clocksource/drivers/c-sky: Add C-SKY SMP timer

The driver is for C-SKY SMP timer. It only supports oneshot event
and 32bit overflow for clocksource. Per cpu core has one timer and
all timers share one clock-counter-input from the same clocksource.

This use mfcr&mtcr instructions to access the regs.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index a11f4ba98b05c57d08b211ac933f93fcf7cb4616..591c9a8649a5e3a7b32128e35ade7f3035f3bd45 100644 (file)
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -620,4 +620,14 @@ config RISCV_TIMER
          is accessed via both the SBI and the rdcycle instruction.  This is
          required for all RISC-V systems.
 
+config CSKY_MP_TIMER
+       bool "SMP Timer for the C-SKY platform" if COMPILE_TEST
+       depends on CSKY
+       select TIMER_OF
+       help
+         Say yes here to enable C-SKY SMP timer driver used for C-SKY SMP
+         system.
+         csky,mptimer is not only used in SMP system, it also could be used
+         single core system. It's not a mmio reg and it use mtcr/mfcr instruction.
+
 endmenu

diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index db51b2427e8a64e9bfe20bbb41a9363069b101f4..5ce82d39cda7d5e8d293d4347855e18526214ce2 100644 (file)
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -79,3 +79,4 @@ obj-$(CONFIG_CLKSRC_ST_LPC)           += clksrc_st_lpc.o
 obj-$(CONFIG_X86_NUMACHIP)             += numachip.o
 obj-$(CONFIG_ATCPIT100_TIMER)          += timer-atcpit100.o
 obj-$(CONFIG_RISCV_TIMER)              += riscv_timer.o
+obj-$(CONFIG_CSKY_MP_TIMER)            += timer-mp-csky.o

diff --git a/drivers/clocksource/timer-mp-csky.c b/drivers/clocksource/timer-mp-csky.c
new file mode 100644 (file)
index 0000000..a8acc43
--- /dev/null
+++ b/drivers/clocksource/timer-mp-csky.c
@@ -0,0 +1,173 @@
+// 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 <linux/of_irq.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_irq;
+
+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,
+       },
+};
+
+static irqreturn_t csky_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(csky_mptimer_irq, 0);
+
+       return 0;
+}
+
+static int csky_mptimer_dying_cpu(unsigned int cpu)
+{
+       disable_percpu_irq(csky_mptimer_irq);
+
+       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,
+};
+
+static int __init csky_mptimer_init(struct device_node *np)
+{
+       int ret, cpu, cpu_rollback;
+       struct timer_of *to = NULL;
+
+       /*
+        * 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.
+        */
+       csky_mptimer_irq = irq_of_parse_and_map(np, 0);
+       if (csky_mptimer_irq <= 0)
+               return -EINVAL;
+
+       ret = request_percpu_irq(csky_mptimer_irq, csky_timer_interrupt,
+                                "csky_mp_timer", &csky_to);
+       if (ret)
+               return -EINVAL;
+
+       for_each_possible_cpu(cpu) {
+               to = per_cpu_ptr(&csky_to, cpu);
+               ret = timer_of_init(np, to);
+               if (ret)
+                       goto rollback;
+       }
+
+       clocksource_register_hz(&csky_clocksource, timer_of_rate(to));
+       sched_clock_register(sched_clock_read, 32, timer_of_rate(to));
+
+       ret = cpuhp_setup_state(CPUHP_AP_CSKY_TIMER_STARTING,
+                               "clockevents/csky/timer:starting",
+                               csky_mptimer_starting_cpu,
+                               csky_mptimer_dying_cpu);
+       if (ret)
+               return -EINVAL;
+
+       return 0;
+
+rollback:
+       for_each_possible_cpu(cpu_rollback) {
+               if (cpu_rollback == cpu)
+                       break;
+
+               to = per_cpu_ptr(&csky_to, cpu_rollback);
+               timer_of_cleanup(to);
+       }
+       return -EINVAL;
+}
+TIMER_OF_DECLARE(csky_mptimer, "csky,mptimer", csky_mptimer_init);

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index caf40ad0bbc6e0f42027aa1c68f3fa5d07477c9a..e0cd2baa83809a8cff419d0a65562c3a80870232 100644 (file)
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -126,6 +126,7 @@ enum cpuhp_state {
        CPUHP_AP_MIPS_GIC_TIMER_STARTING,
        CPUHP_AP_ARC_TIMER_STARTING,
        CPUHP_AP_RISCV_TIMER_STARTING,
+       CPUHP_AP_CSKY_TIMER_STARTING,
        CPUHP_AP_KVM_STARTING,
        CPUHP_AP_KVM_ARM_VGIC_INIT_STARTING,
        CPUHP_AP_KVM_ARM_VGIC_STARTING,