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path: root/drivers/clocksource/bcm_kona_timer.c
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Diffstat (limited to 'drivers/clocksource/bcm_kona_timer.c')
-rw-r--r--drivers/clocksource/bcm_kona_timer.c192
1 files changed, 192 insertions, 0 deletions
diff --git a/drivers/clocksource/bcm_kona_timer.c b/drivers/clocksource/bcm_kona_timer.c
new file mode 100644
index 0000000000..39f172d7e2
--- /dev/null
+++ b/drivers/clocksource/bcm_kona_timer.c
@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2012 Broadcom Corporation
+
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/clockchips.h>
+#include <linux/types.h>
+#include <linux/clk.h>
+
+#include <linux/io.h>
+
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+
+#define KONA_GPTIMER_STCS_OFFSET 0x00000000
+#define KONA_GPTIMER_STCLO_OFFSET 0x00000004
+#define KONA_GPTIMER_STCHI_OFFSET 0x00000008
+#define KONA_GPTIMER_STCM0_OFFSET 0x0000000C
+
+#define KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT 0
+#define KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT 4
+
+struct kona_bcm_timers {
+ int tmr_irq;
+ void __iomem *tmr_regs;
+};
+
+static struct kona_bcm_timers timers;
+
+static u32 arch_timer_rate;
+
+/*
+ * We use the peripheral timers for system tick, the cpu global timer for
+ * profile tick
+ */
+static void kona_timer_disable_and_clear(void __iomem *base)
+{
+ uint32_t reg;
+
+ /*
+ * clear and disable interrupts
+ * We are using compare/match register 0 for our system interrupts
+ */
+ reg = readl(base + KONA_GPTIMER_STCS_OFFSET);
+
+ /* Clear compare (0) interrupt */
+ reg |= 1 << KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT;
+ /* disable compare */
+ reg &= ~(1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
+
+ writel(reg, base + KONA_GPTIMER_STCS_OFFSET);
+
+}
+
+static int
+kona_timer_get_counter(void __iomem *timer_base, uint32_t *msw, uint32_t *lsw)
+{
+ int loop_limit = 3;
+
+ /*
+ * Read 64-bit free running counter
+ * 1. Read hi-word
+ * 2. Read low-word
+ * 3. Read hi-word again
+ * 4.1
+ * if new hi-word is not equal to previously read hi-word, then
+ * start from #1
+ * 4.2
+ * if new hi-word is equal to previously read hi-word then stop.
+ */
+
+ do {
+ *msw = readl(timer_base + KONA_GPTIMER_STCHI_OFFSET);
+ *lsw = readl(timer_base + KONA_GPTIMER_STCLO_OFFSET);
+ if (*msw == readl(timer_base + KONA_GPTIMER_STCHI_OFFSET))
+ break;
+ } while (--loop_limit);
+ if (!loop_limit) {
+ pr_err("bcm_kona_timer: getting counter failed.\n");
+ pr_err(" Timer will be impacted\n");
+ return -ETIMEDOUT;
+ }
+
+ return 0;
+}
+
+static int kona_timer_set_next_event(unsigned long clc,
+ struct clock_event_device *unused)
+{
+ /*
+ * timer (0) is disabled by the timer interrupt already
+ * so, here we reload the next event value and re-enable
+ * the timer.
+ *
+ * This way, we are potentially losing the time between
+ * timer-interrupt->set_next_event. CPU local timers, when
+ * they come in should get rid of skew.
+ */
+
+ uint32_t lsw, msw;
+ uint32_t reg;
+ int ret;
+
+ ret = kona_timer_get_counter(timers.tmr_regs, &msw, &lsw);
+ if (ret)
+ return ret;
+
+ /* Load the "next" event tick value */
+ writel(lsw + clc, timers.tmr_regs + KONA_GPTIMER_STCM0_OFFSET);
+
+ /* Enable compare */
+ reg = readl(timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
+ reg |= (1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
+ writel(reg, timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
+
+ return 0;
+}
+
+static int kona_timer_shutdown(struct clock_event_device *evt)
+{
+ kona_timer_disable_and_clear(timers.tmr_regs);
+ return 0;
+}
+
+static struct clock_event_device kona_clockevent_timer = {
+ .name = "timer 1",
+ .features = CLOCK_EVT_FEAT_ONESHOT,
+ .set_next_event = kona_timer_set_next_event,
+ .set_state_shutdown = kona_timer_shutdown,
+ .tick_resume = kona_timer_shutdown,
+};
+
+static void __init kona_timer_clockevents_init(void)
+{
+ kona_clockevent_timer.cpumask = cpumask_of(0);
+ clockevents_config_and_register(&kona_clockevent_timer,
+ arch_timer_rate, 6, 0xffffffff);
+}
+
+static irqreturn_t kona_timer_interrupt(int irq, void *dev_id)
+{
+ struct clock_event_device *evt = &kona_clockevent_timer;
+
+ kona_timer_disable_and_clear(timers.tmr_regs);
+ evt->event_handler(evt);
+ return IRQ_HANDLED;
+}
+
+static int __init kona_timer_init(struct device_node *node)
+{
+ u32 freq;
+ struct clk *external_clk;
+
+ external_clk = of_clk_get_by_name(node, NULL);
+
+ if (!IS_ERR(external_clk)) {
+ arch_timer_rate = clk_get_rate(external_clk);
+ clk_prepare_enable(external_clk);
+ } else if (!of_property_read_u32(node, "clock-frequency", &freq)) {
+ arch_timer_rate = freq;
+ } else {
+ pr_err("Kona Timer v1 unable to determine clock-frequency\n");
+ return -EINVAL;
+ }
+
+ /* Setup IRQ numbers */
+ timers.tmr_irq = irq_of_parse_and_map(node, 0);
+
+ /* Setup IO addresses */
+ timers.tmr_regs = of_iomap(node, 0);
+
+ kona_timer_disable_and_clear(timers.tmr_regs);
+
+ kona_timer_clockevents_init();
+ if (request_irq(timers.tmr_irq, kona_timer_interrupt, IRQF_TIMER,
+ "Kona Timer Tick", NULL))
+ pr_err("%s: request_irq() failed\n", "Kona Timer Tick");
+ kona_timer_set_next_event((arch_timer_rate / HZ), NULL);
+
+ return 0;
+}
+
+TIMER_OF_DECLARE(brcm_kona, "brcm,kona-timer", kona_timer_init);
+/*
+ * bcm,kona-timer is deprecated by brcm,kona-timer
+ * being kept here for driver compatibility
+ */
+TIMER_OF_DECLARE(bcm_kona, "bcm,kona-timer", kona_timer_init);