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Message-ID: <1392027058-11680-2-git-send-email-ivan.khoronzhuk@ti.com>
Date: Mon, 10 Feb 2014 12:10:56 +0200
From: Ivan Khoronzhuk <ivan.khoronzhuk@...com>
To: <santosh.shilimkar@...com>, <rob@...dley.net>,
<linux@....linux.org.uk>, <galak@...eaurora.org>
CC: <robh+dt@...nel.org>, <pawel.moll@....com>, <mark.rutland@....com>,
<ijc+devicetree@...lion.org.uk>, <daniel.lezcano@...aro.org>,
<tglx@...utronix.de>, <devicetree@...r.kernel.org>,
<linux-doc@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <grygorii.strashko@...com>,
<joshc@...eaurora.org>, Ivan Khoronzhuk <ivan.khoronzhuk@...com>
Subject: [PATCH v6 1/3] clocksource: timer-keystone: introduce clocksource driver for Keystone
Add broadcast clock-event device for the Keystone arch.
The timer can be configured as a general-purpose 64-bit timer,
dual general-purpose 32-bit timers. When configured as dual 32-bit
timers, each half can operate in conjunction (chain mode) or
independently (unchained mode) of each other.
Reviewed-by: Stephen Boyd <sboyd@...eaurora.org>
Acked-by: Santosh shilimkar <santosh.shilimkar@...com>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@...com>
---
drivers/clocksource/Makefile | 1 +
drivers/clocksource/timer-keystone.c | 244 +++++++++++++++++++++++++++++++++++
2 files changed, 245 insertions(+)
create mode 100644 drivers/clocksource/timer-keystone.c
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index c7ca50a..4abe5aa 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -37,3 +37,4 @@ obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o
obj-$(CONFIG_ARM_GLOBAL_TIMER) += arm_global_timer.o
obj-$(CONFIG_CLKSRC_METAG_GENERIC) += metag_generic.o
obj-$(CONFIG_ARCH_HAS_TICK_BROADCAST) += dummy_timer.o
+obj-$(CONFIG_ARCH_KEYSTONE) += timer-keystone.o
diff --git a/drivers/clocksource/timer-keystone.c b/drivers/clocksource/timer-keystone.c
new file mode 100644
index 0000000..86b08cd
--- /dev/null
+++ b/drivers/clocksource/timer-keystone.c
@@ -0,0 +1,244 @@
+/*
+ * Keystone broadcast clock-event
+ *
+ * Copyright 2013 Texas Instruments, Inc.
+ *
+ * Author: Ivan Khoronzhuk <ivan.khoronzhuk@...com>
+ *
+ * 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/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/interrupt.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+#define TIMER_NAME "timer-keystone"
+
+/* Timer register offsets */
+#define TIM12 0x10
+#define TIM34 0x14
+#define PRD12 0x18
+#define PRD34 0x1c
+#define TCR 0x20
+#define TGCR 0x24
+#define INTCTLSTAT 0x44
+
+/* Timer register bitfields */
+#define TCR_ENAMODE_MASK 0xC0
+#define TCR_ENAMODE_ONESHOT_MASK 0x40
+#define TCR_ENAMODE_PERIODIC_MASK 0x80
+
+#define TGCR_TIM_UNRESET_MASK 0x03
+#define INTCTLSTAT_ENINT_MASK 0x01
+
+/**
+ * struct keystone_timer: holds timer's data
+ * @base: timer memory base address
+ * @hz_period: cycles per HZ period
+ * @event_dev: event device based on timer
+ */
+static struct keystone_timer {
+ void __iomem *base;
+ unsigned long hz_period;
+ struct clock_event_device event_dev;
+} timer;
+
+static inline u32 keystone_timer_readl(unsigned long rg)
+{
+ return readl_relaxed(timer.base + rg);
+}
+
+static inline void keystone_timer_writel(u32 val, unsigned long rg)
+{
+ writel_relaxed(val, timer.base + rg);
+}
+
+/**
+ * keystone_timer_barrier: write memory barrier
+ * use explicit barrier to avoid using readl/writel non relaxed function
+ * variants, because in our case non relaxed variants hide the true places
+ * where barrier is needed.
+ */
+static inline void keystone_timer_barrier(void)
+{
+ __iowmb();
+}
+
+/**
+ * keystone_timer_config: configures timer to work in oneshot/periodic modes.
+ * @ mode: mode to configure
+ * @ period: cycles number to configure for
+ */
+static int keystone_timer_config(u64 period, enum clock_event_mode mode)
+{
+ u32 tcr;
+ u32 off;
+
+ tcr = keystone_timer_readl(TCR);
+ off = tcr & ~(TCR_ENAMODE_MASK);
+
+ /* set enable mode */
+ switch (mode) {
+ case CLOCK_EVT_MODE_ONESHOT:
+ tcr |= TCR_ENAMODE_ONESHOT_MASK;
+ break;
+ case CLOCK_EVT_MODE_PERIODIC:
+ tcr |= TCR_ENAMODE_PERIODIC_MASK;
+ break;
+ default:
+ return -1;
+ }
+
+ /* disable timer */
+ keystone_timer_writel(off, TCR);
+ /* here we have to be sure the timer has been disabled */
+ keystone_timer_barrier();
+
+ /* reset counter to zero, set new period */
+ keystone_timer_writel(0, TIM12);
+ keystone_timer_writel(0, TIM34);
+ keystone_timer_writel(period & 0xffffffff, PRD12);
+ keystone_timer_writel(period >> 32, PRD34);
+
+ /*
+ * enable timer
+ * here we have to be sure that CNTLO, CNTHI, PRDLO, PRDHI registers
+ * have been written.
+ */
+ keystone_timer_barrier();
+ keystone_timer_writel(tcr, TCR);
+ return 0;
+}
+
+static void keystone_timer_disable(void)
+{
+ u32 tcr;
+
+ tcr = keystone_timer_readl(TCR);
+
+ /* disable timer */
+ tcr &= ~(TCR_ENAMODE_MASK);
+ keystone_timer_writel(tcr, TCR);
+}
+
+static irqreturn_t keystone_timer_interrupt(int irq, void *dev_id)
+{
+ struct clock_event_device *evt = dev_id;
+
+ evt->event_handler(evt);
+ return IRQ_HANDLED;
+}
+
+static int keystone_set_next_event(unsigned long cycles,
+ struct clock_event_device *evt)
+{
+ return keystone_timer_config(cycles, evt->mode);
+}
+
+static void keystone_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ keystone_timer_config(timer.hz_period, CLOCK_EVT_MODE_PERIODIC);
+ break;
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ case CLOCK_EVT_MODE_ONESHOT:
+ keystone_timer_disable();
+ break;
+ default:
+ break;
+ }
+}
+
+static void __init keystone_timer_init(struct device_node *np)
+{
+ struct clock_event_device *event_dev = &timer.event_dev;
+ unsigned long rate;
+ struct clk *clk;
+ int irq, error;
+ u32 tgcr;
+
+ irq = irq_of_parse_and_map(np, 0);
+ if (irq == NO_IRQ) {
+ pr_err("%s: failed to map interrupts\n", __func__);
+ return;
+ }
+
+ timer.base = of_iomap(np, 0);
+ if (!timer.base) {
+ pr_err("%s: failed to map registers\n", __func__);
+ return;
+ }
+
+ clk = of_clk_get(np, 0);
+ if (IS_ERR(clk)) {
+ pr_err("%s: failed to get clock\n", __func__);
+ iounmap(timer.base);
+ return;
+ }
+
+ error = clk_prepare_enable(clk);
+ if (error) {
+ pr_err("%s: failed to enable clock\n", __func__);
+ goto err;
+ }
+
+ rate = clk_get_rate(clk);
+
+ /* disable, use internal clock source */
+ keystone_timer_writel(0, TCR);
+ /* here we have to be sure the timer has been disabled */
+ keystone_timer_barrier();
+
+ /* reset timer as 64-bit, no pre-scaler, plus features are disabled */
+ tgcr = 0;
+ keystone_timer_writel(0, TGCR);
+
+ /* unreset timer */
+ tgcr |= TGCR_TIM_UNRESET_MASK;
+ keystone_timer_writel(tgcr, TGCR);
+
+ /* init counter to zero */
+ keystone_timer_writel(0, TIM12);
+ keystone_timer_writel(0, TIM34);
+
+ timer.hz_period = DIV_ROUND_UP(rate, HZ);
+
+ /* enable timer interrupts */
+ keystone_timer_writel(INTCTLSTAT_ENINT_MASK, INTCTLSTAT);
+
+ error = request_irq(irq, keystone_timer_interrupt, IRQF_TIMER,
+ TIMER_NAME, event_dev);
+ if (error) {
+ pr_err("%s: failed to setup irq\n", __func__);
+ goto err;
+ }
+
+ /* setup clockevent */
+ event_dev->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+ event_dev->set_next_event = keystone_set_next_event;
+ event_dev->set_mode = keystone_set_mode;
+ event_dev->cpumask = cpu_all_mask;
+ event_dev->owner = THIS_MODULE;
+ event_dev->name = TIMER_NAME;
+ event_dev->irq = irq;
+
+ clockevents_config_and_register(event_dev, rate, 1, ULONG_MAX);
+
+ pr_info("keystone timer clock @%lu Hz\n", rate);
+ return;
+err:
+ clk_put(clk);
+ iounmap(timer.base);
+}
+
+CLOCKSOURCE_OF_DECLARE(keystone_timer, "ti,keystone-timer",
+ keystone_timer_init);
--
1.8.3.2
--
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