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Subject[PATCH V3 24/26] clocksource: add C-SKY SMP timer
Date
This timer is used by SMP system and use mfcr/mtcr instruction
to access the regs.

Changelog:
- Support csky mp timer alpha version.
- Just use low-counter with 32bit width as clocksource.
- Coding convention with upstream feed-back.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
---
drivers/clocksource/csky_mptimer.c | 178 +++++++++++++++++++++++++++++++++++++
1 file changed, 178 insertions(+)
create mode 100644 drivers/clocksource/csky_mptimer.c

diff --git a/drivers/clocksource/csky_mptimer.c b/drivers/clocksource/csky_mptimer.c
new file mode 100644
index 0000000..da2b239
--- /dev/null
+++ b/drivers/clocksource/csky_mptimer.c
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/sched_clock.h>
+#include <linux/cpu.h>
+#include <asm/reg_ops.h>
+
+#include "timer-of.h"
+
+#define PTIM_CCVR "cr<3, 14>"
+#define PTIM_CTLR "cr<0, 14>"
+#define PTIM_LVR "cr<6, 14>"
+#define PTIM_TSR "cr<1, 14>"
+
+static int csky_mptimer_set_next_event(unsigned long delta, struct clock_event_device *ce)
+{
+ mtcr(PTIM_LVR, delta);
+
+ return 0;
+}
+
+static int csky_mptimer_shutdown(struct clock_event_device *ce)
+{
+ mtcr(PTIM_CTLR, 0);
+
+ return 0;
+}
+
+static int csky_mptimer_oneshot(struct clock_event_device *ce)
+{
+ mtcr(PTIM_CTLR, 1);
+
+ return 0;
+}
+
+static int csky_mptimer_oneshot_stopped(struct clock_event_device *ce)
+{
+ mtcr(PTIM_CTLR, 0);
+
+ return 0;
+}
+
+static DEFINE_PER_CPU(struct timer_of, csky_to) = {
+ .flags = TIMER_OF_CLOCK,
+ .clkevt = {
+ .rating = 300,
+ .features = CLOCK_EVT_FEAT_PERCPU |
+ CLOCK_EVT_FEAT_ONESHOT,
+ .set_state_shutdown = csky_mptimer_shutdown,
+ .set_state_oneshot = csky_mptimer_oneshot,
+ .set_state_oneshot_stopped = csky_mptimer_oneshot_stopped,
+ .set_next_event = csky_mptimer_set_next_event,
+ },
+ .of_irq = {
+ .flags = IRQF_TIMER,
+ .percpu = 1,
+ },
+};
+
+static irqreturn_t timer_interrupt(int irq, void *dev)
+{
+ struct timer_of *to = this_cpu_ptr(&csky_to);
+
+ mtcr(PTIM_TSR, 0);
+
+ to->clkevt.event_handler(&to->clkevt);
+
+ return IRQ_HANDLED;
+}
+
+/*
+ * clock event for percpu
+ */
+static int csky_mptimer_starting_cpu(unsigned int cpu)
+{
+ struct timer_of *to = per_cpu_ptr(&csky_to, cpu);
+
+ to->clkevt.cpumask = cpumask_of(cpu);
+
+ clockevents_config_and_register(&to->clkevt, timer_of_rate(to), 2, ULONG_MAX);
+
+ enable_percpu_irq(timer_of_irq(to), 0);
+
+ return 0;
+}
+
+static int csky_mptimer_dying_cpu(unsigned int cpu)
+{
+ struct timer_of *to = per_cpu_ptr(&csky_to, cpu);
+
+ disable_percpu_irq(timer_of_irq(to));
+
+ return 0;
+}
+
+/*
+ * clock source
+ */
+static u64 sched_clock_read(void)
+{
+ return (u64) mfcr(PTIM_CCVR);
+}
+
+static u64 clksrc_read(struct clocksource *c)
+{
+ return (u64) mfcr(PTIM_CCVR);
+}
+
+struct clocksource csky_clocksource = {
+ .name = "csky",
+ .rating = 400,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+ .read = clksrc_read,
+};
+
+#define CPUHP_AP_CSKY_TIMER_STARTING CPUHP_AP_DUMMY_TIMER_STARTING
+
+static int __init csky_mptimer_init(struct device_node *np)
+{
+ int ret, cpu;
+ struct timer_of *to;
+ int rate = 0;
+ int irq = 0;
+
+ /*
+ * Csky_mptimer is designed for C-SKY SMP multi-processors and
+ * every core has it's own private irq and regs for clkevt and
+ * clksrc.
+ *
+ * The regs is accessed by cpu instruction: mfcr/mtcr instead of
+ * mmio map style. So we needn't mmio-address in dts, but we still
+ * need to give clk and irq number.
+ *
+ * We use private irq for the mptimer and irq number is the same
+ * for every core. So we use request_percpu_irq() in timer_of_init.
+ */
+
+ for_each_possible_cpu(cpu) {
+ to = per_cpu_ptr(&csky_to, cpu);
+
+ if (cpu == 0) {
+ to->flags |= TIMER_OF_IRQ;
+ to->of_irq.handler = timer_interrupt;
+
+ ret = timer_of_init(np, to);
+ if (ret)
+ return ret;
+
+ rate = timer_of_rate(to);
+ irq = to->of_irq.irq;
+ } else {
+ ret = timer_of_init(np, to);
+ if (ret)
+ return ret;
+
+ to->of_clk.rate = rate;
+ to->of_irq.irq = irq;
+ }
+ }
+
+ ret = cpuhp_setup_state(CPUHP_AP_CSKY_TIMER_STARTING,
+ "clockevents/csky/timer:starting",
+ csky_mptimer_starting_cpu,
+ csky_mptimer_dying_cpu);
+ if (ret) {
+ pr_err("%s: Failed to cpuhp_setup_state.\n", __func__);
+ return ret;
+ }
+
+ clocksource_register_hz(&csky_clocksource, rate);
+ sched_clock_register(sched_clock_read, 32, rate);
+
+ return 0;
+}
+TIMER_OF_DECLARE(csky_mptimer, "csky,mptimer", csky_mptimer_init);
--
2.7.4
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