[PATCH v4 3/4] clocksource/drivers/exynos_mct: Support local-timers property

[Vincent Whitchurch]

If the device tree indicates that the hardware requires that the
processor only use certain local timers, respect that.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch at axis.com>
---

Notes:
    v4:
    - Add function documentation
    - Add const for local_idx
    - Rename irqidx -> irq_idx
    - Error out on invalid number of CPUs
    
    v3:
    - Use array in devicetree
    - Remove addition of global variable
    - Split out FRC sharing changes

 drivers/clocksource/exynos_mct.c | 62 ++++++++++++++++++++++++++++----
 1 file changed, 56 insertions(+), 6 deletions(-)

diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index 12023831dedf..bfd60093ee1c 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -33,7 +33,7 @@
 #define EXYNOS4_MCT_G_INT_ENB		EXYNOS4_MCTREG(0x248)
 #define EXYNOS4_MCT_G_WSTAT		EXYNOS4_MCTREG(0x24C)
 #define _EXYNOS4_MCT_L_BASE		EXYNOS4_MCTREG(0x300)
-#define EXYNOS4_MCT_L_BASE(x)		(_EXYNOS4_MCT_L_BASE + (0x100 * x))
+#define EXYNOS4_MCT_L_BASE(x)		(_EXYNOS4_MCT_L_BASE + (0x100 * (x)))
 #define EXYNOS4_MCT_L_MASK		(0xffffff00)
 
 #define MCT_L_TCNTB_OFFSET		(0x00)
@@ -66,6 +66,8 @@
 #define MCT_L0_IRQ	4
 /* Max number of IRQ as per DT binding document */
 #define MCT_NR_IRQS	20
+/* Max number of local timers */
+#define MCT_NR_LOCAL	(MCT_NR_IRQS - MCT_L0_IRQ)
 
 enum {
 	MCT_INT_SPI,
@@ -456,7 +458,6 @@ static int exynos4_mct_starting_cpu(unsigned int cpu)
 		per_cpu_ptr(&percpu_mct_tick, cpu);
 	struct clock_event_device *evt = &mevt->evt;
 
-	mevt->base = EXYNOS4_MCT_L_BASE(cpu);
 	snprintf(mevt->name, sizeof(mevt->name), "mct_tick%d", cpu);
 
 	evt->name = mevt->name;
@@ -527,8 +528,17 @@ static int __init exynos4_timer_resources(struct device_node *np)
 	return 0;
 }
 
+/**
+ * exynos4_timer_interrupts - initialize MCT interrupts
+ * @np: device node for MCT
+ * @int_type: interrupt type, MCT_INT_PPI or MCT_INT_SPI
+ * @local_idx: array mapping CPU numbers to local timer indices
+ * @nr_local: size of @local_idx array
+ */
 static int __init exynos4_timer_interrupts(struct device_node *np,
-					   unsigned int int_type)
+					   unsigned int int_type,
+					   const u32 *local_idx,
+					   size_t nr_local)
 {
 	int nr_irqs, i, err, cpu;
 
@@ -561,13 +571,21 @@ static int __init exynos4_timer_interrupts(struct device_node *np,
 	} else {
 		for_each_possible_cpu(cpu) {
 			int mct_irq;
+			unsigned int irq_idx;
 			struct mct_clock_event_device *pcpu_mevt =
 				per_cpu_ptr(&percpu_mct_tick, cpu);
 
+			if (cpu >= nr_local) {
+				err = -EINVAL;
+				goto out_irq;
+			}
+
+			irq_idx = MCT_L0_IRQ + local_idx[cpu];
+
 			pcpu_mevt->evt.irq = -1;
-			if (MCT_L0_IRQ + cpu >= ARRAY_SIZE(mct_irqs))
+			if (irq_idx >= ARRAY_SIZE(mct_irqs))
 				break;
-			mct_irq = mct_irqs[MCT_L0_IRQ + cpu];
+			mct_irq = mct_irqs[irq_idx];
 
 			irq_set_status_flags(mct_irq, IRQ_NOAUTOEN);
 			if (request_irq(mct_irq,
@@ -583,6 +601,17 @@ static int __init exynos4_timer_interrupts(struct device_node *np,
 		}
 	}
 
+	for_each_possible_cpu(cpu) {
+		struct mct_clock_event_device *mevt = per_cpu_ptr(&percpu_mct_tick, cpu);
+
+		if (cpu >= nr_local) {
+			err = -EINVAL;
+			goto out_irq;
+		}
+
+		mevt->base = EXYNOS4_MCT_L_BASE(local_idx[cpu]);
+	}
+
 	/* Install hotplug callbacks which configure the timer on this CPU */
 	err = cpuhp_setup_state(CPUHP_AP_EXYNOS4_MCT_TIMER_STARTING,
 				"clockevents/exynos4/mct_timer:starting",
@@ -613,13 +642,34 @@ static int __init exynos4_timer_interrupts(struct device_node *np,
 static int __init mct_init_dt(struct device_node *np, unsigned int int_type)
 {
 	bool frc_shared = of_property_read_bool(np, "samsung,frc-shared");
+	u32 local_idx[MCT_NR_LOCAL] = {0};
+	int nr_local;
 	int ret;
 
+	nr_local = of_property_count_u32_elems(np, "samsung,local-timers");
+	if (nr_local == 0)
+		return -EINVAL;
+	if (nr_local > 0) {
+		if (nr_local > ARRAY_SIZE(local_idx))
+			return -EINVAL;
+
+		ret = of_property_read_u32_array(np, "samsung,local-timers",
+						 local_idx, nr_local);
+		if (ret)
+			return ret;
+	} else {
+		int i;
+
+		nr_local = ARRAY_SIZE(local_idx);
+		for (i = 0; i < nr_local; i++)
+			local_idx[i] = i;
+	}
+
 	ret = exynos4_timer_resources(np);
 	if (ret)
 		return ret;
 
-	ret = exynos4_timer_interrupts(np, int_type);
+	ret = exynos4_timer_interrupts(np, int_type, local_idx, nr_local);
 	if (ret)
 		return ret;
 
-- 
2.34.1