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[PATCH v12 0/8] acpi, clocksource: add GTDT driver and GTDT support in arm_arch_timer

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  [PATCH v12 0/8] acpi, clocksource: add GTDT driver and GTDT support in arm_arch_timer fu.wei@linaro.org - 2016-09-13 12:50 +0200
    [PATCH v12 7/8] clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped timer fu.wei@linaro.org - 2016-09-13 12:50 +0200
      Re: [PATCH v12 7/8] clocksource/drivers/arm_arch_timer: Add GTDT  support for memory-mapped timer Marc Zyngier <marc.zyngier@arm.com> - 2016-09-13 13:10 +0200
        Re: [PATCH v12 7/8] clocksource/drivers/arm_arch_timer: Add GTDT  support for memory-mapped timer Fu Wei <fu.wei@linaro.org> - 2016-09-13 13:40 +0200
    [PATCH v12 4/8] acpi/arm64: Add GTDT table parse driver fu.wei@linaro.org - 2016-09-13 12:50 +0200

#1482367 — [PATCH v12 0/8] acpi, clocksource: add GTDT driver and GTDT support in arm_arch_timer

From: Fu Wei <fu.wei@linaro.org>

This patchset:
    (1)Preparation for adding GTDT support in arm_arch_timer:
        1. Move some enums and marcos to header file;
        2. Add a new enum for spi type;
        3. Improve printk relevant code.

    (2)Introduce ACPI GTDT parser: drivers/acpi/arm64/acpi_gtdt.c
    Parse all kinds of timer in GTDT table of ACPI:arch timer,
    memory-mapped timer and SBSA Generic Watchdog timer.
    This driver can help to simplify all the relevant timer drivers,
    and separate all the ACPI GTDT knowledge from them.

    (3)Simplify ACPI code for arm_arch_timer

    (4)Add GTDT support for ARM memory-mapped timer

This patchset depends on the following patchset:
[UPDATE PATCH V11 1/8] ACPI: I/O Remapping Table (IORT) initial support
https://lkml.org/lkml/2016/9/12/949

This patchset has been tested on the following platforms:
    (1)ARM Foundation v8 model

Changelog:
v12: https://lkml.org/lkml/2016/9/13/
     Rebase to latest Linux 4.8-rc6
     Delete the confusing "skipping" in the error message.

V11: https://lkml.org/lkml/2016/9/6/354
     Rebase to latest Linux 4.8-rc5
     Delete typedef (suggested by checkpatch.pl)

V10: https://lkml.org/lkml/2016/7/26/215
     Drop the "readq" patch.
     Rebase to latest Linux 4.7.

V9: https://lkml.org/lkml/2016/7/25/345
    Improve pr_err message in acpi gtdt driver.
    Update Commit message for 7/9
    shorten the irq mapping function name
    Improve GTDT driver for memory-mapped timer

v8: https://lkml.org/lkml/2016/7/19/660
    Improve "pr_fmt(fmt)" definition: add "ACPI" in front of "GTDT",
    and also improve printk message.
    Simplify is_timer_block and is_watchdog.
    Merge acpi_gtdt_desc_init and gtdt_arch_timer_init into acpi_gtdt_init();
    Delete __init in include/linux/acpi.h for GTDT API
    Make ARM64 select GTDT.
    Delete "#include <linux/module.h>" from acpi_gtdt.c
    Simplify GT block parse code.

v7: https://lkml.org/lkml/2016/7/13/769
    Move the GTDT driver to drivers/acpi/arm64
    Add add the ARM64-specific ACPI Support maintainers in MAINTAINERS
    Merge 3 patches of GTDT parser driver.
    Fix the for_each_platform_timer bug.

v6: https://lkml.org/lkml/2016/6/29/580
    split the GTDT driver to 4 parts: basic, arch_timer, memory-mapped timer,
    and SBSA Generic Watchdog timer
    Improve driver by suggestions and example code from Daniel Lezcano

v5: https://lkml.org/lkml/2016/5/24/356
    Sorting out all patches, simplify the API of GTDT driver:
    GTDT driver just fills the data struct for arm_arch_timer driver.

v4: https://lists.linaro.org/pipermail/linaro-acpi/2016-March/006667.html
    Delete the kvm relevant patches
    Separate two patches for sorting out the code for arm_arch_timer.
    Improve irq info export code to allow missing irq info in GTDT table.

v3: https://lkml.org/lkml/2016/2/1/658
    Improve GTDT driver code:
      (1)improve pr_* by defining pr_fmt(fmt)
      (2)simplify gtdt_sbsa_gwdt_init
      (3)improve gtdt_arch_timer_data_init, if table is NULL, it will try
      to get GTDT table.
    Move enum ppi_nr to arm_arch_timer.h, and add enum spi_nr.
    Add arm_arch_timer get ppi from DT and GTDT support for kvm.

v2: https://lkml.org/lkml/2015/12/2/10
    Rebase to latest kernel version(4.4-rc3).
    Fix the bug about the config problem,
    use CONFIG_ACPI_GTDT instead of CONFIG_ACPI in arm_arch_timer.c

v1: The first upstreaming version: https://lkml.org/lkml/2015/10/28/553

Fu Wei (8):
  clocksource/drivers/arm_arch_timer: Move enums and defines to header
    file
  clocksource/drivers/arm_arch_timer: Add a new enum for spi type
  clocksource/drivers/arm_arch_timer: Improve printk relevant code
  acpi/arm64: Add GTDT table parse driver
  clocksource/drivers/arm_arch_timer: Simplify ACPI support code.
  acpi/arm64: Add memory-mapped timer support in GTDT driver
  clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped
    timer
  acpi/arm64: Add SBSA Generic Watchdog support in GTDT driver

 arch/arm64/Kconfig                   |   1 +
 drivers/acpi/arm64/Kconfig           |   3 +
 drivers/acpi/arm64/Makefile          |   1 +
 drivers/acpi/arm64/gtdt.c            | 309 +++++++++++++++++++++++++++++++++++
 drivers/clocksource/Kconfig          |   2 +-
 drivers/clocksource/arm_arch_timer.c | 225 +++++++++++++++++--------
 drivers/watchdog/Kconfig             |   1 +
 include/clocksource/arm_arch_timer.h |  32 ++++
 include/linux/acpi.h                 |   7 +
 9 files changed, 510 insertions(+), 71 deletions(-)
 create mode 100644 drivers/acpi/arm64/gtdt.c

-- 
2.7.4

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#1482368 — [PATCH v12 7/8] clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped timer

From: Fu Wei <fu.wei@linaro.org>

The patch add memory-mapped timer register support by using the information
provided by the new GTDT driver of ACPI.

Signed-off-by: Fu Wei <fu.wei@linaro.org>
---
 drivers/clocksource/arm_arch_timer.c | 127 ++++++++++++++++++++++++++++++++++-
 1 file changed, 124 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 0197ef9..d33802b 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -888,7 +888,128 @@ CLOCKSOURCE_OF_DECLARE(armv7_arch_timer_mem, "arm,armv7-timer-mem",
 		       arch_timer_mem_init);
 
 #ifdef CONFIG_ACPI_GTDT
-/* Initialize per-processor generic timer */
+static struct gt_timer_data __init *arch_timer_mem_get_timer(
+						struct gt_block_data *gt_blocks)
+{
+	struct gt_block_data *gt_block = gt_blocks;
+	struct gt_timer_data *best_frame = NULL;
+	void __iomem *cntctlbase;
+	u32 cnttidr;
+	int i;
+
+	/*
+	 * According to ARMv8 Architecture Reference Manual(ARM),
+	 * the size of CNTCTLBase frame of memory-mapped timer
+	 * is SZ_4K(Offset 0x000 – 0xFFF).
+	 */
+	cntctlbase = ioremap(gt_block->cntctlbase_phy, SZ_4K);
+	if (!cntctlbase) {
+		pr_err("Failed to map mem timer control frame base address\n");
+		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 < gt_block->timer_count; i++) {
+		int n;
+		u32 cntacr;
+
+		n = gt_block->timer[i].frame_nr;
+
+		/* Try enabling everything, and see what sticks */
+		cntacr = CNTACR_RFRQ | CNTACR_RWPT | CNTACR_RPCT |
+			 CNTACR_RWVT | CNTACR_RVOFF | CNTACR_RVCT;
+		writel_relaxed(cntacr, cntctlbase + CNTACR(n));
+		cntacr = readl_relaxed(cntctlbase + CNTACR(n));
+
+		if ((cnttidr & CNTTIDR_VIRT(n)) &&
+		    !(~cntacr & (CNTACR_RWVT | CNTACR_RVCT))) {
+			best_frame = &gt_block->timer[i];
+			arch_timer_mem_use_virtual = true;
+			break;
+		}
+
+		if (~cntacr & (CNTACR_RWPT | CNTACR_RPCT))
+			continue;
+
+		best_frame = &gt_block->timer[i];
+	}
+	iounmap(cntctlbase);
+
+	return best_frame;
+}
+
+static int __init arch_timer_mem_acpi_init(size_t timer_count)
+{
+	struct gt_block_data *gt_blocks;
+	struct gt_timer_data *gt_timer;
+	void __iomem *timer_cntbase;
+	int ret = -EINVAL;
+	int timer_irq;
+
+	/*
+	 * If we don't have any Platform Timer Structures, just return.
+	 */
+	if (!timer_count)
+		return 0;
+
+	/*
+	 * before really check all the Platform Timer Structures,
+	 * we assume they are GT block, and allocate memory for them.
+	 * We will free these memory once we finish the initialization.
+	 */
+	gt_blocks = kcalloc(timer_count, sizeof(*gt_blocks), GFP_KERNEL);
+	if (!gt_blocks)
+		return -ENOMEM;
+
+	if (gtdt_arch_timer_mem_init(gt_blocks) > 0) {
+		gt_timer = arch_timer_mem_get_timer(gt_blocks);
+		if (!gt_timer) {
+			pr_err("Failed to get mem timer info.\n");
+			goto error;
+		}
+
+		if (arch_timer_mem_use_virtual)
+			timer_irq = gt_timer->virtual_irq;
+		else
+			timer_irq = gt_timer->irq;
+		if (!timer_irq) {
+			pr_err("Failed to get %s irq for mem timer.",
+			       arch_timer_mem_use_virtual ? "virt" : "phys");
+			goto error;
+		}
+
+		/*
+		 * According to ARMv8 Architecture Reference Manual(ARM),
+		 * the size of CNTBaseN frames of memory-mapped timer
+		 * is SZ_4K(Offset 0x000 – 0xFFF).
+		 */
+		timer_cntbase = ioremap(gt_timer->cntbase_phy, SZ_4K);
+		if (!timer_cntbase) {
+			pr_err("Failed to map mem timer base address.\n");
+			goto error;
+		}
+
+		ret = arch_timer_mem_register(timer_cntbase, timer_irq);
+		if (ret) {
+			iounmap(timer_cntbase);
+			pr_err("Failed to register mem timer.\n");
+			goto error;
+		}
+
+		arch_counter_base = timer_cntbase;
+		arch_timers_present |= ARCH_MEM_TIMER;
+	}
+
+error:
+	kfree(gt_blocks);
+	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 timer_count;
@@ -912,8 +1033,8 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
 	/* Get the frequency from CNTFRQ */
 	arch_timer_detect_rate(NULL, NULL);
 
-	if (timer_count < 0)
-		pr_err("Failed to get platform timer info.\n");
+	if (timer_count < 0 || arch_timer_mem_acpi_init((size_t)timer_count))
+		pr_err("Failed to initialize memory-mapped timer.\n");
 
 	return arch_timer_init();
 }
-- 
2.7.4

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#1482377 — Re: [PATCH v12 7/8] clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped timer

Argh, new version...

On 13/09/16 11:39, fu.wei@linaro.org wrote:
> From: Fu Wei <fu.wei@linaro.org>
> 
> The patch add memory-mapped timer register support by using the information
> provided by the new GTDT driver of ACPI.
> 
> Signed-off-by: Fu Wei <fu.wei@linaro.org>
> ---
>  drivers/clocksource/arm_arch_timer.c | 127 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 124 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index 0197ef9..d33802b 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -888,7 +888,128 @@ CLOCKSOURCE_OF_DECLARE(armv7_arch_timer_mem, "arm,armv7-timer-mem",
>  		       arch_timer_mem_init);
>  
>  #ifdef CONFIG_ACPI_GTDT
> -/* Initialize per-processor generic timer */
> +static struct gt_timer_data __init *arch_timer_mem_get_timer(
> +						struct gt_block_data *gt_blocks)
> +{
> +	struct gt_block_data *gt_block = gt_blocks;
> +	struct gt_timer_data *best_frame = NULL;
> +	void __iomem *cntctlbase;
> +	u32 cnttidr;
> +	int i;
> +
> +	/*
> +	 * According to ARMv8 Architecture Reference Manual(ARM),
> +	 * the size of CNTCTLBase frame of memory-mapped timer
> +	 * is SZ_4K(Offset 0x000 – 0xFFF).
> +	 */
> +	cntctlbase = ioremap(gt_block->cntctlbase_phy, SZ_4K);
> +	if (!cntctlbase) {
> +		pr_err("Failed to map mem timer control frame base address\n");
> +		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 < gt_block->timer_count; i++) {
> +		int n;
> +		u32 cntacr;
> +
> +		n = gt_block->timer[i].frame_nr;
> +
> +		/* Try enabling everything, and see what sticks */
> +		cntacr = CNTACR_RFRQ | CNTACR_RWPT | CNTACR_RPCT |
> +			 CNTACR_RWVT | CNTACR_RVOFF | CNTACR_RVCT;
> +		writel_relaxed(cntacr, cntctlbase + CNTACR(n));
> +		cntacr = readl_relaxed(cntctlbase + CNTACR(n));
> +
> +		if ((cnttidr & CNTTIDR_VIRT(n)) &&
> +		    !(~cntacr & (CNTACR_RWVT | CNTACR_RVCT))) {
> +			best_frame = &gt_block->timer[i];
> +			arch_timer_mem_use_virtual = true;
> +			break;
> +		}
> +
> +		if (~cntacr & (CNTACR_RWPT | CNTACR_RPCT))
> +			continue;
> +
> +		best_frame = &gt_block->timer[i];
> +	}
> +	iounmap(cntctlbase);

As I just said in my reply to the same patch in v11, all of this is
duplicating existing infrastructure that already exists for DT. Please
consider decoupling the core driver code from the firmware side and make
this reusable.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

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#1482384 — Re: [PATCH v12 7/8] clocksource/drivers/arm_arch_timer: Add GTDT support for memory-mapped timer

Hi Marc,


On 09/13/2016 07:00 PM, Marc Zyngier wrote:
> Argh, new version...
>
> On 13/09/16 11:39, fu.wei@linaro.org wrote:
>> From: Fu Wei <fu.wei@linaro.org>
>>
>> The patch add memory-mapped timer register support by using the information
>> provided by the new GTDT driver of ACPI.
>>
>> Signed-off-by: Fu Wei <fu.wei@linaro.org>
>> ---
>>  drivers/clocksource/arm_arch_timer.c | 127 ++++++++++++++++++++++++++++++++++-
>>  1 file changed, 124 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
>> index 0197ef9..d33802b 100644
>> --- a/drivers/clocksource/arm_arch_timer.c
>> +++ b/drivers/clocksource/arm_arch_timer.c
>> @@ -888,7 +888,128 @@ CLOCKSOURCE_OF_DECLARE(armv7_arch_timer_mem, "arm,armv7-timer-mem",
>>  		       arch_timer_mem_init);
>>  
>>  #ifdef CONFIG_ACPI_GTDT
>> -/* Initialize per-processor generic timer */
>> +static struct gt_timer_data __init *arch_timer_mem_get_timer(
>> +						struct gt_block_data *gt_blocks)
>> +{
>> +	struct gt_block_data *gt_block = gt_blocks;
>> +	struct gt_timer_data *best_frame = NULL;
>> +	void __iomem *cntctlbase;
>> +	u32 cnttidr;
>> +	int i;
>> +
>> +	/*
>> +	 * According to ARMv8 Architecture Reference Manual(ARM),
>> +	 * the size of CNTCTLBase frame of memory-mapped timer
>> +	 * is SZ_4K(Offset 0x000 – 0xFFF).
>> +	 */
>> +	cntctlbase = ioremap(gt_block->cntctlbase_phy, SZ_4K);
>> +	if (!cntctlbase) {
>> +		pr_err("Failed to map mem timer control frame base address\n");
>> +		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 < gt_block->timer_count; i++) {
>> +		int n;
>> +		u32 cntacr;
>> +
>> +		n = gt_block->timer[i].frame_nr;
>> +
>> +		/* Try enabling everything, and see what sticks */
>> +		cntacr = CNTACR_RFRQ | CNTACR_RWPT | CNTACR_RPCT |
>> +			 CNTACR_RWVT | CNTACR_RVOFF | CNTACR_RVCT;
>> +		writel_relaxed(cntacr, cntctlbase + CNTACR(n));
>> +		cntacr = readl_relaxed(cntctlbase + CNTACR(n));
>> +
>> +		if ((cnttidr & CNTTIDR_VIRT(n)) &&
>> +		    !(~cntacr & (CNTACR_RWVT | CNTACR_RVCT))) {
>> +			best_frame = &gt_block->timer[i];
>> +			arch_timer_mem_use_virtual = true;
>> +			break;
>> +		}
>> +
>> +		if (~cntacr & (CNTACR_RWPT | CNTACR_RPCT))
>> +			continue;
>> +
>> +		best_frame = &gt_block->timer[i];
>> +	}
>> +	iounmap(cntctlbase);
> As I just said in my reply to the same patch in v11, all of this is
> duplicating existing infrastructure that already exists for DT. Please
> consider decoupling the core driver code from the firmware side and make
> this reusable.

Great thanks for your help, I am working on it now.
Any suggestion for other arm_arch_timer patches?

> Thanks,
>
> 	M.

-- 
Best regards,

Fu Wei
Software Engineer
Red Hat 

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#1482369 — [PATCH v12 4/8] acpi/arm64: Add GTDT table parse driver

From: Fu Wei <fu.wei@linaro.org>

This patch adds support for parsing arch timer in GTDT,
provides some kernel APIs to parse all the PPIs and
always-on info in GTDT and export them.

By this driver, we can simplify arm_arch_timer drivers, and
separate the ACPI GTDT knowledge from it.

Signed-off-by: Fu Wei <fu.wei@linaro.org>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 arch/arm64/Kconfig          |   1 +
 drivers/acpi/arm64/Kconfig  |   3 +
 drivers/acpi/arm64/Makefile |   1 +
 drivers/acpi/arm64/gtdt.c   | 152 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/clocksource/Kconfig |   1 -
 include/linux/acpi.h        |   6 ++
 6 files changed, 163 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index bc3f00f..0607728 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -2,6 +2,7 @@ config ARM64
 	def_bool y
 	select ACPI_CCA_REQUIRED if ACPI
 	select ACPI_GENERIC_GSI if ACPI
+	select ACPI_GTDT if ACPI
 	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
 	select ACPI_MCFG if ACPI
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
diff --git a/drivers/acpi/arm64/Kconfig b/drivers/acpi/arm64/Kconfig
index 4616da4..5a6f80f 100644
--- a/drivers/acpi/arm64/Kconfig
+++ b/drivers/acpi/arm64/Kconfig
@@ -4,3 +4,6 @@
 
 config ACPI_IORT
 	bool
+
+config ACPI_GTDT
+	bool
diff --git a/drivers/acpi/arm64/Makefile b/drivers/acpi/arm64/Makefile
index 72331f2..1017def 100644
--- a/drivers/acpi/arm64/Makefile
+++ b/drivers/acpi/arm64/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_ACPI_IORT) 	+= iort.o
+obj-$(CONFIG_ACPI_GTDT) 	+= gtdt.o
diff --git a/drivers/acpi/arm64/gtdt.c b/drivers/acpi/arm64/gtdt.c
new file mode 100644
index 0000000..b24844d
--- /dev/null
+++ b/drivers/acpi/arm64/gtdt.c
@@ -0,0 +1,152 @@
+/*
+ * ARM Specific GTDT table Support
+ *
+ * Copyright (C) 2016, Linaro Ltd.
+ * Author: Daniel Lezcano <daniel.lezcano@linaro.org>
+ *         Fu Wei <fu.wei@linaro.org>
+ *         Hanjun Guo <hanjun.guo@linaro.org>
+ *
+ * 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/acpi.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+
+#include <clocksource/arm_arch_timer.h>
+
+#undef pr_fmt
+#define pr_fmt(fmt) "ACPI GTDT: " fmt
+
+struct acpi_gtdt_descriptor {
+	struct acpi_table_gtdt *gtdt;
+	void *platform_timer_start;
+	void *gtdt_end;
+};
+
+static struct acpi_gtdt_descriptor acpi_gtdt_desc __initdata;
+
+static inline void *next_platform_timer(void *platform_timer)
+{
+	struct acpi_gtdt_header *gh = platform_timer;
+
+	platform_timer += gh->length;
+	if (platform_timer < acpi_gtdt_desc.gtdt_end)
+		return platform_timer;
+
+	return NULL;
+}
+
+#define for_each_platform_timer(_g)				\
+	for (_g = acpi_gtdt_desc.platform_timer_start; _g;	\
+	     _g = next_platform_timer(_g))
+
+static inline bool is_timer_block(void *platform_timer)
+{
+	struct acpi_gtdt_header *gh = platform_timer;
+
+	return gh->type == ACPI_GTDT_TYPE_TIMER_BLOCK;
+}
+
+static inline bool is_watchdog(void *platform_timer)
+{
+	struct acpi_gtdt_header *gh = platform_timer;
+
+	return gh->type == ACPI_GTDT_TYPE_WATCHDOG;
+}
+
+static int __init map_gt_gsi(u32 interrupt, u32 flags)
+{
+	int trigger, polarity;
+
+	if (!interrupt)
+		return 0;
+
+	trigger = (flags & ACPI_GTDT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
+			: ACPI_LEVEL_SENSITIVE;
+
+	polarity = (flags & ACPI_GTDT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
+			: ACPI_ACTIVE_HIGH;
+
+	return acpi_register_gsi(NULL, interrupt, trigger, polarity);
+}
+
+/*
+ * Map the PPIs of per-cpu arch_timer.
+ * @type: the type of PPI
+ * Returns 0 if error.
+ */
+int __init acpi_gtdt_map_ppi(int type)
+{
+	struct acpi_table_gtdt *gtdt = acpi_gtdt_desc.gtdt;
+
+	switch (type) {
+	case PHYS_SECURE_PPI:
+		return map_gt_gsi(gtdt->secure_el1_interrupt,
+				  gtdt->secure_el1_flags);
+	case PHYS_NONSECURE_PPI:
+		return map_gt_gsi(gtdt->non_secure_el1_interrupt,
+				  gtdt->non_secure_el1_flags);
+	case VIRT_PPI:
+		return map_gt_gsi(gtdt->virtual_timer_interrupt,
+				  gtdt->virtual_timer_flags);
+
+	case HYP_PPI:
+		return map_gt_gsi(gtdt->non_secure_el2_interrupt,
+				  gtdt->non_secure_el2_flags);
+	default:
+		pr_err("Failed to map timer interrupt: invalid type.\n");
+	}
+
+	return 0;
+}
+
+/*
+ * acpi_gtdt_c3stop - got c3stop info from GTDT
+ *
+ * Returns 1 if the timer is powered in deep idle state, 0 otherwise.
+ */
+bool __init acpi_gtdt_c3stop(void)
+{
+	struct acpi_table_gtdt *gtdt = acpi_gtdt_desc.gtdt;
+
+	return !(gtdt->non_secure_el1_flags & ACPI_GTDT_ALWAYS_ON);
+}
+
+/*
+ * Get some basic info from GTDT table, and init the global variables above
+ * for all timers initialization of Generic Timer.
+ * This function does some validation on GTDT table.
+ */
+int __init acpi_gtdt_init(struct acpi_table_header *table)
+{
+	void *start;
+	struct acpi_table_gtdt *gtdt;
+
+	gtdt = container_of(table, struct acpi_table_gtdt, header);
+
+	acpi_gtdt_desc.gtdt = gtdt;
+	acpi_gtdt_desc.gtdt_end = (void *)table + table->length;
+
+	if (table->revision < 2) {
+		pr_debug("Revision:%d doesn't support Platform Timers.\n",
+			 table->revision);
+		return 0;
+	}
+
+	if (!gtdt->platform_timer_count) {
+		pr_debug("No Platform Timer.\n");
+		return 0;
+	}
+
+	start = (void *)gtdt + gtdt->platform_timer_offset;
+	if (start < (void *)table + sizeof(struct acpi_table_gtdt)) {
+		pr_err(FW_BUG "Failed to retrieve timer info from firmware: invalid data.\n");
+		return -EINVAL;
+	}
+	acpi_gtdt_desc.platform_timer_start = start;
+
+	return gtdt->platform_timer_count;
+}
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 5677886..b58d259 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -285,7 +285,6 @@ config CLKSRC_MPS2
 config ARM_ARCH_TIMER
 	bool
 	select CLKSRC_OF if OF
-	select CLKSRC_ACPI if ACPI
 
 config ARM_ARCH_TIMER_EVTSTREAM
 	bool "Enable ARM architected timer event stream generation by default"
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index c5eaf2f..e2f9841 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -567,6 +567,12 @@ enum acpi_reconfig_event  {
 int acpi_reconfig_notifier_register(struct notifier_block *nb);
 int acpi_reconfig_notifier_unregister(struct notifier_block *nb);
 
+#ifdef CONFIG_ACPI_GTDT
+int acpi_gtdt_init(struct acpi_table_header *table);
+int acpi_gtdt_map_ppi(int type);
+bool acpi_gtdt_c3stop(void);
+#endif
+
 #else	/* !CONFIG_ACPI */
 
 #define acpi_disabled 1
-- 
2.7.4

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