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-rw-r--r--arch/arm/mach-spear/time.c245
1 files changed, 245 insertions, 0 deletions
diff --git a/arch/arm/mach-spear/time.c b/arch/arm/mach-spear/time.c
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+++ b/arch/arm/mach-spear/time.c
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+/*
+ * 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/ioport.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/time.h>
+#include <linux/irq.h>
+#include <asm/mach/time.h>
+#include "generic.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(int irq)
+{
+ u32 tick_rate;
+
+ /* program the prescaler */
+ writew(CTRL_PRESCALER16, gpt_base + CR(CLKEVT));
+
+ tick_rate = clk_get_rate(gpt_clk);
+ tick_rate >>= CTRL_PRESCALER16;
+
+ clkevt.cpumask = cpumask_of(0);
+
+ clockevents_config_and_register(&clkevt, tick_rate, 3, 0xfff0);
+
+ setup_irq(irq, &spear_timer_irq);
+}
+
+const static struct of_device_id timer_of_match[] __initconst = {
+ { .compatible = "st,spear-timer", },
+ { },
+};
+
+void __init spear_setup_of_timer(void)
+{
+ struct device_node *np;
+ int irq, ret;
+
+ np = of_find_matching_node(NULL, timer_of_match);
+ if (!np) {
+ pr_err("%s: No timer passed via DT\n", __func__);
+ return;
+ }
+
+ irq = irq_of_parse_and_map(np, 0);
+ if (!irq) {
+ pr_err("%s: No irq passed for timer via DT\n", __func__);
+ return;
+ }
+
+ gpt_base = of_iomap(np, 0);
+ if (!gpt_base) {
+ pr_err("%s: of iomap failed\n", __func__);
+ return;
+ }
+
+ 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_prepare_enable(gpt_clk);
+ if (ret < 0) {
+ pr_err("%s:couldn't prepare-enable gpt clock\n", __func__);
+ goto err_prepare_enable_clk;
+ }
+
+ spear_clockevent_init(irq);
+ spear_clocksource_init();
+
+ return;
+
+err_prepare_enable_clk:
+ clk_put(gpt_clk);
+err_iomap:
+ iounmap(gpt_base);
+}