[PATCH v2] ARM: clocksource: add support for MOXA ART SoCs

[Jonas Jensen <jonas.jensen@gmail.com>]

This patch adds an clocksource driver for the main timer(s)
found on MOXA ART SoCs.

Changes since v2:

1. use clocksource/clockevents infrastructures
2. clock frequency read from system clock

Applies to next-20130619

Signed-off-by: Jonas Jensen <jonas.jensen@gmail.com>
---
 drivers/clocksource/Makefile       |    1 +
 drivers/clocksource/moxart_timer.c |  184 ++++++++++++++++++++++++++++++++++++
 2 files changed, 185 insertions(+), 0 deletions(-)
 create mode 100644 drivers/clocksource/moxart_timer.c

diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 8d979c7..c93e1a8 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -29,3 +29,4 @@ obj-$(CONFIG_CLKSRC_SAMSUNG_PWM)	+= samsung_pwm_timer.o
 
 obj-$(CONFIG_ARM_ARCH_TIMER)		+= arm_arch_timer.o
 obj-$(CONFIG_CLKSRC_METAG_GENERIC)	+= metag_generic.o
+obj-$(CONFIG_ARCH_MOXART)	+= moxart_timer.o
diff --git a/drivers/clocksource/moxart_timer.c b/drivers/clocksource/moxart_timer.c
new file mode 100644
index 0000000..376df31
--- /dev/null
+++ b/drivers/clocksource/moxart_timer.c
@@ -0,0 +1,184 @@
+/*
+ * MOXA ART SoCs timer handling.
+ *
+ * Copyright (C) 2013 Jonas Jensen
+ *
+ * Jonas Jensen <jonas.jensen@gmail.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/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqreturn.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/io.h>
+#include <linux/clocksource.h>
+
+#define MAX_TIMER			2
+#define USED_TIMER			1
+#define APB_CLK				48000000
+
+/* note: timer count is writable */
+
+#define TIMER1_COUNT        0x0
+#define TIMER1_LOAD         0x4
+#define TIMER1_MATCH1       0x8
+#define TIMER1_MATCH2       0xC
+
+#define TIMER2_COUNT        0x10
+#define TIMER2_LOAD         0x14
+#define TIMER2_MATCH1       0x18
+#define TIMER2_MATCH2       0x1C
+
+#define TIMER3_COUNT        0x20
+#define TIMER3_LOAD         0x24
+#define TIMER3_MATCH1       0x28
+#define TIMER3_MATCH2       0x2C
+
+#define TIMER_CR			0x30
+#define TIMER_INTR_STATE    0x34
+#define TIMER_INTR_MASK     0x38
+
+/* TIMER_CR flags:
+   TIMEREG_CR_1_CLOCK  0: PCLK, 1: EXT1CLK
+   TIMEREG_CR_1_INT    over flow interrupt enable bit */
+
+#define TIMEREG_CR_1_ENABLE         (1 << 0)
+#define TIMEREG_CR_1_CLOCK          (1 << 1)
+#define TIMEREG_CR_1_INT            (1 << 2)
+#define TIMEREG_CR_2_ENABLE         (1 << 3)
+#define TIMEREG_CR_2_CLOCK          (1 << 4)
+#define TIMEREG_CR_2_INT            (1 << 5)
+#define TIMEREG_CR_3_ENABLE         (1 << 6)
+#define TIMEREG_CR_3_CLOCK			(1 << 7)
+#define TIMEREG_CR_3_INT			(1 << 8)
+#define TIMEREG_CR_COUNT_UP			(1 << 9)
+#define TIMEREG_CR_COUNT_DOWN		(0 << 9)
+
+static void __iomem *timer_base;
+static unsigned int clock_frequency;
+
+static void moxart_clkevt_mode(enum clock_event_mode mode,
+	struct clock_event_device *clk)
+{
+	u32 u = readl(timer_base + TIMER_CR);
+
+	switch (mode) {
+	case CLOCK_EVT_MODE_RESUME:
+	case CLOCK_EVT_MODE_ONESHOT:
+		u |= TIMEREG_CR_1_ENABLE;
+		writel(u, timer_base + TIMER_CR);
+		writel(~0, timer_base + TIMER1_LOAD);
+		pr_debug("%s: CLOCK_EVT_MODE_ONESHOT\n", __func__);
+		break;
+	case CLOCK_EVT_MODE_PERIODIC:
+		u |= TIMEREG_CR_1_ENABLE;
+		writel(u, timer_base + TIMER_CR);
+		writel(clock_frequency / HZ, timer_base + TIMER1_LOAD);
+		pr_debug("%s: CLOCK_EVT_MODE_PERIODIC\n", __func__);
+		break;
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+	default:
+		u &= ~TIMEREG_CR_1_ENABLE;
+		writel(u, timer_base + TIMER_CR);
+		break;
+	}
+}
+
+static int moxart_clkevt_next_event(unsigned long cycles,
+	struct clock_event_device *unused)
+{
+	u32 alarm = readl(timer_base + TIMER1_COUNT) - cycles;
+	writel(alarm, timer_base + TIMER1_MATCH1);
+	return 0;
+}
+
+static struct clock_event_device moxart_clockevent = {
+	.name = "moxart_timer",
+	.rating = 300,
+	.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+	.set_mode = moxart_clkevt_mode,
+	.set_next_event = moxart_clkevt_next_event,
+};
+
+static irqreturn_t moxart_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = (struct clock_event_device *)dev_id;
+	evt->event_handler(evt);
+	return IRQ_HANDLED;
+}
+
+static struct irqaction moxart_timer_irq = {
+	.name = "moxart-timer",
+	.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
+	.handler = moxart_timer_interrupt,
+	.dev_id = &moxart_clockevent,
+};
+
+static void __init moxart_timer_init(struct device_node *node)
+{
+	int ret, irq;
+	struct clk *clk;
+
+	timer_base = of_iomap(node, 0);
+	if (!timer_base)
+		panic("%s: failed to map base\n", node->full_name);
+
+	irq = irq_of_parse_and_map(node, 0);
+	if (irq <= 0)
+		panic("%s: can't parse IRQ\n", node->full_name);
+
+	ret = setup_irq(irq, &moxart_timer_irq);
+	if (ret) {
+		pr_err("%s: failed to setup IRQ %d\n", node->full_name, irq);
+		return;
+	}
+
+	clock_frequency = APB_CLK;
+	/* it might be a good idea to have a default other than 0 for
+	   clock_frequency, should any attempt at getting a valid
+	   frequency fail, not that i see how it could, it probably could..
+	   having it APB_CLK can certainly be wrong on some hardware,
+	   why it is set again with the DT specific property: */
+
+	ret = of_property_read_u32(node, "clock-frequency", &clock_frequency);
+	if (ret)
+		pr_err("%s: can't read clock-frequency DT property\n",
+			node->full_name);
+
+	clk = of_clk_get(node, 0);
+	if (IS_ERR(clk))
+		pr_err("%s: of_clk_get failed\n", __func__);
+	else {
+		clock_frequency = clk_get_rate(clk);
+		pr_debug("%s: clk_get_rate=%u success\n", __func__,
+			clock_frequency);
+	}
+
+	writel(~0, timer_base + TIMER2_LOAD);
+
+	writel(TIMEREG_CR_1_ENABLE | TIMEREG_CR_2_ENABLE |
+		TIMEREG_CR_COUNT_DOWN, timer_base + TIMER_CR);
+
+	if (clocksource_mmio_init(timer_base + TIMER2_COUNT, "moxart_timer",
+		clock_frequency, 200, 32, clocksource_mmio_readl_down))
+		pr_err("%s: clocksource_mmio_init failed\n", __func__);
+
+	moxart_clockevent.cpumask = cpumask_of(0);
+
+	clockevents_config_and_register(&moxart_clockevent, clock_frequency,
+		0x4, 0xf0000000);
+
+	pr_info("%s: %s finished clock_frequency=%d HZ=%d IRQ=%d\n",
+		node->full_name, __func__, clock_frequency, HZ, irq);
+}
+CLOCKSOURCE_OF_DECLARE(moxart, "moxa,moxart-timer", moxart_timer_init);
+
-- 
1.7.2.5