[PATCH v2 0/4] clocksource: Add standalone MMIO ARM arch timer driver

[PATCH v2 0/4] clocksource: Add standalone MMIO ARM arch timer driver

[Marc Zyngier]

For the past 10 years, both Mark and I have been lamenting about the
sorry state of the badly named "arch_timer" driver, and about the way
the MMIO part is intricately weaved into the system-register part.

The time has finally come to take a stab at it.

This small series simply creates a new timer driver for the MMIO arch
timer, and only that. It is an actual driver, and not some kludge that
has to run super early (that's what the per-CPU timers are for). This
allows, in turn, a pretty large cleanup of the per-CPU driver, though
there is more to come -- one thing at a time.

As an added bonus, we get a clocksource, which the original code
didn't provide. Just in case it might be useful. The end-result is far
more readable, and about 100 lines smaller.

Patches on top of 6.17-rc1.

* From v1 [1]:

  - Narrow the max delta to something that fits an unsigned long, as
    the core code doesn't deal with 64bit quantities on 32bit CPUs.

  - Collected RBs and TBs from Sudeep, with thanks.

Marc Zyngier (4):
  ACPI: GTDT: Generate platform devices for MMIO timers
  clocksource/drivers/arm_arch_timer: Add standalone MMIO driver
  clocksource/drivers/arm_arch_timer_mmio: Switch over to standalone
    driver
  clocksource/drivers/arm_arch_timer_mmio: Add MMIO clocksource

 MAINTAINERS                               |   1 +
 drivers/acpi/arm64/gtdt.c                 |  29 +-
 drivers/clocksource/Makefile              |   1 +
 drivers/clocksource/arm_arch_timer.c      | 686 ++--------------------
 drivers/clocksource/arm_arch_timer_mmio.c | 440 ++++++++++++++
 include/clocksource/arm_arch_timer.h      |   5 -
 6 files changed, 532 insertions(+), 630 deletions(-)
 create mode 100644 drivers/clocksource/arm_arch_timer_mmio.c

-- 
2.39.2

[PATCH v2 1/4] ACPI: GTDT: Generate platform devices for MMIO timers

[Marc Zyngier]

In preparation for the MMIO timer support code becoming an actual
driver, mimic what is done for the SBSA watchdog and expose
a synthetic device for each MMIO timer block.

Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20250807160243.1970533-2-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/acpi/arm64/gtdt.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/arm64/gtdt.c b/drivers/acpi/arm64/gtdt.c
index 70f8290b659de..fd995a1d3d248 100644
--- a/drivers/acpi/arm64/gtdt.c
+++ b/drivers/acpi/arm64/gtdt.c
@@ -388,11 +388,11 @@ static int __init gtdt_import_sbsa_gwdt(struct acpi_gtdt_watchdog *wd,
 	return 0;
 }
 
-static int __init gtdt_sbsa_gwdt_init(void)
+static int __init gtdt_platform_timer_init(void)
 {
 	void *platform_timer;
 	struct acpi_table_header *table;
-	int ret, timer_count, gwdt_count = 0;
+	int ret, timer_count, gwdt_count = 0, mmio_timer_count = 0;
 
 	if (acpi_disabled)
 		return 0;
@@ -414,20 +414,41 @@ static int __init gtdt_sbsa_gwdt_init(void)
 		goto out_put_gtdt;
 
 	for_each_platform_timer(platform_timer) {
+		ret = 0;
+
 		if (is_non_secure_watchdog(platform_timer)) {
 			ret = gtdt_import_sbsa_gwdt(platform_timer, gwdt_count);
 			if (ret)
-				break;
+				continue;
 			gwdt_count++;
+		} else 	if (is_timer_block(platform_timer)) {
+			struct arch_timer_mem atm = {};
+			struct platform_device *pdev;
+
+			ret = gtdt_parse_timer_block(platform_timer, &atm);
+			if (ret)
+				continue;
+
+			pdev = platform_device_register_data(NULL, "gtdt-arm-mmio-timer",
+							     gwdt_count, &atm,
+							     sizeof(atm));
+			if (IS_ERR(pdev)) {
+				pr_err("Can't register timer %d\n", gwdt_count);
+				continue;
+			}
+
+			mmio_timer_count++;
 		}
 	}
 
 	if (gwdt_count)
 		pr_info("found %d SBSA generic Watchdog(s).\n", gwdt_count);
+	if (mmio_timer_count)
+		pr_info("found %d Generic MMIO timer(s).\n", mmio_timer_count);
 
 out_put_gtdt:
 	acpi_put_table(table);
 	return ret;
 }
 
-device_initcall(gtdt_sbsa_gwdt_init);
+device_initcall(gtdt_platform_timer_init);
-- 
2.39.2

[PATCH v2 2/4] clocksource/drivers/arm_arch_timer: Add standalone MMIO driver

[Marc Zyngier]

Add a new driver for the MMIO side of the ARM architected timer.
Most of it has been lifted from the existing arch timer code,
massaged, and finally rewritten.

It supports both DT and ACPI as firmware descriptions.

Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20250807160243.1970533-3-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 MAINTAINERS                               |   1 +
 drivers/clocksource/arm_arch_timer_mmio.c | 421 ++++++++++++++++++++++
 2 files changed, 422 insertions(+)
 create mode 100644 drivers/clocksource/arm_arch_timer_mmio.c

diff --git a/MAINTAINERS b/MAINTAINERS
index fe168477caa45..2243b726edd7e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1990,6 +1990,7 @@ S:	Maintained
 F:	arch/arm/include/asm/arch_timer.h
 F:	arch/arm64/include/asm/arch_timer.h
 F:	drivers/clocksource/arm_arch_timer.c
+F:	drivers/clocksource/arm_arch_timer_mmio.c
 
 ARM GENERIC INTERRUPT CONTROLLER DRIVERS
 M:	Marc Zyngier <maz@kernel.org>
diff --git a/drivers/clocksource/arm_arch_timer_mmio.c b/drivers/clocksource/arm_arch_timer_mmio.c
new file mode 100644
index 0000000000000..3522d1d8cb97b
--- /dev/null
+++ b/drivers/clocksource/arm_arch_timer_mmio.c
@@ -0,0 +1,421 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  ARM Generic Memory Mapped Timer support
+ *
+ *  Split from drivers/clocksource/arm_arch_timer.c
+ *
+ *  Copyright (C) 2011 ARM Ltd.
+ *  All Rights Reserved
+ */
+
+#define pr_fmt(fmt) 	"arch_timer_mmio: " fmt
+
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+
+#include <clocksource/arm_arch_timer.h>
+
+#define CNTTIDR		0x08
+#define CNTTIDR_VIRT(n)	(BIT(1) << ((n) * 4))
+
+#define CNTACR(n)	(0x40 + ((n) * 4))
+#define CNTACR_RPCT	BIT(0)
+#define CNTACR_RVCT	BIT(1)
+#define CNTACR_RFRQ	BIT(2)
+#define CNTACR_RVOFF	BIT(3)
+#define CNTACR_RWVT	BIT(4)
+#define CNTACR_RWPT	BIT(5)
+
+#define CNTPCT_LO	0x00
+#define CNTVCT_LO	0x08
+#define CNTFRQ		0x10
+#define CNTP_CVAL_LO	0x20
+#define CNTP_CTL	0x2c
+#define CNTV_CVAL_LO	0x30
+#define CNTV_CTL	0x3c
+
+enum arch_timer_access {
+	PHYS_ACCESS,
+	VIRT_ACCESS,
+};
+
+struct arch_timer {
+	struct clock_event_device	evt;
+	struct arch_timer_mem		*gt_block;
+	void __iomem			*base;
+	enum arch_timer_access		access;
+	u32				rate;
+};
+
+#define evt_to_arch_timer(e) container_of(e, struct arch_timer, evt)
+
+static void arch_timer_mmio_write(struct arch_timer *timer,
+				  enum arch_timer_reg reg, u64 val)
+{
+	switch (timer->access) {
+	case PHYS_ACCESS:
+		switch (reg) {
+		case ARCH_TIMER_REG_CTRL:
+			writel_relaxed((u32)val, timer->base + CNTP_CTL);
+			return;
+		case ARCH_TIMER_REG_CVAL:
+			/*
+			 * Not guaranteed to be atomic, so the timer
+			 * must be disabled at this point.
+			 */
+			writeq_relaxed(val, timer->base + CNTP_CVAL_LO);
+			return;
+		}
+		break;
+	case VIRT_ACCESS:
+		switch (reg) {
+		case ARCH_TIMER_REG_CTRL:
+			writel_relaxed((u32)val, timer->base + CNTV_CTL);
+			return;
+		case ARCH_TIMER_REG_CVAL:
+			/* Same restriction as above */
+			writeq_relaxed(val, timer->base + CNTV_CVAL_LO);
+			return;
+		}
+		break;
+	}
+
+	/* Should never be here */
+	WARN_ON_ONCE(1);
+}
+
+static u32 arch_timer_mmio_read(struct arch_timer *timer, enum arch_timer_reg reg)
+{
+	switch (timer->access) {
+	case PHYS_ACCESS:
+		switch (reg) {
+		case ARCH_TIMER_REG_CTRL:
+			return readl_relaxed(timer->base + CNTP_CTL);
+		default:
+			break;
+		}
+		break;
+	case VIRT_ACCESS:
+		switch (reg) {
+		case ARCH_TIMER_REG_CTRL:
+			return readl_relaxed(timer->base + CNTV_CTL);
+		default:
+			break;
+		}
+		break;
+	}
+
+	/* Should never be here */
+	WARN_ON_ONCE(1);
+	return 0;
+}
+
+static noinstr u64 arch_counter_mmio_get_cnt(struct arch_timer *t)
+{
+	int offset_lo = t->access == VIRT_ACCESS ? CNTVCT_LO : CNTPCT_LO;
+	u32 cnt_lo, cnt_hi, tmp_hi;
+
+	do {
+		cnt_hi = __le32_to_cpu((__le32 __force)__raw_readl(t->base + offset_lo + 4));
+		cnt_lo = __le32_to_cpu((__le32 __force)__raw_readl(t->base + offset_lo));
+		tmp_hi = __le32_to_cpu((__le32 __force)__raw_readl(t->base + offset_lo + 4));
+	} while (cnt_hi != tmp_hi);
+
+	return ((u64) cnt_hi << 32) | cnt_lo;
+}
+
+static int arch_timer_mmio_shutdown(struct clock_event_device *clk)
+{
+	struct arch_timer *at = evt_to_arch_timer(clk);
+	unsigned long ctrl;
+
+	ctrl = arch_timer_mmio_read(at, ARCH_TIMER_REG_CTRL);
+	ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
+	arch_timer_mmio_write(at, ARCH_TIMER_REG_CTRL, ctrl);
+
+	return 0;
+}
+
+static int arch_timer_mmio_set_next_event(unsigned long evt,
+					  struct clock_event_device *clk)
+{
+	struct arch_timer *timer = evt_to_arch_timer(clk);
+	unsigned long ctrl;
+	u64 cnt;
+
+	ctrl = arch_timer_mmio_read(timer, ARCH_TIMER_REG_CTRL);
+
+	/* Timer must be disabled before programming CVAL */
+	if (ctrl & ARCH_TIMER_CTRL_ENABLE) {
+		ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
+		arch_timer_mmio_write(timer, ARCH_TIMER_REG_CTRL, ctrl);
+	}
+
+	ctrl |= ARCH_TIMER_CTRL_ENABLE;
+	ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
+
+	cnt = arch_counter_mmio_get_cnt(timer);
+
+	arch_timer_mmio_write(timer, ARCH_TIMER_REG_CVAL, evt + cnt);
+	arch_timer_mmio_write(timer, ARCH_TIMER_REG_CTRL, ctrl);
+	return 0;
+}
+
+static irqreturn_t arch_timer_mmio_handler(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = dev_id;
+	struct arch_timer *at = evt_to_arch_timer(evt);
+	unsigned long ctrl;
+
+	ctrl = arch_timer_mmio_read(at, ARCH_TIMER_REG_CTRL);
+	if (ctrl & ARCH_TIMER_CTRL_IT_STAT) {
+		ctrl |= ARCH_TIMER_CTRL_IT_MASK;
+		arch_timer_mmio_write(at, ARCH_TIMER_REG_CTRL, ctrl);
+		evt->event_handler(evt);
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static struct arch_timer_mem_frame *find_best_frame(struct platform_device *pdev)
+{
+	struct arch_timer_mem_frame *frame, *best_frame = NULL;
+	struct arch_timer *at = platform_get_drvdata(pdev);
+	void __iomem *cntctlbase;
+	u32 cnttidr;
+
+	cntctlbase = ioremap(at->gt_block->cntctlbase, at->gt_block->size);
+	if (!cntctlbase) {
+		dev_err(&pdev->dev, "Can't map CNTCTLBase @ %pa\n",
+			&at->gt_block->cntctlbase);
+		return NULL;
+	}
+
+	cnttidr = readl_relaxed(cntctlbase + CNTTIDR);
+
+	/*
+	 * Try to find a virtual capable frame. Otherwise fall back to a
+	 * physical capable frame.
+	 */
+	for (int i = 0; i < ARCH_TIMER_MEM_MAX_FRAMES; i++) {
+		u32 cntacr = CNTACR_RFRQ | CNTACR_RWPT | CNTACR_RPCT |
+			     CNTACR_RWVT | CNTACR_RVOFF | CNTACR_RVCT;
+
+		frame = &at->gt_block->frame[i];
+		if (!frame->valid)
+			continue;
+
+		/* Try enabling everything, and see what sticks */
+		writel_relaxed(cntacr, cntctlbase + CNTACR(i));
+		cntacr = readl_relaxed(cntctlbase + CNTACR(i));
+
+		/* Pick a suitable frame for which we have an IRQ */
+		if ((cnttidr & CNTTIDR_VIRT(i)) &&
+		    !(~cntacr & (CNTACR_RWVT | CNTACR_RVCT)) &&
+		    frame->virt_irq) {
+			best_frame = frame;
+			at->access = VIRT_ACCESS;
+			break;
+		}
+
+		if ((~cntacr & (CNTACR_RWPT | CNTACR_RPCT)) ||
+		     !frame->phys_irq)
+			continue;
+
+		at->access = PHYS_ACCESS;
+		best_frame = frame;
+	}
+
+	iounmap(cntctlbase);
+
+	return best_frame;
+}
+
+static void arch_timer_mmio_setup(struct arch_timer *at, int irq)
+{
+	at->evt = (struct clock_event_device) {
+		.features		   = (CLOCK_EVT_FEAT_ONESHOT |
+					      CLOCK_EVT_FEAT_DYNIRQ),
+		.name			   = "arch_mem_timer",
+		.rating			   = 400,
+		.cpumask		   = cpu_possible_mask,
+		.irq 			   = irq,
+		.set_next_event		   = arch_timer_mmio_set_next_event,
+		.set_state_oneshot_stopped = arch_timer_mmio_shutdown,
+		.set_state_shutdown	   = arch_timer_mmio_shutdown,
+	};
+
+	at->evt.set_state_shutdown(&at->evt);
+
+	clockevents_config_and_register(&at->evt, at->rate, 0xf,
+					(unsigned long)CLOCKSOURCE_MASK(56));
+
+	enable_irq(at->evt.irq);
+}
+
+static int arch_timer_mmio_frame_register(struct platform_device *pdev,
+					  struct arch_timer_mem_frame *frame)
+{
+	struct arch_timer *at = platform_get_drvdata(pdev);
+	struct device_node *np = pdev->dev.of_node;
+	int ret, irq;
+	u32 rate;
+
+	if (!devm_request_mem_region(&pdev->dev, frame->cntbase, frame->size,
+				     "arch_mem_timer"))
+		return -EBUSY;
+
+	at->base = devm_ioremap(&pdev->dev, frame->cntbase, frame->size);
+	if (!at->base) {
+		dev_err(&pdev->dev, "Can't map frame's registers\n");
+		return -ENXIO;
+	}
+
+	/*
+	 * Allow "clock-frequency" to override the probed rate. If neither
+	 * lead to something useful, use the CPU timer frequency as the
+	 * fallback. The nice thing about that last point is that we woudn't
+	 * made it here if we didn't have a valid frequency.
+	 */
+	rate = readl_relaxed(at->base + CNTFRQ);
+
+	if (!np || of_property_read_u32(np, "clock-frequency", &at->rate))
+		at->rate = rate;
+
+	if (!at->rate)
+		at->rate = arch_timer_get_rate();
+
+	irq = at->access == VIRT_ACCESS ? frame->virt_irq : frame->phys_irq;
+	ret = devm_request_irq(&pdev->dev, irq, arch_timer_mmio_handler,
+			       IRQF_TIMER | IRQF_NO_AUTOEN, "arch_mem_timer",
+			       &at->evt);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to request mem timer irq\n");
+		return ret;
+	}
+
+	/* Afer this point, we're not allowed to fail anymore */
+	arch_timer_mmio_setup(at, irq);
+	return 0;
+}
+
+static int of_populate_gt_block(struct platform_device *pdev,
+				struct arch_timer *at)
+{
+	struct resource res;
+
+	if (of_address_to_resource(pdev->dev.of_node, 0, &res))
+		return -EINVAL;
+
+	at->gt_block->cntctlbase = res.start;
+	at->gt_block->size = resource_size(&res);
+
+	for_each_available_child_of_node_scoped(pdev->dev.of_node, frame_node) {
+		struct arch_timer_mem_frame *frame;
+		u32 n;
+
+		if (of_property_read_u32(frame_node, "frame-number", &n)) {
+			dev_err(&pdev->dev, FW_BUG "Missing frame-number\n");
+			return -EINVAL;
+		}
+		if (n >= ARCH_TIMER_MEM_MAX_FRAMES) {
+			dev_err(&pdev->dev,
+				FW_BUG "Wrong frame-number, only 0-%u are permitted\n",
+			       ARCH_TIMER_MEM_MAX_FRAMES - 1);
+			return -EINVAL;
+		}
+
+		frame = &at->gt_block->frame[n];
+
+		if (frame->valid) {
+			dev_err(&pdev->dev, FW_BUG "Duplicated frame-number\n");
+			return -EINVAL;
+		}
+
+		if (of_address_to_resource(frame_node, 0, &res))
+			return -EINVAL;
+
+		frame->cntbase = res.start;
+		frame->size = resource_size(&res);
+
+		frame->phys_irq = irq_of_parse_and_map(frame_node, 0);
+		frame->virt_irq = irq_of_parse_and_map(frame_node, 1);
+
+		frame->valid = true;
+	}
+
+	return 0;
+}
+
+static int arch_timer_mmio_probe(struct platform_device *pdev)
+{
+	struct arch_timer_mem_frame *frame;
+	struct arch_timer *at;
+	struct device_node *np;
+	int ret;
+
+	np = pdev->dev.of_node;
+
+	at = devm_kmalloc(&pdev->dev, sizeof(*at), GFP_KERNEL | __GFP_ZERO);
+	if (!at)
+		return -ENOMEM;
+
+	if (np) {
+		at->gt_block = devm_kmalloc(&pdev->dev, sizeof(*at->gt_block),
+					    GFP_KERNEL | __GFP_ZERO);
+		if (!at->gt_block)
+			return -ENOMEM;
+		ret = of_populate_gt_block(pdev, at);
+		if (ret)
+			return ret;
+	} else {
+		at->gt_block = dev_get_platdata(&pdev->dev);
+	}
+
+	platform_set_drvdata(pdev, at);
+
+	frame = find_best_frame(pdev);
+	if (!frame) {
+		dev_err(&pdev->dev,
+			"Unable to find a suitable frame in timer @ %pa\n",
+			&at->gt_block->cntctlbase);
+		return -EINVAL;
+	}
+
+	ret = arch_timer_mmio_frame_register(pdev, frame);
+	if (!ret)
+		dev_info(&pdev->dev,
+			 "mmio timer running at %lu.%02luMHz (%s)\n",
+			 (unsigned long)at->rate / 1000000,
+			 (unsigned long)(at->rate / 10000) % 100,
+			 at->access == VIRT_ACCESS ? "virt" : "phys");
+
+	return ret;
+}
+
+static const struct of_device_id arch_timer_mmio_of_table[] = {
+	{ .compatible = "arm,armv7-timer-mem", },
+	{}
+};
+
+static struct platform_driver arch_timer_mmio_drv = {
+	.driver	= {
+		.name = "arch-timer-mmio",
+		.of_match_table	= arch_timer_mmio_of_table,
+	},
+	.probe	= arch_timer_mmio_probe,
+};
+builtin_platform_driver(arch_timer_mmio_drv);
+
+static struct platform_driver arch_timer_mmio_acpi_drv = {
+	.driver	= {
+		.name = "gtdt-arm-mmio-timer",
+	},
+	.probe	= arch_timer_mmio_probe,
+};
+builtin_platform_driver(arch_timer_mmio_acpi_drv);
-- 
2.39.2

[PATCH v2 3/4] clocksource/drivers/arm_arch_timer_mmio: Switch over to standalone driver

[Marc Zyngier]

Remove all the MMIO support from the per-CPU timer driver, and switch
over to the standalove driver.

Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20250807160243.1970533-4-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/clocksource/Makefile         |   1 +
 drivers/clocksource/arm_arch_timer.c | 686 +++------------------------
 include/clocksource/arm_arch_timer.h |   5 -
 3 files changed, 66 insertions(+), 626 deletions(-)

diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 205bf3b0a8f3f..0dcd958e21443 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -64,6 +64,7 @@ obj-$(CONFIG_REALTEK_OTTO_TIMER)	+= timer-rtl-otto.o
 
 obj-$(CONFIG_ARC_TIMERS)		+= arc_timer.o
 obj-$(CONFIG_ARM_ARCH_TIMER)		+= arm_arch_timer.o
+obj-$(CONFIG_ARM_ARCH_TIMER)		+= arm_arch_timer_mmio.o
 obj-$(CONFIG_ARM_GLOBAL_TIMER)		+= arm_global_timer.o
 obj-$(CONFIG_ARMV7M_SYSTICK)		+= armv7m_systick.o
 obj-$(CONFIG_ARM_TIMER_SP804)		+= timer-sp804.o
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 80ba6a54248c4..90aeff44a2764 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -34,42 +34,12 @@
 
 #include <clocksource/arm_arch_timer.h>
 
-#define CNTTIDR		0x08
-#define CNTTIDR_VIRT(n)	(BIT(1) << ((n) * 4))
-
-#define CNTACR(n)	(0x40 + ((n) * 4))
-#define CNTACR_RPCT	BIT(0)
-#define CNTACR_RVCT	BIT(1)
-#define CNTACR_RFRQ	BIT(2)
-#define CNTACR_RVOFF	BIT(3)
-#define CNTACR_RWVT	BIT(4)
-#define CNTACR_RWPT	BIT(5)
-
-#define CNTPCT_LO	0x00
-#define CNTVCT_LO	0x08
-#define CNTFRQ		0x10
-#define CNTP_CVAL_LO	0x20
-#define CNTP_CTL	0x2c
-#define CNTV_CVAL_LO	0x30
-#define CNTV_CTL	0x3c
-
 /*
  * The minimum amount of time a generic counter is guaranteed to not roll over
  * (40 years)
  */
 #define MIN_ROLLOVER_SECS	(40ULL * 365 * 24 * 3600)
 
-static unsigned arch_timers_present __initdata;
-
-struct arch_timer {
-	void __iomem *base;
-	struct clock_event_device evt;
-};
-
-static struct arch_timer *arch_timer_mem __ro_after_init;
-
-#define to_arch_timer(e) container_of(e, struct arch_timer, evt)
-
 static u32 arch_timer_rate __ro_after_init;
 static int arch_timer_ppi[ARCH_TIMER_MAX_TIMER_PPI] __ro_after_init;
 
@@ -85,7 +55,6 @@ static struct clock_event_device __percpu *arch_timer_evt;
 
 static enum arch_timer_ppi_nr arch_timer_uses_ppi __ro_after_init = ARCH_TIMER_VIRT_PPI;
 static bool arch_timer_c3stop __ro_after_init;
-static bool arch_timer_mem_use_virtual __ro_after_init;
 static bool arch_counter_suspend_stop __ro_after_init;
 #ifdef CONFIG_GENERIC_GETTIMEOFDAY
 static enum vdso_clock_mode vdso_default = VDSO_CLOCKMODE_ARCHTIMER;
@@ -121,76 +90,6 @@ static int arch_counter_get_width(void)
 /*
  * Architected system timer support.
  */
-
-static __always_inline
-void arch_timer_reg_write(int access, enum arch_timer_reg reg, u64 val,
-			  struct clock_event_device *clk)
-{
-	if (access == ARCH_TIMER_MEM_PHYS_ACCESS) {
-		struct arch_timer *timer = to_arch_timer(clk);
-		switch (reg) {
-		case ARCH_TIMER_REG_CTRL:
-			writel_relaxed((u32)val, timer->base + CNTP_CTL);
-			break;
-		case ARCH_TIMER_REG_CVAL:
-			/*
-			 * Not guaranteed to be atomic, so the timer
-			 * must be disabled at this point.
-			 */
-			writeq_relaxed(val, timer->base + CNTP_CVAL_LO);
-			break;
-		default:
-			BUILD_BUG();
-		}
-	} else if (access == ARCH_TIMER_MEM_VIRT_ACCESS) {
-		struct arch_timer *timer = to_arch_timer(clk);
-		switch (reg) {
-		case ARCH_TIMER_REG_CTRL:
-			writel_relaxed((u32)val, timer->base + CNTV_CTL);
-			break;
-		case ARCH_TIMER_REG_CVAL:
-			/* Same restriction as above */
-			writeq_relaxed(val, timer->base + CNTV_CVAL_LO);
-			break;
-		default:
-			BUILD_BUG();
-		}
-	} else {
-		arch_timer_reg_write_cp15(access, reg, val);
-	}
-}
-
-static __always_inline
-u32 arch_timer_reg_read(int access, enum arch_timer_reg reg,
-			struct clock_event_device *clk)
-{
-	u32 val;
-
-	if (access == ARCH_TIMER_MEM_PHYS_ACCESS) {
-		struct arch_timer *timer = to_arch_timer(clk);
-		switch (reg) {
-		case ARCH_TIMER_REG_CTRL:
-			val = readl_relaxed(timer->base + CNTP_CTL);
-			break;
-		default:
-			BUILD_BUG();
-		}
-	} else if (access == ARCH_TIMER_MEM_VIRT_ACCESS) {
-		struct arch_timer *timer = to_arch_timer(clk);
-		switch (reg) {
-		case ARCH_TIMER_REG_CTRL:
-			val = readl_relaxed(timer->base + CNTV_CTL);
-			break;
-		default:
-			BUILD_BUG();
-		}
-	} else {
-		val = arch_timer_reg_read_cp15(access, reg);
-	}
-
-	return val;
-}
-
 static noinstr u64 raw_counter_get_cntpct_stable(void)
 {
 	return __arch_counter_get_cntpct_stable();
@@ -424,7 +323,7 @@ void erratum_set_next_event_generic(const int access, unsigned long evt,
 	unsigned long ctrl;
 	u64 cval;
 
-	ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL, clk);
+	ctrl = arch_timer_reg_read_cp15(access, ARCH_TIMER_REG_CTRL);
 	ctrl |= ARCH_TIMER_CTRL_ENABLE;
 	ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
 
@@ -436,7 +335,7 @@ void erratum_set_next_event_generic(const int access, unsigned long evt,
 		write_sysreg(cval, cntv_cval_el0);
 	}
 
-	arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl, clk);
+	arch_timer_reg_write_cp15(access, ARCH_TIMER_REG_CTRL, ctrl);
 }
 
 static __maybe_unused int erratum_set_next_event_virt(unsigned long evt,
@@ -667,10 +566,10 @@ static __always_inline irqreturn_t timer_handler(const int access,
 {
 	unsigned long ctrl;
 
-	ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL, evt);
+	ctrl = arch_timer_reg_read_cp15(access, ARCH_TIMER_REG_CTRL);
 	if (ctrl & ARCH_TIMER_CTRL_IT_STAT) {
 		ctrl |= ARCH_TIMER_CTRL_IT_MASK;
-		arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl, evt);
+		arch_timer_reg_write_cp15(access, ARCH_TIMER_REG_CTRL, ctrl);
 		evt->event_handler(evt);
 		return IRQ_HANDLED;
 	}
@@ -692,28 +591,14 @@ static irqreturn_t arch_timer_handler_phys(int irq, void *dev_id)
 	return timer_handler(ARCH_TIMER_PHYS_ACCESS, evt);
 }
 
-static irqreturn_t arch_timer_handler_phys_mem(int irq, void *dev_id)
-{
-	struct clock_event_device *evt = dev_id;
-
-	return timer_handler(ARCH_TIMER_MEM_PHYS_ACCESS, evt);
-}
-
-static irqreturn_t arch_timer_handler_virt_mem(int irq, void *dev_id)
-{
-	struct clock_event_device *evt = dev_id;
-
-	return timer_handler(ARCH_TIMER_MEM_VIRT_ACCESS, evt);
-}
-
 static __always_inline int arch_timer_shutdown(const int access,
 					       struct clock_event_device *clk)
 {
 	unsigned long ctrl;
 
-	ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL, clk);
+	ctrl = arch_timer_reg_read_cp15(access, ARCH_TIMER_REG_CTRL);
 	ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
-	arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl, clk);
+	arch_timer_reg_write_cp15(access, ARCH_TIMER_REG_CTRL, ctrl);
 
 	return 0;
 }
@@ -728,23 +613,13 @@ static int arch_timer_shutdown_phys(struct clock_event_device *clk)
 	return arch_timer_shutdown(ARCH_TIMER_PHYS_ACCESS, clk);
 }
 
-static int arch_timer_shutdown_virt_mem(struct clock_event_device *clk)
-{
-	return arch_timer_shutdown(ARCH_TIMER_MEM_VIRT_ACCESS, clk);
-}
-
-static int arch_timer_shutdown_phys_mem(struct clock_event_device *clk)
-{
-	return arch_timer_shutdown(ARCH_TIMER_MEM_PHYS_ACCESS, clk);
-}
-
 static __always_inline void set_next_event(const int access, unsigned long evt,
 					   struct clock_event_device *clk)
 {
 	unsigned long ctrl;
 	u64 cnt;
 
-	ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL, clk);
+	ctrl = arch_timer_reg_read_cp15(access, ARCH_TIMER_REG_CTRL);
 	ctrl |= ARCH_TIMER_CTRL_ENABLE;
 	ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
 
@@ -753,8 +628,8 @@ static __always_inline void set_next_event(const int access, unsigned long evt,
 	else
 		cnt = __arch_counter_get_cntvct();
 
-	arch_timer_reg_write(access, ARCH_TIMER_REG_CVAL, evt + cnt, clk);
-	arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl, clk);
+	arch_timer_reg_write_cp15(access, ARCH_TIMER_REG_CVAL, evt + cnt);
+	arch_timer_reg_write_cp15(access, ARCH_TIMER_REG_CTRL, ctrl);
 }
 
 static int arch_timer_set_next_event_virt(unsigned long evt,
@@ -771,60 +646,6 @@ static int arch_timer_set_next_event_phys(unsigned long evt,
 	return 0;
 }
 
-static noinstr u64 arch_counter_get_cnt_mem(struct arch_timer *t, int offset_lo)
-{
-	u32 cnt_lo, cnt_hi, tmp_hi;
-
-	do {
-		cnt_hi = __le32_to_cpu((__le32 __force)__raw_readl(t->base + offset_lo + 4));
-		cnt_lo = __le32_to_cpu((__le32 __force)__raw_readl(t->base + offset_lo));
-		tmp_hi = __le32_to_cpu((__le32 __force)__raw_readl(t->base + offset_lo + 4));
-	} while (cnt_hi != tmp_hi);
-
-	return ((u64) cnt_hi << 32) | cnt_lo;
-}
-
-static __always_inline void set_next_event_mem(const int access, unsigned long evt,
-					   struct clock_event_device *clk)
-{
-	struct arch_timer *timer = to_arch_timer(clk);
-	unsigned long ctrl;
-	u64 cnt;
-
-	ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL, clk);
-
-	/* Timer must be disabled before programming CVAL */
-	if (ctrl & ARCH_TIMER_CTRL_ENABLE) {
-		ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
-		arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl, clk);
-	}
-
-	ctrl |= ARCH_TIMER_CTRL_ENABLE;
-	ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
-
-	if (access ==  ARCH_TIMER_MEM_VIRT_ACCESS)
-		cnt = arch_counter_get_cnt_mem(timer, CNTVCT_LO);
-	else
-		cnt = arch_counter_get_cnt_mem(timer, CNTPCT_LO);
-
-	arch_timer_reg_write(access, ARCH_TIMER_REG_CVAL, evt + cnt, clk);
-	arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl, clk);
-}
-
-static int arch_timer_set_next_event_virt_mem(unsigned long evt,
-					      struct clock_event_device *clk)
-{
-	set_next_event_mem(ARCH_TIMER_MEM_VIRT_ACCESS, evt, clk);
-	return 0;
-}
-
-static int arch_timer_set_next_event_phys_mem(unsigned long evt,
-					      struct clock_event_device *clk)
-{
-	set_next_event_mem(ARCH_TIMER_MEM_PHYS_ACCESS, evt, clk);
-	return 0;
-}
-
 static u64 __arch_timer_check_delta(void)
 {
 #ifdef CONFIG_ARM64
@@ -850,63 +671,41 @@ static u64 __arch_timer_check_delta(void)
 	return CLOCKSOURCE_MASK(arch_counter_get_width());
 }
 
-static void __arch_timer_setup(unsigned type,
-			       struct clock_event_device *clk)
+static void __arch_timer_setup(struct clock_event_device *clk)
 {
+	typeof(clk->set_next_event) sne;
 	u64 max_delta;
 
 	clk->features = CLOCK_EVT_FEAT_ONESHOT;
 
-	if (type == ARCH_TIMER_TYPE_CP15) {
-		typeof(clk->set_next_event) sne;
-
-		arch_timer_check_ool_workaround(ate_match_local_cap_id, NULL);
-
-		if (arch_timer_c3stop)
-			clk->features |= CLOCK_EVT_FEAT_C3STOP;
-		clk->name = "arch_sys_timer";
-		clk->rating = 450;
-		clk->cpumask = cpumask_of(smp_processor_id());
-		clk->irq = arch_timer_ppi[arch_timer_uses_ppi];
-		switch (arch_timer_uses_ppi) {
-		case ARCH_TIMER_VIRT_PPI:
-			clk->set_state_shutdown = arch_timer_shutdown_virt;
-			clk->set_state_oneshot_stopped = arch_timer_shutdown_virt;
-			sne = erratum_handler(set_next_event_virt);
-			break;
-		case ARCH_TIMER_PHYS_SECURE_PPI:
-		case ARCH_TIMER_PHYS_NONSECURE_PPI:
-		case ARCH_TIMER_HYP_PPI:
-			clk->set_state_shutdown = arch_timer_shutdown_phys;
-			clk->set_state_oneshot_stopped = arch_timer_shutdown_phys;
-			sne = erratum_handler(set_next_event_phys);
-			break;
-		default:
-			BUG();
-		}
+	arch_timer_check_ool_workaround(ate_match_local_cap_id, NULL);
 
-		clk->set_next_event = sne;
-		max_delta = __arch_timer_check_delta();
-	} else {
-		clk->features |= CLOCK_EVT_FEAT_DYNIRQ;
-		clk->name = "arch_mem_timer";
-		clk->rating = 400;
-		clk->cpumask = cpu_possible_mask;
-		if (arch_timer_mem_use_virtual) {
-			clk->set_state_shutdown = arch_timer_shutdown_virt_mem;
-			clk->set_state_oneshot_stopped = arch_timer_shutdown_virt_mem;
-			clk->set_next_event =
-				arch_timer_set_next_event_virt_mem;
-		} else {
-			clk->set_state_shutdown = arch_timer_shutdown_phys_mem;
-			clk->set_state_oneshot_stopped = arch_timer_shutdown_phys_mem;
-			clk->set_next_event =
-				arch_timer_set_next_event_phys_mem;
-		}
-
-		max_delta = CLOCKSOURCE_MASK(56);
+	if (arch_timer_c3stop)
+		clk->features |= CLOCK_EVT_FEAT_C3STOP;
+	clk->name = "arch_sys_timer";
+	clk->rating = 450;
+	clk->cpumask = cpumask_of(smp_processor_id());
+	clk->irq = arch_timer_ppi[arch_timer_uses_ppi];
+	switch (arch_timer_uses_ppi) {
+	case ARCH_TIMER_VIRT_PPI:
+		clk->set_state_shutdown = arch_timer_shutdown_virt;
+		clk->set_state_oneshot_stopped = arch_timer_shutdown_virt;
+		sne = erratum_handler(set_next_event_virt);
+		break;
+	case ARCH_TIMER_PHYS_SECURE_PPI:
+	case ARCH_TIMER_PHYS_NONSECURE_PPI:
+	case ARCH_TIMER_HYP_PPI:
+		clk->set_state_shutdown = arch_timer_shutdown_phys;
+		clk->set_state_oneshot_stopped = arch_timer_shutdown_phys;
+		sne = erratum_handler(set_next_event_phys);
+		break;
+	default:
+		BUG();
 	}
 
+	clk->set_next_event = sne;
+	max_delta = __arch_timer_check_delta();
+
 	clk->set_state_shutdown(clk);
 
 	clockevents_config_and_register(clk, arch_timer_rate, 0xf, max_delta);
@@ -1029,7 +828,7 @@ static int arch_timer_starting_cpu(unsigned int cpu)
 	struct clock_event_device *clk = this_cpu_ptr(arch_timer_evt);
 	u32 flags;
 
-	__arch_timer_setup(ARCH_TIMER_TYPE_CP15, clk);
+	__arch_timer_setup(clk);
 
 	flags = check_ppi_trigger(arch_timer_ppi[arch_timer_uses_ppi]);
 	enable_percpu_irq(arch_timer_ppi[arch_timer_uses_ppi], flags);
@@ -1075,22 +874,12 @@ static void __init arch_timer_of_configure_rate(u32 rate, struct device_node *np
 		pr_warn("frequency not available\n");
 }
 
-static void __init arch_timer_banner(unsigned type)
+static void __init arch_timer_banner(void)
 {
-	pr_info("%s%s%s timer(s) running at %lu.%02luMHz (%s%s%s).\n",
-		type & ARCH_TIMER_TYPE_CP15 ? "cp15" : "",
-		type == (ARCH_TIMER_TYPE_CP15 | ARCH_TIMER_TYPE_MEM) ?
-			" and " : "",
-		type & ARCH_TIMER_TYPE_MEM ? "mmio" : "",
+	pr_info("cp15 timer running at %lu.%02luMHz (%s).\n",
 		(unsigned long)arch_timer_rate / 1000000,
 		(unsigned long)(arch_timer_rate / 10000) % 100,
-		type & ARCH_TIMER_TYPE_CP15 ?
-			(arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) ? "virt" : "phys" :
-			"",
-		type == (ARCH_TIMER_TYPE_CP15 | ARCH_TIMER_TYPE_MEM) ? "/" : "",
-		type & ARCH_TIMER_TYPE_MEM ?
-			arch_timer_mem_use_virtual ? "virt" : "phys" :
-			"");
+		(arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) ? "virt" : "phys");
 }
 
 u32 arch_timer_get_rate(void)
@@ -1108,11 +897,6 @@ bool arch_timer_evtstrm_available(void)
 	return cpumask_test_cpu(raw_smp_processor_id(), &evtstrm_available);
 }
 
-static noinstr u64 arch_counter_get_cntvct_mem(void)
-{
-	return arch_counter_get_cnt_mem(arch_timer_mem, CNTVCT_LO);
-}
-
 static struct arch_timer_kvm_info arch_timer_kvm_info;
 
 struct arch_timer_kvm_info *arch_timer_get_kvm_info(void)
@@ -1120,42 +904,35 @@ struct arch_timer_kvm_info *arch_timer_get_kvm_info(void)
 	return &arch_timer_kvm_info;
 }
 
-static void __init arch_counter_register(unsigned type)
+static void __init arch_counter_register(void)
 {
 	u64 (*scr)(void);
+	u64 (*rd)(void);
 	u64 start_count;
 	int width;
 
-	/* Register the CP15 based counter if we have one */
-	if (type & ARCH_TIMER_TYPE_CP15) {
-		u64 (*rd)(void);
-
-		if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
-		    arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
-			if (arch_timer_counter_has_wa()) {
-				rd = arch_counter_get_cntvct_stable;
-				scr = raw_counter_get_cntvct_stable;
-			} else {
-				rd = arch_counter_get_cntvct;
-				scr = arch_counter_get_cntvct;
-			}
+	if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
+	    arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
+		if (arch_timer_counter_has_wa()) {
+			rd = arch_counter_get_cntvct_stable;
+			scr = raw_counter_get_cntvct_stable;
 		} else {
-			if (arch_timer_counter_has_wa()) {
-				rd = arch_counter_get_cntpct_stable;
-				scr = raw_counter_get_cntpct_stable;
-			} else {
-				rd = arch_counter_get_cntpct;
-				scr = arch_counter_get_cntpct;
-			}
+			rd = arch_counter_get_cntvct;
+			scr = arch_counter_get_cntvct;
 		}
-
-		arch_timer_read_counter = rd;
-		clocksource_counter.vdso_clock_mode = vdso_default;
 	} else {
-		arch_timer_read_counter = arch_counter_get_cntvct_mem;
-		scr = arch_counter_get_cntvct_mem;
+		if (arch_timer_counter_has_wa()) {
+			rd = arch_counter_get_cntpct_stable;
+			scr = raw_counter_get_cntpct_stable;
+		} else {
+			rd = arch_counter_get_cntpct;
+			scr = arch_counter_get_cntpct;
+		}
 	}
 
+	arch_timer_read_counter = rd;
+	clocksource_counter.vdso_clock_mode = vdso_default;
+
 	width = arch_counter_get_width();
 	clocksource_counter.mask = CLOCKSOURCE_MASK(width);
 	cyclecounter.mask = CLOCKSOURCE_MASK(width);
@@ -1303,76 +1080,10 @@ static int __init arch_timer_register(void)
 	return err;
 }
 
-static int __init arch_timer_mem_register(void __iomem *base, unsigned int irq)
-{
-	int ret;
-	irq_handler_t func;
-
-	arch_timer_mem = kzalloc(sizeof(*arch_timer_mem), GFP_KERNEL);
-	if (!arch_timer_mem)
-		return -ENOMEM;
-
-	arch_timer_mem->base = base;
-	arch_timer_mem->evt.irq = irq;
-	__arch_timer_setup(ARCH_TIMER_TYPE_MEM, &arch_timer_mem->evt);
-
-	if (arch_timer_mem_use_virtual)
-		func = arch_timer_handler_virt_mem;
-	else
-		func = arch_timer_handler_phys_mem;
-
-	ret = request_irq(irq, func, IRQF_TIMER, "arch_mem_timer", &arch_timer_mem->evt);
-	if (ret) {
-		pr_err("Failed to request mem timer irq\n");
-		kfree(arch_timer_mem);
-		arch_timer_mem = NULL;
-	}
-
-	return ret;
-}
-
-static const struct of_device_id arch_timer_of_match[] __initconst = {
-	{ .compatible   = "arm,armv7-timer",    },
-	{ .compatible   = "arm,armv8-timer",    },
-	{},
-};
-
-static const struct of_device_id arch_timer_mem_of_match[] __initconst = {
-	{ .compatible   = "arm,armv7-timer-mem", },
-	{},
-};
-
-static bool __init arch_timer_needs_of_probing(void)
-{
-	struct device_node *dn;
-	bool needs_probing = false;
-	unsigned int mask = ARCH_TIMER_TYPE_CP15 | ARCH_TIMER_TYPE_MEM;
-
-	/* We have two timers, and both device-tree nodes are probed. */
-	if ((arch_timers_present & mask) == mask)
-		return false;
-
-	/*
-	 * Only one type of timer is probed,
-	 * check if we have another type of timer node in device-tree.
-	 */
-	if (arch_timers_present & ARCH_TIMER_TYPE_CP15)
-		dn = of_find_matching_node(NULL, arch_timer_mem_of_match);
-	else
-		dn = of_find_matching_node(NULL, arch_timer_of_match);
-
-	if (dn && of_device_is_available(dn))
-		needs_probing = true;
-
-	of_node_put(dn);
-
-	return needs_probing;
-}
-
 static int __init arch_timer_common_init(void)
 {
-	arch_timer_banner(arch_timers_present);
-	arch_counter_register(arch_timers_present);
+	arch_timer_banner();
+	arch_counter_register();
 	return arch_timer_arch_init();
 }
 
@@ -1421,13 +1132,11 @@ static int __init arch_timer_of_init(struct device_node *np)
 	u32 rate;
 	bool has_names;
 
-	if (arch_timers_present & ARCH_TIMER_TYPE_CP15) {
+	if (arch_timer_evt) {
 		pr_warn("multiple nodes in dt, skipping\n");
 		return 0;
 	}
 
-	arch_timers_present |= ARCH_TIMER_TYPE_CP15;
-
 	has_names = of_property_present(np, "interrupt-names");
 
 	for (i = ARCH_TIMER_PHYS_SECURE_PPI; i < ARCH_TIMER_MAX_TIMER_PPI; i++) {
@@ -1472,283 +1181,22 @@ static int __init arch_timer_of_init(struct device_node *np)
 	if (ret)
 		return ret;
 
-	if (arch_timer_needs_of_probing())
-		return 0;
-
 	return arch_timer_common_init();
 }
 TIMER_OF_DECLARE(armv7_arch_timer, "arm,armv7-timer", arch_timer_of_init);
 TIMER_OF_DECLARE(armv8_arch_timer, "arm,armv8-timer", arch_timer_of_init);
 
-static u32 __init
-arch_timer_mem_frame_get_cntfrq(struct arch_timer_mem_frame *frame)
-{
-	void __iomem *base;
-	u32 rate;
-
-	base = ioremap(frame->cntbase, frame->size);
-	if (!base) {
-		pr_err("Unable to map frame @ %pa\n", &frame->cntbase);
-		return 0;
-	}
-
-	rate = readl_relaxed(base + CNTFRQ);
-
-	iounmap(base);
-
-	return rate;
-}
-
-static struct arch_timer_mem_frame * __init
-arch_timer_mem_find_best_frame(struct arch_timer_mem *timer_mem)
-{
-	struct arch_timer_mem_frame *frame, *best_frame = NULL;
-	void __iomem *cntctlbase;
-	u32 cnttidr;
-	int i;
-
-	cntctlbase = ioremap(timer_mem->cntctlbase, timer_mem->size);
-	if (!cntctlbase) {
-		pr_err("Can't map CNTCTLBase @ %pa\n",
-			&timer_mem->cntctlbase);
-		return NULL;
-	}
-
-	cnttidr = readl_relaxed(cntctlbase + CNTTIDR);
-
-	/*
-	 * Try to find a virtual capable frame. Otherwise fall back to a
-	 * physical capable frame.
-	 */
-	for (i = 0; i < ARCH_TIMER_MEM_MAX_FRAMES; i++) {
-		u32 cntacr = CNTACR_RFRQ | CNTACR_RWPT | CNTACR_RPCT |
-			     CNTACR_RWVT | CNTACR_RVOFF | CNTACR_RVCT;
-
-		frame = &timer_mem->frame[i];
-		if (!frame->valid)
-			continue;
-
-		/* Try enabling everything, and see what sticks */
-		writel_relaxed(cntacr, cntctlbase + CNTACR(i));
-		cntacr = readl_relaxed(cntctlbase + CNTACR(i));
-
-		if ((cnttidr & CNTTIDR_VIRT(i)) &&
-		    !(~cntacr & (CNTACR_RWVT | CNTACR_RVCT))) {
-			best_frame = frame;
-			arch_timer_mem_use_virtual = true;
-			break;
-		}
-
-		if (~cntacr & (CNTACR_RWPT | CNTACR_RPCT))
-			continue;
-
-		best_frame = frame;
-	}
-
-	iounmap(cntctlbase);
-
-	return best_frame;
-}
-
-static int __init
-arch_timer_mem_frame_register(struct arch_timer_mem_frame *frame)
-{
-	void __iomem *base;
-	int ret, irq;
-
-	if (arch_timer_mem_use_virtual)
-		irq = frame->virt_irq;
-	else
-		irq = frame->phys_irq;
-
-	if (!irq) {
-		pr_err("Frame missing %s irq.\n",
-		       arch_timer_mem_use_virtual ? "virt" : "phys");
-		return -EINVAL;
-	}
-
-	if (!request_mem_region(frame->cntbase, frame->size,
-				"arch_mem_timer"))
-		return -EBUSY;
-
-	base = ioremap(frame->cntbase, frame->size);
-	if (!base) {
-		pr_err("Can't map frame's registers\n");
-		return -ENXIO;
-	}
-
-	ret = arch_timer_mem_register(base, irq);
-	if (ret) {
-		iounmap(base);
-		return ret;
-	}
-
-	arch_timers_present |= ARCH_TIMER_TYPE_MEM;
-
-	return 0;
-}
-
-static int __init arch_timer_mem_of_init(struct device_node *np)
-{
-	struct arch_timer_mem *timer_mem;
-	struct arch_timer_mem_frame *frame;
-	struct resource res;
-	int ret = -EINVAL;
-	u32 rate;
-
-	timer_mem = kzalloc(sizeof(*timer_mem), GFP_KERNEL);
-	if (!timer_mem)
-		return -ENOMEM;
-
-	if (of_address_to_resource(np, 0, &res))
-		goto out;
-	timer_mem->cntctlbase = res.start;
-	timer_mem->size = resource_size(&res);
-
-	for_each_available_child_of_node_scoped(np, frame_node) {
-		u32 n;
-		struct arch_timer_mem_frame *frame;
-
-		if (of_property_read_u32(frame_node, "frame-number", &n)) {
-			pr_err(FW_BUG "Missing frame-number.\n");
-			goto out;
-		}
-		if (n >= ARCH_TIMER_MEM_MAX_FRAMES) {
-			pr_err(FW_BUG "Wrong frame-number, only 0-%u are permitted.\n",
-			       ARCH_TIMER_MEM_MAX_FRAMES - 1);
-			goto out;
-		}
-		frame = &timer_mem->frame[n];
-
-		if (frame->valid) {
-			pr_err(FW_BUG "Duplicated frame-number.\n");
-			goto out;
-		}
-
-		if (of_address_to_resource(frame_node, 0, &res))
-			goto out;
-
-		frame->cntbase = res.start;
-		frame->size = resource_size(&res);
-
-		frame->virt_irq = irq_of_parse_and_map(frame_node,
-						       ARCH_TIMER_VIRT_SPI);
-		frame->phys_irq = irq_of_parse_and_map(frame_node,
-						       ARCH_TIMER_PHYS_SPI);
-
-		frame->valid = true;
-	}
-
-	frame = arch_timer_mem_find_best_frame(timer_mem);
-	if (!frame) {
-		pr_err("Unable to find a suitable frame in timer @ %pa\n",
-			&timer_mem->cntctlbase);
-		ret = -EINVAL;
-		goto out;
-	}
-
-	rate = arch_timer_mem_frame_get_cntfrq(frame);
-	arch_timer_of_configure_rate(rate, np);
-
-	ret = arch_timer_mem_frame_register(frame);
-	if (!ret && !arch_timer_needs_of_probing())
-		ret = arch_timer_common_init();
-out:
-	kfree(timer_mem);
-	return ret;
-}
-TIMER_OF_DECLARE(armv7_arch_timer_mem, "arm,armv7-timer-mem",
-		       arch_timer_mem_of_init);
-
 #ifdef CONFIG_ACPI_GTDT
-static int __init
-arch_timer_mem_verify_cntfrq(struct arch_timer_mem *timer_mem)
-{
-	struct arch_timer_mem_frame *frame;
-	u32 rate;
-	int i;
-
-	for (i = 0; i < ARCH_TIMER_MEM_MAX_FRAMES; i++) {
-		frame = &timer_mem->frame[i];
-
-		if (!frame->valid)
-			continue;
-
-		rate = arch_timer_mem_frame_get_cntfrq(frame);
-		if (rate == arch_timer_rate)
-			continue;
-
-		pr_err(FW_BUG "CNTFRQ mismatch: frame @ %pa: (0x%08lx), CPU: (0x%08lx)\n",
-			&frame->cntbase,
-			(unsigned long)rate, (unsigned long)arch_timer_rate);
-
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
-static int __init arch_timer_mem_acpi_init(int platform_timer_count)
-{
-	struct arch_timer_mem *timers, *timer;
-	struct arch_timer_mem_frame *frame, *best_frame = NULL;
-	int timer_count, i, ret = 0;
-
-	timers = kcalloc(platform_timer_count, sizeof(*timers),
-			    GFP_KERNEL);
-	if (!timers)
-		return -ENOMEM;
-
-	ret = acpi_arch_timer_mem_init(timers, &timer_count);
-	if (ret || !timer_count)
-		goto out;
-
-	/*
-	 * While unlikely, it's theoretically possible that none of the frames
-	 * in a timer expose the combination of feature we want.
-	 */
-	for (i = 0; i < timer_count; i++) {
-		timer = &timers[i];
-
-		frame = arch_timer_mem_find_best_frame(timer);
-		if (!best_frame)
-			best_frame = frame;
-
-		ret = arch_timer_mem_verify_cntfrq(timer);
-		if (ret) {
-			pr_err("Disabling MMIO timers due to CNTFRQ mismatch\n");
-			goto out;
-		}
-
-		if (!best_frame) /* implies !frame */
-			/*
-			 * Only complain about missing suitable frames if we
-			 * haven't already found one in a previous iteration.
-			 */
-			pr_err("Unable to find a suitable frame in timer @ %pa\n",
-				&timer->cntctlbase);
-	}
-
-	if (best_frame)
-		ret = arch_timer_mem_frame_register(best_frame);
-out:
-	kfree(timers);
-	return ret;
-}
-
-/* Initialize per-processor generic timer and memory-mapped timer(if present) */
 static int __init arch_timer_acpi_init(struct acpi_table_header *table)
 {
-	int ret, platform_timer_count;
+	int ret;
 
-	if (arch_timers_present & ARCH_TIMER_TYPE_CP15) {
+	if (arch_timer_evt) {
 		pr_warn("already initialized, skipping\n");
 		return -EINVAL;
 	}
 
-	arch_timers_present |= ARCH_TIMER_TYPE_CP15;
-
-	ret = acpi_gtdt_init(table, &platform_timer_count);
+	ret = acpi_gtdt_init(table, NULL);
 	if (ret)
 		return ret;
 
@@ -1790,10 +1238,6 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
 	if (ret)
 		return ret;
 
-	if (platform_timer_count &&
-	    arch_timer_mem_acpi_init(platform_timer_count))
-		pr_err("Failed to initialize memory-mapped timer.\n");
-
 	return arch_timer_common_init();
 }
 TIMER_ACPI_DECLARE(arch_timer, ACPI_SIG_GTDT, arch_timer_acpi_init);
diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h
index ce6521ad04d12..2eda895f19f54 100644
--- a/include/clocksource/arm_arch_timer.h
+++ b/include/clocksource/arm_arch_timer.h
@@ -9,9 +9,6 @@
 #include <linux/timecounter.h>
 #include <linux/types.h>
 
-#define ARCH_TIMER_TYPE_CP15		BIT(0)
-#define ARCH_TIMER_TYPE_MEM		BIT(1)
-
 #define ARCH_TIMER_CTRL_ENABLE		(1 << 0)
 #define ARCH_TIMER_CTRL_IT_MASK		(1 << 1)
 #define ARCH_TIMER_CTRL_IT_STAT		(1 << 2)
@@ -51,8 +48,6 @@ enum arch_timer_spi_nr {
 
 #define ARCH_TIMER_PHYS_ACCESS		0
 #define ARCH_TIMER_VIRT_ACCESS		1
-#define ARCH_TIMER_MEM_PHYS_ACCESS	2
-#define ARCH_TIMER_MEM_VIRT_ACCESS	3
 
 #define ARCH_TIMER_MEM_MAX_FRAMES	8
 
-- 
2.39.2

[PATCH v2 4/4] clocksource/drivers/arm_arch_timer_mmio: Add MMIO clocksource

[Marc Zyngier]

The MMIO driver can also double as a clocksource, something that was
missing in its previous incarnation. Add it for completeness.

Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20250807160243.1970533-5-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/clocksource/arm_arch_timer_mmio.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/clocksource/arm_arch_timer_mmio.c b/drivers/clocksource/arm_arch_timer_mmio.c
index 3522d1d8cb97b..ebe1987d651eb 100644
--- a/drivers/clocksource/arm_arch_timer_mmio.c
+++ b/drivers/clocksource/arm_arch_timer_mmio.c
@@ -45,6 +45,7 @@ enum arch_timer_access {
 
 struct arch_timer {
 	struct clock_event_device	evt;
+	struct clocksource		cs;
 	struct arch_timer_mem		*gt_block;
 	void __iomem			*base;
 	enum arch_timer_access		access;
@@ -52,6 +53,7 @@ struct arch_timer {
 };
 
 #define evt_to_arch_timer(e) container_of(e, struct arch_timer, evt)
+#define cs_to_arch_timer(c) container_of(c, struct arch_timer, cs)
 
 static void arch_timer_mmio_write(struct arch_timer *timer,
 				  enum arch_timer_reg reg, u64 val)
@@ -128,6 +130,13 @@ static noinstr u64 arch_counter_mmio_get_cnt(struct arch_timer *t)
 	return ((u64) cnt_hi << 32) | cnt_lo;
 }
 
+static u64 arch_mmio_counter_read(struct clocksource *cs)
+{
+	struct arch_timer *at = cs_to_arch_timer(cs);
+
+	return arch_counter_mmio_get_cnt(at);
+}
+
 static int arch_timer_mmio_shutdown(struct clock_event_device *clk)
 {
 	struct arch_timer *at = evt_to_arch_timer(clk);
@@ -256,6 +265,16 @@ static void arch_timer_mmio_setup(struct arch_timer *at, int irq)
 					(unsigned long)CLOCKSOURCE_MASK(56));
 
 	enable_irq(at->evt.irq);
+
+	at->cs = (struct clocksource) {
+		.name	= "arch_mmio_counter",
+		.rating	= 300,
+		.read	= arch_mmio_counter_read,
+		.mask	= CLOCKSOURCE_MASK(56),
+		.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+	};
+
+	clocksource_register_hz(&at->cs, at->rate);
 }
 
 static int arch_timer_mmio_frame_register(struct platform_device *pdev,
-- 
2.39.2