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Subject: [PATCH v4 2/6] clocksource: Ingenic: Add high resolution timer support for SMP.
Date:   Sat, 15 Feb 2020 02:02:36 +0800
Message-Id: <1581703360-112557-4-git-send-email-zhouyanjie@wanyeetech.com>
In-Reply-To: <1581703360-112557-1-git-send-email-zhouyanjie@wanyeetech.com>
References: <1581703360-112557-1-git-send-email-zhouyanjie@wanyeetech.com>
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Enable clock event handling on per CPU core basis.
Make sure that interrupts raised on the first core execute
event handlers on the correct CPU core.

Tested-by: H. Nikolaus Schaller <hns@goldelico.com>
Tested-by: Paul Boddie <paul@boddie.org.uk>
Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
---

Notes:
    v1->v2:
    1.Adjust function naming to make it more reasonable.
    2.Replace function smp_call_function_single() with
      smp_call_function_single_async() in order to resolve
      the warning below:
    
    [    0.350942] smp: Brought up 1 node, 2 CPUs
    [    0.365497] ------------[ cut here ]------------
    [    0.365522] WARNING: CPU: 0 PID: 1 at kernel/smp.c:300 smp_call_function_single+0x110/0x200
    [    0.365533] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.5.0-rc1+ #5
    [    0.365537] Stack : 00000000 59c73bcd 00000037 80074e80 80000000 80670000 805a0000 80620590
    [    0.365557]         8065ce38 8fc0dc8c 806d0000 00000000 80670000 00000001 8fc0dc20 59c73bcd
    [    0.365574]         00000000 00000000 806f0000 80670000 00000000 806dab00 00000000 2d302e35
    [    0.365591]         203a6d6d 806e0000 806e0000 70617773 80670000 00000000 00000000 00000009
    [    0.365610]         00000000 8fc94e20 8fc0de30 80690000 00000018 803592dc 00000000 806d0000
    [    0.365627]         ...
    [    0.365634] Call Trace:
    [    0.365647] [<8001b9a0>] show_stack+0x6c/0x12c
    [    0.365663] [<804aed20>] dump_stack+0x98/0xc8
    [    0.365673] [<8003044c>] __warn+0xc4/0xe8
    [    0.365682] [<800304f4>] warn_slowpath_fmt+0x84/0xb8
    [    0.365690] [<800a886c>] smp_call_function_single+0x110/0x200
    [    0.365703] ---[ end trace 5785856ca39c79d5 ]---
    [    0.365557]         8065ce38 8fc0dc8c 806d0000 00000000 80670000 00000001 8fc0dc20 59c73bcd
    [    0.365574]         00000000 00000000 806f0000 80670000 00000000 806dab00 00000000 2d302e35
    [    0.365591]         203a6d6d 806e0000 806e0000 70617773 80670000 00000000 00000000 00000009
    [    0.365610]         00000000 8fc94e20 8fc0de30 80690000 00000018 803592dc 00000000 806d0000
    [    0.365627]         ...
    [    0.365634] Call Trace:
    [    0.365647] [<8001b9a0>] show_stack+0x6c/0x12c
    [    0.365663] [<804aed20>] dump_stack+0x98/0xc8
    [    0.365673] [<8003044c>] __warn+0xc4/0xe8
    [    0.365682] [<800304f4>] warn_slowpath_fmt+0x84/0xb8
    [    0.365690] [<800a886c>] smp_call_function_single+0x110/0x200
    [    0.365703] ---[ end trace 5785856ca39c79d5 ]---
    
    v2->v3:
    No Change.
    
    v3->v4:
    Rebase on top of kernel 5.6-rc1.

 drivers/clocksource/ingenic-timer.c | 200 ++++++++++++++++++++++++------------
 1 file changed, 134 insertions(+), 66 deletions(-)

diff --git a/drivers/clocksource/ingenic-timer.c b/drivers/clocksource/ingenic-timer.c
index 4bbdb3d..9127c73 100644
--- a/drivers/clocksource/ingenic-timer.c
+++ b/drivers/clocksource/ingenic-timer.c
@@ -1,7 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * JZ47xx SoCs TCU IRQ driver
+ * XBurst SoCs TCU IRQ driver
  * Copyright (C) 2019 Paul Cercueil <paul@crapouillou.net>
+ * Copyright (C) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
  */
 
 #include <linux/bitops.h>
@@ -21,18 +22,23 @@
 
 #include <dt-bindings/clock/ingenic,tcu.h>
 
+static DEFINE_PER_CPU(call_single_data_t, ingenic_cevt_csd);
+
 struct ingenic_soc_info {
 	unsigned int num_channels;
 };
 
 struct ingenic_tcu {
 	struct regmap *map;
+	struct device_node *np;
 	struct clk *timer_clk, *cs_clk;
+	unsigned int timer_local[NR_CPUS];
 	unsigned int timer_channel, cs_channel;
 	struct clock_event_device cevt;
 	struct clocksource cs;
-	char name[4];
+	char name[16];
 	unsigned long pwm_channels_mask;
+	int cpu;
 };
 
 static struct ingenic_tcu *ingenic_tcu;
@@ -81,6 +87,25 @@ static int ingenic_tcu_cevt_set_next(unsigned long next,
 	return 0;
 }
 
+static void ingenic_per_cpu_event_handler(void *info)
+{
+	struct clock_event_device *cevt = (struct clock_event_device *) info;
+
+	if (cevt->event_handler)
+		cevt->event_handler(cevt);
+}
+
+static void ingenic_tcu_per_cpu_cb(struct clock_event_device *evt)
+{
+	struct ingenic_tcu *tcu = to_ingenic_tcu(evt);
+	call_single_data_t *csd;
+
+	csd = &per_cpu(ingenic_cevt_csd, tcu->cpu);
+	csd->info = (void *) evt;
+	csd->func = ingenic_per_cpu_event_handler;
+	smp_call_function_single_async(tcu->cpu, csd);
+}
+
 static irqreturn_t ingenic_tcu_cevt_cb(int irq, void *dev_id)
 {
 	struct clock_event_device *evt = dev_id;
@@ -88,8 +113,7 @@ static irqreturn_t ingenic_tcu_cevt_cb(int irq, void *dev_id)
 
 	regmap_write(tcu->map, TCU_REG_TECR, BIT(tcu->timer_channel));
 
-	if (evt->event_handler)
-		evt->event_handler(evt);
+	ingenic_tcu_per_cpu_cb(evt);
 
 	return IRQ_HANDLED;
 }
@@ -105,14 +129,73 @@ static struct clk * __init ingenic_tcu_get_clock(struct device_node *np, int id)
 	return of_clk_get_from_provider(&args);
 }
 
-static int __init ingenic_tcu_timer_init(struct device_node *np,
-					 struct ingenic_tcu *tcu)
+static int __init ingenic_tcu_clocksource_init(struct device_node *np,
+					       struct ingenic_tcu *tcu)
+{
+	unsigned int channel = tcu->cs_channel;
+	struct clocksource *cs = &tcu->cs;
+	unsigned long rate;
+	int err;
+
+	tcu->cs_clk = ingenic_tcu_get_clock(np, channel);
+	if (IS_ERR(tcu->cs_clk))
+		return PTR_ERR(tcu->cs_clk);
+
+	err = clk_prepare_enable(tcu->cs_clk);
+	if (err)
+		goto err_clk_put;
+
+	rate = clk_get_rate(tcu->cs_clk);
+	if (!rate) {
+		err = -EINVAL;
+		goto err_clk_disable;
+	}
+
+	/* Reset channel */
+	regmap_update_bits(tcu->map, TCU_REG_TCSRc(channel),
+			   0xffff & ~TCU_TCSR_RESERVED_BITS, 0);
+
+	/* Reset counter */
+	regmap_write(tcu->map, TCU_REG_TDFRc(channel), 0xffff);
+	regmap_write(tcu->map, TCU_REG_TCNTc(channel), 0);
+
+	/* Enable channel */
+	regmap_write(tcu->map, TCU_REG_TESR, BIT(channel));
+
+	cs->name = "ingenic-timer";
+	cs->rating = 200;
+	cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
+	cs->mask = CLOCKSOURCE_MASK(16);
+	cs->read = ingenic_tcu_timer_cs_read;
+
+	err = clocksource_register_hz(cs, rate);
+	if (err)
+		goto err_clk_disable;
+
+	return 0;
+
+err_clk_disable:
+	clk_disable_unprepare(tcu->cs_clk);
+err_clk_put:
+	clk_put(tcu->cs_clk);
+	return err;
+}
+
+static int ingenic_tcu_setup_per_cpu_cevt(struct device_node *np,
+				     unsigned int channel)
 {
-	unsigned int timer_virq, channel = tcu->timer_channel;
+	unsigned int timer_virq;
 	struct irq_domain *domain;
+	struct ingenic_tcu *tcu;
 	unsigned long rate;
 	int err;
 
+	tcu = kzalloc(sizeof(*tcu), GFP_KERNEL);
+	if (!tcu)
+		return -ENOMEM;
+
+	tcu->map = ingenic_tcu->map;
+
 	tcu->timer_clk = ingenic_tcu_get_clock(np, channel);
 	if (IS_ERR(tcu->timer_clk))
 		return PTR_ERR(tcu->timer_clk);
@@ -139,13 +222,15 @@ static int __init ingenic_tcu_timer_init(struct device_node *np,
 		goto err_clk_disable;
 	}
 
-	snprintf(tcu->name, sizeof(tcu->name), "TCU");
+	snprintf(tcu->name, sizeof(tcu->name), "TCU channel.%u", channel);
 
 	err = request_irq(timer_virq, ingenic_tcu_cevt_cb, IRQF_TIMER,
 			  tcu->name, &tcu->cevt);
 	if (err)
 		goto err_irq_dispose_mapping;
 
+	tcu->cpu = smp_processor_id();
+	tcu->timer_channel = channel;
 	tcu->cevt.cpumask = cpumask_of(smp_processor_id());
 	tcu->cevt.features = CLOCK_EVT_FEAT_ONESHOT;
 	tcu->cevt.name = tcu->name;
@@ -166,56 +251,23 @@ static int __init ingenic_tcu_timer_init(struct device_node *np,
 	return err;
 }
 
-static int __init ingenic_tcu_clocksource_init(struct device_node *np,
-					       struct ingenic_tcu *tcu)
+static int ingenic_tcu_setup_cevt(unsigned int cpu)
 {
-	unsigned int channel = tcu->cs_channel;
-	struct clocksource *cs = &tcu->cs;
-	unsigned long rate;
-	int err;
-
-	tcu->cs_clk = ingenic_tcu_get_clock(np, channel);
-	if (IS_ERR(tcu->cs_clk))
-		return PTR_ERR(tcu->cs_clk);
-
-	err = clk_prepare_enable(tcu->cs_clk);
-	if (err)
-		goto err_clk_put;
-
-	rate = clk_get_rate(tcu->cs_clk);
-	if (!rate) {
-		err = -EINVAL;
-		goto err_clk_disable;
-	}
-
-	/* Reset channel */
-	regmap_update_bits(tcu->map, TCU_REG_TCSRc(channel),
-			   0xffff & ~TCU_TCSR_RESERVED_BITS, 0);
-
-	/* Reset counter */
-	regmap_write(tcu->map, TCU_REG_TDFRc(channel), 0xffff);
-	regmap_write(tcu->map, TCU_REG_TCNTc(channel), 0);
-
-	/* Enable channel */
-	regmap_write(tcu->map, TCU_REG_TESR, BIT(channel));
-
-	cs->name = "ingenic-timer";
-	cs->rating = 200;
-	cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
-	cs->mask = CLOCKSOURCE_MASK(16);
-	cs->read = ingenic_tcu_timer_cs_read;
+	int ret;
 
-	err = clocksource_register_hz(cs, rate);
-	if (err)
-		goto err_clk_disable;
+	ret = ingenic_tcu_setup_per_cpu_cevt(ingenic_tcu->np,
+						ingenic_tcu->timer_local[cpu]);
+	if (ret)
+		goto err_tcu_clocksource_cleanup;
 
 	return 0;
 
-err_clk_disable:
-	clk_disable_unprepare(tcu->cs_clk);
-err_clk_put:
-	clk_put(tcu->cs_clk);
-	return err;
+err_tcu_clocksource_cleanup:
+	clocksource_unregister(&ingenic_tcu->cs);
+	clk_disable_unprepare(ingenic_tcu->cs_clk);
+	clk_put(ingenic_tcu->cs_clk);
+	kfree(ingenic_tcu);
+	return ret;
 }
 
 static const struct ingenic_soc_info jz4740_soc_info = {
@@ -239,6 +291,7 @@ static int __init ingenic_tcu_init(struct device_node *np)
 	const struct ingenic_soc_info *soc_info = id->data;
 	struct ingenic_tcu *tcu;
 	struct regmap *map;
+	unsigned cpu = 0;
 	long rate;
 	int ret;
 
@@ -253,12 +306,14 @@ static int __init ingenic_tcu_init(struct device_node *np)
 		return -ENOMEM;
 
 	/* Enable all TCU channels for PWM use by default except channels 0/1 */
-	tcu->pwm_channels_mask = GENMASK(soc_info->num_channels - 1, 2);
+	tcu->pwm_channels_mask = GENMASK(soc_info->num_channels - 1,
+								NR_CPUS + 1);
 	of_property_read_u32(np, "ingenic,pwm-channels-mask",
 			     (u32 *)&tcu->pwm_channels_mask);
 
 	/* Verify that we have at least two free channels */
-	if (hweight8(tcu->pwm_channels_mask) > soc_info->num_channels - 2) {
+	if (hweight8(tcu->pwm_channels_mask) >
+			soc_info->num_channels - NR_CPUS + 1) {
 		pr_crit("%s: Invalid PWM channel mask: 0x%02lx\n", __func__,
 			tcu->pwm_channels_mask);
 		ret = -EINVAL;
@@ -266,13 +321,29 @@ static int __init ingenic_tcu_init(struct device_node *np)
 	}
 
 	tcu->map = map;
+	tcu->np = np;
 	ingenic_tcu = tcu;
 
-	tcu->timer_channel = find_first_zero_bit(&tcu->pwm_channels_mask,
+	tcu->timer_local[cpu] = find_first_zero_bit(&tcu->pwm_channels_mask,
 						 soc_info->num_channels);
-	tcu->cs_channel = find_next_zero_bit(&tcu->pwm_channels_mask,
-					     soc_info->num_channels,
-					     tcu->timer_channel + 1);
+
+	if (NR_CPUS > 1) {
+		for (cpu = 1; cpu < NR_CPUS; cpu++)
+			tcu->timer_local[cpu] = find_next_zero_bit(
+						&tcu->pwm_channels_mask,
+						soc_info->num_channels,
+						tcu->timer_local[cpu - 1] + 1);
+
+		tcu->cs_channel = find_next_zero_bit(&tcu->pwm_channels_mask,
+					soc_info->num_channels,
+					tcu->timer_local[cpu-1] + 1);
+	} else {
+		tcu->cs_channel = find_next_zero_bit(&tcu->pwm_channels_mask,
+					soc_info->num_channels,
+					tcu->timer_local[cpu] + 1);
+	}
+
+
 
 	ret = ingenic_tcu_clocksource_init(np, tcu);
 	if (ret) {
@@ -280,9 +351,10 @@ static int __init ingenic_tcu_init(struct device_node *np)
 		goto err_free_ingenic_tcu;
 	}
 
-	ret = ingenic_tcu_timer_init(np, tcu);
-	if (ret)
-		goto err_tcu_clocksource_cleanup;
+	/* Setup clock events on each CPU core */
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "Ingenic XBurst: online",
+				ingenic_tcu_setup_cevt, NULL);
+	WARN_ON(ret < 0);
 
 	/* Register the sched_clock at the end as there's no way to undo it */
 	rate = clk_get_rate(tcu->cs_clk);
@@ -290,10 +362,6 @@ static int __init ingenic_tcu_init(struct device_node *np)
 
 	return 0;
 
-err_tcu_clocksource_cleanup:
-	clocksource_unregister(&tcu->cs);
-	clk_disable_unprepare(tcu->cs_clk);
-	clk_put(tcu->cs_clk);
 err_free_ingenic_tcu:
 	kfree(tcu);
 	return ret;
-- 
2.7.4