Hi Rafael,

On 21 July 2016 at 21:28, Rafael J. Wysocki [off-list ref] wrote:

On Wednesday, July 20, 2016 02:18:00 AM fu.wei at linaro.org 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>
---
 arch/arm64/Kconfig             |   1 +
 drivers/acpi/Kconfig           |   5 ++
 drivers/acpi/Makefile          |   1 +
 drivers/acpi/arm64/Kconfig     |   5 ++
 drivers/acpi/arm64/Makefile    |   1 +
 drivers/acpi/arm64/acpi_gtdt.c | 152 +++++++++++++++++++++++++++++++++++++++++
 drivers/clocksource/Kconfig    |   1 -
 include/linux/acpi.h           |   6 ++
 8 files changed, 171 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 5a0a691..0b9fba7 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 ARCH_HAS_DEVMEM_IS_ALLOWED
      select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE

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..80201be
--- /dev/null
+++ b/drivers/acpi/arm64/Kconfig

@@ -0,0 +1,5 @@
+#
+# ACPI Configuration for ARM64
+#
+config ACPI_GTDT
+     bool

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..e1cfc9e
--- /dev/null
+++ b/drivers/acpi/arm64/acpi_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
+
+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;
+
+     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_generic_timer_interrupt(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_generic_timer_interrupt(gtdt->secure_el1_interrupt,
+                                                gtdt->secure_el1_flags);
+     case PHYS_NONSECURE_PPI:
+             return map_generic_timer_interrupt(gtdt->non_secure_el1_interrupt,
+                                                gtdt->non_secure_el1_flags);
+     case VIRT_PPI:
+             return map_generic_timer_interrupt(gtdt->virtual_timer_interrupt,
+                                                gtdt->virtual_timer_flags);
+
+     case HYP_PPI:
+             return map_generic_timer_interrupt(gtdt->non_secure_el2_interrupt,
+                                                gtdt->non_secure_el2_flags);
+     default:
+             pr_err("Map PPI failed: 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 init table: ACPI/GTDT is buggy.\n");

I would prefer something like

                pr_err(FW_BUG "Failed to retrieve timer information from firmware (invalid data)\n");

which is clear enough IMO and doesn't require whoever reads this message
to know anything about ACPI/GTDT etc.

OK, NP, I will do, and Thanks for your suggestion :-)
I will also check other pr_* , see If I can update them

thanks

Thanks,
Rafael

-- 
Best regards,

Fu Wei
Software Engineer
Red Hat