From: Fu Wei <[email protected]> The patch refactor original arch_timer_detect_rate function: (1) Separate out device-tree code, keep them in device-tree init function: arch_timer_of_init, arch_timer_mem_init; (2) Improve original mechanism, if getting from memory-mapped timer fail, try arch_timer_get_cntfrq() again.
Signed-off-by: Fu Wei <[email protected]> --- drivers/clocksource/arm_arch_timer.c | 45 +++++++++++++++++++++++------------- 1 file changed, 29 insertions(+), 16 deletions(-) diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index af22953..fe4e812 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 __iomem *cntbase) { /* Who has more than one independent system counter? */ if (arch_timer_rate) return; - /* - * Try to determine the frequency from the device tree or CNTFRQ, - * if ACPI is enabled, get the frequency from CNTFRQ ONLY. + * If we got memory-mapped timer(cntbase != NULL), + * 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 (cntbase) + arch_timer_rate = readl_relaxed(cntbase + CNTFRQ); + /* + * Because in a system that implements both Secure and + * Non-secure states, CNTFRQ is only accessible in Secure state. + * So the operation above may fail, even if (cntbase != NULL), + * especially on ARM64. + * In this case, we can try cntfrq_el0(system coprocessor register). + */ + if (!arch_timer_rate) + arch_timer_rate = arch_timer_get_cntfrq(); + else + return; /* 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(NULL); arch_timer_c3stop = !of_property_read_bool(np, "always-on"); @@ -983,7 +989,14 @@ 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_detect_rate(base); + ret = arch_timer_mem_register(base, irq); if (ret) goto out; @@ -1046,7 +1059,7 @@ 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(NULL); ret = arch_timer_uses_ppi_init(); if (ret) -- 2.7.4
