realtek: add support for the RTL9300 timer

this adds support for the SoC timer of the RTL9300 chips, it
provides 6 independent timer/counters, of which the first one
is used as a clocksource and the second one as event timer.

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

1 files changed, 196 insertions, 0 deletions

diff --git a/target/linux/realtek/files-5.4/drivers/clocksource/timer-rtl9300.c b/target/linux/realtek/files-5.4/drivers/clocksource/timer-rtl9300.c
new file mode 100644
index 0000000000..9ab1733fe3
--- /dev/null
+++ b/target/linux/realtek/files-5.4/drivers/clocksource/timer-rtl9300.c
@@ -0,0 +1,196 @@
+// 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);