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    Subject[Patch v4 3/6] cpufreq: qcom-cpufreq-hw: Add dcvs interrupt support
    Date
    Add interrupt support to notify the kernel of h/w initiated frequency
    throttling by LMh. Convey this to scheduler via thermal presssure
    interface.

    Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
    ---

    v3->v4:
    - Dropped devm_ versions of request_irq and free_irq as per comments on
    mailing list.
    - Introduced locking to prevent race between LMh de-init sequence and
    re-enabling of interrupts/polling after a thermal throttle event.
    - Moved the LMh de-init sequence to qcom_cpufreq_hw_lmh_exit as per
    Viresh's review comments
    - Code rearrangement as per Bjorn's review comments.
    - Moved the interrupt handling to threaded interrupt handling since Steev
    reported some scheduling while atomic bug on the mailing list.

    v2->v3:
    - Cosmetic fixes from review comments on the list.
    - Moved all LMh initializations to qcom_cpufreq_hw_lmh_init.
    - Added freeing of LMh interrupt and cancelling the polling worker to
    qcom_cpufreq_hw_cpu_exit as per Viresh's suggestion.
    - LMh interrupts are now tied to cpu dev and not cpufreq dev. This will be
    useful for further generation of SoCs where the same interrupt signals
    multiple cpu clusters.

    v1->v2:
    - Introduced qcom_cpufreq_hw_lmh_init to consolidate LMh related initializations
    as per Viresh's review comment.
    - Moved the piece of code restarting polling/re-enabling LMh interrupt to
    qcom_lmh_dcvs_notify therby simplifying isr and timer callback as per Viresh's
    suggestion.
    - Droped cpus from qcom_cpufreq_data and instead using cpus from cpufreq_policy in
    qcom_lmh_dcvs_notify as per Viresh's review comment.
    - Dropped dt property qcom,support-lmh as per Bjorn's suggestion.
    - Other minor/cosmetic fixes

    drivers/cpufreq/qcom-cpufreq-hw.c | 142 ++++++++++++++++++++++++++++++
    1 file changed, 142 insertions(+)

    diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
    index f86859bf76f1..3cc27d9e2ed1 100644
    --- a/drivers/cpufreq/qcom-cpufreq-hw.c
    +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
    @@ -7,12 +7,14 @@
    #include <linux/cpufreq.h>
    #include <linux/init.h>
    #include <linux/interconnect.h>
    +#include <linux/interrupt.h>
    #include <linux/kernel.h>
    #include <linux/module.h>
    #include <linux/of_address.h>
    #include <linux/of_platform.h>
    #include <linux/pm_opp.h>
    #include <linux/slab.h>
    +#include <linux/spinlock.h>

    #define LUT_MAX_ENTRIES 40U
    #define LUT_SRC GENMASK(31, 30)
    @@ -22,10 +24,13 @@
    #define CLK_HW_DIV 2
    #define LUT_TURBO_IND 1

    +#define HZ_PER_KHZ 1000
    +
    struct qcom_cpufreq_soc_data {
    u32 reg_enable;
    u32 reg_freq_lut;
    u32 reg_volt_lut;
    + u32 reg_current_vote;
    u32 reg_perf_state;
    u8 lut_row_size;
    };
    @@ -33,7 +38,13 @@ struct qcom_cpufreq_soc_data {
    struct qcom_cpufreq_data {
    void __iomem *base;
    struct resource *res;
    + struct delayed_work throttle_work;
    const struct qcom_cpufreq_soc_data *soc_data;
    + struct cpufreq_policy *policy;
    + /* Lock to synchronize between de-init sequence and re-starting LMh polling/interrupts */
    + spinlock_t throttle_lock;
    + int throttle_irq;
    + bool cancel_throttle;
    };

    static unsigned long cpu_hw_rate, xo_rate;
    @@ -251,10 +262,92 @@ static void qcom_get_related_cpus(int index, struct cpumask *m)
    }
    }

    +static unsigned int qcom_lmh_get_throttle_freq(struct qcom_cpufreq_data *data)
    +{
    + unsigned int val = readl_relaxed(data->base + data->soc_data->reg_current_vote);
    +
    + return (val & 0x3FF) * 19200;
    +}
    +
    +static void qcom_lmh_dcvs_notify(struct qcom_cpufreq_data *data)
    +{
    + struct cpufreq_policy *policy = data->policy;
    + struct dev_pm_opp *opp;
    + struct device *dev;
    + unsigned long max_capacity, capacity, freq_hz, throttled_freq;
    + unsigned int freq;
    +
    + /*
    + * Get the h/w throttled frequency, normalize it using the
    + * registered opp table and use it to calculate thermal pressure.
    + */
    + freq = qcom_lmh_get_throttle_freq(data);
    + freq_hz = freq * HZ_PER_KHZ;
    +
    + dev = get_cpu_device(cpumask_first(policy->cpus));
    + opp = dev_pm_opp_find_freq_floor(dev, &freq_hz);
    + if (IS_ERR(opp) && PTR_ERR(opp) == -ERANGE)
    + opp = dev_pm_opp_find_freq_ceil(dev, &freq_hz);
    +
    + throttled_freq = freq_hz / HZ_PER_KHZ;
    +
    + /* Update thermal pressure */
    +
    + max_capacity = arch_scale_cpu_capacity(cpumask_first(policy->cpus));
    + capacity = mult_frac(max_capacity, throttled_freq, policy->cpuinfo.max_freq);
    + /* Don't pass boost capacity to scheduler */
    + if (capacity > max_capacity)
    + capacity = max_capacity;
    +
    + arch_set_thermal_pressure(policy->cpus, max_capacity - capacity);
    +
    + /* In the unlikely case cpufreq is de-registered do not enable polling or h/w interrupt */
    +
    + spin_lock(&data->throttle_lock);
    + if (data->cancel_throttle) {
    + spin_unlock(&data->throttle_lock);
    + return;
    + }
    + spin_unlock(&data->throttle_lock);
    +
    + /*
    + * If h/w throttled frequency is higher than what cpufreq has requested for, stop
    + * polling and switch back to interrupt mechanism
    + */
    +
    + if (throttled_freq >= qcom_cpufreq_hw_get(cpumask_first(policy->cpus)))
    + /* Clear the existing interrupts and enable it back */
    + enable_irq(data->throttle_irq);
    + else
    + mod_delayed_work(system_highpri_wq, &data->throttle_work,
    + msecs_to_jiffies(10));
    +}
    +
    +static void qcom_lmh_dcvs_poll(struct work_struct *work)
    +{
    + struct qcom_cpufreq_data *data;
    +
    + data = container_of(work, struct qcom_cpufreq_data, throttle_work.work);
    +
    + qcom_lmh_dcvs_notify(data);
    +}
    +
    +static irqreturn_t qcom_lmh_dcvs_handle_irq(int irq, void *data)
    +{
    + struct qcom_cpufreq_data *c_data = data;
    +
    + /* Disable interrupt and enable polling */
    + disable_irq_nosync(c_data->throttle_irq);
    + qcom_lmh_dcvs_notify(c_data);
    +
    + return 0;
    +}
    +
    static const struct qcom_cpufreq_soc_data qcom_soc_data = {
    .reg_enable = 0x0,
    .reg_freq_lut = 0x110,
    .reg_volt_lut = 0x114,
    + .reg_current_vote = 0x704,
    .reg_perf_state = 0x920,
    .lut_row_size = 32,
    };
    @@ -274,6 +367,50 @@ static const struct of_device_id qcom_cpufreq_hw_match[] = {
    };
    MODULE_DEVICE_TABLE(of, qcom_cpufreq_hw_match);

    +static int qcom_cpufreq_hw_lmh_init(struct cpufreq_policy *policy, int index)
    +{
    + struct qcom_cpufreq_data *data = policy->driver_data;
    + struct platform_device *pdev = cpufreq_get_driver_data();
    + char irq_name[15];
    + int ret;
    +
    + /*
    + * Look for LMh interrupt. If no interrupt line is specified /
    + * if there is an error, allow cpufreq to be enabled as usual.
    + */
    + data->throttle_irq = platform_get_irq(pdev, index);
    + if (data->throttle_irq <= 0)
    + return data->throttle_irq == -EPROBE_DEFER ? -EPROBE_DEFER : 0;
    +
    + data->cancel_throttle = false;
    + data->policy = policy;
    +
    + spin_lock_init(&data->throttle_lock);
    + INIT_DEFERRABLE_WORK(&data->throttle_work, qcom_lmh_dcvs_poll);
    +
    + snprintf(irq_name, sizeof(irq_name), "dcvsh-irq-%u", policy->cpu);
    + ret = request_threaded_irq(data->throttle_irq, NULL, qcom_lmh_dcvs_handle_irq,
    + IRQF_ONESHOT, irq_name, data);
    + if (ret) {
    + dev_err(&pdev->dev, "Error registering %s: %d\n", irq_name, ret);
    + return 0;
    + }
    +
    + return 0;
    +}
    +
    +static void qcom_cpufreq_hw_lmh_exit(struct qcom_cpufreq_data *data)
    +{
    + if (data->throttle_irq <= 0)
    + return;
    +
    + spin_lock(&data->throttle_lock);
    + data->cancel_throttle = true;
    + spin_unlock(&data->throttle_lock);
    + cancel_delayed_work_sync(&data->throttle_work);
    + free_irq(data->throttle_irq, data);
    +}
    +
    static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
    {
    struct platform_device *pdev = cpufreq_get_driver_data();
    @@ -370,6 +507,10 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
    dev_warn(cpu_dev, "failed to enable boost: %d\n", ret);
    }

    + ret = qcom_cpufreq_hw_lmh_init(policy, index);
    + if (ret)
    + goto error;
    +
    return 0;
    error:
    kfree(data);
    @@ -389,6 +530,7 @@ static int qcom_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy)

    dev_pm_opp_remove_all_dynamic(cpu_dev);
    dev_pm_opp_of_cpumask_remove_table(policy->related_cpus);
    + qcom_cpufreq_hw_lmh_exit(data);
    kfree(policy->freq_table);
    kfree(data);
    iounmap(base);
    --
    2.25.1
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