On Friday, July 15, 2016 03:32:35 PM Fu Wei wrote:

Hi Rafael,



On 14 July 2016 at 04:30, Rafael J. Wysocki [off-list ref] wrote:

quoted

On Wed, Jul 13, 2016 at 7:53 PM,  [off-list ref] wrote:

quoted

From: Fu Wei <redacted>

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 <redacted>
Signed-off-by: Hanjun Guo <redacted>
---
 drivers/acpi/Kconfig           |   5 ++
 drivers/acpi/Makefile          |   1 +
 drivers/acpi/arm64/Kconfig     |  15 ++++
 drivers/acpi/arm64/Makefile    |   1 +
 drivers/acpi/arm64/acpi_gtdt.c | 170 +++++++++++++++++++++++++++++++++++++++++
 include/linux/acpi.h           |   6 ++
 6 files changed, 198 insertions(+)

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index b7e2e77..1cdc7d2 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig

@@ -521,4 +521,9 @@ config XPOWER_PMIC_OPREGION

 endif

+if ARM64
+source "drivers/acpi/arm64/Kconfig"
+
+endif
+
 endif  # ACPI

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 251ce85..1a94ff7 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile

@@ -99,5 +99,6 @@ obj-$(CONFIG_ACPI_EXTLOG)     += acpi_extlog.o
 obj-$(CONFIG_PMIC_OPREGION)    += pmic/intel_pmic.o
 obj-$(CONFIG_CRC_PMIC_OPREGION) += pmic/intel_pmic_crc.o
 obj-$(CONFIG_XPOWER_PMIC_OPREGION) += pmic/intel_pmic_xpower.o
+obj-$(CONFIG_ARM64)    += arm64/

 video-objs                     += acpi_video.o video_detect.o

diff --git a/drivers/acpi/arm64/Kconfig b/drivers/acpi/arm64/Kconfig
new file mode 100644
index 0000000..ff5c253
--- /dev/null
+++ b/drivers/acpi/arm64/Kconfig

@@ -0,0 +1,15 @@
+#
+# ACPI Configuration for ARM64
+#
+
+menu "The ARM64-specific ACPI Support"
+
+config ACPI_GTDT
+       bool "ACPI GTDT table Support"

This should depend on ARM64.

Also I wonder if it needs to be user-selectable?  Wouldn't it be
better to enable it by default when building for ARM64 with ACPI?

quoted

+       help
+         GTDT (Generic Timer Description Table) provides information
+         for per-processor timers and Platform (memory-mapped) timers
+         for ARM platforms. Select this option to provide information
+         needed for the timers init.
+
+endmenu

diff --git a/drivers/acpi/arm64/Makefile b/drivers/acpi/arm64/Makefile
new file mode 100644
index 0000000..466de6b
--- /dev/null
+++ b/drivers/acpi/arm64/Makefile

@@ -0,0 +1 @@
+obj-$(CONFIG_ACPI_GTDT)                += acpi_gtdt.o

diff --git a/drivers/acpi/arm64/acpi_gtdt.c b/drivers/acpi/arm64/acpi_gtdt.c
new file mode 100644
index 0000000..9ee977d
--- /dev/null
+++ b/drivers/acpi/arm64/acpi_gtdt.c

@@ -0,0 +1,170 @@
+/*
+ * 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 <linux/module.h>
+
+#include <clocksource/arm_arch_timer.h>
+
+#undef pr_fmt
+#define pr_fmt(fmt) "GTDT: " fmt

I would add "ACPI" to the prefix too if I were you, but that's me.

good idea, you are right, will do

quoted

quoted

+
+typedef struct {
+       struct acpi_table_gtdt *gtdt;
+       void *platform_timer_start;
+       void *gtdt_end;
+} acpi_gtdt_desc_t;
+
+static acpi_gtdt_desc_t 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;
+
+       if (gh->type == ACPI_GTDT_TYPE_TIMER_BLOCK)
+               return true;
+
+       return false;

This is just too much code.  It would suffice to do

    return gh->type == ACPI_GTDT_TYPE_TIMER_BLOCK;

quoted

+}
+
+static inline bool is_watchdog(void *platform_timer)
+{
+       struct acpi_gtdt_header *gh = platform_timer;
+
+       if (gh->type == ACPI_GTDT_TYPE_WATCHDOG)
+               return true;
+
+       return false;

Just like above.

Thanks, this is better :-) will do

quoted

quoted

+}
+
+/*
+ * 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.
+ */
+static int __init acpi_gtdt_desc_init(struct acpi_table_header *table)
+{
+       struct acpi_table_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_info("Revision:%d doesn't support Platform Timers.\n",
+                       table->revision);

Is it really useful to print this message (and the one below) at the
"info" level?  What about changing them to pr_debug()?

yes, pr_debug is better, thanks :-) will do

quoted

quoted

+               return 0;
+       }
+
+       if (!gtdt->platform_timer_count) {
+               pr_info("No Platform Timer.\n");
+               return 0;
+       }
+
+       acpi_gtdt_desc.platform_timer_start = (void *)gtdt +
+                                             gtdt->platform_timer_offset;
+       if (acpi_gtdt_desc.platform_timer_start <
+           (void *)table + sizeof(struct acpi_table_gtdt)) {
+               pr_err(FW_BUG "Platform Timer pointer error.\n");

Why pr_err()?

if (true), that means the GTDT table has bugs.

And that's not a very useful piece of information unless you're debugging the
platform, is it?

Thanks,
Rafael