Initial import

1 files changed, 1110 insertions, 0 deletions

diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c
new file mode 100644
index 000000000..b8ff3c64c
--- /dev/null
+++ b/drivers/clocksource/sh_cmt.c
@@ -0,0 +1,1110 @@
+/*
+ * SuperH Timer Support - CMT
+ *
+ *  Copyright (C) 2008 Magnus Damm
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
+#include <linux/sh_timer.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+struct sh_cmt_device;
+
+/*
+ * The CMT comes in 5 different identified flavours, depending not only on the
+ * SoC but also on the particular instance. The following table lists the main
+ * characteristics of those flavours.
+ *
+ *			16B	32B	32B-F	48B	48B-2
+ * -----------------------------------------------------------------------------
+ * Channels		2	1/4	1	6	2/8
+ * Control Width	16	16	16	16	32
+ * Counter Width	16	32	32	32/48	32/48
+ * Shared Start/Stop	Y	Y	Y	Y	N
+ *
+ * The 48-bit gen2 version has a per-channel start/stop register located in the
+ * channel registers block. All other versions have a shared start/stop register
+ * located in the global space.
+ *
+ * Channels are indexed from 0 to N-1 in the documentation. The channel index
+ * infers the start/stop bit position in the control register and the channel
+ * registers block address. Some CMT instances have a subset of channels
+ * available, in which case the index in the documentation doesn't match the
+ * "real" index as implemented in hardware. This is for instance the case with
+ * CMT0 on r8a7740, which is a 32-bit variant with a single channel numbered 0
+ * in the documentation but using start/stop bit 5 and having its registers
+ * block at 0x60.
+ *
+ * Similarly CMT0 on r8a73a4, r8a7790 and r8a7791, while implementing 32-bit
+ * channels only, is a 48-bit gen2 CMT with the 48-bit channels unavailable.
+ */
+
+enum sh_cmt_model {
+	SH_CMT_16BIT,
+	SH_CMT_32BIT,
+	SH_CMT_32BIT_FAST,
+	SH_CMT_48BIT,
+	SH_CMT_48BIT_GEN2,
+};
+
+struct sh_cmt_info {
+	enum sh_cmt_model model;
+
+	unsigned long width; /* 16 or 32 bit version of hardware block */
+	unsigned long overflow_bit;
+	unsigned long clear_bits;
+
+	/* callbacks for CMSTR and CMCSR access */
+	unsigned long (*read_control)(void __iomem *base, unsigned long offs);
+	void (*write_control)(void __iomem *base, unsigned long offs,
+			      unsigned long value);
+
+	/* callbacks for CMCNT and CMCOR access */
+	unsigned long (*read_count)(void __iomem *base, unsigned long offs);
+	void (*write_count)(void __iomem *base, unsigned long offs,
+			    unsigned long value);
+};
+
+struct sh_cmt_channel {
+	struct sh_cmt_device *cmt;
+
+	unsigned int index;	/* Index in the documentation */
+	unsigned int hwidx;	/* Real hardware index */
+
+	void __iomem *iostart;
+	void __iomem *ioctrl;
+
+	unsigned int timer_bit;
+	unsigned long flags;
+	unsigned long match_value;
+	unsigned long next_match_value;
+	unsigned long max_match_value;
+	unsigned long rate;
+	raw_spinlock_t lock;
+	struct clock_event_device ced;
+	struct clocksource cs;
+	unsigned long total_cycles;
+	bool cs_enabled;
+};
+
+struct sh_cmt_device {
+	struct platform_device *pdev;
+
+	const struct sh_cmt_info *info;
+
+	void __iomem *mapbase;
+	struct clk *clk;
+
+	raw_spinlock_t lock; /* Protect the shared start/stop register */
+
+	struct sh_cmt_channel *channels;
+	unsigned int num_channels;
+	unsigned int hw_channels;
+
+	bool has_clockevent;
+	bool has_clocksource;
+};
+
+#define SH_CMT16_CMCSR_CMF		(1 << 7)
+#define SH_CMT16_CMCSR_CMIE		(1 << 6)
+#define SH_CMT16_CMCSR_CKS8		(0 << 0)
+#define SH_CMT16_CMCSR_CKS32		(1 << 0)
+#define SH_CMT16_CMCSR_CKS128		(2 << 0)
+#define SH_CMT16_CMCSR_CKS512		(3 << 0)
+#define SH_CMT16_CMCSR_CKS_MASK		(3 << 0)
+
+#define SH_CMT32_CMCSR_CMF		(1 << 15)
+#define SH_CMT32_CMCSR_OVF		(1 << 14)
+#define SH_CMT32_CMCSR_WRFLG		(1 << 13)
+#define SH_CMT32_CMCSR_STTF		(1 << 12)
+#define SH_CMT32_CMCSR_STPF		(1 << 11)
+#define SH_CMT32_CMCSR_SSIE		(1 << 10)
+#define SH_CMT32_CMCSR_CMS		(1 << 9)
+#define SH_CMT32_CMCSR_CMM		(1 << 8)
+#define SH_CMT32_CMCSR_CMTOUT_IE	(1 << 7)
+#define SH_CMT32_CMCSR_CMR_NONE		(0 << 4)
+#define SH_CMT32_CMCSR_CMR_DMA		(1 << 4)
+#define SH_CMT32_CMCSR_CMR_IRQ		(2 << 4)
+#define SH_CMT32_CMCSR_CMR_MASK		(3 << 4)
+#define SH_CMT32_CMCSR_DBGIVD		(1 << 3)
+#define SH_CMT32_CMCSR_CKS_RCLK8	(4 << 0)
+#define SH_CMT32_CMCSR_CKS_RCLK32	(5 << 0)
+#define SH_CMT32_CMCSR_CKS_RCLK128	(6 << 0)
+#define SH_CMT32_CMCSR_CKS_RCLK1	(7 << 0)
+#define SH_CMT32_CMCSR_CKS_MASK		(7 << 0)
+
+static unsigned long sh_cmt_read16(void __iomem *base, unsigned long offs)
+{
+	return ioread16(base + (offs << 1));
+}
+
+static unsigned long sh_cmt_read32(void __iomem *base, unsigned long offs)
+{
+	return ioread32(base + (offs << 2));
+}
+
+static void sh_cmt_write16(void __iomem *base, unsigned long offs,
+			   unsigned long value)
+{
+	iowrite16(value, base + (offs << 1));
+}
+
+static void sh_cmt_write32(void __iomem *base, unsigned long offs,
+			   unsigned long value)
+{
+	iowrite32(value, base + (offs << 2));
+}
+
+static const struct sh_cmt_info sh_cmt_info[] = {
+	[SH_CMT_16BIT] = {
+		.model = SH_CMT_16BIT,
+		.width = 16,
+		.overflow_bit = SH_CMT16_CMCSR_CMF,
+		.clear_bits = ~SH_CMT16_CMCSR_CMF,
+		.read_control = sh_cmt_read16,
+		.write_control = sh_cmt_write16,
+		.read_count = sh_cmt_read16,
+		.write_count = sh_cmt_write16,
+	},
+	[SH_CMT_32BIT] = {
+		.model = SH_CMT_32BIT,
+		.width = 32,
+		.overflow_bit = SH_CMT32_CMCSR_CMF,
+		.clear_bits = ~(SH_CMT32_CMCSR_CMF | SH_CMT32_CMCSR_OVF),
+		.read_control = sh_cmt_read16,
+		.write_control = sh_cmt_write16,
+		.read_count = sh_cmt_read32,
+		.write_count = sh_cmt_write32,
+	},
+	[SH_CMT_32BIT_FAST] = {
+		.model = SH_CMT_32BIT_FAST,
+		.width = 32,
+		.overflow_bit = SH_CMT32_CMCSR_CMF,
+		.clear_bits = ~(SH_CMT32_CMCSR_CMF | SH_CMT32_CMCSR_OVF),
+		.read_control = sh_cmt_read16,
+		.write_control = sh_cmt_write16,
+		.read_count = sh_cmt_read32,
+		.write_count = sh_cmt_write32,
+	},
+	[SH_CMT_48BIT] = {
+		.model = SH_CMT_48BIT,
+		.width = 32,
+		.overflow_bit = SH_CMT32_CMCSR_CMF,
+		.clear_bits = ~(SH_CMT32_CMCSR_CMF | SH_CMT32_CMCSR_OVF),
+		.read_control = sh_cmt_read32,
+		.write_control = sh_cmt_write32,
+		.read_count = sh_cmt_read32,
+		.write_count = sh_cmt_write32,
+	},
+	[SH_CMT_48BIT_GEN2] = {
+		.model = SH_CMT_48BIT_GEN2,
+		.width = 32,
+		.overflow_bit = SH_CMT32_CMCSR_CMF,
+		.clear_bits = ~(SH_CMT32_CMCSR_CMF | SH_CMT32_CMCSR_OVF),
+		.read_control = sh_cmt_read32,
+		.write_control = sh_cmt_write32,
+		.read_count = sh_cmt_read32,
+		.write_count = sh_cmt_write32,
+	},
+};
+
+#define CMCSR 0 /* channel register */
+#define CMCNT 1 /* channel register */
+#define CMCOR 2 /* channel register */
+
+static inline unsigned long sh_cmt_read_cmstr(struct sh_cmt_channel *ch)
+{
+	if (ch->iostart)
+		return ch->cmt->info->read_control(ch->iostart, 0);
+	else
+		return ch->cmt->info->read_control(ch->cmt->mapbase, 0);
+}
+
+static inline void sh_cmt_write_cmstr(struct sh_cmt_channel *ch,
+				      unsigned long value)
+{
+	if (ch->iostart)
+		ch->cmt->info->write_control(ch->iostart, 0, value);
+	else
+		ch->cmt->info->write_control(ch->cmt->mapbase, 0, value);
+}
+
+static inline unsigned long sh_cmt_read_cmcsr(struct sh_cmt_channel *ch)
+{
+	return ch->cmt->info->read_control(ch->ioctrl, CMCSR);
+}
+
+static inline void sh_cmt_write_cmcsr(struct sh_cmt_channel *ch,
+				      unsigned long value)
+{
+	ch->cmt->info->write_control(ch->ioctrl, CMCSR, value);
+}
+
+static inline unsigned long sh_cmt_read_cmcnt(struct sh_cmt_channel *ch)
+{
+	return ch->cmt->info->read_count(ch->ioctrl, CMCNT);
+}
+
+static inline void sh_cmt_write_cmcnt(struct sh_cmt_channel *ch,
+				      unsigned long value)
+{
+	ch->cmt->info->write_count(ch->ioctrl, CMCNT, value);
+}
+
+static inline void sh_cmt_write_cmcor(struct sh_cmt_channel *ch,
+				      unsigned long value)
+{
+	ch->cmt->info->write_count(ch->ioctrl, CMCOR, value);
+}
+
+static unsigned long sh_cmt_get_counter(struct sh_cmt_channel *ch,
+					int *has_wrapped)
+{
+	unsigned long v1, v2, v3;
+	int o1, o2;
+
+	o1 = sh_cmt_read_cmcsr(ch) & ch->cmt->info->overflow_bit;
+
+	/* Make sure the timer value is stable. Stolen from acpi_pm.c */
+	do {
+		o2 = o1;
+		v1 = sh_cmt_read_cmcnt(ch);
+		v2 = sh_cmt_read_cmcnt(ch);
+		v3 = sh_cmt_read_cmcnt(ch);
+		o1 = sh_cmt_read_cmcsr(ch) & ch->cmt->info->overflow_bit;
+	} while (unlikely((o1 != o2) || (v1 > v2 && v1 < v3)
+			  || (v2 > v3 && v2 < v1) || (v3 > v1 && v3 < v2)));
+
+	*has_wrapped = o1;
+	return v2;
+}
+
+static void sh_cmt_start_stop_ch(struct sh_cmt_channel *ch, int start)
+{
+	unsigned long flags, value;
+
+	/* start stop register shared by multiple timer channels */
+	raw_spin_lock_irqsave(&ch->cmt->lock, flags);
+	value = sh_cmt_read_cmstr(ch);
+
+	if (start)
+		value |= 1 << ch->timer_bit;
+	else
+		value &= ~(1 << ch->timer_bit);
+
+	sh_cmt_write_cmstr(ch, value);
+	raw_spin_unlock_irqrestore(&ch->cmt->lock, flags);
+}
+
+static int sh_cmt_enable(struct sh_cmt_channel *ch, unsigned long *rate)
+{
+	int k, ret;
+
+	pm_runtime_get_sync(&ch->cmt->pdev->dev);
+	dev_pm_syscore_device(&ch->cmt->pdev->dev, true);
+
+	/* enable clock */
+	ret = clk_enable(ch->cmt->clk);
+	if (ret) {
+		dev_err(&ch->cmt->pdev->dev, "ch%u: cannot enable clock\n",
+			ch->index);
+		goto err0;
+	}
+
+	/* make sure channel is disabled */
+	sh_cmt_start_stop_ch(ch, 0);
+
+	/* configure channel, periodic mode and maximum timeout */
+	if (ch->cmt->info->width == 16) {
+		*rate = clk_get_rate(ch->cmt->clk) / 512;
+		sh_cmt_write_cmcsr(ch, SH_CMT16_CMCSR_CMIE |
+				   SH_CMT16_CMCSR_CKS512);
+	} else {
+		*rate = clk_get_rate(ch->cmt->clk) / 8;
+		sh_cmt_write_cmcsr(ch, SH_CMT32_CMCSR_CMM |
+				   SH_CMT32_CMCSR_CMTOUT_IE |
+				   SH_CMT32_CMCSR_CMR_IRQ |
+				   SH_CMT32_CMCSR_CKS_RCLK8);
+	}
+
+	sh_cmt_write_cmcor(ch, 0xffffffff);
+	sh_cmt_write_cmcnt(ch, 0);
+
+	/*
+	 * According to the sh73a0 user's manual, as CMCNT can be operated
+	 * only by the RCLK (Pseudo 32 KHz), there's one restriction on
+	 * modifying CMCNT register; two RCLK cycles are necessary before
+	 * this register is either read or any modification of the value
+	 * it holds is reflected in the LSI's actual operation.
+	 *
+	 * While at it, we're supposed to clear out the CMCNT as of this
+	 * moment, so make sure it's processed properly here.  This will
+	 * take RCLKx2 at maximum.
+	 */
+	for (k = 0; k < 100; k++) {
+		if (!sh_cmt_read_cmcnt(ch))
+			break;
+		udelay(1);
+	}
+
+	if (sh_cmt_read_cmcnt(ch)) {
+		dev_err(&ch->cmt->pdev->dev, "ch%u: cannot clear CMCNT\n",
+			ch->index);
+		ret = -ETIMEDOUT;
+		goto err1;
+	}
+
+	/* enable channel */
+	sh_cmt_start_stop_ch(ch, 1);
+	return 0;
+ err1:
+	/* stop clock */
+	clk_disable(ch->cmt->clk);
+
+ err0:
+	return ret;
+}
+
+static void sh_cmt_disable(struct sh_cmt_channel *ch)
+{
+	/* disable channel */
+	sh_cmt_start_stop_ch(ch, 0);
+
+	/* disable interrupts in CMT block */
+	sh_cmt_write_cmcsr(ch, 0);
+
+	/* stop clock */
+	clk_disable(ch->cmt->clk);
+
+	dev_pm_syscore_device(&ch->cmt->pdev->dev, false);
+	pm_runtime_put(&ch->cmt->pdev->dev);
+}
+
+/* private flags */
+#define FLAG_CLOCKEVENT (1 << 0)
+#define FLAG_CLOCKSOURCE (1 << 1)
+#define FLAG_REPROGRAM (1 << 2)
+#define FLAG_SKIPEVENT (1 << 3)
+#define FLAG_IRQCONTEXT (1 << 4)
+
+static void sh_cmt_clock_event_program_verify(struct sh_cmt_channel *ch,
+					      int absolute)
+{
+	unsigned long new_match;
+	unsigned long value = ch->next_match_value;
+	unsigned long delay = 0;
+	unsigned long now = 0;
+	int has_wrapped;
+
+	now = sh_cmt_get_counter(ch, &has_wrapped);
+	ch->flags |= FLAG_REPROGRAM; /* force reprogram */
+
+	if (has_wrapped) {
+		/* we're competing with the interrupt handler.
+		 *  -> let the interrupt handler reprogram the timer.
+		 *  -> interrupt number two handles the event.
+		 */
+		ch->flags |= FLAG_SKIPEVENT;
+		return;
+	}
+
+	if (absolute)
+		now = 0;
+
+	do {
+		/* reprogram the timer hardware,
+		 * but don't save the new match value yet.
+		 */
+		new_match = now + value + delay;
+		if (new_match > ch->max_match_value)
+			new_match = ch->max_match_value;
+
+		sh_cmt_write_cmcor(ch, new_match);
+
+		now = sh_cmt_get_counter(ch, &has_wrapped);
+		if (has_wrapped && (new_match > ch->match_value)) {
+			/* we are changing to a greater match value,
+			 * so this wrap must be caused by the counter
+			 * matching the old value.
+			 * -> first interrupt reprograms the timer.
+			 * -> interrupt number two handles the event.
+			 */
+			ch->flags |= FLAG_SKIPEVENT;
+			break;
+		}
+
+		if (has_wrapped) {
+			/* we are changing to a smaller match value,
+			 * so the wrap must be caused by the counter
+			 * matching the new value.
+			 * -> save programmed match value.
+			 * -> let isr handle the event.
+			 */
+			ch->match_value = new_match;
+			break;
+		}
+
+		/* be safe: verify hardware settings */
+		if (now < new_match) {
+			/* timer value is below match value, all good.
+			 * this makes sure we won't miss any match events.
+			 * -> save programmed match value.
+			 * -> let isr handle the event.
+			 */
+			ch->match_value = new_match;
+			break;
+		}
+
+		/* the counter has reached a value greater
+		 * than our new match value. and since the
+		 * has_wrapped flag isn't set we must have
+		 * programmed a too close event.
+		 * -> increase delay and retry.
+		 */
+		if (delay)
+			delay <<= 1;
+		else
+			delay = 1;
+
+		if (!delay)
+			dev_warn(&ch->cmt->pdev->dev, "ch%u: too long delay\n",
+				 ch->index);
+
+	} while (delay);
+}
+
+static void __sh_cmt_set_next(struct sh_cmt_channel *ch, unsigned long delta)
+{
+	if (delta > ch->max_match_value)
+		dev_warn(&ch->cmt->pdev->dev, "ch%u: delta out of range\n",
+			 ch->index);
+
+	ch->next_match_value = delta;
+	sh_cmt_clock_event_program_verify(ch, 0);
+}
+
+static void sh_cmt_set_next(struct sh_cmt_channel *ch, unsigned long delta)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&ch->lock, flags);
+	__sh_cmt_set_next(ch, delta);
+	raw_spin_unlock_irqrestore(&ch->lock, flags);
+}
+
+static irqreturn_t sh_cmt_interrupt(int irq, void *dev_id)
+{
+	struct sh_cmt_channel *ch = dev_id;
+
+	/* clear flags */
+	sh_cmt_write_cmcsr(ch, sh_cmt_read_cmcsr(ch) &
+			   ch->cmt->info->clear_bits);
+
+	/* update clock source counter to begin with if enabled
+	 * the wrap flag should be cleared by the timer specific
+	 * isr before we end up here.
+	 */
+	if (ch->flags & FLAG_CLOCKSOURCE)
+		ch->total_cycles += ch->match_value + 1;
+
+	if (!(ch->flags & FLAG_REPROGRAM))
+		ch->next_match_value = ch->max_match_value;
+
+	ch->flags |= FLAG_IRQCONTEXT;
+
+	if (ch->flags & FLAG_CLOCKEVENT) {
+		if (!(ch->flags & FLAG_SKIPEVENT)) {
+			if (ch->ced.mode == CLOCK_EVT_MODE_ONESHOT) {
+				ch->next_match_value = ch->max_match_value;
+				ch->flags |= FLAG_REPROGRAM;
+			}
+
+			ch->ced.event_handler(&ch->ced);
+		}
+	}
+
+	ch->flags &= ~FLAG_SKIPEVENT;
+
+	if (ch->flags & FLAG_REPROGRAM) {
+		ch->flags &= ~FLAG_REPROGRAM;
+		sh_cmt_clock_event_program_verify(ch, 1);
+
+		if (ch->flags & FLAG_CLOCKEVENT)
+			if ((ch->ced.mode == CLOCK_EVT_MODE_SHUTDOWN)
+			    || (ch->match_value == ch->next_match_value))
+				ch->flags &= ~FLAG_REPROGRAM;
+	}
+
+	ch->flags &= ~FLAG_IRQCONTEXT;
+
+	return IRQ_HANDLED;
+}
+
+static int sh_cmt_start(struct sh_cmt_channel *ch, unsigned long flag)
+{
+	int ret = 0;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&ch->lock, flags);
+
+	if (!(ch->flags & (FLAG_CLOCKEVENT | FLAG_CLOCKSOURCE)))
+		ret = sh_cmt_enable(ch, &ch->rate);
+
+	if (ret)
+		goto out;
+	ch->flags |= flag;
+
+	/* setup timeout if no clockevent */
+	if ((flag == FLAG_CLOCKSOURCE) && (!(ch->flags & FLAG_CLOCKEVENT)))
+		__sh_cmt_set_next(ch, ch->max_match_value);
+ out:
+	raw_spin_unlock_irqrestore(&ch->lock, flags);
+
+	return ret;
+}
+
+static void sh_cmt_stop(struct sh_cmt_channel *ch, unsigned long flag)
+{
+	unsigned long flags;
+	unsigned long f;
+
+	raw_spin_lock_irqsave(&ch->lock, flags);
+
+	f = ch->flags & (FLAG_CLOCKEVENT | FLAG_CLOCKSOURCE);
+	ch->flags &= ~flag;
+
+	if (f && !(ch->flags & (FLAG_CLOCKEVENT | FLAG_CLOCKSOURCE)))
+		sh_cmt_disable(ch);
+
+	/* adjust the timeout to maximum if only clocksource left */
+	if ((flag == FLAG_CLOCKEVENT) && (ch->flags & FLAG_CLOCKSOURCE))
+		__sh_cmt_set_next(ch, ch->max_match_value);
+
+	raw_spin_unlock_irqrestore(&ch->lock, flags);
+}
+
+static struct sh_cmt_channel *cs_to_sh_cmt(struct clocksource *cs)
+{
+	return container_of(cs, struct sh_cmt_channel, cs);
+}
+
+static cycle_t sh_cmt_clocksource_read(struct clocksource *cs)
+{
+	struct sh_cmt_channel *ch = cs_to_sh_cmt(cs);
+	unsigned long flags, raw;
+	unsigned long value;
+	int has_wrapped;
+
+	raw_spin_lock_irqsave(&ch->lock, flags);
+	value = ch->total_cycles;
+	raw = sh_cmt_get_counter(ch, &has_wrapped);
+
+	if (unlikely(has_wrapped))
+		raw += ch->match_value + 1;
+	raw_spin_unlock_irqrestore(&ch->lock, flags);
+
+	return value + raw;
+}
+
+static int sh_cmt_clocksource_enable(struct clocksource *cs)
+{
+	int ret;
+	struct sh_cmt_channel *ch = cs_to_sh_cmt(cs);
+
+	WARN_ON(ch->cs_enabled);
+
+	ch->total_cycles = 0;
+
+	ret = sh_cmt_start(ch, FLAG_CLOCKSOURCE);
+	if (!ret) {
+		__clocksource_update_freq_hz(cs, ch->rate);
+		ch->cs_enabled = true;
+	}
+	return ret;
+}
+
+static void sh_cmt_clocksource_disable(struct clocksource *cs)
+{
+	struct sh_cmt_channel *ch = cs_to_sh_cmt(cs);
+
+	WARN_ON(!ch->cs_enabled);
+
+	sh_cmt_stop(ch, FLAG_CLOCKSOURCE);
+	ch->cs_enabled = false;
+}
+
+static void sh_cmt_clocksource_suspend(struct clocksource *cs)
+{
+	struct sh_cmt_channel *ch = cs_to_sh_cmt(cs);
+
+	sh_cmt_stop(ch, FLAG_CLOCKSOURCE);
+	pm_genpd_syscore_poweroff(&ch->cmt->pdev->dev);
+}
+
+static void sh_cmt_clocksource_resume(struct clocksource *cs)
+{
+	struct sh_cmt_channel *ch = cs_to_sh_cmt(cs);
+
+	pm_genpd_syscore_poweron(&ch->cmt->pdev->dev);
+	sh_cmt_start(ch, FLAG_CLOCKSOURCE);
+}
+
+static int sh_cmt_register_clocksource(struct sh_cmt_channel *ch,
+				       const char *name)
+{
+	struct clocksource *cs = &ch->cs;
+
+	cs->name = name;
+	cs->rating = 125;
+	cs->read = sh_cmt_clocksource_read;
+	cs->enable = sh_cmt_clocksource_enable;
+	cs->disable = sh_cmt_clocksource_disable;
+	cs->suspend = sh_cmt_clocksource_suspend;
+	cs->resume = sh_cmt_clocksource_resume;
+	cs->mask = CLOCKSOURCE_MASK(sizeof(unsigned long) * 8);
+	cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
+
+	dev_info(&ch->cmt->pdev->dev, "ch%u: used as clock source\n",
+		 ch->index);
+
+	/* Register with dummy 1 Hz value, gets updated in ->enable() */
+	clocksource_register_hz(cs, 1);
+	return 0;
+}
+
+static struct sh_cmt_channel *ced_to_sh_cmt(struct clock_event_device *ced)
+{
+	return container_of(ced, struct sh_cmt_channel, ced);
+}
+
+static void sh_cmt_clock_event_start(struct sh_cmt_channel *ch, int periodic)
+{
+	struct clock_event_device *ced = &ch->ced;
+
+	sh_cmt_start(ch, FLAG_CLOCKEVENT);
+
+	/* TODO: calculate good shift from rate and counter bit width */
+
+	ced->shift = 32;
+	ced->mult = div_sc(ch->rate, NSEC_PER_SEC, ced->shift);
+	ced->max_delta_ns = clockevent_delta2ns(ch->max_match_value, ced);
+	ced->min_delta_ns = clockevent_delta2ns(0x1f, ced);
+
+	if (periodic)
+		sh_cmt_set_next(ch, ((ch->rate + HZ/2) / HZ) - 1);
+	else
+		sh_cmt_set_next(ch, ch->max_match_value);
+}
+
+static void sh_cmt_clock_event_mode(enum clock_event_mode mode,
+				    struct clock_event_device *ced)
+{
+	struct sh_cmt_channel *ch = ced_to_sh_cmt(ced);
+
+	/* deal with old setting first */
+	switch (ced->mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+	case CLOCK_EVT_MODE_ONESHOT:
+		sh_cmt_stop(ch, FLAG_CLOCKEVENT);
+		break;
+	default:
+		break;
+	}
+
+	switch (mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		dev_info(&ch->cmt->pdev->dev,
+			 "ch%u: used for periodic clock events\n", ch->index);
+		sh_cmt_clock_event_start(ch, 1);
+		break;
+	case CLOCK_EVT_MODE_ONESHOT:
+		dev_info(&ch->cmt->pdev->dev,
+			 "ch%u: used for oneshot clock events\n", ch->index);
+		sh_cmt_clock_event_start(ch, 0);
+		break;
+	case CLOCK_EVT_MODE_SHUTDOWN:
+	case CLOCK_EVT_MODE_UNUSED:
+		sh_cmt_stop(ch, FLAG_CLOCKEVENT);
+		break;
+	default:
+		break;
+	}
+}
+
+static int sh_cmt_clock_event_next(unsigned long delta,
+				   struct clock_event_device *ced)
+{
+	struct sh_cmt_channel *ch = ced_to_sh_cmt(ced);
+
+	BUG_ON(ced->mode != CLOCK_EVT_MODE_ONESHOT);
+	if (likely(ch->flags & FLAG_IRQCONTEXT))
+		ch->next_match_value = delta - 1;
+	else
+		sh_cmt_set_next(ch, delta - 1);
+
+	return 0;
+}
+
+static void sh_cmt_clock_event_suspend(struct clock_event_device *ced)
+{
+	struct sh_cmt_channel *ch = ced_to_sh_cmt(ced);
+
+	pm_genpd_syscore_poweroff(&ch->cmt->pdev->dev);
+	clk_unprepare(ch->cmt->clk);
+}
+
+static void sh_cmt_clock_event_resume(struct clock_event_device *ced)
+{
+	struct sh_cmt_channel *ch = ced_to_sh_cmt(ced);
+
+	clk_prepare(ch->cmt->clk);
+	pm_genpd_syscore_poweron(&ch->cmt->pdev->dev);
+}
+
+static int sh_cmt_register_clockevent(struct sh_cmt_channel *ch,
+				      const char *name)
+{
+	struct clock_event_device *ced = &ch->ced;
+	int irq;
+	int ret;
+
+	irq = platform_get_irq(ch->cmt->pdev, ch->index);
+	if (irq < 0) {
+		dev_err(&ch->cmt->pdev->dev, "ch%u: failed to get irq\n",
+			ch->index);
+		return irq;
+	}
+
+	ret = request_irq(irq, sh_cmt_interrupt,
+			  IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
+			  dev_name(&ch->cmt->pdev->dev), ch);
+	if (ret) {
+		dev_err(&ch->cmt->pdev->dev, "ch%u: failed to request irq %d\n",
+			ch->index, irq);
+		return ret;
+	}
+
+	ced->name = name;
+	ced->features = CLOCK_EVT_FEAT_PERIODIC;
+	ced->features |= CLOCK_EVT_FEAT_ONESHOT;
+	ced->rating = 125;
+	ced->cpumask = cpu_possible_mask;
+	ced->set_next_event = sh_cmt_clock_event_next;
+	ced->set_mode = sh_cmt_clock_event_mode;
+	ced->suspend = sh_cmt_clock_event_suspend;
+	ced->resume = sh_cmt_clock_event_resume;
+
+	dev_info(&ch->cmt->pdev->dev, "ch%u: used for clock events\n",
+		 ch->index);
+	clockevents_register_device(ced);
+
+	return 0;
+}
+
+static int sh_cmt_register(struct sh_cmt_channel *ch, const char *name,
+			   bool clockevent, bool clocksource)
+{
+	int ret;
+
+	if (clockevent) {
+		ch->cmt->has_clockevent = true;
+		ret = sh_cmt_register_clockevent(ch, name);
+		if (ret < 0)
+			return ret;
+	}
+
+	if (clocksource) {
+		ch->cmt->has_clocksource = true;
+		sh_cmt_register_clocksource(ch, name);
+	}
+
+	return 0;
+}
+
+static int sh_cmt_setup_channel(struct sh_cmt_channel *ch, unsigned int index,
+				unsigned int hwidx, bool clockevent,
+				bool clocksource, struct sh_cmt_device *cmt)
+{
+	int ret;
+
+	/* Skip unused channels. */
+	if (!clockevent && !clocksource)
+		return 0;
+
+	ch->cmt = cmt;
+	ch->index = index;
+	ch->hwidx = hwidx;
+
+	/*
+	 * Compute the address of the channel control register block. For the
+	 * timers with a per-channel start/stop register, compute its address
+	 * as well.
+	 */
+	switch (cmt->info->model) {
+	case SH_CMT_16BIT:
+		ch->ioctrl = cmt->mapbase + 2 + ch->hwidx * 6;
+		break;
+	case SH_CMT_32BIT:
+	case SH_CMT_48BIT:
+		ch->ioctrl = cmt->mapbase + 0x10 + ch->hwidx * 0x10;
+		break;
+	case SH_CMT_32BIT_FAST:
+		/*
+		 * The 32-bit "fast" timer has a single channel at hwidx 5 but
+		 * is located at offset 0x40 instead of 0x60 for some reason.
+		 */
+		ch->ioctrl = cmt->mapbase + 0x40;
+		break;
+	case SH_CMT_48BIT_GEN2:
+		ch->iostart = cmt->mapbase + ch->hwidx * 0x100;
+		ch->ioctrl = ch->iostart + 0x10;
+		break;
+	}
+
+	if (cmt->info->width == (sizeof(ch->max_match_value) * 8))
+		ch->max_match_value = ~0;
+	else
+		ch->max_match_value = (1 << cmt->info->width) - 1;
+
+	ch->match_value = ch->max_match_value;
+	raw_spin_lock_init(&ch->lock);
+
+	ch->timer_bit = cmt->info->model == SH_CMT_48BIT_GEN2 ? 0 : ch->hwidx;
+
+	ret = sh_cmt_register(ch, dev_name(&cmt->pdev->dev),
+			      clockevent, clocksource);
+	if (ret) {
+		dev_err(&cmt->pdev->dev, "ch%u: registration failed\n",
+			ch->index);
+		return ret;
+	}
+	ch->cs_enabled = false;
+
+	return 0;
+}
+
+static int sh_cmt_map_memory(struct sh_cmt_device *cmt)
+{
+	struct resource *mem;
+
+	mem = platform_get_resource(cmt->pdev, IORESOURCE_MEM, 0);
+	if (!mem) {
+		dev_err(&cmt->pdev->dev, "failed to get I/O memory\n");
+		return -ENXIO;
+	}
+
+	cmt->mapbase = ioremap_nocache(mem->start, resource_size(mem));
+	if (cmt->mapbase == NULL) {
+		dev_err(&cmt->pdev->dev, "failed to remap I/O memory\n");
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static const struct platform_device_id sh_cmt_id_table[] = {
+	{ "sh-cmt-16", (kernel_ulong_t)&sh_cmt_info[SH_CMT_16BIT] },
+	{ "sh-cmt-32", (kernel_ulong_t)&sh_cmt_info[SH_CMT_32BIT] },
+	{ "sh-cmt-32-fast", (kernel_ulong_t)&sh_cmt_info[SH_CMT_32BIT_FAST] },
+	{ "sh-cmt-48", (kernel_ulong_t)&sh_cmt_info[SH_CMT_48BIT] },
+	{ "sh-cmt-48-gen2", (kernel_ulong_t)&sh_cmt_info[SH_CMT_48BIT_GEN2] },
+	{ }
+};
+MODULE_DEVICE_TABLE(platform, sh_cmt_id_table);
+
+static const struct of_device_id sh_cmt_of_table[] __maybe_unused = {
+	{ .compatible = "renesas,cmt-32", .data = &sh_cmt_info[SH_CMT_32BIT] },
+	{ .compatible = "renesas,cmt-32-fast", .data = &sh_cmt_info[SH_CMT_32BIT_FAST] },
+	{ .compatible = "renesas,cmt-48", .data = &sh_cmt_info[SH_CMT_48BIT] },
+	{ .compatible = "renesas,cmt-48-gen2", .data = &sh_cmt_info[SH_CMT_48BIT_GEN2] },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sh_cmt_of_table);
+
+static int sh_cmt_parse_dt(struct sh_cmt_device *cmt)
+{
+	struct device_node *np = cmt->pdev->dev.of_node;
+
+	return of_property_read_u32(np, "renesas,channels-mask",
+				    &cmt->hw_channels);
+}
+
+static int sh_cmt_setup(struct sh_cmt_device *cmt, struct platform_device *pdev)
+{
+	unsigned int mask;
+	unsigned int i;
+	int ret;
+
+	memset(cmt, 0, sizeof(*cmt));
+	cmt->pdev = pdev;
+	raw_spin_lock_init(&cmt->lock);
+
+	if (IS_ENABLED(CONFIG_OF) && pdev->dev.of_node) {
+		const struct of_device_id *id;
+
+		id = of_match_node(sh_cmt_of_table, pdev->dev.of_node);
+		cmt->info = id->data;
+
+		ret = sh_cmt_parse_dt(cmt);
+		if (ret < 0)
+			return ret;
+	} else if (pdev->dev.platform_data) {
+		struct sh_timer_config *cfg = pdev->dev.platform_data;
+		const struct platform_device_id *id = pdev->id_entry;
+
+		cmt->info = (const struct sh_cmt_info *)id->driver_data;
+		cmt->hw_channels = cfg->channels_mask;
+	} else {
+		dev_err(&cmt->pdev->dev, "missing platform data\n");
+		return -ENXIO;
+	}
+
+	/* Get hold of clock. */
+	cmt->clk = clk_get(&cmt->pdev->dev, "fck");
+	if (IS_ERR(cmt->clk)) {
+		dev_err(&cmt->pdev->dev, "cannot get clock\n");
+		return PTR_ERR(cmt->clk);
+	}
+
+	ret = clk_prepare(cmt->clk);
+	if (ret < 0)
+		goto err_clk_put;
+
+	/* Map the memory resource(s). */
+	ret = sh_cmt_map_memory(cmt);
+	if (ret < 0)
+		goto err_clk_unprepare;
+
+	/* Allocate and setup the channels. */
+	cmt->num_channels = hweight8(cmt->hw_channels);
+	cmt->channels = kzalloc(cmt->num_channels * sizeof(*cmt->channels),
+				GFP_KERNEL);
+	if (cmt->channels == NULL) {
+		ret = -ENOMEM;
+		goto err_unmap;
+	}
+
+	/*
+	 * Use the first channel as a clock event device and the second channel
+	 * as a clock source. If only one channel is available use it for both.
+	 */
+	for (i = 0, mask = cmt->hw_channels; i < cmt->num_channels; ++i) {
+		unsigned int hwidx = ffs(mask) - 1;
+		bool clocksource = i == 1 || cmt->num_channels == 1;
+		bool clockevent = i == 0;
+
+		ret = sh_cmt_setup_channel(&cmt->channels[i], i, hwidx,
+					   clockevent, clocksource, cmt);
+		if (ret < 0)
+			goto err_unmap;
+
+		mask &= ~(1 << hwidx);
+	}
+
+	platform_set_drvdata(pdev, cmt);
+
+	return 0;
+
+err_unmap:
+	kfree(cmt->channels);
+	iounmap(cmt->mapbase);
+err_clk_unprepare:
+	clk_unprepare(cmt->clk);
+err_clk_put:
+	clk_put(cmt->clk);
+	return ret;
+}
+
+static int sh_cmt_probe(struct platform_device *pdev)
+{
+	struct sh_cmt_device *cmt = platform_get_drvdata(pdev);
+	int ret;
+
+	if (!is_early_platform_device(pdev)) {
+		pm_runtime_set_active(&pdev->dev);
+		pm_runtime_enable(&pdev->dev);
+	}
+
+	if (cmt) {
+		dev_info(&pdev->dev, "kept as earlytimer\n");
+		goto out;
+	}
+
+	cmt = kzalloc(sizeof(*cmt), GFP_KERNEL);
+	if (cmt == NULL)
+		return -ENOMEM;
+
+	ret = sh_cmt_setup(cmt, pdev);
+	if (ret) {
+		kfree(cmt);
+		pm_runtime_idle(&pdev->dev);
+		return ret;
+	}
+	if (is_early_platform_device(pdev))
+		return 0;
+
+ out:
+	if (cmt->has_clockevent || cmt->has_clocksource)
+		pm_runtime_irq_safe(&pdev->dev);
+	else
+		pm_runtime_idle(&pdev->dev);
+
+	return 0;
+}
+
+static int sh_cmt_remove(struct platform_device *pdev)
+{
+	return -EBUSY; /* cannot unregister clockevent and clocksource */
+}
+
+static struct platform_driver sh_cmt_device_driver = {
+	.probe		= sh_cmt_probe,
+	.remove		= sh_cmt_remove,
+	.driver		= {
+		.name	= "sh_cmt",
+		.of_match_table = of_match_ptr(sh_cmt_of_table),
+	},
+	.id_table	= sh_cmt_id_table,
+};
+
+static int __init sh_cmt_init(void)
+{
+	return platform_driver_register(&sh_cmt_device_driver);
+}
+
+static void __exit sh_cmt_exit(void)
+{
+	platform_driver_unregister(&sh_cmt_device_driver);
+}
+
+early_platform_init("earlytimer", &sh_cmt_device_driver);
+subsys_initcall(sh_cmt_init);
+module_exit(sh_cmt_exit);
+
+MODULE_AUTHOR("Magnus Damm");
+MODULE_DESCRIPTION("SuperH CMT Timer Driver");
+MODULE_LICENSE("GPL v2");