From: Fu Wei fu.wei@linaro.org
Currently, the counter frequency detection call(arch_timer_detect_rate) combines all the ways to get counter frequency: device-tree property, system coprocessor register, MMIO timer. But in the most of use cases, we don't need all the ways to try: For example, reading device-tree property will be needed only when system boot with device-tree, getting frequency from MMIO timer register will beneeded only when we init MMIO timer.
This patch separates paths to determine frequency: Separate out device-tree code, keep them in device-tree init function. Separate out the MMIO frequency and the sysreg frequency detection call, and use the appropriate one for the counter.
Signed-off-by: Fu Wei fu.wei@linaro.org --- drivers/clocksource/arm_arch_timer.c | 49 +++++++++++++++++++++++------------- 1 file changed, 31 insertions(+), 18 deletions(-)
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index e43be0a..e554081 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -487,27 +487,31 @@ static int arch_timer_starting_cpu(unsigned int cpu) return 0; }
-static void -arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np) +static void arch_timer_detect_rate(void) { - /* Who has more than one independent system counter? */ - if (arch_timer_rate) - return; + /* + * Try to get the timer frequency from + * cntfrq_el0(system coprocessor register). + */ + if (!arch_timer_rate) + arch_timer_rate = arch_timer_get_cntfrq(); + + /* Check the timer frequency. */ + if (!arch_timer_rate) + pr_warn("frequency not available\n"); +}
+static void arch_timer_mem_detect_rate(void __iomem *cntbase) +{ /* - * Try to determine the frequency from the device tree or CNTFRQ, - * if ACPI is enabled, get the frequency from CNTFRQ ONLY. + * Try to determine the frequency from + * CNTFRQ in memory-mapped timer. */ - if (!acpi_disabled || - of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) { - if (cntbase) - arch_timer_rate = readl_relaxed(cntbase + CNTFRQ); - else - arch_timer_rate = arch_timer_get_cntfrq(); - } + if (!arch_timer_rate) + arch_timer_rate = readl_relaxed(cntbase + CNTFRQ);
/* Check the timer frequency. */ - if (arch_timer_rate == 0) + if (!arch_timer_rate) pr_warn("frequency not available\n"); }
@@ -883,7 +887,9 @@ static int __init arch_timer_of_init(struct device_node *np) for (i = ARCH_TIMER_PHYS_SECURE_PPI; i < ARCH_TIMER_MAX_TIMER_PPI; i++) arch_timer_ppi[i] = irq_of_parse_and_map(np, i);
- arch_timer_detect_rate(NULL, np); + if (!arch_timer_rate && + of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) + arch_timer_detect_rate();
arch_timer_c3stop = !of_property_read_bool(np, "always-on");
@@ -986,7 +992,14 @@ static int __init arch_timer_mem_init(struct device_node *np) goto out; }
- arch_timer_detect_rate(base, np); + /* + * Try to determine the frequency from the device tree, + * if fail, get the frequency from CNTFRQ. + */ + if (!arch_timer_rate && + of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) + arch_timer_mem_detect_rate(base); + ret = arch_timer_mem_register(base, irq); if (ret) goto out; @@ -1048,7 +1061,7 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table) gtdt->non_secure_el2_flags);
/* Get the frequency from CNTFRQ */ - arch_timer_detect_rate(NULL, NULL); + arch_timer_detect_rate();
arch_timer_uses_ppi = arch_timer_select_ppi(); if (!arch_timer_ppi[arch_timer_uses_ppi]) {