ARM: S5PV310: Add Timer support

This patch adds timer support for S5PV310.  Until now, all S5P SoCs
use CONFIG_ARCH_USES_GETTIMEOFFSET macro as a default configuration.
Instead,S5PV310 implements clocksource and clock_event_device to
support the high resolution timer and tickless system.

Signed-off-by: Changhwan Youn <chaos.youn@samsung.com>
Signed-off-by: Hyuk Lee <hyuk1.lee@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

1 files changed, 287 insertions, 0 deletions

diff --git a/arch/arm/mach-s5pv310/time.c b/arch/arm/mach-s5pv310/time.c
new file mode 100644
index 000000000000..01b012ad1bfd
--- /dev/null
+++ b/arch/arm/mach-s5pv310/time.c
@@ -0,0 +1,287 @@
+/* linux/arch/arm/mach-s5pv310/time.c
+ *
+ * Copyright (c) 2010 Samsung Electronics Co., Ltd.
+ *              http://www.samsung.com
+ *
+ * S5PV310 (and compatible) HRT support
+ * PWM 2/4 is used for this feature
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/platform_device.h>
+
+#include <asm/smp_twd.h>
+
+#include <mach/map.h>
+#include <plat/regs-timer.h>
+#include <asm/mach/time.h>
+
+static unsigned long clock_count_per_tick;
+
+static struct clk *tin2;
+static struct clk *tin4;
+static struct clk *tdiv2;
+static struct clk *tdiv4;
+static struct clk *timerclk;
+
+static void s5pv310_pwm_stop(unsigned int pwm_id)
+{
+        unsigned long tcon;
+
+        tcon = __raw_readl(S3C2410_TCON);
+
+        switch (pwm_id) {
+        case 2:
+                tcon &= ~S3C2410_TCON_T2START;
+                break;
+        case 4:
+                tcon &= ~S3C2410_TCON_T4START;
+                break;
+        default:
+                break;
+        }
+        __raw_writel(tcon, S3C2410_TCON);
+}
+
+static void s5pv310_pwm_init(unsigned int pwm_id, unsigned long tcnt)
+{
+        unsigned long tcon;
+
+        tcon = __raw_readl(S3C2410_TCON);
+
+        /* timers reload after counting zero, so reduce the count by 1 */
+        tcnt--;
+
+        /* ensure timer is stopped... */
+        switch (pwm_id) {
+        case 2:
+                tcon &= ~(0xf<<12);
+                tcon |= S3C2410_TCON_T2MANUALUPD;
+
+                __raw_writel(tcnt, S3C2410_TCNTB(2));
+                __raw_writel(tcnt, S3C2410_TCMPB(2));
+                __raw_writel(tcon, S3C2410_TCON);
+
+                break;
+        case 4:
+                tcon &= ~(7<<20);
+                tcon |= S3C2410_TCON_T4MANUALUPD;
+
+                __raw_writel(tcnt, S3C2410_TCNTB(4));
+                __raw_writel(tcnt, S3C2410_TCMPB(4));
+                __raw_writel(tcon, S3C2410_TCON);
+
+                break;
+        default:
+                break;
+        }
+}
+
+static inline void s5pv310_pwm_start(unsigned int pwm_id, bool periodic)
+{
+        unsigned long tcon;
+
+        tcon  = __raw_readl(S3C2410_TCON);
+
+        switch (pwm_id) {
+        case 2:
+                tcon |= S3C2410_TCON_T2START;
+                tcon &= ~S3C2410_TCON_T2MANUALUPD;
+
+                if (periodic)
+                        tcon |= S3C2410_TCON_T2RELOAD;
+                else
+                        tcon &= ~S3C2410_TCON_T2RELOAD;
+                break;
+        case 4:
+                tcon |= S3C2410_TCON_T4START;
+                tcon &= ~S3C2410_TCON_T4MANUALUPD;
+
+                if (periodic)
+                        tcon |= S3C2410_TCON_T4RELOAD;
+                else
+                        tcon &= ~S3C2410_TCON_T4RELOAD;
+                break;
+        default:
+                break;
+        }
+        __raw_writel(tcon, S3C2410_TCON);
+}
+
+static int s5pv310_pwm_set_next_event(unsigned long cycles,
+                                        struct clock_event_device *evt)
+{
+        s5pv310_pwm_init(2, cycles);
+        s5pv310_pwm_start(2, 0);
+        return 0;
+}
+
+static void s5pv310_pwm_set_mode(enum clock_event_mode mode,
+                                struct clock_event_device *evt)
+{
+        s5pv310_pwm_stop(2);
+
+        switch (mode) {
+        case CLOCK_EVT_MODE_PERIODIC:
+                s5pv310_pwm_init(2, clock_count_per_tick);
+                s5pv310_pwm_start(2, 1);
+                break;
+        case CLOCK_EVT_MODE_ONESHOT:
+                break;
+        case CLOCK_EVT_MODE_UNUSED:
+        case CLOCK_EVT_MODE_SHUTDOWN:
+        case CLOCK_EVT_MODE_RESUME:
+                break;
+        }
+}
+
+static struct clock_event_device pwm_event_device = {
+        .name           = "pwm_timer2",
+        .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+        .rating         = 200,
+        .shift          = 32,
+        .set_next_event = s5pv310_pwm_set_next_event,
+        .set_mode       = s5pv310_pwm_set_mode,
+};
+
+irqreturn_t s5pv310_clock_event_isr(int irq, void *dev_id)
+{
+        struct clock_event_device *evt = &pwm_event_device;
+
+        evt->event_handler(evt);
+
+        return IRQ_HANDLED;
+}
+
+static struct irqaction s5pv310_clock_event_irq = {
+        .name           = "pwm_timer2_irq",
+        .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
+        .handler        = s5pv310_clock_event_isr,
+};
+
+static void __init s5pv310_clockevent_init(void)
+{
+        unsigned long pclk;
+        unsigned long clock_rate;
+        struct clk *tscaler;
+
+        pclk = clk_get_rate(timerclk);
+
+        /* configure clock tick */
+
+        tscaler = clk_get_parent(tdiv2);
+
+        clk_set_rate(tscaler, pclk / 2);
+        clk_set_rate(tdiv2, pclk / 2);
+        clk_set_parent(tin2, tdiv2);
+
+        clock_rate = clk_get_rate(tin2);
+
+        clock_count_per_tick = clock_rate / HZ;
+
+        pwm_event_device.mult =
+                div_sc(clock_rate, NSEC_PER_SEC, pwm_event_device.shift);
+        pwm_event_device.max_delta_ns =
+                clockevent_delta2ns(-1, &pwm_event_device);
+        pwm_event_device.min_delta_ns =
+                clockevent_delta2ns(1, &pwm_event_device);
+
+        pwm_event_device.cpumask = cpumask_of(0);
+        clockevents_register_device(&pwm_event_device);
+
+        setup_irq(IRQ_TIMER2, &s5pv310_clock_event_irq);
+}
+
+static cycle_t s5pv310_pwm4_read(struct clocksource *cs)
+{
+        return (cycle_t) ~__raw_readl(S3C_TIMERREG(0x40));
+}
+
+struct clocksource pwm_clocksource = {
+        .name           = "pwm_timer4",
+        .rating         = 250,
+        .read           = s5pv310_pwm4_read,
+        .mask           = CLOCKSOURCE_MASK(32),
+        .shift          = 20,
+        .flags          = CLOCK_SOURCE_IS_CONTINUOUS ,
+};
+
+static void __init s5pv310_clocksource_init(void)
+{
+        unsigned long pclk;
+        unsigned long clock_rate;
+
+        pclk = clk_get_rate(timerclk);
+
+        clk_set_rate(tdiv4, pclk / 2);
+        clk_set_parent(tin4, tdiv4);
+
+        clock_rate = clk_get_rate(tin4);
+
+        s5pv310_pwm_init(4, ~0);
+        s5pv310_pwm_start(4, 1);
+
+        pwm_clocksource.mult =
+                clocksource_khz2mult(clock_rate/1000, pwm_clocksource.shift);
+
+        if (clocksource_register(&pwm_clocksource))
+                panic("%s: can't register clocksource\n", pwm_clocksource.name);
+}
+
+static void __init s5pv310_timer_resources(void)
+{
+        struct platform_device tmpdev;
+
+        tmpdev.dev.bus = &platform_bus_type;
+
+        timerclk = clk_get(NULL, "timers");
+        if (IS_ERR(timerclk))
+                panic("failed to get timers clock for system timer");
+
+        clk_enable(timerclk);
+
+        tmpdev.id = 2;
+        tin2 = clk_get(&tmpdev.dev, "pwm-tin");
+        if (IS_ERR(tin2))
+                panic("failed to get pwm-tin2 clock for system timer");
+
+        tdiv2 = clk_get(&tmpdev.dev, "pwm-tdiv");
+        if (IS_ERR(tdiv2))
+                panic("failed to get pwm-tdiv2 clock for system timer");
+        clk_enable(tin2);
+
+        tmpdev.id = 4;
+        tin4 = clk_get(&tmpdev.dev, "pwm-tin");
+        if (IS_ERR(tin4))
+                panic("failed to get pwm-tin4 clock for system timer");
+
+        tdiv4 = clk_get(&tmpdev.dev, "pwm-tdiv");
+        if (IS_ERR(tdiv4))
+                panic("failed to get pwm-tdiv4 clock for system timer");
+
+        clk_enable(tin4);
+}
+
+static void __init s5pv310_timer_init(void)
+{
+#ifdef CONFIG_LOCAL_TIMERS
+        twd_base = S5P_VA_TWD;
+#endif
+
+        s5pv310_timer_resources();
+        s5pv310_clockevent_init();
+        s5pv310_clocksource_init();
+}
+
+struct sys_timer s5pv310_timer = {
+        .init           = s5pv310_timer_init,
+};