
+        writel(OWL_Tx_CTL_INTEN, base + OWL_Tx_CTL);
+        writel(0, base + OWL_Tx_VAL);
+        writel(evt, base + OWL_Tx_CMP);
+        owl_timer_set_enabled(base, true);
+
+        return 0;
+}
+
+static struct clock_event_device owl_clockevent = {
+        .name                   = "owl_tick",
+        .rating                 = 200,
+        .features               = CLOCK_EVT_FEAT_ONESHOT |
+                                  CLOCK_EVT_FEAT_DYNIRQ,
+        .set_state_shutdown     = owl_timer_set_state_shutdown,
+        .set_state_oneshot      = owl_timer_set_state_oneshot,
+        .tick_resume            = owl_timer_tick_resume,
+        .set_next_event         = owl_timer_set_next_event,
+};
+
+static irqreturn_t owl_timer1_interrupt(int irq, void *dev_id)
+{
+        struct clock_event_device *evt = (struct clock_event_device *)dev_id;
+
+        writel(OWL_Tx_CTL_PD, owl_clkevt_base + OWL_Tx_CTL);
+
+        evt->event_handler(evt);
+
+        return IRQ_HANDLED;
+}
+
+static int __init owl_timer_init(struct device_node *node)
+{
+        struct clk *clk;
+        unsigned long rate;
+        int timer1_irq, ret;
+
+        owl_timer_base = of_io_request_and_map(node, 0, "owl-timer");
+        if (IS_ERR(owl_timer_base)) {
+                pr_err("Can't map timer registers");
+                return PTR_ERR(owl_timer_base);
+        }
+
+        owl_clksrc_base = owl_timer_base + 0x08;
+        owl_clkevt_base = owl_timer_base + 0x14;
+
+        timer1_irq = of_irq_get_byname(node, "timer1");
+        if (timer1_irq <= 0) {
+                pr_err("Can't parse timer1 IRQ");
+                return -EINVAL;
+        }
+
+        clk = of_clk_get(node, 0);
+        if (IS_ERR(clk))
+                return PTR_ERR(clk);
+
+        rate = clk_get_rate(clk);
+
+        owl_timer_reset(owl_clksrc_base);
+        owl_timer_set_enabled(owl_clksrc_base, true);
+
+        sched_clock_register(owl_timer_sched_read, 32, rate);
+        clocksource_mmio_init(owl_clksrc_base + OWL_Tx_VAL, node->name,
+                              rate, 200, 32, clocksource_mmio_readl_up);
+
+        owl_timer_reset(owl_clkevt_base);
+
+        ret = request_irq(timer1_irq, owl_timer1_interrupt, IRQF_TIMER,
+                          "owl-timer", &owl_clockevent);
+        if (ret) {
+                pr_err("failed to request irq %d\n", timer1_irq);
+                return ret;
+        }
+
+        owl_clockevent.cpumask = cpumask_of(0);
+        owl_clockevent.irq = timer1_irq;
+
+        clockevents_config_and_register(&owl_clockevent, rate,
+                                        0xf, 0xffffffff);
+
+        return 0;
+}
+CLOCKSOURCE_OF_DECLARE(owl_s500, "actions,s500-timer", owl_timer_init);