realtek: Replace the RTL9300 generic timer with a CEVT timer

The RTL9300 has a broken R4K MIPS timer interrupt, however, the
R4K clocksource works. We replace the RTL9300 timer with a
Clock Event Timer (CEVT), which is VSMP aware and can be instantiated
as part of brining a VSMTP cpu up instead of the R4K CEVT source.
For this we place the RTL9300 CEVT timer in arch/mips/kernel
together with other MIPS CEVT timers, initialize the SoC IRQs
from a modified smp-mt.c and instantiate each timer as part
of the MIPS time setup in arch/mips/include/asm/time.h instead
of the R4K CEVT, similarly as is done by other MIPS CEVT timers.

Signed-off-by: Birger Koblitz <git@birger-koblitz.de>

4 files changed, 266 insertions, 224 deletions

diff --git a/target/linux/realtek/files-5.10/arch/mips/kernel/cevt-rtl9300.c b/target/linux/realtek/files-5.10/arch/mips/kernel/cevt-rtl9300.c
new file mode 100644
index 0000000000..cf3a4fe437
--- /dev/null
+++ b/target/linux/realtek/files-5.10/arch/mips/kernel/cevt-rtl9300.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/clockchips.h>
+#include <linux/init.h>
+#include <asm/time.h>
+#include <asm/idle.h>
+#include <linux/interrupt.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/sched_clock.h>
+
+#include <mach-rtl83xx.h>
+
+/* 
+ * Timer registers
+ * the RTL9300/9310 SoCs have 6 timers, each register block 0x10 apart
+ */
+#define RTL9300_TC_DATA		0x0
+#define RTL9300_TC_CNT		0x4
+#define RTL9300_TC_CTRL		0x8
+#define RTL9300_TC_CTRL_MODE	BIT(24)
+#define RTL9300_TC_CTRL_EN	BIT(28)
+#define RTL9300_TC_INT		0xc
+#define RTL9300_TC_INT_IP	BIT(16)
+#define RTL9300_TC_INT_IE	BIT(20)
+
+// Clocksource is using timer 0, clock event uses timer 1
+#define TIMER_CLK_SRC		0
+#define TIMER_CLK_EVT		0
+#define TIMER_BLK_EVT		(TIMER_CLK_EVT << 4)
+
+// Timer modes
+#define TIMER_MODE_REPEAT	1
+#define TIMER_MODE_ONCE		0
+
+// Minimum divider is 2
+#define DIVISOR_RTL9300		2
+
+#define N_BITS			28
+
+#define RTL9300_TC1_IRQ		8
+#define RTL9300_CLOCK_RATE	87500000
+#define RTL9300_TC0_BASE	(void *)0xb8003200
+
+int irq_tc0 = 7;
+
+static void __iomem *rtl9300_tc_base(struct clock_event_device *clk)
+{
+	struct irq_desc *desc = irq_to_desc(clk->irq);
+	int tc = desc->irq_data.hwirq - irq_tc0;
+
+	return RTL9300_TC0_BASE + (tc << 4);
+}
+
+static irqreturn_t rtl9300_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *clk = dev_id;
+//	int cpu = smp_processor_id();
+	struct irq_desc *desc = irq_to_desc(irq);
+	int tc = desc->irq_data.hwirq - irq_tc0;
+	void __iomem *base = RTL9300_TC0_BASE + (tc << 4);
+	static atomic_t count = ATOMIC_INIT(0);
+	unsigned int c;
+	u32 v = readl(base + RTL9300_TC_INT);
+
+	c = (unsigned int)atomic_inc_return(&count);
+
+	// Acknowledge the IRQ
+	v |= RTL9300_TC_INT_IP;
+	writel(v, base + RTL9300_TC_INT);
+	if (readl(base + RTL9300_TC_INT) & RTL9300_TC_INT_IP)
+		dump_stack();
+
+	clk->event_handler(clk);
+	return IRQ_HANDLED;
+}
+
+static void rtl9300_clock_stop(void __iomem *base)
+{
+	u32 v;
+
+	writel(0, base + RTL9300_TC_CTRL);
+
+	// Acknowledge possibly pending IRQ
+	v = readl(base + RTL9300_TC_INT);
+//	if (v & RTL9300_TC_INT_IP)
+		writel(v | RTL9300_TC_INT_IP, base + RTL9300_TC_INT);
+	if (readl(base + RTL9300_TC_INT) & RTL9300_TC_INT_IP)
+		dump_stack();
+}
+
+static void rtl9300_timer_start(void __iomem *base, bool periodic)
+{
+	u32 v = (periodic ? RTL9300_TC_CTRL_MODE : 0) | RTL9300_TC_CTRL_EN | DIVISOR_RTL9300;
+
+	writel(0, base + RTL9300_TC_CNT);
+	pr_debug("------------- starting timer base %08x\n", (u32)base);
+	writel(v, base + RTL9300_TC_CTRL);
+}
+
+static int rtl9300_next_event(unsigned long delta, struct clock_event_device *clk)
+{
+	void __iomem *base = rtl9300_tc_base(clk);
+
+	rtl9300_clock_stop(base);
+	writel(delta, base + RTL9300_TC_DATA);
+	rtl9300_timer_start(base, TIMER_MODE_ONCE);
+
+	return 0;
+}
+
+static int rtl9300_state_periodic(struct clock_event_device *clk)
+{
+	void __iomem *base = rtl9300_tc_base(clk);
+
+	pr_debug("------------- rtl9300_state_periodic %08x\n", (u32)base);
+	rtl9300_clock_stop(base);
+	writel(RTL9300_CLOCK_RATE / HZ, base + RTL9300_TC_DATA);
+	rtl9300_timer_start(base, TIMER_MODE_REPEAT);
+	return 0;
+}
+
+static int rtl9300_state_oneshot(struct clock_event_device *clk)
+{
+	void __iomem *base = rtl9300_tc_base(clk);
+
+	pr_debug("------------- rtl9300_state_oneshot %08x\n", (u32)base);
+	rtl9300_clock_stop(base);
+	writel(RTL9300_CLOCK_RATE / HZ, base + RTL9300_TC_DATA);
+	rtl9300_timer_start(base, TIMER_MODE_ONCE);
+	return 0;
+}
+
+static int rtl9300_shutdown(struct clock_event_device *clk)
+{
+	void __iomem *base = rtl9300_tc_base(clk);
+
+	pr_debug("------------- rtl9300_shutdown %08x\n", (u32)base);
+	rtl9300_clock_stop(base);
+	return 0;
+}
+
+static void rtl9300_clock_setup(void __iomem *base)
+{
+	u32 v;
+
+	// Disable timer
+	writel(0, base + RTL9300_TC_CTRL);
+
+	// Acknowledge possibly pending IRQ
+	v = readl(base + RTL9300_TC_INT);
+//	if (v & RTL9300_TC_INT_IP)
+		writel(v | RTL9300_TC_INT_IP, base + RTL9300_TC_INT);
+	if (readl(base + RTL9300_TC_INT) & RTL9300_TC_INT_IP)
+		dump_stack();
+
+	// Setup maximum period (for use as clock-source)
+	writel(0x0fffffff, base + RTL9300_TC_DATA);
+}
+
+static DEFINE_PER_CPU(struct clock_event_device, rtl9300_clockevent);
+static DEFINE_PER_CPU(char [18], rtl9300_clock_name);
+
+void rtl9300_clockevent_init(void)
+{
+	int cpu = smp_processor_id();
+	int irq;
+	struct clock_event_device *cd = &per_cpu(rtl9300_clockevent, cpu);
+	unsigned char *name = per_cpu(rtl9300_clock_name, cpu);
+	unsigned long flags =  IRQF_PERCPU | IRQF_TIMER;
+	struct device_node *node;
+
+	pr_info("%s called for cpu%d\n", __func__, cpu);
+	BUG_ON(cpu > 3);	/* Only have 4 general purpose timers */
+
+	node = of_find_compatible_node(NULL, NULL, "realtek,rtl9300clock");
+	if (!node) {
+		pr_err("No DT entry found for realtek,rtl9300clock\n");
+		return;
+	}
+
+	irq = irq_of_parse_and_map(node, cpu);
+	pr_info("%s using IRQ %d\n", __func__, irq);
+
+	rtl9300_clock_setup(RTL9300_TC0_BASE + TIMER_BLK_EVT + (cpu << 4));
+
+	sprintf(name, "rtl9300-counter-%d", cpu);
+	cd->name		= name;
+	cd->features		= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+
+	clockevent_set_clock(cd, RTL9300_CLOCK_RATE);
+
+	cd->max_delta_ns	= clockevent_delta2ns(0x0fffffff, cd);
+	cd->max_delta_ticks	= 0x0fffffff;
+	cd->min_delta_ns	= clockevent_delta2ns(0x20, cd);
+	cd->min_delta_ticks	= 0x20;
+	cd->rating		= 300;
+	cd->irq			= irq;
+	cd->cpumask		= cpumask_of(cpu);
+	cd->set_next_event	= rtl9300_next_event;
+	cd->set_state_shutdown	= rtl9300_shutdown;
+	cd->set_state_periodic	= rtl9300_state_periodic;
+	cd->set_state_oneshot	= rtl9300_state_oneshot;
+	clockevents_register_device(cd);
+
+	irq_set_affinity(irq, cd->cpumask);
+
+	if (request_irq(irq, rtl9300_timer_interrupt, flags, name, cd))
+		pr_err("Failed to request irq %d (%s)\n", irq, name);
+
+	writel(RTL9300_TC_INT_IE, RTL9300_TC0_BASE + TIMER_BLK_EVT + (cpu << 4) + RTL9300_TC_INT);
+}
diff --git a/target/linux/realtek/files-5.10/drivers/clocksource/timer-rtl9300.c b/target/linux/realtek/files-5.10/drivers/clocksource/timer-rtl9300.c
deleted file mode 100644
index 9ab1733fe3..0000000000
--- a/target/linux/realtek/files-5.10/drivers/clocksource/timer-rtl9300.c
+++ /dev/null
@@ -1,196 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-
-#include <linux/clockchips.h>
-#include <linux/init.h>
-#include <asm/time.h>
-#include <linux/interrupt.h>
-#include <linux/of_address.h>
-#include <linux/of_irq.h>
-#include <linux/sched_clock.h>
-#include "timer-of.h"
-
-#include <mach-rtl83xx.h>
-
-/* 
- * Timer registers
- * the RTL9300/9310 SoCs have 6 timers, each register block 0x10 apart
- */
-#define RTL9300_TC_DATA		0x0
-#define RTL9300_TC_CNT		0x4
-#define RTL9300_TC_CTRL		0x8
-#define RTL9300_TC_CTRL_MODE	BIT(24)
-#define RTL9300_TC_CTRL_EN	BIT(28)
-#define RTL9300_TC_INT		0xc
-#define RTL9300_TC_INT_IP	BIT(16)
-#define RTL9300_TC_INT_IE	BIT(20)
-
-// Clocksource is using timer 0, clock event uses timer 1
-#define TIMER_CLK_SRC		0
-#define TIMER_CLK_EVT		1
-#define TIMER_BLK_EVT		(TIMER_CLK_EVT << 4)
-
-// Timer modes
-#define TIMER_MODE_REPEAT	1
-#define TIMER_MODE_ONCE		0
-
-// Minimum divider is 2
-#define DIVISOR_RTL9300		2
-
-#define N_BITS			28
-
-static void __iomem *rtl9300_sched_reg __read_mostly;
-
-static u64 notrace rtl9300_sched_clock_read(void)
-{
-/*	pr_info("In %s: %x\n", __func__, readl_relaxed(rtl9300_sched_reg));
-	dump_stack();*/
-	return readl_relaxed(rtl9300_sched_reg);
-}
-
-static irqreturn_t rtl9300_timer_interrupt(int irq, void *dev_id)
-{
-	struct clock_event_device *clk = dev_id;
-	struct timer_of *to = to_timer_of(clk);
-	u32 v = readl(timer_of_base(to) + TIMER_BLK_EVT + RTL9300_TC_INT);
-
-	// Acknowledge the IRQ
-	v |= RTL9300_TC_INT_IP;
-	writel(v, timer_of_base(to) + TIMER_BLK_EVT + RTL9300_TC_INT);
-
-	clk->event_handler(clk);
-	return IRQ_HANDLED;
-}
-
-static void rtl9300_timer_stop(struct timer_of *to)
-{
-	u32 v;
-
-	writel(0, timer_of_base(to) + TIMER_BLK_EVT + RTL9300_TC_CTRL);
-
-	// Acknowledge possibly pending IRQ
-	v = readl(timer_of_base(to) + TIMER_BLK_EVT + RTL9300_TC_INT);
-	if (v & RTL9300_TC_INT_IP)
-		writel(v, timer_of_base(to) + TIMER_BLK_EVT + RTL9300_TC_INT);
-}
-
-static void rtl9300_timer_start(struct timer_of *to, int timer, bool periodic)
-{
-	u32 v = (periodic ? RTL9300_TC_CTRL_MODE : 0) | RTL9300_TC_CTRL_EN | DIVISOR_RTL9300;
-	writel(v, timer_of_base(to) + timer * 0x10 + RTL9300_TC_CTRL);
-}
-
-static int rtl9300_set_next_event(unsigned long delta, struct clock_event_device *clk)
-{
-	struct timer_of *to = to_timer_of(clk);
-
-	rtl9300_timer_stop(to);
-	writel(delta, timer_of_base(to) + TIMER_BLK_EVT + RTL9300_TC_DATA);
-	rtl9300_timer_start(to, TIMER_CLK_EVT, TIMER_MODE_ONCE);
-	return 0;
-}
-
-static int rtl9300_set_state_periodic(struct clock_event_device *clk)
-{
-	struct timer_of *to = to_timer_of(clk);
-
-	rtl9300_timer_stop(to);
-	writel(to->of_clk.period, timer_of_base(to) + TIMER_BLK_EVT + RTL9300_TC_DATA);
-	rtl9300_timer_start(to, TIMER_CLK_EVT, TIMER_MODE_REPEAT);
-	return 0;
-}
-
-static int rtl9300_set_state_oneshot(struct clock_event_device *clk)
-{
-	struct timer_of *to = to_timer_of(clk);
-
-	rtl9300_timer_stop(to);
-	writel(to->of_clk.period, timer_of_base(to) + TIMER_BLK_EVT + RTL9300_TC_DATA);
-	rtl9300_timer_start(to, TIMER_CLK_EVT, TIMER_MODE_ONCE);
-	return 0;
-}
-
-static int rtl9300_set_state_shutdown(struct clock_event_device *clk)
-{
-	struct timer_of *to = to_timer_of(clk);
-
-	rtl9300_timer_stop(to);
-	return 0;
-}
-
-static struct timer_of t_of = {
-	.flags = TIMER_OF_BASE | TIMER_OF_IRQ | TIMER_OF_CLOCK,
-
-	.clkevt = {
-		.name = "rtl9300_timer",
-		.rating = 350,
-		.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
-		.set_next_event	= rtl9300_set_next_event,
-		.set_state_oneshot = rtl9300_set_state_oneshot,
-		.set_state_periodic = rtl9300_set_state_periodic,
-		.set_state_shutdown = rtl9300_set_state_shutdown,
-	},
-
-	.of_irq = {
-		.name = "ostimer",
-		.handler = rtl9300_timer_interrupt,
-		.flags = IRQF_TIMER,
-	},
-};
-
-static void __init rtl9300_timer_setup(u8 timer)
-{
-	u32 v;
-
-	// Disable timer
-	writel(0, timer_of_base(&t_of) + 0x10 * timer + RTL9300_TC_CTRL);
-
-	// Acknowledge possibly pending IRQ
-	v = readl(timer_of_base(&t_of) + 0x10 * timer + RTL9300_TC_INT);
-	if (v & RTL9300_TC_INT_IP)
-		writel(v, timer_of_base(&t_of) + 0x10 * timer + RTL9300_TC_INT);
-
-	// Setup maximum period (for use as clock-source)
-	writel(0x0fffffff, timer_of_base(&t_of) + 0x10 * timer + RTL9300_TC_DATA);
-}
-
-
-static int __init rtl9300_timer_init(struct device_node *node)
-{
-	int err = 0;
-	unsigned long rate;
-
-	pr_info("%s: setting up timer\n", __func__);
-
-	err = timer_of_init(node, &t_of);
-	if (err)
-		return err;
-
-	rate = timer_of_rate(&t_of) / DIVISOR_RTL9300;
-	pr_info("Frequency in dts: %ld, my rate is %ld, period %ld\n",
-		timer_of_rate(&t_of), rate, timer_of_period(&t_of));
-	pr_info("With base %08x IRQ: %d\n", (u32)timer_of_base(&t_of), timer_of_irq(&t_of));
-
-	// Configure clock source and register it for scheduling
-	rtl9300_timer_setup(TIMER_CLK_SRC);
-	rtl9300_timer_start(&t_of, TIMER_CLK_SRC, TIMER_MODE_REPEAT);
-
-	rtl9300_sched_reg = timer_of_base(&t_of) + TIMER_CLK_SRC * 0x10 + RTL9300_TC_CNT;
-
-	err = clocksource_mmio_init(rtl9300_sched_reg, node->name, rate , 100, N_BITS,
-				    clocksource_mmio_readl_up);
-	if (err)
-		return err;
-
-	sched_clock_register(rtl9300_sched_clock_read, N_BITS, rate);
-
-	// Configure clock event source
-	rtl9300_timer_setup(TIMER_CLK_EVT);
-	clockevents_config_and_register(&t_of.clkevt, rate, 100, 0x0fffffff);
-
-	// Enable interrupt
-	writel(RTL9300_TC_INT_IE, timer_of_base(&t_of) + TIMER_BLK_EVT + RTL9300_TC_INT);
-
-	return err;
-}
-
-TIMER_OF_DECLARE(rtl9300_timer, "realtek,rtl9300-timer", rtl9300_timer_init);
diff --git a/target/linux/realtek/patches-5.10/302-clocksource-add-rtl9300-driver.patch b/target/linux/realtek/patches-5.10/302-clocksource-add-rtl9300-driver.patch
deleted file mode 100644
index 365a62bf30..0000000000
--- a/target/linux/realtek/patches-5.10/302-clocksource-add-rtl9300-driver.patch
+++ /dev/null
@@ -1,28 +0,0 @@
---- a/drivers/clocksource/Kconfig
-+++ b/drivers/clocksource/Kconfig
-@@ -127,6 +127,15 @@ config RDA_TIMER
- 	help
- 	  Enables the support for the RDA Micro timer driver.
- 
-+config RTL9300_TIMER
-+	bool "Clocksource/timer for the Realtek RTL9300 family of SoCs"
-+	depends on MIPS
-+	select COMMON_CLK
-+	select TIMER_OF
-+	select CLKSRC_MMIO
-+	help
-+	  Enables support for the Realtek RTL9300 timer driver.
-+
- config SUN4I_TIMER
- 	bool "Sun4i timer driver" if COMPILE_TEST
- 	depends on HAS_IOMEM
---- a/drivers/clocksource/Makefile
-+++ b/drivers/clocksource/Makefile
-@@ -63,6 +63,7 @@ obj-$(CONFIG_MILBEAUT_TIMER)	+= timer-mi
- obj-$(CONFIG_SPRD_TIMER)	+= timer-sprd.o
- obj-$(CONFIG_NPCM7XX_TIMER)	+= timer-npcm7xx.o
- obj-$(CONFIG_RDA_TIMER)		+= timer-rda.o
-+obj-$(CONFIG_RTL9300_TIMER)	+= timer-rtl9300.o
- 
- obj-$(CONFIG_ARC_TIMERS)		+= arc_timer.o
- obj-$(CONFIG_ARM_ARCH_TIMER)		+= arm_arch_timer.o
diff --git a/target/linux/realtek/patches-5.10/309-cevt-rtl9300-support.patch b/target/linux/realtek/patches-5.10/309-cevt-rtl9300-support.patch
new file mode 100644
index 0000000000..6a0038d86b
--- /dev/null
+++ b/target/linux/realtek/patches-5.10/309-cevt-rtl9300-support.patch
@@ -0,0 +1,54 @@
+--- a/arch/mips/kernel/Makefile
++++ b/arch/mips/kernel/Makefile
+@@ -27,6 +27,7 @@ obj-$(CONFIG_CEVT_BCM1480)	+= cevt-bcm14
+ obj-$(CONFIG_CEVT_R4K)		+= cevt-r4k.o
+ obj-$(CONFIG_CEVT_DS1287)	+= cevt-ds1287.o
+ obj-$(CONFIG_CEVT_GT641XX)	+= cevt-gt641xx.o
++obj-$(CONFIG_CEVT_RTL9300)	+= cevt-rtl9300.o
+ obj-$(CONFIG_CEVT_SB1250)	+= cevt-sb1250.o
+ obj-$(CONFIG_CEVT_TXX9)		+= cevt-txx9.o
+ obj-$(CONFIG_CSRC_BCM1480)	+= csrc-bcm1480.o
+--- a/arch/mips/include/asm/time.h
++++ b/arch/mips/include/asm/time.h
+@@ -15,6 +15,8 @@
+ #include <linux/clockchips.h>
+ #include <linux/clocksource.h>
+ 
++extern void rtl9300_clockevent_init(void);
++
+ extern spinlock_t rtc_lock;
+ 
+ /*
+@@ -43,6 +45,11 @@ extern int r4k_clockevent_init(void);
+ 
+ static inline int mips_clockevent_init(void)
+ {
++#ifdef CONFIG_CEVT_RTL9300
++	rtl9300_clockevent_init();
++	return 0;
++#endif
++
+ #ifdef CONFIG_CEVT_R4K
+ 	return r4k_clockevent_init();
+ #else
+--- a/arch/mips/kernel/smp-mt.c
++++ b/arch/mips/kernel/smp-mt.c
+@@ -108,12 +108,18 @@ static void __init smvp_tc_init(unsigned
+ static void vsmp_init_secondary(void)
+ {
+ 	/* This is Malta specific: IPI,performance and timer interrupts */
++
++	/* RTL9300 Clear internal timer interrupt */
++	write_c0_compare(0);
++
+ 	if (mips_gic_present())
+ 		change_c0_status(ST0_IM, STATUSF_IP2 | STATUSF_IP3 |
+ 					 STATUSF_IP4 | STATUSF_IP5 |
+ 					 STATUSF_IP6 | STATUSF_IP7);
+ 	else
+ 		change_c0_status(ST0_IM, STATUSF_IP0 | STATUSF_IP1 |
++					 STATUSF_IP2 | STATUSF_IP3 |
++					 STATUSF_IP4 | STATUSF_IP5 |
+ 					 STATUSF_IP6 | STATUSF_IP7);
+ }
+