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    Subject[PATCH v23 02/11] clocksource: arm_arch_timer: split dt-only rate handling
    Date
    From: Fu Wei <fu.wei@linaro.org>

    Currently Currently arch_timer_detect_rate() tried to handle both the
    sysreg timer and MMIO timer, with DT-specific fallback code. This gets
    in the way of implementing deterministic and correct rate probing when
    using ACPI.

    This patch moves this logic out into the (DT-specific) probe functions,
    allowing different logic to be used in the ACPI case, and making it
    easier to see which CNTFRQ register is being read in each case.

    Signed-off-by: Fu Wei <fu.wei@linaro.org>
    [Mark: reword commit message, TODO: rework comments]
    Signed-off-by: Mark Rutland <mark.rutland@arm.com>
    ---
    drivers/clocksource/arm_arch_timer.c | 58 +++++++++++++++++++-----------------
    1 file changed, 30 insertions(+), 28 deletions(-)

    diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
    index 843f923..1b6a7e6 100644
    --- a/drivers/clocksource/arm_arch_timer.c
    +++ b/drivers/clocksource/arm_arch_timer.c
    @@ -560,30 +560,6 @@ static u32 arch_timer_mem_get_cntfrq(void __iomem *cntbase)
    return readl_relaxed(cntbase + CNTFRQ);
    }

    -static void
    -arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np)
    -{
    - /* 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 (!acpi_disabled ||
    - of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) {
    - if (cntbase)
    - arch_timer_rate = arch_timer_mem_get_cntfrq(cntbase);
    - else
    - arch_timer_rate = arch_timer_get_cntfrq();
    - }
    -
    - /* Check the timer frequency. */
    - if (arch_timer_rate == 0)
    - pr_warn("frequency not available\n");
    -}
    -
    static void arch_timer_banner(unsigned type)
    {
    pr_info("%s%s%s timer(s) running at %lu.%02luMHz (%s%s%s).\n",
    @@ -958,7 +934,17 @@ 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);
    + /*
    + * Determine the frequency of system counter:
    + * Try to get the frequency from the device tree.
    + * If fail, try the sysreg CNTFRQ. Then verify the frequency.
    + */
    + if (of_property_read_u32(np, "clock-frequency", &arch_timer_rate))
    + arch_timer_rate = arch_timer_get_cntfrq();
    + if (!arch_timer_rate) {
    + pr_err(FW_BUG "frequency not available.\n");
    + return -EINVAL;
    + }

    arch_timer_c3stop = !of_property_read_bool(np, "always-on");

    @@ -1069,7 +1055,19 @@ 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 the CNTFRQ reg of MMIO timer.
    + */
    + if (!arch_timer_rate &&
    + of_property_read_u32(np, "clock-frequency", &arch_timer_rate))
    + arch_timer_rate = arch_timer_mem_get_cntfrq(base);
    + if (!arch_timer_rate) {
    + pr_err(FW_BUG "MMIO frequency not available.\n");
    + ret = -EINVAL;
    + goto out;
    + }
    +
    ret = arch_timer_mem_register(base, irq);
    if (ret)
    goto out;
    @@ -1130,8 +1128,12 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
    map_generic_timer_interrupt(gtdt->non_secure_el2_interrupt,
    gtdt->non_secure_el2_flags);

    - /* Get the frequency from CNTFRQ */
    - arch_timer_detect_rate(NULL, NULL);
    + /* Get the frequency from the sysreg CNTFRQ */
    + arch_timer_rate = arch_timer_get_cntfrq();
    + if (!arch_timer_rate) {
    + pr_err(FW_BUG "frequency not available.\n");
    + return -EINVAL;
    + }

    arch_timer_uses_ppi = arch_timer_select_ppi();
    if (!arch_timer_ppi[arch_timer_uses_ppi]) {
    --
    2.9.3
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