Re: [PATCH] firmware/psci: Add debugfs support to ease debugging

Bhupesh Sharma <bhupesh.sharma@xxxxxxxxxx> · Thu, 28 Jul 2022 02:25:20 +0530

On 7/28/22 2:23 AM, Dmitry Baryshkov wrote:
On Wed, 27 Jul 2022 at 23:15, Bhupesh Sharma <bhupesh.sharma@xxxxxxxxxx> wrote:

Hi Dmitry,

On 7/28/22 1:39 AM, Dmitry Baryshkov wrote:
To ease debugging of PSCI supported features, add debugfs file called
'psci' describing PSCI and SMC CC versions, enabled features and
options.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
---
   drivers/firmware/psci/psci.c | 112 ++++++++++++++++++++++++++++++++++-
   include/uapi/linux/psci.h    |   9 +++
   2 files changed, 120 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index b907768eea01..6595cc964635 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -9,6 +9,7 @@
   #include <linux/acpi.h>
   #include <linux/arm-smccc.h>
   #include <linux/cpuidle.h>
+#include <linux/debugfs.h>
   #include <linux/errno.h>
   #include <linux/linkage.h>
   #include <linux/of.h>
@@ -324,12 +325,121 @@ static void psci_sys_poweroff(void)
       invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
   }

-static int __init psci_features(u32 psci_func_id)
+static int psci_features(u32 psci_func_id)

This change doesn't seem related to the patch $SUBJECT.
Also is it really needed? If yes, probably this should be a separate patch.

It is related and I don't think it should be moved to a separate
patch. Removing the __init annotation from psci_features() is
necessary to allow using psci_features() from psci_debufs_read(),
which is definitely not an __init code. Otherwise reading from
debugfs/psci would cause null pointer exceptions.

Ok, and what is the behavior with CONFIG_DEBUG_FS = n?
Does your patch work well in that case?

Thanks.


   {
       return invoke_psci_fn(PSCI_1_0_FN_PSCI_FEATURES,
                             psci_func_id, 0, 0);
   }

+#ifdef CONFIG_DEBUG_FS
+
+#define PSCI_ID(ver, _name) \
+     { .fn = PSCI_##ver##_FN_##_name, .name = #_name, }
+#define PSCI_ID_NATIVE(ver, _name) \
+     { .fn = PSCI_FN_NATIVE(ver, _name), .name = #_name, }
+
+/* A table of all optional functions */
+static const struct {
+     u32 fn;
+     const char *name;
+} psci_fn_ids[] = {
+     PSCI_ID_NATIVE(0_2, MIGRATE),
+     PSCI_ID(0_2, MIGRATE_INFO_TYPE),
+     PSCI_ID_NATIVE(0_2, MIGRATE_INFO_UP_CPU),
+     PSCI_ID(1_0, CPU_FREEZE),
+     PSCI_ID_NATIVE(1_0, CPU_DEFAULT_SUSPEND),
+     PSCI_ID_NATIVE(1_0, NODE_HW_STATE),
+     PSCI_ID_NATIVE(1_0, SYSTEM_SUSPEND),
+     PSCI_ID(1_0, SET_SUSPEND_MODE),
+     PSCI_ID_NATIVE(1_0, STAT_RESIDENCY),
+     PSCI_ID_NATIVE(1_0, STAT_COUNT),
+     PSCI_ID_NATIVE(1_1, SYSTEM_RESET2),
+};
+
+static int psci_debugfs_read(struct seq_file *s, void *data)
+{
+     int feature, type, i;
+     u32 ver;
+
+     ver = psci_ops.get_version();
+     seq_printf(s, "PSCIv%d.%d\n",
+                PSCI_VERSION_MAJOR(ver),
+                PSCI_VERSION_MINOR(ver));
+
+     /* PSCI_FEATURES is available only starting from 1.0 */
+     if (PSCI_VERSION_MAJOR(ver) < 1)
+             return 0;
+
+     feature = psci_features(ARM_SMCCC_VERSION_FUNC_ID);
+     if (feature != PSCI_RET_NOT_SUPPORTED) {
+             ver = invoke_psci_fn(ARM_SMCCC_VERSION_FUNC_ID, 0, 0, 0);
+             seq_printf(s, "SMC Calling Convention v%d.%d\n",
+                        PSCI_VERSION_MAJOR(ver),
+                        PSCI_VERSION_MINOR(ver));
+     } else {
+             seq_printf(s, "SMC Calling Convention v1.0 is assumed\n");
+     }
+
+     feature = psci_features(PSCI_FN_NATIVE(0_2, CPU_SUSPEND));
+     if (feature < 0) {
+             seq_printf(s, "PSCI_FEATURES(CPU_SUSPEND) error (%d)\n", feature);
+     } else {
+             seq_printf(s, "OSI is %ssupported\n",
+                        (feature & BIT(0)) ? "" : "not ");
+             seq_printf(s, "%s StateID format is used\n",
+                        (feature & BIT(1)) ? "Extended" : "Original");
+     }
+
+     type = psci_ops.migrate_info_type();
+     if (type == PSCI_0_2_TOS_UP_MIGRATE ||
+         type == PSCI_0_2_TOS_UP_NO_MIGRATE) {
+             unsigned long cpuid;
+
+             seq_printf(s, "Trusted OS %smigrate capable\n",
+                        type == PSCI_0_2_TOS_UP_NO_MIGRATE ? "not " : "");
+             cpuid = psci_migrate_info_up_cpu();
+             seq_printf(s, "Trusted OS resident on physical CPU 0x%lx (#%d)\n", cpuid, resident_cpu);
+     } else if (type == PSCI_0_2_TOS_MP) {
+             seq_printf(s, "Trusted OS migration not required\n");
+     } else {
+             if (type != PSCI_RET_NOT_SUPPORTED)
+                     seq_printf(s, "MIGRATE_INFO_TYPE returned unknown type (%d)\n", type);
+     }
+
+     for (i = 0; i < ARRAY_SIZE(psci_fn_ids); i++) {
+             feature = psci_features(psci_fn_ids[i].fn);
+             if (feature == PSCI_RET_NOT_SUPPORTED)
+                     continue;
+             if (feature < 0)
+                     seq_printf(s, "PSCI_FEATURES(%s) error (%d)\n", psci_fn_ids[i].name, feature);
+             else
+                     seq_printf(s, "%s is supported\n", psci_fn_ids[i].name);
+     }
+
+     return 0;
+}
+
+static int psci_debugfs_open(struct inode *inode, struct file *f)
+{
+     return single_open(f, psci_debugfs_read, NULL);
+}
+
+static const struct file_operations psci_debugfs_ops = {
+     .owner = THIS_MODULE,
+     .open = psci_debugfs_open,
+     .release = single_release,
+     .read = seq_read,
+     .llseek = seq_lseek
+};
+
+static int __init psci_debugfs_init(void)
+{
+     return PTR_ERR_OR_ZERO(debugfs_create_file("psci", S_IRUGO, NULL, NULL,
+                                                &psci_debugfs_ops));
+}
+late_initcall(psci_debugfs_init)
+#endif
+
   #ifdef CONFIG_CPU_IDLE
   static int psci_suspend_finisher(unsigned long state)
   {
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index 2bf93c0d6354..f6f0bad5858b 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -48,11 +48,20 @@
   #define PSCI_0_2_FN64_MIGRATE_INFO_UP_CPU   PSCI_0_2_FN64(7)

   #define PSCI_1_0_FN_PSCI_FEATURES           PSCI_0_2_FN(10)
+#define PSCI_1_0_FN_CPU_FREEZE                       PSCI_0_2_FN(11)
+#define PSCI_1_0_FN_CPU_DEFAULT_SUSPEND              PSCI_0_2_FN(12)
+#define PSCI_1_0_FN_NODE_HW_STATE            PSCI_0_2_FN(13)
   #define PSCI_1_0_FN_SYSTEM_SUSPEND          PSCI_0_2_FN(14)
   #define PSCI_1_0_FN_SET_SUSPEND_MODE                PSCI_0_2_FN(15)
+#define PSCI_1_0_FN_STAT_RESIDENCY           PSCI_0_2_FN(16)
+#define PSCI_1_0_FN_STAT_COUNT                       PSCI_0_2_FN(17)
   #define PSCI_1_1_FN_SYSTEM_RESET2           PSCI_0_2_FN(18)

+#define PSCI_1_0_FN64_CPU_DEFAULT_SUSPEND    PSCI_0_2_FN64(12)
+#define PSCI_1_0_FN64_NODE_HW_STATE          PSCI_0_2_FN64(13)
   #define PSCI_1_0_FN64_SYSTEM_SUSPEND                PSCI_0_2_FN64(14)
+#define PSCI_1_0_FN64_STAT_RESIDENCY         PSCI_0_2_FN64(16)
+#define PSCI_1_0_FN64_STAT_COUNT             PSCI_0_2_FN64(17)
   #define PSCI_1_1_FN64_SYSTEM_RESET2         PSCI_0_2_FN64(18)

   /* PSCI v0.2 power state encoding for CPU_SUSPEND function */









