1 files changed, 239 insertions, 0 deletions
diff --git a/arch/arm/plat-spear/time.c b/arch/arm/plat-spear/time.c
new file mode 100644
index 00000000..abb5bdec
--- /dev/null
+++ b/arch/arm/plat-spear/time.c
@@ -0,0 +1,239 @@
+/*
+ * arch/arm/plat-spear/time.c
+ *
+ * Copyright (C) 2010 ST Microelectronics
+ * Shiraz Hashim<shiraz.hashim@st.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/time.h>
+#include <linux/irq.h>
+#include <asm/mach/time.h>
+#include <mach/generic.h>
+#include <mach/hardware.h>
+#include <mach/irqs.h>
+
+/*
+ * We would use TIMER0 and TIMER1 as clockevent and clocksource.
+ * Timer0 and Timer1 both belong to same gpt block in cpu subbsystem. Further
+ * they share same functional clock. Any change in one's functional clock will
+ * also affect other timer.
+ */
+
+#define CLKEVT	0	/* gpt0, channel0 as clockevent */
+#define CLKSRC	1	/* gpt0, channel1 as clocksource */
+
+/* Register offsets, x is channel number */
+#define CR(x)		((x) * 0x80 + 0x80)
+#define IR(x)		((x) * 0x80 + 0x84)
+#define LOAD(x)		((x) * 0x80 + 0x88)
+#define COUNT(x)	((x) * 0x80 + 0x8C)
+
+/* Reg bit definitions */
+#define CTRL_INT_ENABLE		0x0100
+#define CTRL_ENABLE		0x0020
+#define CTRL_ONE_SHOT		0x0010
+
+#define CTRL_PRESCALER1		0x0
+#define CTRL_PRESCALER2		0x1
+#define CTRL_PRESCALER4		0x2
+#define CTRL_PRESCALER8		0x3
+#define CTRL_PRESCALER16	0x4
+#define CTRL_PRESCALER32	0x5
+#define CTRL_PRESCALER64	0x6
+#define CTRL_PRESCALER128	0x7
+#define CTRL_PRESCALER256	0x8
+
+#define INT_STATUS		0x1
+
+/*
+ * Minimum clocksource/clockevent timer range in seconds
+ */
+#define SPEAR_MIN_RANGE 4
+
+static __iomem void *gpt_base;
+static struct clk *gpt_clk;
+
+static void clockevent_set_mode(enum clock_event_mode mode,
+				struct clock_event_device *clk_event_dev);
+static int clockevent_next_event(unsigned long evt,
+				 struct clock_event_device *clk_event_dev);
+
+static void spear_clocksource_init(void)
+{
+	u32 tick_rate;
+	u16 val;
+
+	/* program the prescaler (/256)*/
+	writew(CTRL_PRESCALER256, gpt_base + CR(CLKSRC));
+
+	/* find out actual clock driving Timer */
+	tick_rate = clk_get_rate(gpt_clk);
+	tick_rate >>= CTRL_PRESCALER256;
+
+	writew(0xFFFF, gpt_base + LOAD(CLKSRC));
+
+	val = readw(gpt_base + CR(CLKSRC));
+	val &= ~CTRL_ONE_SHOT;	/* autoreload mode */
+	val |= CTRL_ENABLE ;
+	writew(val, gpt_base + CR(CLKSRC));
+
+	/* register the clocksource */
+	clocksource_mmio_init(gpt_base + COUNT(CLKSRC), "tmr1", tick_rate,
+		200, 16, clocksource_mmio_readw_up);
+}
+
+static struct clock_event_device clkevt = {
+	.name = "tmr0",
+	.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+	.set_mode = clockevent_set_mode,
+	.set_next_event = clockevent_next_event,
+	.shift = 0,	/* to be computed */
+};
+
+static void clockevent_set_mode(enum clock_event_mode mode,
+				struct clock_event_device *clk_event_dev)
+{
+	u32 period;
+	u16 val;
+
+	/* stop the timer */
+	val = readw(gpt_base + CR(CLKEVT));
+	val &= ~CTRL_ENABLE;
+	writew(val, gpt_base + CR(CLKEVT));
+
+	switch (mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		period = clk_get_rate(gpt_clk) / HZ;
+		period >>= CTRL_PRESCALER16;
+		writew(period, gpt_base + LOAD(CLKEVT));
+
+		val = readw(gpt_base + CR(CLKEVT));
+		val &= ~CTRL_ONE_SHOT;
+		val |= CTRL_ENABLE | CTRL_INT_ENABLE;
+		writew(val, gpt_base + CR(CLKEVT));
+
+		break;
+	case CLOCK_EVT_MODE_ONESHOT:
+		val = readw(gpt_base + CR(CLKEVT));
+		val |= CTRL_ONE_SHOT;
+		writew(val, gpt_base + CR(CLKEVT));
+
+		break;
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+	case CLOCK_EVT_MODE_RESUME:
+
+		break;
+	default:
+		pr_err("Invalid mode requested\n");
+		break;
+	}
+}
+
+static int clockevent_next_event(unsigned long cycles,
+				 struct clock_event_device *clk_event_dev)
+{
+	u16 val = readw(gpt_base + CR(CLKEVT));
+
+	if (val & CTRL_ENABLE)
+		writew(val & ~CTRL_ENABLE, gpt_base + CR(CLKEVT));
+
+	writew(cycles, gpt_base + LOAD(CLKEVT));
+
+	val |= CTRL_ENABLE | CTRL_INT_ENABLE;
+	writew(val, gpt_base + CR(CLKEVT));
+
+	return 0;
+}
+
+static irqreturn_t spear_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = &clkevt;
+
+	writew(INT_STATUS, gpt_base + IR(CLKEVT));
+
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static struct irqaction spear_timer_irq = {
+	.name = "timer",
+	.flags = IRQF_DISABLED | IRQF_TIMER,
+	.handler = spear_timer_interrupt
+};
+
+static void __init spear_clockevent_init(void)
+{
+	u32 tick_rate;
+
+	/* program the prescaler */
+	writew(CTRL_PRESCALER16, gpt_base + CR(CLKEVT));
+
+	tick_rate = clk_get_rate(gpt_clk);
+	tick_rate >>= CTRL_PRESCALER16;
+
+	clockevents_calc_mult_shift(&clkevt, tick_rate, SPEAR_MIN_RANGE);
+
+	clkevt.max_delta_ns = clockevent_delta2ns(0xfff0,
+			&clkevt);
+	clkevt.min_delta_ns = clockevent_delta2ns(3, &clkevt);
+
+	clkevt.cpumask = cpumask_of(0);
+
+	clockevents_register_device(&clkevt);
+
+	setup_irq(SPEAR_GPT0_CHAN0_IRQ, &spear_timer_irq);
+}
+
+void __init spear_setup_timer(void)
+{
+	int ret;
+
+	if (!request_mem_region(SPEAR_GPT0_BASE, SZ_1K, "gpt0")) {
+		pr_err("%s:cannot get IO addr\n", __func__);
+		return;
+	}
+
+	gpt_base = (void __iomem *)ioremap(SPEAR_GPT0_BASE, SZ_1K);
+	if (!gpt_base) {
+		pr_err("%s:ioremap failed for gpt\n", __func__);
+		goto err_mem;
+	}
+
+	gpt_clk = clk_get_sys("gpt0", NULL);
+	if (!gpt_clk) {
+		pr_err("%s:couldn't get clk for gpt\n", __func__);
+		goto err_iomap;
+	}
+
+	ret = clk_enable(gpt_clk);
+	if (ret < 0) {
+		pr_err("%s:couldn't enable gpt clock\n", __func__);
+		goto err_clk;
+	}
+
+	spear_clockevent_init();
+	spear_clocksource_init();
+
+	return;
+
+err_clk:
+	clk_put(gpt_clk);
+err_iomap:
+	iounmap(gpt_base);
+err_mem:
+	release_mem_region(SPEAR_GPT0_BASE, SZ_1K);
+}