clocksource: arm_arch_timer: rework PPI selection

Currently, the arch timer driver uses ARCH_TIMER_PHYS_SECURE_PPI to mean
the driver will use the secure PPI *and* potentially also use the
non-secure PPI. This is somewhat confusing.

For arm64 it never makes sense to use the secure PPI, but we do anyway,
inheriting this behaviour from 32-bit arm. For ACPI, we may not even
have a valid secure PPI, so we need to be able to only request the
non-secure PPI.

To that end, this patch reworks the timer driver so that we can request
the non-secure PPI alone. The PPI selection is split out into a new
function, arch_timer_select_ppi(), and verification of the selected PPI
is shifted out to callers (as DT may select the PPI by other means and
must handle this anyway).

We now consistently use arch_timer_has_nonsecure_ppi() to determine
whether we must manage a non-secure PPI *in addition* to a secure PPI.
When we only have a non-secure PPI, this returns false.

Signed-off-by: Fu Wei <fu.wei@linaro.org>
Tested-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
[Mark: reword commit message]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>

1 files changed, 46 insertions, 31 deletions

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 15059c958be7..94de018c65d0 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -992,7 +992,7 @@ static int __init arch_timer_register(void)
         case ARCH_TIMER_PHYS_NONSECURE_PPI:
                 err = request_percpu_irq(ppi, arch_timer_handler_phys,
                                          "arch_timer", arch_timer_evt);
-                if (!err && arch_timer_ppi[ARCH_TIMER_PHYS_NONSECURE_PPI]) {
+                if (!err && arch_timer_has_nonsecure_ppi()) {
                         ppi = arch_timer_ppi[ARCH_TIMER_PHYS_NONSECURE_PPI];
                         err = request_percpu_irq(ppi, arch_timer_handler_phys,
                                                  "arch_timer", arch_timer_evt);
@@ -1114,39 +1114,41 @@ static int __init arch_timer_common_init(void)
         return arch_timer_arch_init();
 }
 
-static int __init arch_timer_init(void)
+/**
+ * arch_timer_select_ppi() - Select suitable PPI for the current system.
+ *
+ * If HYP mode is available, we know that the physical timer
+ * has been configured to be accessible from PL1. Use it, so
+ * that a guest can use the virtual timer instead.
+ *
+ * On ARMv8.1 with VH extensions, the kernel runs in HYP. VHE
+ * accesses to CNTP_*_EL1 registers are silently redirected to
+ * their CNTHP_*_EL2 counterparts, and use a different PPI
+ * number.
+ *
+ * If no interrupt provided for virtual timer, we'll have to
+ * stick to the physical timer. It'd better be accessible...
+ * For arm64 we never use the secure interrupt.
+ *
+ * Return: a suitable PPI type for the current system.
+ */
+static enum arch_timer_ppi_nr __init arch_timer_select_ppi(void)
 {
-        int ret;
-        /*
-         * If HYP mode is available, we know that the physical timer
-         * has been configured to be accessible from PL1. Use it, so
-         * that a guest can use the virtual timer instead.
-         *
-         * If no interrupt provided for virtual timer, we'll have to
-         * stick to the physical timer. It'd better be accessible...
-         *
-         * On ARMv8.1 with VH extensions, the kernel runs in HYP. VHE
-         * accesses to CNTP_*_EL1 registers are silently redirected to
-         * their CNTHP_*_EL2 counterparts, and use a different PPI
-         * number.
-         */
-        if (is_hyp_mode_available() || !arch_timer_ppi[ARCH_TIMER_VIRT_PPI]) {
-                bool has_ppi;
+        if (is_kernel_in_hyp_mode())
+                return ARCH_TIMER_HYP_PPI;
 
-                if (is_kernel_in_hyp_mode()) {
-                        arch_timer_uses_ppi = ARCH_TIMER_HYP_PPI;
-                        has_ppi = !!arch_timer_ppi[ARCH_TIMER_HYP_PPI];
-                } else {
-                        arch_timer_uses_ppi = ARCH_TIMER_PHYS_SECURE_PPI;
-                        has_ppi = (!!arch_timer_ppi[ARCH_TIMER_PHYS_SECURE_PPI] ||
-                                   !!arch_timer_ppi[ARCH_TIMER_PHYS_NONSECURE_PPI]);
-                }
+        if (!is_hyp_mode_available() && arch_timer_ppi[ARCH_TIMER_VIRT_PPI])
+                return ARCH_TIMER_VIRT_PPI;
 
-                if (!has_ppi) {
-                        pr_warn("No interrupt available, giving up\n");
-                        return -EINVAL;
-                }
-        }
+        if (IS_ENABLED(CONFIG_ARM64))
+                return ARCH_TIMER_PHYS_NONSECURE_PPI;
+
+        return ARCH_TIMER_PHYS_SECURE_PPI;
+}
+
+static int __init arch_timer_init(void)
+{
+        int ret;
 
         ret = arch_timer_register();
         if (ret)
@@ -1188,6 +1190,13 @@ static int __init arch_timer_of_init(struct device_node *np)
         if (IS_ENABLED(CONFIG_ARM) &&
             of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
                 arch_timer_uses_ppi = ARCH_TIMER_PHYS_SECURE_PPI;
+        else
+                arch_timer_uses_ppi = arch_timer_select_ppi();
+
+        if (!arch_timer_ppi[arch_timer_uses_ppi]) {
+                pr_err("No interrupt available, giving up\n");
+                return -EINVAL;
+        }
 
         /* On some systems, the counter stops ticking when in suspend. */
         arch_counter_suspend_stop = of_property_read_bool(np,
@@ -1333,6 +1342,12 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
         /* Get the frequency from CNTFRQ */
         arch_timer_detect_rate(NULL, NULL);
 
+        arch_timer_uses_ppi = arch_timer_select_ppi();
+        if (!arch_timer_ppi[arch_timer_uses_ppi]) {
+                pr_err("No interrupt available, giving up\n");
+                return -EINVAL;
+        }
+
         /* Always-on capability */
         arch_timer_c3stop = !(gtdt->non_secure_el1_flags & ACPI_GTDT_ALWAYS_ON);