ATCPIT100 is often used on the Andes architecture,
This timer provide 4 PIT channels. Each PIT channel is a
multi-function timer, can be configured as 32,16,8 bit timers
or PWM as well.
For system timer it will set 32-bit timer0 as clock source
and count downwards until underflow and restart again.
It also set 32-bit timer1 as clock event and count downwards
until condition match. It will generate an interrupt for
handling periodically.
Signed-off-by: Greentime Hu <green.hu@xxxxxxxxx>
Signed-off-by: Rick Chen <rickchen36@xxxxxxxxx>
---
drivers/clocksource/timer-atcpit100.c | 199 ++++++++++++++++++++++++++++++++++
1 file changed, 199 insertions(+)
create mode 100644 drivers/clocksource/timer-atcpit100.c
diff --git a/drivers/clocksource/timer-atcpit100.c b/drivers/clocksource/timer-atcpit100.c
new file mode 100644
index 0000000..6b224c4
--- /dev/null
+++ b/drivers/clocksource/timer-atcpit100.c
@@ -0,0 +1,199 @@
+/*
+ * Andestech ATCPIT100 Timer Device Driver Implementation
+ *
+ * Copyright (C) 2016 Andes Technology Corporation
+ *
+ * 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.
+ *
+ * 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/irq.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/cpufreq.h>
+#include <linux/sched.h>
+#include <linux/sched_clock.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+
+void __iomem *base;
+static u32 freq;
+
+/*
+ * Definition of register offsets
+ */
+
+/* ID and Revision Register */
+#define ID_REV 0x0
+
+/* Configuration Register */
+#define CFG 0x10
+
+/* Interrupt Enable Register */
+#define INT_EN 0x14
+#define CH_INT_EN(c, i) ((1<<i)<<(4*c))
+
+/* Interrupt Status Register */
+#define INT_STA 0x18
+#define CH_INT_STA(c, i) ((1<<i)<<(4*c))
+
+/* Channel Enable Register */
+#define CH_EN 0x1C
+#define CH_TMR_EN(c, t) ((1<<t)<<(4*c))
+
+/* Ch n Control REgister */
+#define CH_CTL(n) (0x20+0x10*n)
+/* Channel clock source , bit 3 , 0:External clock , 1:APB clock */
+#define APB_CLK (1<<3)
+/* Channel mode , bit 0~2 */
+#define TMR_32 1
+#define TMR_16 2
+#define TMR_8 3
+#define PWM 4
+
+#define CH_REL(n) (0x24+0x10*n)
+#define CH_CNT(n) (0x28+0x10*n)
+
+static unsigned long atcpit100_read_current_timer_down(void)
+{
+ return ~readl(base + CH_CNT(1));
+}
+
+static u64 notrace atcpit100_read_sched_clock_down(void)
+{
+ return atcpit100_read_current_timer_down();
+}
+
+static void atcpit100_clocksource_init(void)
+{
+ writel(0xffffffff, base + CH_REL(1));
+ writel(APB_CLK|TMR_32, base + CH_CTL(1));
+ writel(readl(base + CH_EN) | CH_TMR_EN(1, 0), base + CH_EN);
+ clocksource_mmio_init(base + CH_CNT(1),
+ "atcpit100_tm1",
+ freq,
+ 300, 32, clocksource_mmio_readl_down);
+ sched_clock_register(atcpit100_read_sched_clock_down, 32, freq);
+}
+
+static int atcpit100_set_next_event(unsigned long cycles,
+ struct clock_event_device *evt)
+{
+ writel(cycles, base + CH_REL(0));
+
+ return 0;
+}
+
+static int atcpit100_set_state_shutdown(struct clock_event_device *evt)
+{
+ writel(readl(base + CH_EN) & ~CH_TMR_EN(0, 0), base + CH_EN);
+
+ return 0;
+}
+static int atcpit100_set_state_periodic(struct clock_event_device *evt)
+{
+ writel(freq / HZ - 1, base + CH_CNT(0));
+ writel(freq / HZ - 1, base + CH_REL(0));
+ writel(readl(base + CH_EN) | CH_TMR_EN(0, 0), base + CH_EN);
+
+ return 0;
+}
+static int atcpit100_tick_resume(struct clock_event_device *evt)
+{
+ writel(readl(base + INT_STA) | CH_INT_STA(0, 0), base + INT_STA);
+ writel(readl(base + CH_EN) | CH_TMR_EN(0, 0), base + CH_EN);
+
+ return 0;
+}
+static int atcpit100_set_state_oneshot(struct clock_event_device *evt)
+{
+ writel(0xffffffff, base + CH_REL(0));
+ writel(readl(base + CH_EN) | CH_TMR_EN(0, 0), base + CH_EN);
+
+ return 0;
+}
+
+static struct clock_event_device clockevent_atcpit100 = {
+ .name = "atcpit100_tm0",
+ .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
+ .shift = 32,
+ .cpumask = cpu_all_mask,
+ .set_next_event = atcpit100_set_next_event,
+ .set_state_shutdown = atcpit100_set_state_shutdown,
+ .set_state_periodic = atcpit100_set_state_periodic,
+ .set_state_oneshot = atcpit100_set_state_oneshot,
+ .tick_resume = atcpit100_tick_resume,
+};
+
+static irqreturn_t timer1_interrupt(int irq, void *dev_id)
+{
+ struct clock_event_device *evt = dev_id;
+
+ writel(readl(base + INT_STA) | CH_INT_STA(0, 0), base + INT_STA);
+
+ evt->event_handler(evt);
+
+ return IRQ_HANDLED;
+}
+
+static struct irqaction timer1_irq = {
+ .name = "Timer Tick",
+ .flags = IRQF_TIMER | IRQF_IRQPOLL,
+ .handler = timer1_interrupt,
+ .dev_id = &clockevent_atcpit100
+};
+
+static void __init atcpit100_clockevent_init(int irq)
+{
+ struct clock_event_device *evt = &clockevent_atcpit100;
+
+ evt->mult = div_sc(freq, NSEC_PER_SEC, evt->shift);
+ evt->max_delta_ns = clockevent_delta2ns(0xffffffff, evt);
+ evt->min_delta_ns = clockevent_delta2ns(3, evt);
+ clockevents_register_device(evt);
+ setup_irq(irq, &timer1_irq);
+}
+
+static int __init atcpit100_init(struct device_node *dev)
+{
+ int irq;
+
+ base = of_iomap(dev, 0);
+ if (!base) {
+ pr_warn("Can't remap registers");
+ return -ENXIO;
+ }
+
+ if (of_property_read_u32(dev, "clock-frequency", &freq)) {
+ pr_warn("Can't read clock-frequency");
+ return -EINVAL;
+ }
+ irq = irq_of_parse_and_map(dev, 0);
+
+ if (irq <= 0) {
+ pr_warn("Failed to map timer IRQ\n");
+ return -EINVAL;
+ }
+ pr_info("ATCPIT100 timer 1 installed on IRQ %d, with clock %d at %d HZ. in 0x%08x\r\n",
+ irq, freq, HZ, (u32)base);
+ writel(APB_CLK|TMR_32, base + CH_CTL(0));
+ writel(readl(base + INT_EN) | CH_INT_EN(0, 0), base + INT_EN);
+ writel(readl(base + CH_EN) | CH_TMR_EN(0, 0), base + CH_EN);
+ atcpit100_clocksource_init();
+ atcpit100_clockevent_init(irq);
+
+ return 0;
+}
+
+TIMER_OF_DECLARE(atcpit100, "andestech,atcpit100", atcpit100_init);
--
2.7.4
--
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