Re: [PATCH v5 3/3] cpufreq: qcom-hw: Add CPU clock provider support

Matthias Kaehlcke
2022-11-08T18:27:41Z

Hi,

On Tue, Nov 08, 2022 at 09:10:37PM +0530, Manivannan Sadhasivam wrote:
> Qcom CPUFreq hardware (EPSS/OSM) controls clock and voltage to the CPU
> cores. But this relationship is not represented with the clk framework
> so far.
>
> So, let's make the qcom-cpufreq-hw driver a clock provider. This makes the
> clock producer/consumer relationship cleaner and is also useful for CPU
> related frameworks like OPP to know the frequency at which the CPUs are
> running.
>
> The clock frequency provided by the driver is for each frequency domain.
> We cannot get the frequency of each CPU core because, not all platforms
> support per-core DCVS feature.
>
> Also the frequency supplied by the driver is the actual frequency that
> comes out of the EPSS/OSM block after the DCVS operation. This frequency is
> not same as what the CPUFreq framework has set but it is the one that gets
> supplied to the CPUs after throttling by LMh.
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
> drivers/cpufreq/qcom-cpufreq-hw.c | 43 +++++++++++++++++++++++++++++++
> 1 file changed, 43 insertions(+)
>
> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
> index 5e0598730a04..86bb11de347f 100644
> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> @@ -4,6 +4,7 @@
> */
>
> #include <linux/bitfield.h>
> +#include <linux/clk-provider.h>
> #include <linux/cpufreq.h>
> #include <linux/init.h>
> #include <linux/interconnect.h>
> @@ -54,6 +55,7 @@ struct qcom_cpufreq_data {
> bool cancel_throttle;
> struct delayed_work throttle_work;
> struct cpufreq_policy *policy;
> + struct clk_hw cpu_clk;
>
> bool per_core_dcvs;
>
> @@ -615,8 +617,20 @@ static struct cpufreq_driver cpufreq_qcom_hw_driver = {
> .ready = qcom_cpufreq_ready,
> };
>
> +static unsigned long qcom_cpufreq_hw_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
> +{
> + struct qcom_cpufreq_data *data = container_of(hw, struct qcom_cpufreq_data, cpu_clk);
> +
> + return qcom_lmh_get_throttle_freq(data);
> +}
> +
> +static const struct clk_ops qcom_cpufreq_hw_clk_ops = {
> + .recalc_rate = qcom_cpufreq_hw_recalc_rate,
> +};
> +
> static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
> {
> + struct clk_hw_onecell_data *clk_data;
> struct device *dev = &pdev->dev;
> struct device *cpu_dev;
> struct clk *clk;
> @@ -659,8 +673,16 @@ static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
>
> qcom_cpufreq.soc_data = of_device_get_match_data(dev);
>
> + clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, num_domains), GFP_KERNEL);
> + if (!clk_data)
> + return -ENOMEM;
> +
> + clk_data->num = num_domains;
> +
> for (i = 0; i < num_domains; i++) {
> struct qcom_cpufreq_data *data = &qcom_cpufreq.data[i];
> + struct clk_init_data init = {};
> + const char *clk_name;
> struct resource *res;
> void __iomem *base;
>
> @@ -672,6 +694,27 @@ static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
>
> data->base = base;
> data->res = res;
> +
> + /* Register CPU clock for each frequency domain */
> + clk_name = devm_kasprintf(dev, GFP_KERNEL, "qcom_cpufreq%d", i);
> + init.name = clk_name;

nit: 'clk_name' isn't really needed, the result of devm_kasprintf() could be
assigned directly to 'init.name'. 'init' could be renamed to 'clk_init' if
the purpose of using 'clk_name' is to make clear that this is the name of a
clock.

> + init.flags = CLK_GET_RATE_NOCACHE;
> + init.ops = &qcom_cpufreq_hw_clk_ops;
> + data->cpu_clk.init = &init;
> +
> + ret = devm_clk_hw_register(dev, &data->cpu_clk);
> + if (ret < 0) {
> + dev_err(dev, "Failed to register Qcom CPUFreq clock\n");
> + return ret;
> + }
> +
> + clk_data->hws[i] = &data->cpu_clk;
> + }
> +
> + ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get, clk_data);
> + if (ret < 0) {
> + dev_err(dev, "Failed to add Qcom CPUFreq clock provider\n");
> + return ret;
> }
>
> ret = cpufreq_register_driver(&cpufreq_qcom_hw_driver);
> --
> 2.25.1
>