--- /dev/null
+/*
+ * arch/arm/plat-spear/time.c
+ *
+ * Copyright (C) 2009 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/irqs.h>
+#include <mach/hardware.h>
+#include <mach/spear.h>
+#include <mach/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
+
+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);
+
+/*
+ * Following clocksource_set_clock and clockevent_set_clock picked
+ * from arch/mips/kernel/time.c
+ */
+
+void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
+{
+ u64 temp;
+ u32 shift;
+
+ /* Find a shift value */
+ for (shift = 32; shift > 0; shift--) {
+ temp = (u64) NSEC_PER_SEC << shift;
+ do_div(temp, clock);
+ if ((temp >> 32) == 0)
+ break;
+ }
+ cs->shift = shift;
+ cs->mult = (u32) temp;
+}
+
+void __init clockevent_set_clock(struct clock_event_device *cd,
+ unsigned int clock)
+{
+ u64 temp;
+ u32 shift;
+
+ /* Find a shift value */
+ for (shift = 32; shift > 0; shift--) {
+ temp = (u64) clock << shift;
+ do_div(temp, NSEC_PER_SEC);
+ if ((temp >> 32) == 0)
+ break;
+ }
+ cd->shift = shift;
+ cd->mult = (u32) temp;
+}
+
+static cycle_t clocksource_read_cycles(struct clocksource *cs)
+{
+ return (cycle_t) readw(gpt_base + COUNT(CLKSRC));
+}
+
+static struct clocksource clksrc = {
+ .name = "tmr1",
+ .rating = 200, /* its a pretty decent clock */
+ .read = clocksource_read_cycles,
+ .mask = 0xFFFF, /* 16 bits */
+ .mult = 0, /* to be computed */
+ .shift = 0, /* to be computed */
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+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));
+
+ clocksource_set_clock(&clksrc, tick_rate);
+
+ /* register the clocksource */
+ clocksource_register(&clksrc);
+}
+
+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;
+
+ writew(cycles, gpt_base + LOAD(CLKEVT));
+
+ val = readw(gpt_base + CR(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;
+
+ clockevent_set_clock(&clkevt, tick_rate);
+
+ 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)
+{
+ struct clk *pll3_clk;
+
+ 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;
+ }
+
+ pll3_clk = clk_get(NULL, "pll3_48m_clk");
+ if (!pll3_clk) {
+ pr_err("%s:couldn't get PLL3 as parent for gpt\n", __func__);
+ goto err_iomap;
+ }
+
+ clk_set_parent(gpt_clk, pll3_clk);
+
+ spear_clockevent_init();
+ spear_clocksource_init();
+
+ return;
+
+err_iomap:
+ iounmap(gpt_base);
+
+err_mem:
+ release_mem_region(SPEAR_GPT0_BASE, SZ_1K);
+}
+
+struct sys_timer spear_sys_timer = {
+ .init = spear_setup_timer,
+};
projects / platform / kernel / linux-3.10.git / commitdiff