[PATCH v2 3/3] clocksource/drivers/timer-clint: Add T-Head C9xx clint

[Jisheng Zhang <jszhang@kernel.org>]

The mtimecmp in T-Head C9xx clint only supports 32bit read/write,
implement such support.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 drivers/clocksource/timer-clint.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/clocksource/timer-clint.c b/drivers/clocksource/timer-clint.c
index 0d3890e00b75..655ea81071ff 100644
--- a/drivers/clocksource/timer-clint.c
+++ b/drivers/clocksource/timer-clint.c
@@ -39,6 +39,7 @@ static u64 __iomem *clint_timer_cmp;
 static u64 __iomem *clint_timer_val;
 static unsigned long clint_timer_freq;
 static unsigned int clint_timer_irq;
+static bool is_c900_clint;
 
 #ifdef CONFIG_RISCV_M_MODE
 u64 __iomem *clint_time_val;
@@ -135,6 +136,19 @@ static int clint_clock_shutdown(struct clock_event_device *evt)
 	return 0;
 }
 
+static int c900_clint_clock_next_event(unsigned long delta,
+				       struct clock_event_device *ce)
+{
+	void __iomem *r = clint_timer_cmp +
+			  cpuid_to_hartid_map(smp_processor_id());
+	u64 val = clint_get_cycles64() + delta;
+
+	csr_set(CSR_IE, IE_TIE);
+	writel_relaxed(val, r);
+	writel_relaxed(val >> 32, r + 4);
+	return 0;
+}
+
 static DEFINE_PER_CPU(struct clock_event_device, clint_clock_event) = {
 	.name				= "clint_clockevent",
 	.features			= CLOCK_EVT_FEAT_ONESHOT,
@@ -148,6 +162,9 @@ static int clint_timer_starting_cpu(unsigned int cpu)
 {
 	struct clock_event_device *ce = per_cpu_ptr(&clint_clock_event, cpu);
 
+	if (is_c900_clint)
+		ce->set_next_event = c900_clint_clock_next_event;
+
 	ce->cpumask = cpumask_of(cpu);
 	clockevents_config_and_register(ce, clint_timer_freq, 100, ULONG_MAX);
 
@@ -291,5 +308,12 @@ static int __init clint_timer_init_dt(struct device_node *np)
 	return rc;
 }
 
+static int __init c900_clint_timer_init_dt(struct device_node *np)
+{
+	is_c900_clint = true;
+	return clint_timer_init_dt(np);
+}
+
 TIMER_OF_DECLARE(clint_timer, "riscv,clint0", clint_timer_init_dt);
 TIMER_OF_DECLARE(clint_timer1, "sifive,clint0", clint_timer_init_dt);
+TIMER_OF_DECLARE(clint_timer2, "thead,c900-clint", c900_clint_timer_init_dt);
-- 
2.43.0