On Wed, Mar 29, 2017 at 10:31:42PM +0800, Fu Wei wrote:

On 29 March 2017 at 22:29, Fu Wei [off-list ref] wrote:

quoted

Hi Lorenzo,

On 28 March 2017 at 19:35, Lorenzo Pieralisi [off-list ref] wrote:

quoted

On Wed, Mar 22, 2017 at 12:31:18AM +0800, fu.wei at linaro.org wrote:

quoted

From: Fu Wei <redacted>

This patch adds support for parsing arch timer info 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>
Acked-by: Rafael J. Wysocki <redacted>

Acked-by: Lorenzo Pieralisi <redacted>

Some nits below.

quoted

Tested-by: Xiongfeng Wang <redacted>
Reviewed-by: Hanjun Guo <redacted>
Tested-by: Hanjun Guo <redacted>
---
 arch/arm64/Kconfig          |   1 +
 drivers/acpi/arm64/Kconfig  |   3 +
 drivers/acpi/arm64/Makefile |   1 +
 drivers/acpi/arm64/gtdt.c   | 157 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/acpi.h        |   6 ++
 5 files changed, 168 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 3741859..7e2baec 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 ACPI_SPCR_TABLE if ACPI

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..8a03b4b
--- /dev/null
+++ b/drivers/acpi/arm64/gtdt.c

@@ -0,0 +1,157 @@
+/*
+ * 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 - Store the key info of GTDT for all functions
+ * @gtdt:    The pointer to the struct acpi_table_gtdt of GTDT table.
+ * @gtdt_end:        The pointer to the end of GTDT table.
+ * @platform_timer:  The pointer to the start of Platform Timer Structure
+ *
+ * The struct store the key info of GTDT table, it should be initialized by
+ * acpi_gtdt_init.
+ */
+struct acpi_gtdt_descriptor {
+     struct acpi_table_gtdt *gtdt;
+     void *gtdt_end;
+     void *platform_timer;
+};
+
+static struct acpi_gtdt_descriptor acpi_gtdt_desc __initdata;
+
+static int __init map_gt_gsi(u32 interrupt, u32 flags)
+{
+     int trigger, polarity;
+
+     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);
+}
+
+/**
+ * acpi_gtdt_map_ppi() - Map the PPIs of per-cpu arch_timer.
+ * @type:    the type of PPI.
+ *
+ * Note: Linux on arm64 isn't supported on the secure side.

Note: Secure state is not managed by the kernel on ARM64 systems.

Is that what you wanted to say ?

quoted

+ * So we only handle the non-secure timer PPIs,
+ * ARCH_TIMER_PHYS_SECURE_PPI is treated as invalid type.
+ *
+ * Return: the mapped PPI value, 0 if error.
+ */
+int __init acpi_gtdt_map_ppi(int type)
+{
+     struct acpi_table_gtdt *gtdt = acpi_gtdt_desc.gtdt;
+
+     switch (type) {
+     case ARCH_TIMER_PHYS_NONSECURE_PPI:
+             return map_gt_gsi(gtdt->non_secure_el1_interrupt,
+                               gtdt->non_secure_el1_flags);
+     case ARCH_TIMER_VIRT_PPI:
+             return map_gt_gsi(gtdt->virtual_timer_interrupt,
+                               gtdt->virtual_timer_flags);
+
+     case ARCH_TIMER_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 according to the type of PPI.
+ * @type:    the type of PPI.
+ *
+ * Return: 1 if the timer can be in deep idle state, 0 otherwise.

Return: true if the timer HW state is lost when a CPU enters an idle
        state, false otherwise

quoted

+ */
+bool __init acpi_gtdt_c3stop(int type)
+{
+     struct acpi_table_gtdt *gtdt = acpi_gtdt_desc.gtdt;
+
+     switch (type) {
+     case ARCH_TIMER_PHYS_NONSECURE_PPI:
+             return !(gtdt->non_secure_el1_flags & ACPI_GTDT_ALWAYS_ON);
+
+     case ARCH_TIMER_VIRT_PPI:
+             return !(gtdt->virtual_timer_flags & ACPI_GTDT_ALWAYS_ON);
+
+     case ARCH_TIMER_HYP_PPI:
+             return !(gtdt->non_secure_el2_flags & ACPI_GTDT_ALWAYS_ON);
+
+     default:
+             pr_err("Failed to get c3stop info: invalid type.\n");
+     }
+
+     return 0;
+}
+
+/**
+ * acpi_gtdt_init() - Get the info of GTDT table to prepare for further init.
+ * @table:   The pointer to GTDT table.
+ * @platform_timer_count:    The pointer of int variate for returning the

I do not understand what this means.

quoted

+ *                           number of platform timers. It can be NULL, if
+ *                           driver don't need this info.

driver doesn't

quoted

+ *
+ * Return: 0 if success, -EINVAL if error.
+ */
+int __init acpi_gtdt_init(struct acpi_table_header *table,
+                       int *platform_timer_count)
+{
+     int ret = 0;
+     int timer_count = 0;
+     void *platform_timer = NULL;
+     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_warn("Revision:%d doesn't support Platform Timers.\n",
+                     table->revision);

Ok, two points here. First, I am not sure why you should warn if the
table revision is < 2, is that a FW bug ? I do not think it is, you
can just return 0.

quoted

+     else if (!gtdt->platform_timer_count)
+             pr_debug("No Platform Timer.\n");

Ditto. Why keep executing ? There is nothing to do, just bail out
with a return 0.

quoted

+     else
+             timer_count = gtdt->platform_timer_count;
+
+     if (timer_count) {
+             platform_timer = (void *)gtdt + gtdt->platform_timer_offset;
+             if (platform_timer < (void *)table +
+                                  sizeof(struct acpi_table_gtdt)) {
+                     pr_err(FW_BUG "invalid timer data.\n");
+                     timer_count = 0;
+                     platform_timer = NULL;
+             ret = -EINVAL;

Same here, I suspect you want to consolidate the return path (I missed
previous rounds of reviews so you should not worry too much, I can clean
this up later) but to me a:

return -EINVAL;

would just do.

For this problem, Can I do this:

/**
 * acpi_gtdt_init() - Get the info of GTDT table to prepare for further init.
 * @table:                        The pointer to GTDT table.
 * @platform_timer_count:        It points to a integer variable which is used
 *                                for storing the number of platform timers.
 *                                This pointer could be NULL, if the caller
 *                                doesn't need this info.
 *
 * Return: 0 if success, -EINVAL if error.
 */
int __init acpi_gtdt_init(struct acpi_table_header *table,
                          int *platform_timer_count)
{
        void *platform_timer;
        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;
        acpi_gtdt_desc.platform_timer = NULL;
        if (platform_timer_count)
                *platform_timer_count = 0;

        if (table->revision < 2) {
                pr_warn("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;
        }
        if (platform_timer_count)
                *platform_timer_count = gtdt->platform_timer_count;

sorry , this should be moved,

quoted

        platform_timer = (void *)gtdt + gtdt->platform_timer_offset;
        if (platform_timer < (void *)table + sizeof(struct acpi_table_gtdt)) {
                pr_err(FW_BUG "invalid timer data.\n");
                return -EINVAL;
        }
        acpi_gtdt_desc.platform_timer = platform_timer;

         if (platform_timer_count)
                 *platform_timer_count = gtdt->platform_timer_count;

Here is the right place

Ok, to avoid adding bugs to code that has been tested already keep
the current function version (as of v22) and send me a patch to clean
this up at -rc1.

Multiple calls to acpi_gtdt_init() were my main concern.

Thanks,
Lorenzo

quoted

        return 0;
}

quoted

Lorenzo

quoted

+             }
+     }
+
+     acpi_gtdt_desc.platform_timer = platform_timer;
+     if (platform_timer_count)
+             *platform_timer_count = timer_count;
+
+     return ret;
+}

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 9b05886..4b5c146 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h

@@ -595,6 +595,12 @@ 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 *platform_timer_count);
+int acpi_gtdt_map_ppi(int type);
+bool acpi_gtdt_c3stop(int type);
+#endif
+
 #else        /* !CONFIG_ACPI */

 #define acpi_disabled 1
--

2.9.3

--
Best regards,

Fu Wei
Software Engineer
Red Hat

-- 
Best regards,

Fu Wei
Software Engineer
Red Hat