1 files changed, 188 insertions, 73 deletions

diff --git a/arch/arm/mach-zynq/timer.c b/arch/arm/mach-zynq/timer.c
index f9fbc9c1e7a..82357d94a0e 100644
--- a/arch/arm/mach-zynq/timer.c
+++ b/arch/arm/mach-zynq/timer.c
@@ -1,7 +1,7 @@
 /*
  * This file contains driver for the Xilinx PS Timer Counter IP.
  *
- *  Copyright (C) 2011 Xilinx
+ *  Copyright (C) 2011-2013 Xilinx
  *
  * based on arch/mips/kernel/time.c timer driver
  *
@@ -15,6 +15,7 @@
  * GNU General Public License for more details.
  */
 
+#include <linux/clk.h>
 #include <linux/interrupt.h>
 #include <linux/clockchips.h>
 #include <linux/of_address.h>
@@ -24,6 +25,21 @@
 #include "common.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
  */
@@ -44,17 +60,24 @@
 #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)
+#define CNT_CNTRL_RESET		(1 << 4)
 
 /**
  * struct xttcps_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 xttcps_timer {
-	void __iomem	*base_addr;
+	void __iomem *base_addr;
+	struct clk *clk;
+	struct notifier_block clk_rate_change_nb;
 };
 
+#define to_xttcps_timer(x) \
+		container_of(x, struct xttcps_timer, clk_rate_change_nb)
+
 struct xttcps_timer_clocksource {
 	struct xttcps_timer	xttc;
 	struct clocksource	cs;
@@ -66,7 +89,6 @@ struct xttcps_timer_clocksource {
 struct xttcps_timer_clockevent {
 	struct xttcps_timer		xttc;
 	struct clock_event_device	ce;
-	struct clk			*clk;
 };
 
 #define to_xttcps_timer_clkevent(x) \
@@ -167,8 +189,8 @@ static void xttcps_set_mode(enum clock_event_mode mode,
 	switch (mode) {
 	case CLOCK_EVT_MODE_PERIODIC:
 		xttcps_set_interval(timer,
-				     DIV_ROUND_CLOSEST(clk_get_rate(xttce->clk),
-						       PRESCALE * HZ));
+				DIV_ROUND_CLOSEST(clk_get_rate(xttce->xttc.clk),
+					PRESCALE * HZ));
 		break;
 	case CLOCK_EVT_MODE_ONESHOT:
 	case CLOCK_EVT_MODE_UNUSED:
@@ -189,79 +211,148 @@ static void xttcps_set_mode(enum clock_event_mode mode,
 	}
 }
 
-static void __init zynq_ttc_setup_clocksource(struct device_node *np,
-					     void __iomem *base)
+static int xttcps_rate_change_clocksource_cb(struct notifier_block *nb,
+		unsigned long event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+	struct xttcps_timer *xttcps = to_xttcps_timer(nb);
+	struct xttcps_timer_clocksource *xttccs = container_of(xttcps,
+			struct xttcps_timer_clocksource, xttc);
+
+	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(&xttccs->cs);
+		clocksource_register_hz(&xttccs->cs,
+				ndata->new_rate / PRESCALE);
+		/* fall through */
+	case PRE_RATE_CHANGE:
+	case ABORT_RATE_CHANGE:
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
+static void __init xttc_setup_clocksource(struct clk *clk, void __iomem *base)
 {
 	struct xttcps_timer_clocksource *ttccs;
-	struct clk *clk;
 	int err;
-	u32 reg;
 
 	ttccs = kzalloc(sizeof(*ttccs), GFP_KERNEL);
 	if (WARN_ON(!ttccs))
 		return;
 
-	err = of_property_read_u32(np, "reg", &reg);
-	if (WARN_ON(err))
-		return;
+	ttccs->xttc.clk = clk;
 
-	clk = of_clk_get_by_name(np, "cpu_1x");
-	if (WARN_ON(IS_ERR(clk)))
-		return;
-
-	err = clk_prepare_enable(clk);
+	err = clk_prepare_enable(ttccs->xttc.clk);
 	if (WARN_ON(err))
 		return;
 
-	ttccs->xttc.base_addr = base + reg * 4;
+	ttccs->xttc.clk_rate_change_nb.notifier_call =
+		xttcps_rate_change_clocksource_cb;
+	ttccs->xttc.clk_rate_change_nb.next = NULL;
+	if (clk_notifier_register(ttccs->xttc.clk,
+				&ttccs->xttc.clk_rate_change_nb))
+		pr_warn("Unable to register clock notifier.\n");
 
-	ttccs->cs.name = np->name;
+	ttccs->xttc.base_addr = base;
+	ttccs->cs.name = "xttcps_clocksource";
 	ttccs->cs.rating = 200;
 	ttccs->cs.read = __xttc_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->xttc.base_addr + XTTCPS_IER_OFFSET);
 	__raw_writel(CLK_CNTRL_PRESCALE | CLK_CNTRL_PRESCALE_EN,
 		     ttccs->xttc.base_addr + XTTCPS_CLK_CNTRL_OFFSET);
 	__raw_writel(CNT_CNTRL_RESET,
 		     ttccs->xttc.base_addr + XTTCPS_CNT_CNTRL_OFFSET);
 
-	err = clocksource_register_hz(&ttccs->cs, clk_get_rate(clk) / PRESCALE);
+	err = clocksource_register_hz(&ttccs->cs,
+			clk_get_rate(ttccs->xttc.clk) / PRESCALE);
 	if (WARN_ON(err))
 		return;
+
 }
 
-static void __init zynq_ttc_setup_clockevent(struct device_node *np,
-					    void __iomem *base)
+static int xttcps_rate_change_clockevent_cb(struct notifier_block *nb,
+		unsigned long event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+	struct xttcps_timer *xttcps = to_xttcps_timer(nb);
+	struct xttcps_timer_clockevent *xttcce = container_of(xttcps,
+			struct xttcps_timer_clockevent, xttc);
+
+	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(&xttcce->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 xttc_setup_clockevent(struct clk *clk,
+						void __iomem *base, u32 irq)
 {
 	struct xttcps_timer_clockevent *ttcce;
-	int err, irq;
-	u32 reg;
+	int err;
 
 	ttcce = kzalloc(sizeof(*ttcce), GFP_KERNEL);
 	if (WARN_ON(!ttcce))
 		return;
 
-	err = of_property_read_u32(np, "reg", &reg);
-	if (WARN_ON(err))
-		return;
+	ttcce->xttc.clk = clk;
 
-	ttcce->xttc.base_addr = base + reg * 4;
-
-	ttcce->clk = of_clk_get_by_name(np, "cpu_1x");
-	if (WARN_ON(IS_ERR(ttcce->clk)))
-		return;
-
-	err = clk_prepare_enable(ttcce->clk);
+	err = clk_prepare_enable(ttcce->xttc.clk);
 	if (WARN_ON(err))
 		return;
 
-	irq = irq_of_parse_and_map(np, 0);
-	if (WARN_ON(!irq))
-		return;
+	ttcce->xttc.clk_rate_change_nb.notifier_call =
+		xttcps_rate_change_clockevent_cb;
+	ttcce->xttc.clk_rate_change_nb.next = NULL;
+	if (clk_notifier_register(ttcce->xttc.clk,
+				&ttcce->xttc.clk_rate_change_nb))
+		pr_warn("Unable to register clock notifier.\n");
 
-	ttcce->ce.name = np->name;
+	ttcce->xttc.base_addr = base;
+	ttcce->ce.name = "xttcps_clockevent";
 	ttcce->ce.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
 	ttcce->ce.set_next_event = xttcps_set_next_event;
 	ttcce->ce.set_mode = xttcps_set_mode;
@@ -269,56 +360,80 @@ static void __init zynq_ttc_setup_clockevent(struct device_node *np,
 	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->xttc.base_addr + XTTCPS_CNT_CNTRL_OFFSET);
 	__raw_writel(CLK_CNTRL_PRESCALE | CLK_CNTRL_PRESCALE_EN,
 		     ttcce->xttc.base_addr + XTTCPS_CLK_CNTRL_OFFSET);
 	__raw_writel(0x1,  ttcce->xttc.base_addr + XTTCPS_IER_OFFSET);
 
-	err = request_irq(irq, xttcps_clock_event_interrupt, IRQF_TIMER,
-			  np->name, ttcce);
+	err = request_irq(irq, xttcps_clock_event_interrupt,
+			  IRQF_DISABLED | IRQF_TIMER,
+			  ttcce->ce.name, ttcce);
 	if (WARN_ON(err))
 		return;
 
 	clockevents_config_and_register(&ttcce->ce,
-					clk_get_rate(ttcce->clk) / PRESCALE,
-					1, 0xfffe);
+			clk_get_rate(ttcce->xttc.clk) / PRESCALE, 1, 0xfffe);
 }
 
-static const __initconst struct of_device_id zynq_ttc_match[] = {
-	{ .compatible = "xlnx,ttc-counter-clocksource",
-		.data = zynq_ttc_setup_clocksource, },
-	{ .compatible = "xlnx,ttc-counter-clockevent",
-		.data = zynq_ttc_setup_clockevent, },
-	{}
-};
-
 /**
  * xttcps_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 xttcps_timer_init_of(struct device_node *timer)
+{
+	unsigned int irq;
+	void __iomem *timer_baseaddr;
+	struct clk *clk;
+
+	/*
+	 * 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();
+	}
+
+	xttc_setup_clocksource(clk, timer_baseaddr);
+	xttc_setup_clockevent(clk, timer_baseaddr + 4, irq);
+
+	pr_info("%s #0 at %p, irq=%d\n", timer->name, timer_baseaddr, irq);
+}
+
 void __init xttcps_timer_init(void)
 {
-	struct device_node *np;
-
-	for_each_compatible_node(np, NULL, "xlnx,ttc") {
-		struct device_node *np_chld;
-		void __iomem *base;
-
-		base = of_iomap(np, 0);
-		if (WARN_ON(!base))
-			return;
-
-		for_each_available_child_of_node(np, np_chld) {
-			int (*cb)(struct device_node *np, void __iomem *base);
-			const struct of_device_id *match;
-
-			match = of_match_node(zynq_ttc_match, np_chld);
-			if (match) {
-				cb = match->data;
-				cb(np_chld, base);
-			}
-		}
+	const char * const timer_list[] = {
+		"cdns,ttc",
+		NULL
+	};
+	struct device_node *timer;
+
+	timer = of_find_compatible_node(NULL, NULL, timer_list[0]);
+	if (!timer) {
+		pr_err("ERROR: no compatible timer found\n");
+		BUG();
 	}
+
+	xttcps_timer_init_of(timer);
 }