1 files changed, 436 insertions, 0 deletions
diff --git a/drivers/clocksource/cadence_ttc_timer.c b/drivers/clocksource/cadence_ttc_timer.c
new file mode 100644
index 000000000000..685bc60e210a
--- /dev/null
+++ b/drivers/clocksource/cadence_ttc_timer.c
@@ -0,0 +1,436 @@
+/*
+ * This file contains driver for the Cadence Triple Timer Counter Rev 06
+ *
+ *  Copyright (C) 2011-2013 Xilinx
+ *
+ * based on arch/mips/kernel/time.c timer driver
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/clockchips.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/slab.h>
+#include <linux/clk-provider.h>
+
+/*
+ * This driver configures the 2 16-bit count-up timers as follows:
+ *
+ * T1: Timer 1, clocksource for generic timekeeping
+ * T2: Timer 2, clockevent source for hrtimers
+ * T3: Timer 3, <unused>
+ *
+ * The input frequency to the timer module for emulation is 2.5MHz which is
+ * common to all the timer channels (T1, T2, and T3). With a pre-scaler of 32,
+ * the timers are clocked at 78.125KHz (12.8 us resolution).
+
+ * The input frequency to the timer module in silicon is configurable and
+ * obtained from device tree. The pre-scaler of 32 is used.
+ */
+
+/*
+ * Timer Register Offset Definitions of Timer 1, Increment base address by 4
+ * and use same offsets for Timer 2
+ */
+#define TTC_CLK_CNTRL_OFFSET		0x00 /* Clock Control Reg, RW */
+#define TTC_CNT_CNTRL_OFFSET		0x0C /* Counter Control Reg, RW */
+#define TTC_COUNT_VAL_OFFSET		0x18 /* Counter Value Reg, RO */
+#define TTC_INTR_VAL_OFFSET		0x24 /* Interval Count Reg, RW */
+#define TTC_ISR_OFFSET		0x54 /* Interrupt Status Reg, RO */
+#define TTC_IER_OFFSET		0x60 /* Interrupt Enable Reg, RW */
+
+#define TTC_CNT_CNTRL_DISABLE_MASK	0x1
+
+/*
+ * Setup the timers to use pre-scaling, using a fixed value for now that will
+ * work across most input frequency, but it may need to be more dynamic
+ */
+#define PRESCALE_EXPONENT	11	/* 2 ^ PRESCALE_EXPONENT = PRESCALE */
+#define PRESCALE		2048	/* The exponent must match this */
+#define CLK_CNTRL_PRESCALE	((PRESCALE_EXPONENT - 1) << 1)
+#define CLK_CNTRL_PRESCALE_EN	1
+#define CNT_CNTRL_RESET		(1 << 4)
+
+/**
+ * struct ttc_timer - This definition defines local timer structure
+ *
+ * @base_addr:	Base address of timer
+ * @clk:	Associated clock source
+ * @clk_rate_change_nb	Notifier block for clock rate changes
+ */
+struct ttc_timer {
+	void __iomem *base_addr;
+	struct clk *clk;
+	struct notifier_block clk_rate_change_nb;
+};
+
+#define to_ttc_timer(x) \
+		container_of(x, struct ttc_timer, clk_rate_change_nb)
+
+struct ttc_timer_clocksource {
+	struct ttc_timer	ttc;
+	struct clocksource	cs;
+};
+
+#define to_ttc_timer_clksrc(x) \
+		container_of(x, struct ttc_timer_clocksource, cs)
+
+struct ttc_timer_clockevent {
+	struct ttc_timer		ttc;
+	struct clock_event_device	ce;
+};
+
+#define to_ttc_timer_clkevent(x) \
+		container_of(x, struct ttc_timer_clockevent, ce)
+
+/**
+ * ttc_set_interval - Set the timer interval value
+ *
+ * @timer:	Pointer to the timer instance
+ * @cycles:	Timer interval ticks
+ **/
+static void ttc_set_interval(struct ttc_timer *timer,
+					unsigned long cycles)
+{
+	u32 ctrl_reg;
+
+	/* Disable the counter, set the counter value  and re-enable counter */
+	ctrl_reg = __raw_readl(timer->base_addr + TTC_CNT_CNTRL_OFFSET);
+	ctrl_reg |= TTC_CNT_CNTRL_DISABLE_MASK;
+	__raw_writel(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET);
+
+	__raw_writel(cycles, timer->base_addr + TTC_INTR_VAL_OFFSET);
+
+	/*
+	 * Reset the counter (0x10) so that it starts from 0, one-shot
+	 * mode makes this needed for timing to be right.
+	 */
+	ctrl_reg |= CNT_CNTRL_RESET;
+	ctrl_reg &= ~TTC_CNT_CNTRL_DISABLE_MASK;
+	__raw_writel(ctrl_reg, timer->base_addr + TTC_CNT_CNTRL_OFFSET);
+}
+
+/**
+ * ttc_clock_event_interrupt - Clock event timer interrupt handler
+ *
+ * @irq:	IRQ number of the Timer
+ * @dev_id:	void pointer to the ttc_timer instance
+ *
+ * returns: Always IRQ_HANDLED - success
+ **/
+static irqreturn_t ttc_clock_event_interrupt(int irq, void *dev_id)
+{
+	struct ttc_timer_clockevent *ttce = dev_id;
+	struct ttc_timer *timer = &ttce->ttc;
+
+	/* Acknowledge the interrupt and call event handler */
+	__raw_readl(timer->base_addr + TTC_ISR_OFFSET);
+
+	ttce->ce.event_handler(&ttce->ce);
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * __ttc_clocksource_read - Reads the timer counter register
+ *
+ * returns: Current timer counter register value
+ **/
+static cycle_t __ttc_clocksource_read(struct clocksource *cs)
+{
+	struct ttc_timer *timer = &to_ttc_timer_clksrc(cs)->ttc;
+
+	return (cycle_t)__raw_readl(timer->base_addr +
+				TTC_COUNT_VAL_OFFSET);
+}
+
+/**
+ * ttc_set_next_event - Sets the time interval for next event
+ *
+ * @cycles:	Timer interval ticks
+ * @evt:	Address of clock event instance
+ *
+ * returns: Always 0 - success
+ **/
+static int ttc_set_next_event(unsigned long cycles,
+					struct clock_event_device *evt)
+{
+	struct ttc_timer_clockevent *ttce = to_ttc_timer_clkevent(evt);
+	struct ttc_timer *timer = &ttce->ttc;
+
+	ttc_set_interval(timer, cycles);
+	return 0;
+}
+
+/**
+ * ttc_set_mode - Sets the mode of timer
+ *
+ * @mode:	Mode to be set
+ * @evt:	Address of clock event instance
+ **/
+static void ttc_set_mode(enum clock_event_mode mode,
+					struct clock_event_device *evt)
+{
+	struct ttc_timer_clockevent *ttce = to_ttc_timer_clkevent(evt);
+	struct ttc_timer *timer = &ttce->ttc;
+	u32 ctrl_reg;
+
+	switch (mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		ttc_set_interval(timer,
+				DIV_ROUND_CLOSEST(clk_get_rate(ttce->ttc.clk),
+					PRESCALE * HZ));
+		break;
+	case CLOCK_EVT_MODE_ONESHOT:
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+		ctrl_reg = __raw_readl(timer->base_addr +
+					TTC_CNT_CNTRL_OFFSET);
+		ctrl_reg |= TTC_CNT_CNTRL_DISABLE_MASK;
+		__raw_writel(ctrl_reg,
+				timer->base_addr + TTC_CNT_CNTRL_OFFSET);
+		break;
+	case CLOCK_EVT_MODE_RESUME:
+		ctrl_reg = __raw_readl(timer->base_addr +
+					TTC_CNT_CNTRL_OFFSET);
+		ctrl_reg &= ~TTC_CNT_CNTRL_DISABLE_MASK;
+		__raw_writel(ctrl_reg,
+				timer->base_addr + TTC_CNT_CNTRL_OFFSET);
+		break;
+	}
+}
+
+static int ttc_rate_change_clocksource_cb(struct notifier_block *nb,
+		unsigned long event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+	struct ttc_timer *ttc = to_ttc_timer(nb);
+	struct ttc_timer_clocksource *ttccs = container_of(ttc,
+			struct ttc_timer_clocksource, ttc);
+
+	switch (event) {
+	case POST_RATE_CHANGE:
+		/*
+		 * Do whatever is necessary to maintain a proper time base
+		 *
+		 * I cannot find a way to adjust the currently used clocksource
+		 * to the new frequency. __clocksource_updatefreq_hz() sounds
+		 * good, but does not work. Not sure what's that missing.
+		 *
+		 * This approach works, but triggers two clocksource switches.
+		 * The first after unregister to clocksource jiffies. And
+		 * another one after the register to the newly registered timer.
+		 *
+		 * Alternatively we could 'waste' another HW timer to ping pong
+		 * between clock sources. That would also use one register and
+		 * one unregister call, but only trigger one clocksource switch
+		 * for the cost of another HW timer used by the OS.
+		 */
+		clocksource_unregister(&ttccs->cs);
+		clocksource_register_hz(&ttccs->cs,
+				ndata->new_rate / PRESCALE);
+		/* fall through */
+	case PRE_RATE_CHANGE:
+	case ABORT_RATE_CHANGE:
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
+static void __init ttc_setup_clocksource(struct clk *clk, void __iomem *base)
+{
+	struct ttc_timer_clocksource *ttccs;
+	int err;
+
+	ttccs = kzalloc(sizeof(*ttccs), GFP_KERNEL);
+	if (WARN_ON(!ttccs))
+		return;
+
+	ttccs->ttc.clk = clk;
+
+	err = clk_prepare_enable(ttccs->ttc.clk);
+	if (WARN_ON(err)) {
+		kfree(ttccs);
+		return;
+	}
+
+	ttccs->ttc.clk_rate_change_nb.notifier_call =
+		ttc_rate_change_clocksource_cb;
+	ttccs->ttc.clk_rate_change_nb.next = NULL;
+	if (clk_notifier_register(ttccs->ttc.clk,
+				&ttccs->ttc.clk_rate_change_nb))
+		pr_warn("Unable to register clock notifier.\n");
+
+	ttccs->ttc.base_addr = base;
+	ttccs->cs.name = "ttc_clocksource";
+	ttccs->cs.rating = 200;
+	ttccs->cs.read = __ttc_clocksource_read;
+	ttccs->cs.mask = CLOCKSOURCE_MASK(16);
+	ttccs->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS;
+
+	/*
+	 * Setup the clock source counter to be an incrementing counter
+	 * with no interrupt and it rolls over at 0xFFFF. Pre-scale
+	 * it by 32 also. Let it start running now.
+	 */
+	__raw_writel(0x0,  ttccs->ttc.base_addr + TTC_IER_OFFSET);
+	__raw_writel(CLK_CNTRL_PRESCALE | CLK_CNTRL_PRESCALE_EN,
+		     ttccs->ttc.base_addr + TTC_CLK_CNTRL_OFFSET);
+	__raw_writel(CNT_CNTRL_RESET,
+		     ttccs->ttc.base_addr + TTC_CNT_CNTRL_OFFSET);
+
+	err = clocksource_register_hz(&ttccs->cs,
+			clk_get_rate(ttccs->ttc.clk) / PRESCALE);
+	if (WARN_ON(err)) {
+		kfree(ttccs);
+		return;
+	}
+}
+
+static int ttc_rate_change_clockevent_cb(struct notifier_block *nb,
+		unsigned long event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+	struct ttc_timer *ttc = to_ttc_timer(nb);
+	struct ttc_timer_clockevent *ttcce = container_of(ttc,
+			struct ttc_timer_clockevent, ttc);
+
+	switch (event) {
+	case POST_RATE_CHANGE:
+	{
+		unsigned long flags;
+
+		/*
+		 * clockevents_update_freq should be called with IRQ disabled on
+		 * the CPU the timer provides events for. The timer we use is
+		 * common to both CPUs, not sure if we need to run on both
+		 * cores.
+		 */
+		local_irq_save(flags);
+		clockevents_update_freq(&ttcce->ce,
+				ndata->new_rate / PRESCALE);
+		local_irq_restore(flags);
+
+		/* fall through */
+	}
+	case PRE_RATE_CHANGE:
+	case ABORT_RATE_CHANGE:
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
+static void __init ttc_setup_clockevent(struct clk *clk,
+						void __iomem *base, u32 irq)
+{
+	struct ttc_timer_clockevent *ttcce;
+	int err;
+
+	ttcce = kzalloc(sizeof(*ttcce), GFP_KERNEL);
+	if (WARN_ON(!ttcce))
+		return;
+
+	ttcce->ttc.clk = clk;
+
+	err = clk_prepare_enable(ttcce->ttc.clk);
+	if (WARN_ON(err)) {
+		kfree(ttcce);
+		return;
+	}
+
+	ttcce->ttc.clk_rate_change_nb.notifier_call =
+		ttc_rate_change_clockevent_cb;
+	ttcce->ttc.clk_rate_change_nb.next = NULL;
+	if (clk_notifier_register(ttcce->ttc.clk,
+				&ttcce->ttc.clk_rate_change_nb))
+		pr_warn("Unable to register clock notifier.\n");
+
+	ttcce->ttc.base_addr = base;
+	ttcce->ce.name = "ttc_clockevent";
+	ttcce->ce.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+	ttcce->ce.set_next_event = ttc_set_next_event;
+	ttcce->ce.set_mode = ttc_set_mode;
+	ttcce->ce.rating = 200;
+	ttcce->ce.irq = irq;
+	ttcce->ce.cpumask = cpu_possible_mask;
+
+	/*
+	 * Setup the clock event timer to be an interval timer which
+	 * is prescaled by 32 using the interval interrupt. Leave it
+	 * disabled for now.
+	 */
+	__raw_writel(0x23, ttcce->ttc.base_addr + TTC_CNT_CNTRL_OFFSET);
+	__raw_writel(CLK_CNTRL_PRESCALE | CLK_CNTRL_PRESCALE_EN,
+		     ttcce->ttc.base_addr + TTC_CLK_CNTRL_OFFSET);
+	__raw_writel(0x1,  ttcce->ttc.base_addr + TTC_IER_OFFSET);
+
+	err = request_irq(irq, ttc_clock_event_interrupt,
+			  IRQF_DISABLED | IRQF_TIMER,
+			  ttcce->ce.name, ttcce);
+	if (WARN_ON(err)) {
+		kfree(ttcce);
+		return;
+	}
+
+	clockevents_config_and_register(&ttcce->ce,
+			clk_get_rate(ttcce->ttc.clk) / PRESCALE, 1, 0xfffe);
+}
+
+/**
+ * ttc_timer_init - Initialize the timer
+ *
+ * Initializes the timer hardware and register the clock source and clock event
+ * timers with Linux kernal timer framework
+ */
+static void __init ttc_timer_init(struct device_node *timer)
+{
+	unsigned int irq;
+	void __iomem *timer_baseaddr;
+	struct clk *clk;
+	static int initialized;
+
+	if (initialized)
+		return;
+
+	initialized = 1;
+
+	/*
+	 * Get the 1st Triple Timer Counter (TTC) block from the device tree
+	 * and use it. Note that the event timer uses the interrupt and it's the
+	 * 2nd TTC hence the irq_of_parse_and_map(,1)
+	 */
+	timer_baseaddr = of_iomap(timer, 0);
+	if (!timer_baseaddr) {
+		pr_err("ERROR: invalid timer base address\n");
+		BUG();
+	}
+
+	irq = irq_of_parse_and_map(timer, 1);
+	if (irq <= 0) {
+		pr_err("ERROR: invalid interrupt number\n");
+		BUG();
+	}
+
+	clk = of_clk_get_by_name(timer, "cpu_1x");
+	if (IS_ERR(clk)) {
+		pr_err("ERROR: timer input clock not found\n");
+		BUG();
+	}
+
+	ttc_setup_clocksource(clk, timer_baseaddr);
+	ttc_setup_clockevent(clk, timer_baseaddr + 4, irq);
+
+	pr_info("%s #0 at %p, irq=%d\n", timer->name, timer_baseaddr, irq);
+}
+
+CLOCKSOURCE_OF_DECLARE(ttc, "cdns,ttc", ttc_timer_init);