[RFC PATCHv3 4/6] clocksource: Add TI-Nspire timer drivers

[dt.tangr@gmail.com (Daniel Tang)]

Signed-off-by: Daniel Tang <dt.tangr@gmail.com>
---
 drivers/clocksource/Makefile               |   1 +
 drivers/clocksource/nspire-classic-timer.c | 199 +++++++++++++++++++++++++++++
 2 files changed, 200 insertions(+)
 create mode 100644 drivers/clocksource/nspire-classic-timer.c

diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 8d979c7..b9b56cb 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_ARCH_PRIMA2)	+= timer-prima2.o
 obj-$(CONFIG_SUN4I_TIMER)	+= sun4i_timer.o
 obj-$(CONFIG_ARCH_TEGRA)	+= tegra20_timer.o
 obj-$(CONFIG_VT8500_TIMER)	+= vt8500_timer.o
+obj-$(CONFIG_ARCH_NSPIRE)	+= nspire-classic-timer.o
 obj-$(CONFIG_ARCH_BCM)		+= bcm_kona_timer.o
 obj-$(CONFIG_CADENCE_TTC_TIMER)	+= cadence_ttc_timer.o
 obj-$(CONFIG_CLKSRC_EXYNOS_MCT)	+= exynos_mct.o
diff --git a/drivers/clocksource/nspire-classic-timer.c b/drivers/clocksource/nspire-classic-timer.c
new file mode 100644
index 0000000..4b92b61
--- /dev/null
+++ b/drivers/clocksource/nspire-classic-timer.c
@@ -0,0 +1,199 @@
+/*
+ *  linux/drivers/clocksource/nspire-classic-timer.c
+ *
+ *  Copyright (C) 2013 Daniel Tang <tangrs@tangrs.id.au>
+ *
+ * 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/io.h>
+#include <linux/irq.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/cpumask.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+
+#define DT_COMPAT	"nspire-classic-timer"
+
+#define IO_CURRENT_VAL	0x00
+#define IO_DIVIDER	0x04
+#define IO_CONTROL	0x08
+
+#define IO_TIMER1	0x00
+#define IO_TIMER2	0x0C
+
+#define IO_MATCH1	0x18
+#define IO_MATCH2	0x1C
+#define IO_MATCH3	0x20
+#define IO_MATCH4	0x24
+#define IO_MATCH5	0x28
+#define IO_MATCH6	0x2C
+
+#define IO_INTR_STS	0x00
+#define IO_INTR_ACK	0x00
+#define IO_INTR_MSK	0x04
+
+#define CNTL_STOP_TIMER	(1<<4)
+#define CNTL_RUN_TIMER	(0<<4)
+
+#define CNTL_INC	(1<<3)
+#define CNTL_DEC	(0<<3)
+
+#define CNTL_TOZERO	0
+#define CNTL_MATCH1	1
+#define CNTL_MATCH2	2
+#define CNTL_MATCH3	3
+#define CNTL_MATCH4	4
+#define CNTL_MATCH5	5
+#define CNTL_MATCH6	6
+#define CNTL_FOREVER	7
+
+struct nspire_timer {
+	void __iomem *base;
+	void __iomem *timer1, *timer2;
+	void __iomem *interrupt_regs;
+
+	int irqnr;
+
+	struct clk *clk;
+	struct clock_event_device clkevt;
+	struct irqaction clkevt_irq;
+
+	char clocksource_name[64];
+	char clockevent_name[64];
+};
+
+static int nspire_timer_set_event(unsigned long delta,
+		struct clock_event_device *dev)
+{
+	unsigned long flags;
+	struct nspire_timer *timer = container_of(dev,
+			struct nspire_timer,
+			clkevt);
+
+	local_irq_save(flags);
+
+	writel(delta, timer->timer1 + IO_CURRENT_VAL);
+	writel(CNTL_RUN_TIMER | CNTL_DEC | CNTL_MATCH1,
+			timer->timer1 + IO_CONTROL);
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+static void nspire_timer_set_mode(enum clock_event_mode mode,
+		struct clock_event_device *evt)
+{
+	evt->mode = mode;
+}
+
+static irqreturn_t nspire_timer_interrupt(int irq, void *dev_id)
+{
+	struct nspire_timer *timer = dev_id;
+
+	writel((1<<0), timer->interrupt_regs + IO_INTR_ACK);
+	writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
+
+	if (timer->clkevt.event_handler)
+		timer->clkevt.event_handler(&timer->clkevt);
+
+	return IRQ_HANDLED;
+}
+
+static int __init nspire_timer_add(struct device_node *node)
+{
+	struct nspire_timer *timer;
+	struct resource res;
+	int ret;
+
+	timer = kzalloc(sizeof(*timer), GFP_ATOMIC);
+	if (!timer)
+		return -ENOMEM;
+
+	timer->base = of_iomap(node, 0);
+	if (!timer->base) {
+		ret = -EINVAL;
+		goto error_free;
+	}
+	timer->timer1 = timer->base + IO_TIMER1;
+	timer->timer2 = timer->base + IO_TIMER2;
+
+	timer->clk = of_clk_get(node, 0);
+	if (IS_ERR(timer->clk)) {
+		ret = PTR_ERR(timer->clk);
+		pr_err("Timer clock not found! (error %d)\n", ret);
+		goto error_unmap;
+	}
+
+	timer->interrupt_regs = of_iomap(node, 1);
+	timer->irqnr = irq_of_parse_and_map(node, 0);
+
+	of_address_to_resource(node, 0, &res);
+	scnprintf(timer->clocksource_name, sizeof(timer->clocksource_name),
+			"%llx.%s_clocksource",
+			(unsigned long long)res.start, node->name);
+
+	scnprintf(timer->clockevent_name, sizeof(timer->clockevent_name),
+			"%llx.%s_clockevent",
+			(unsigned long long)res.start, node->name);
+
+	if (timer->interrupt_regs && timer->irqnr) {
+		timer->clkevt.name	= timer->clockevent_name;
+		timer->clkevt.set_next_event = nspire_timer_set_event;
+		timer->clkevt.set_mode	= nspire_timer_set_mode;
+		timer->clkevt.rating	= 200;
+		timer->clkevt.shift	= 32;
+		timer->clkevt.cpumask	= cpu_all_mask;
+		timer->clkevt.features	=
+			CLOCK_EVT_FEAT_ONESHOT;
+
+		writel(CNTL_STOP_TIMER, timer->timer1 + IO_CONTROL);
+		writel(0, timer->timer1 + IO_DIVIDER);
+
+		/* Mask out interrupts except the one we're using */
+		writel((1<<0), timer->interrupt_regs + IO_INTR_MSK);
+		writel(0x3F, timer->interrupt_regs + IO_INTR_ACK);
+
+		/* Interrupt to occur when timer value matches 0 */
+		writel(0, timer->base + IO_MATCH1);
+
+		timer->clkevt_irq.name	= timer->clockevent_name;
+		timer->clkevt_irq.handler = nspire_timer_interrupt;
+		timer->clkevt_irq.dev_id = timer;
+		timer->clkevt_irq.flags	=
+			IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL;
+
+		setup_irq(timer->irqnr, &timer->clkevt_irq);
+
+		clockevents_config_and_register(&timer->clkevt,
+				clk_get_rate(timer->clk), 0x0001, 0xfffe);
+		pr_info("Added %s as clockevent\n", timer->clockevent_name);
+	}
+
+	writel(CNTL_RUN_TIMER | CNTL_FOREVER | CNTL_INC,
+			timer->timer2 + IO_CONTROL);
+
+	clocksource_mmio_init(timer->timer2 + IO_CURRENT_VAL,
+			timer->clocksource_name,
+			clk_get_rate(timer->clk),
+			200, 16,
+			clocksource_mmio_readw_up);
+
+	pr_info("Added %s as clocksource\n", timer->clocksource_name);
+
+	return 0;
+error_unmap:
+	iounmap(timer->base);
+error_free:
+	kfree(timer);
+	return ret;
+}
+
+CLOCKSOURCE_OF_DECLARE(nspire_classic_timer, DT_COMPAT, nspire_timer_add);
-- 
1.8.1.3