1 files changed, 283 insertions, 0 deletions
diff --git a/drivers/clocksource/nomadik-mtu.c b/drivers/clocksource/nomadik-mtu.c
new file mode 100644
index 0000000000..53d0159cc6
--- /dev/null
+++ b/drivers/clocksource/nomadik-mtu.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2008 STMicroelectronics
+ * Copyright (C) 2010 Alessandro Rubini
+ * Copyright (C) 2010 Linus Walleij for ST-Ericsson
+ */
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/clk.h>
+#include <linux/jiffies.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/sched_clock.h>
+#include <asm/mach/time.h>
+
+/*
+ * The MTU device hosts four different counters, with 4 set of
+ * registers. These are register names.
+ */
+
+#define MTU_IMSC	0x00	/* Interrupt mask set/clear */
+#define MTU_RIS		0x04	/* Raw interrupt status */
+#define MTU_MIS		0x08	/* Masked interrupt status */
+#define MTU_ICR		0x0C	/* Interrupt clear register */
+
+/* per-timer registers take 0..3 as argument */
+#define MTU_LR(x)	(0x10 + 0x10 * (x) + 0x00)	/* Load value */
+#define MTU_VAL(x)	(0x10 + 0x10 * (x) + 0x04)	/* Current value */
+#define MTU_CR(x)	(0x10 + 0x10 * (x) + 0x08)	/* Control reg */
+#define MTU_BGLR(x)	(0x10 + 0x10 * (x) + 0x0c)	/* At next overflow */
+
+/* bits for the control register */
+#define MTU_CRn_ENA		0x80
+#define MTU_CRn_PERIODIC	0x40	/* if 0 = free-running */
+#define MTU_CRn_PRESCALE_MASK	0x0c
+#define MTU_CRn_PRESCALE_1		0x00
+#define MTU_CRn_PRESCALE_16		0x04
+#define MTU_CRn_PRESCALE_256		0x08
+#define MTU_CRn_32BITS		0x02
+#define MTU_CRn_ONESHOT		0x01	/* if 0 = wraps reloading from BGLR*/
+
+/* Other registers are usual amba/primecell registers, currently not used */
+#define MTU_ITCR	0xff0
+#define MTU_ITOP	0xff4
+
+#define MTU_PERIPH_ID0	0xfe0
+#define MTU_PERIPH_ID1	0xfe4
+#define MTU_PERIPH_ID2	0xfe8
+#define MTU_PERIPH_ID3	0xfeC
+
+#define MTU_PCELL0	0xff0
+#define MTU_PCELL1	0xff4
+#define MTU_PCELL2	0xff8
+#define MTU_PCELL3	0xffC
+
+static void __iomem *mtu_base;
+static bool clkevt_periodic;
+static u32 clk_prescale;
+static u32 nmdk_cycle;		/* write-once */
+static struct delay_timer mtu_delay_timer;
+
+/*
+ * Override the global weak sched_clock symbol with this
+ * local implementation which uses the clocksource to get some
+ * better resolution when scheduling the kernel.
+ */
+static u64 notrace nomadik_read_sched_clock(void)
+{
+	if (unlikely(!mtu_base))
+		return 0;
+
+	return -readl(mtu_base + MTU_VAL(0));
+}
+
+static unsigned long nmdk_timer_read_current_timer(void)
+{
+	return ~readl_relaxed(mtu_base + MTU_VAL(0));
+}
+
+/* Clockevent device: use one-shot mode */
+static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev)
+{
+	writel(1 << 1, mtu_base + MTU_IMSC);
+	writel(evt, mtu_base + MTU_LR(1));
+	/* Load highest value, enable device, enable interrupts */
+	writel(MTU_CRn_ONESHOT | clk_prescale |
+	       MTU_CRn_32BITS | MTU_CRn_ENA,
+	       mtu_base + MTU_CR(1));
+
+	return 0;
+}
+
+static void nmdk_clkevt_reset(void)
+{
+	if (clkevt_periodic) {
+		/* Timer: configure load and background-load, and fire it up */
+		writel(nmdk_cycle, mtu_base + MTU_LR(1));
+		writel(nmdk_cycle, mtu_base + MTU_BGLR(1));
+
+		writel(MTU_CRn_PERIODIC | clk_prescale |
+		       MTU_CRn_32BITS | MTU_CRn_ENA,
+		       mtu_base + MTU_CR(1));
+		writel(1 << 1, mtu_base + MTU_IMSC);
+	} else {
+		/* Generate an interrupt to start the clockevent again */
+		(void) nmdk_clkevt_next(nmdk_cycle, NULL);
+	}
+}
+
+static int nmdk_clkevt_shutdown(struct clock_event_device *evt)
+{
+	writel(0, mtu_base + MTU_IMSC);
+	/* disable timer */
+	writel(0, mtu_base + MTU_CR(1));
+	/* load some high default value */
+	writel(0xffffffff, mtu_base + MTU_LR(1));
+	return 0;
+}
+
+static int nmdk_clkevt_set_oneshot(struct clock_event_device *evt)
+{
+	clkevt_periodic = false;
+	return 0;
+}
+
+static int nmdk_clkevt_set_periodic(struct clock_event_device *evt)
+{
+	clkevt_periodic = true;
+	nmdk_clkevt_reset();
+	return 0;
+}
+
+static void nmdk_clksrc_reset(void)
+{
+	/* Disable */
+	writel(0, mtu_base + MTU_CR(0));
+
+	/* ClockSource: configure load and background-load, and fire it up */
+	writel(nmdk_cycle, mtu_base + MTU_LR(0));
+	writel(nmdk_cycle, mtu_base + MTU_BGLR(0));
+
+	writel(clk_prescale | MTU_CRn_32BITS | MTU_CRn_ENA,
+	       mtu_base + MTU_CR(0));
+}
+
+static void nmdk_clkevt_resume(struct clock_event_device *cedev)
+{
+	nmdk_clkevt_reset();
+	nmdk_clksrc_reset();
+}
+
+static struct clock_event_device nmdk_clkevt = {
+	.name			= "mtu_1",
+	.features		= CLOCK_EVT_FEAT_ONESHOT |
+				  CLOCK_EVT_FEAT_PERIODIC |
+				  CLOCK_EVT_FEAT_DYNIRQ,
+	.rating			= 200,
+	.set_state_shutdown	= nmdk_clkevt_shutdown,
+	.set_state_periodic	= nmdk_clkevt_set_periodic,
+	.set_state_oneshot	= nmdk_clkevt_set_oneshot,
+	.set_next_event		= nmdk_clkevt_next,
+	.resume			= nmdk_clkevt_resume,
+};
+
+/*
+ * IRQ Handler for timer 1 of the MTU block.
+ */
+static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evdev = dev_id;
+
+	writel(1 << 1, mtu_base + MTU_ICR); /* Interrupt clear reg */
+	evdev->event_handler(evdev);
+	return IRQ_HANDLED;
+}
+
+static int __init nmdk_timer_init(void __iomem *base, int irq,
+				   struct clk *pclk, struct clk *clk)
+{
+	unsigned long rate;
+	int ret;
+	int min_ticks;
+
+	mtu_base = base;
+
+	BUG_ON(clk_prepare_enable(pclk));
+	BUG_ON(clk_prepare_enable(clk));
+
+	/*
+	 * Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz
+	 * for ux500, and in one specific Ux500 case 32768 Hz.
+	 *
+	 * Use a divide-by-16 counter if the tick rate is more than 32MHz.
+	 * At 32 MHz, the timer (with 32 bit counter) can be programmed
+	 * to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer
+	 * with 16 gives too low timer resolution.
+	 */
+	rate = clk_get_rate(clk);
+	if (rate > 32000000) {
+		rate /= 16;
+		clk_prescale = MTU_CRn_PRESCALE_16;
+	} else {
+		clk_prescale = MTU_CRn_PRESCALE_1;
+	}
+
+	/* Cycles for periodic mode */
+	nmdk_cycle = DIV_ROUND_CLOSEST(rate, HZ);
+
+
+	/* Timer 0 is the free running clocksource */
+	nmdk_clksrc_reset();
+
+	ret = clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0",
+				    rate, 200, 32, clocksource_mmio_readl_down);
+	if (ret) {
+		pr_err("timer: failed to initialize clock source %s\n", "mtu_0");
+		return ret;
+	}
+
+	sched_clock_register(nomadik_read_sched_clock, 32, rate);
+
+	/* Timer 1 is used for events, register irq and clockevents */
+	if (request_irq(irq, nmdk_timer_interrupt, IRQF_TIMER,
+			"Nomadik Timer Tick", &nmdk_clkevt))
+		pr_err("%s: request_irq() failed\n", "Nomadik Timer Tick");
+	nmdk_clkevt.cpumask = cpumask_of(0);
+	nmdk_clkevt.irq = irq;
+	if (rate < 100000)
+		min_ticks = 5;
+	else
+		min_ticks = 2;
+	clockevents_config_and_register(&nmdk_clkevt, rate, min_ticks,
+					0xffffffffU);
+
+	mtu_delay_timer.read_current_timer = &nmdk_timer_read_current_timer;
+	mtu_delay_timer.freq = rate;
+	register_current_timer_delay(&mtu_delay_timer);
+
+	return 0;
+}
+
+static int __init nmdk_timer_of_init(struct device_node *node)
+{
+	struct clk *pclk;
+	struct clk *clk;
+	void __iomem *base;
+	int irq;
+
+	base = of_iomap(node, 0);
+	if (!base) {
+		pr_err("Can't remap registers\n");
+		return -ENXIO;
+	}
+
+	pclk = of_clk_get_by_name(node, "apb_pclk");
+	if (IS_ERR(pclk)) {
+		pr_err("could not get apb_pclk\n");
+		return PTR_ERR(pclk);
+	}
+
+	clk = of_clk_get_by_name(node, "timclk");
+	if (IS_ERR(clk)) {
+		pr_err("could not get timclk\n");
+		return PTR_ERR(clk);
+	}
+
+	irq = irq_of_parse_and_map(node, 0);
+	if (irq <= 0) {
+		pr_err("Can't parse IRQ\n");
+		return -EINVAL;
+	}
+
+	return nmdk_timer_init(base, irq, pclk, clk);
+}
+TIMER_OF_DECLARE(nomadik_mtu, "st,nomadik-mtu",
+		       nmdk_timer_of_init);