1 files changed, 293 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-ixp4xx.c b/drivers/clocksource/timer-ixp4xx.c
new file mode 100644
index 000000000..720ed70a2
--- /dev/null
+++ b/drivers/clocksource/timer-ixp4xx.c
@@ -0,0 +1,293 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * IXP4 timer driver
+ * Copyright (C) 2019 Linus Walleij <linus.walleij@linaro.org>
+ *
+ * Based on arch/arm/mach-ixp4xx/common.c
+ * Copyright 2002 (C) Intel Corporation
+ * Copyright 2003-2004 (C) MontaVista, Software, Inc.
+ * Copyright (C) Deepak Saxena <dsaxena@plexity.net>
+ */
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.h>
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+
+/*
+ * Constants to make it easy to access Timer Control/Status registers
+ */
+#define IXP4XX_OSTS_OFFSET	0x00  /* Continuous Timestamp */
+#define IXP4XX_OST1_OFFSET	0x04  /* Timer 1 Timestamp */
+#define IXP4XX_OSRT1_OFFSET	0x08  /* Timer 1 Reload */
+#define IXP4XX_OST2_OFFSET	0x0C  /* Timer 2 Timestamp */
+#define IXP4XX_OSRT2_OFFSET	0x10  /* Timer 2 Reload */
+#define IXP4XX_OSST_OFFSET	0x20  /* Timer Status */
+
+/*
+ * Timer register values and bit definitions
+ */
+#define IXP4XX_OST_ENABLE		0x00000001
+#define IXP4XX_OST_ONE_SHOT		0x00000002
+/* Low order bits of reload value ignored */
+#define IXP4XX_OST_RELOAD_MASK		0x00000003
+#define IXP4XX_OST_DISABLED		0x00000000
+#define IXP4XX_OSST_TIMER_1_PEND	0x00000001
+#define IXP4XX_OSST_TIMER_2_PEND	0x00000002
+#define IXP4XX_OSST_TIMER_TS_PEND	0x00000004
+/* Remaining registers are for the watchdog and defined in the watchdog driver */
+
+struct ixp4xx_timer {
+	void __iomem *base;
+	u32 latch;
+	struct clock_event_device clkevt;
+#ifdef CONFIG_ARM
+	struct delay_timer delay_timer;
+#endif
+};
+
+/*
+ * A local singleton used by sched_clock and delay timer reads, which are
+ * fast and stateless
+ */
+static struct ixp4xx_timer *local_ixp4xx_timer;
+
+static inline struct ixp4xx_timer *
+to_ixp4xx_timer(struct clock_event_device *evt)
+{
+	return container_of(evt, struct ixp4xx_timer, clkevt);
+}
+
+static unsigned long ixp4xx_read_timer(void)
+{
+	return __raw_readl(local_ixp4xx_timer->base + IXP4XX_OSTS_OFFSET);
+}
+
+static u64 notrace ixp4xx_read_sched_clock(void)
+{
+	return ixp4xx_read_timer();
+}
+
+static u64 ixp4xx_clocksource_read(struct clocksource *c)
+{
+	return ixp4xx_read_timer();
+}
+
+static irqreturn_t ixp4xx_timer_interrupt(int irq, void *dev_id)
+{
+	struct ixp4xx_timer *tmr = dev_id;
+	struct clock_event_device *evt = &tmr->clkevt;
+
+	/* Clear Pending Interrupt */
+	__raw_writel(IXP4XX_OSST_TIMER_1_PEND,
+		     tmr->base + IXP4XX_OSST_OFFSET);
+
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static int ixp4xx_set_next_event(unsigned long cycles,
+				 struct clock_event_device *evt)
+{
+	struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
+	u32 val;
+
+	val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET);
+	/* Keep enable/oneshot bits */
+	val &= IXP4XX_OST_RELOAD_MASK;
+	__raw_writel((cycles & ~IXP4XX_OST_RELOAD_MASK) | val,
+		     tmr->base + IXP4XX_OSRT1_OFFSET);
+
+	return 0;
+}
+
+static int ixp4xx_shutdown(struct clock_event_device *evt)
+{
+	struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
+	u32 val;
+
+	val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET);
+	val &= ~IXP4XX_OST_ENABLE;
+	__raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET);
+
+	return 0;
+}
+
+static int ixp4xx_set_oneshot(struct clock_event_device *evt)
+{
+	struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
+
+	__raw_writel(IXP4XX_OST_ENABLE | IXP4XX_OST_ONE_SHOT,
+		     tmr->base + IXP4XX_OSRT1_OFFSET);
+
+	return 0;
+}
+
+static int ixp4xx_set_periodic(struct clock_event_device *evt)
+{
+	struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
+	u32 val;
+
+	val = tmr->latch & ~IXP4XX_OST_RELOAD_MASK;
+	val |= IXP4XX_OST_ENABLE;
+	__raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET);
+
+	return 0;
+}
+
+static int ixp4xx_resume(struct clock_event_device *evt)
+{
+	struct ixp4xx_timer *tmr = to_ixp4xx_timer(evt);
+	u32 val;
+
+	val = __raw_readl(tmr->base + IXP4XX_OSRT1_OFFSET);
+	val |= IXP4XX_OST_ENABLE;
+	__raw_writel(val, tmr->base + IXP4XX_OSRT1_OFFSET);
+
+	return 0;
+}
+
+/*
+ * IXP4xx timer tick
+ * We use OS timer1 on the CPU for the timer tick and the timestamp
+ * counter as a source of real clock ticks to account for missed jiffies.
+ */
+static __init int ixp4xx_timer_register(void __iomem *base,
+					int timer_irq,
+					unsigned int timer_freq)
+{
+	struct ixp4xx_timer *tmr;
+	int ret;
+
+	tmr = kzalloc(sizeof(*tmr), GFP_KERNEL);
+	if (!tmr)
+		return -ENOMEM;
+	tmr->base = base;
+
+	/*
+	 * The timer register doesn't allow to specify the two least
+	 * significant bits of the timeout value and assumes them being zero.
+	 * So make sure the latch is the best value with the two least
+	 * significant bits unset.
+	 */
+	tmr->latch = DIV_ROUND_CLOSEST(timer_freq,
+				       (IXP4XX_OST_RELOAD_MASK + 1) * HZ)
+		* (IXP4XX_OST_RELOAD_MASK + 1);
+
+	local_ixp4xx_timer = tmr;
+
+	/* Reset/disable counter */
+	__raw_writel(0, tmr->base + IXP4XX_OSRT1_OFFSET);
+
+	/* Clear any pending interrupt on timer 1 */
+	__raw_writel(IXP4XX_OSST_TIMER_1_PEND,
+		     tmr->base + IXP4XX_OSST_OFFSET);
+
+	/* Reset time-stamp counter */
+	__raw_writel(0, tmr->base + IXP4XX_OSTS_OFFSET);
+
+	clocksource_mmio_init(NULL, "OSTS", timer_freq, 200, 32,
+			      ixp4xx_clocksource_read);
+
+	tmr->clkevt.name = "ixp4xx timer1";
+	tmr->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+	tmr->clkevt.rating = 200;
+	tmr->clkevt.set_state_shutdown = ixp4xx_shutdown;
+	tmr->clkevt.set_state_periodic = ixp4xx_set_periodic;
+	tmr->clkevt.set_state_oneshot = ixp4xx_set_oneshot;
+	tmr->clkevt.tick_resume = ixp4xx_resume;
+	tmr->clkevt.set_next_event = ixp4xx_set_next_event;
+	tmr->clkevt.cpumask = cpumask_of(0);
+	tmr->clkevt.irq = timer_irq;
+	ret = request_irq(timer_irq, ixp4xx_timer_interrupt,
+			  IRQF_TIMER, "IXP4XX-TIMER1", tmr);
+	if (ret) {
+		pr_crit("no timer IRQ\n");
+		return -ENODEV;
+	}
+	clockevents_config_and_register(&tmr->clkevt, timer_freq,
+					0xf, 0xfffffffe);
+
+	sched_clock_register(ixp4xx_read_sched_clock, 32, timer_freq);
+
+#ifdef CONFIG_ARM
+	/* Also use this timer for delays */
+	tmr->delay_timer.read_current_timer = ixp4xx_read_timer;
+	tmr->delay_timer.freq = timer_freq;
+	register_current_timer_delay(&tmr->delay_timer);
+#endif
+
+	return 0;
+}
+
+static struct platform_device ixp4xx_watchdog_device = {
+	.name = "ixp4xx-watchdog",
+	.id = -1,
+};
+
+/*
+ * This probe gets called after the timer is already up and running. The main
+ * function on this platform is to spawn the watchdog device as a child.
+ */
+static int ixp4xx_timer_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+
+	/* Pass the base address as platform data and nothing else */
+	ixp4xx_watchdog_device.dev.platform_data = local_ixp4xx_timer->base;
+	ixp4xx_watchdog_device.dev.parent = dev;
+	return platform_device_register(&ixp4xx_watchdog_device);
+}
+
+static const struct of_device_id ixp4xx_timer_dt_id[] = {
+	{ .compatible = "intel,ixp4xx-timer", },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver ixp4xx_timer_driver = {
+	.probe  = ixp4xx_timer_probe,
+	.driver = {
+		.name = "ixp4xx-timer",
+		.of_match_table = ixp4xx_timer_dt_id,
+		.suppress_bind_attrs = true,
+	},
+};
+builtin_platform_driver(ixp4xx_timer_driver);
+
+static __init int ixp4xx_of_timer_init(struct device_node *np)
+{
+	void __iomem *base;
+	int irq;
+	int ret;
+
+	base = of_iomap(np, 0);
+	if (!base) {
+		pr_crit("IXP4xx: can't remap timer\n");
+		return -ENODEV;
+	}
+
+	irq = irq_of_parse_and_map(np, 0);
+	if (irq <= 0) {
+		pr_err("Can't parse IRQ\n");
+		ret = -EINVAL;
+		goto out_unmap;
+	}
+
+	/* TODO: get some fixed clocks into the device tree */
+	ret = ixp4xx_timer_register(base, irq, 66666000);
+	if (ret)
+		goto out_unmap;
+	return 0;
+
+out_unmap:
+	iounmap(base);
+	return ret;
+}
+TIMER_OF_DECLARE(ixp4xx, "intel,ixp4xx-timer", ixp4xx_of_timer_init);