Re: [PATCH v2 13/26] soc: qcom: Add driver for Qualcomm Krait L2 cache scaling

[Konrad Dybcio <konrad.dybcio@linaro.org>]

On 25.06.2023 22:25, Dmitry Baryshkov wrote:
> Add a simple driver that handles scaling of L2 frequency and voltages.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  drivers/soc/qcom/Kconfig          |   9 ++
>  drivers/soc/qcom/Makefile         |   1 +
>  drivers/soc/qcom/krait-l2-cache.c | 190 ++++++++++++++++++++++++++++++
>  3 files changed, 200 insertions(+)
>  create mode 100644 drivers/soc/qcom/krait-l2-cache.c
> 
> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
> index e597799e8121..01090b7a3c06 100644
> --- a/drivers/soc/qcom/Kconfig
> +++ b/drivers/soc/qcom/Kconfig
> @@ -70,6 +70,15 @@ config QCOM_LLCC
>  	  SDM845. This provides interfaces to clients that use the LLCC.
>  	  Say yes here to enable LLCC slice driver.
>  
> +config QCOM_KRAIT_L2_CACHE
> +	tristate "Qualcomm Krait L2 cache scaling"
> +	depends on ARCH_QCOM && ARM || COMPILE_TEST
> +	select INTERCONNECT
> +	select INTERCONNECT_CLK
> +	default ARM_QCOM_CPUFREQ_NVMEM
> +	help
> +	  The driver for scaling the L2 cache frequency on Qualcomm Krait platforms.
> +
>  config QCOM_KRYO_L2_ACCESSORS
>  	bool
>  	depends on (ARCH_QCOM || COMPILE_TEST) && ARM64
> diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
> index 99114c71092b..cdd1cc96e9f9 100644
> --- a/drivers/soc/qcom/Makefile
> +++ b/drivers/soc/qcom/Makefile
> @@ -31,6 +31,7 @@ obj-$(CONFIG_QCOM_APR) += apr.o
>  obj-$(CONFIG_QCOM_LLCC) += llcc-qcom.o
>  obj-$(CONFIG_QCOM_RPMHPD) += rpmhpd.o
>  obj-$(CONFIG_QCOM_RPMPD) += rpmpd.o
> +obj-$(CONFIG_QCOM_KRAIT_L2_CACHE) += krait-l2-cache.o
>  obj-$(CONFIG_QCOM_KRYO_L2_ACCESSORS) +=	kryo-l2-accessors.o
>  obj-$(CONFIG_QCOM_ICC_BWMON)	+= icc-bwmon.o
>  qcom_ice-objs			+= ice.o
> diff --git a/drivers/soc/qcom/krait-l2-cache.c b/drivers/soc/qcom/krait-l2-cache.c
> new file mode 100644
> index 000000000000..af9e7b955daf
> --- /dev/null
> +++ b/drivers/soc/qcom/krait-l2-cache.c
> @@ -0,0 +1,190 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2023, Linaro Ltd.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/interconnect-clk.h>
> +#include <linux/interconnect-provider.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_opp.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <dt-bindings/soc/qcom,krait-l2-cache.h>
> +
> +/* Random ID that doesn't clash with main qnoc and OSM */
> +#define L2_MASTER_NODE 2000
> +
> +/* vdd-mem and vdd-dig */
> +#define NUM_SUPPLIES 2
I *think* the code would be much, much simpler if you made the
debug print, regulator set and error message a separate function
and then called them explicitly, without a for-loop.

> +static int krait_l2_config_regulators(struct device *dev,
> +				      struct dev_pm_opp *old_opp,
> +				      struct dev_pm_opp *new_opp,
> +				      struct regulator **regulators,
> +				      unsigned int count)
> +{
> +	struct dev_pm_opp_supply supplies[NUM_SUPPLIES];
> +	unsigned long old_freq, freq;
> +	unsigned int i;
> +	int ret;
> +
> +	if (WARN_ON_ONCE(count != NUM_SUPPLIES))
> +		return -EINVAL;
> +
> +	ret = dev_pm_opp_get_supplies(new_opp, supplies);
> +	if (WARN_ON(ret))
> +		return ret;
> +
> +	old_freq = dev_pm_opp_get_freq(old_opp);
> +	freq = dev_pm_opp_get_freq(new_opp);
> +
> +	WARN_ON(!old_freq || !freq);
> +	if (freq > old_freq) {
> +		for (i = 0; i < count; i++) {
> +			struct regulator *reg = regulators[i];
> +			struct dev_pm_opp_supply *supply = &supplies[i];
> +
> +			dev_dbg(dev, "%s: voltages (mV): %lu %lu %lu\n", __func__,
> +				supply->u_volt_min, supply->u_volt, supply->u_volt_max);
> +
> +			ret = regulator_set_voltage_triplet(reg,
> +							    supply->u_volt_min,
> +							    supply->u_volt,
> +							    supply->u_volt_max);
> +			if (ret) {
> +				dev_err(dev, "%s: failed to set voltage (%lu %lu %lu mV): %d\n",
> +					__func__, supply->u_volt_min, supply->u_volt,
> +					supply->u_volt_max, ret);
> +				goto restore_backwards;
> +			}
> +		}
> +	} else {
> +		for (i = count; i > 0; i--) {
> +			struct regulator *reg = regulators[i - 1];
> +			struct dev_pm_opp_supply *supply = &supplies[i - 1];
> +
> +			dev_dbg(dev, "%s: voltages (mV): %lu %lu %lu\n", __func__,
> +				supply->u_volt_min, supply->u_volt, supply->u_volt_max);
> +
> +			ret = regulator_set_voltage_triplet(reg,
> +							    supply->u_volt_min,
> +							    supply->u_volt,
> +							    supply->u_volt_max);
> +			if (ret) {
> +				dev_err(dev, "%s: failed to set voltage (%lu %lu %lu mV): %d\n",
> +					__func__, supply->u_volt_min, supply->u_volt,
> +					supply->u_volt_max, ret);
> +				goto restore_forward;
> +			}
> +		}
> +	}
> +
> +	return 0;
> +
> +restore_backwards:
> +
> +	dev_pm_opp_get_supplies(old_opp, supplies);
> +
> +	for (; i > 0; i--) {
> +		struct regulator *reg = regulators[i - 1];
> +		struct dev_pm_opp_supply *supply = &supplies[i - 1];
> +
> +		dev_dbg(dev, "%s: voltages (mV): %lu %lu %lu\n", __func__,
> +			supply->u_volt_min, supply->u_volt, supply->u_volt_max);
> +
> +		regulator_set_voltage_triplet(reg,
> +					      supply->u_volt_min,
> +					      supply->u_volt,
> +					      supply->u_volt_max);
> +	}
> +
> +	return ret;
> +
> +restore_forward:
> +
> +	dev_pm_opp_get_supplies(old_opp, supplies);
> +
> +	for ( ; i < count; i++) {
> +		struct regulator *reg = regulators[i];
> +		struct dev_pm_opp_supply *supply = &supplies[i];
> +
> +		dev_dbg(dev, "%s: voltages (mV): %lu %lu %lu\n", __func__,
> +			supply->u_volt_min, supply->u_volt, supply->u_volt_max);
> +
> +		regulator_set_voltage_triplet(reg,
> +					      supply->u_volt_min,
> +					      supply->u_volt,
> +					      supply->u_volt_max);
> +	}
> +
> +	return ret;
> +}
> +
> +static int krait_l2_probe(struct platform_device *pdev)
> +{
> +	struct dev_pm_opp_config krait_l2_cfg = {
> +		.clk_names = (const char * const[]) { NULL, NULL },
> +		.config_regulators = krait_l2_config_regulators,
> +		.regulator_names = (const char * const[]) { "vdd-mem", "vdd-dig", NULL },
> +	};
> +	struct icc_clk_data data[] = {
> +		{ .name = "l2", .opp = true},
true} -> true }

Konrad
> +	};
> +
> +	struct device *dev = &pdev->dev;
> +	struct icc_provider *provider;
> +	struct clk *clk;
> +	int ret;
> +
> +	clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(clk))
> +		return PTR_ERR(clk);
> +
> +	ret = devm_pm_opp_set_config(dev, &krait_l2_cfg);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_pm_opp_of_add_table(dev);
> +	if (ret)
> +		return ret;
> +
> +	data[0].clk = clk;
> +	provider = icc_clk_register(dev, L2_MASTER_NODE, ARRAY_SIZE(data), data);
> +	if (IS_ERR(provider))
> +		return PTR_ERR(provider);
> +
> +	platform_set_drvdata(pdev, provider);
> +
> +	return 0;
> +}
> +
> +static int krait_l2_remove(struct platform_device *pdev)
> +{
> +	struct icc_provider *provider = platform_get_drvdata(pdev);
> +
> +	icc_clk_unregister(provider);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id krait_l2_match_table[] = {
> +	{ .compatible = "qcom,krait-l2-cache" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, krait_l2_match_table);
> +
> +static struct platform_driver krait_l2_driver = {
> +	.probe = krait_l2_probe,
> +	.remove = krait_l2_remove,
> +	.driver = {
> +		.name = "qcom-krait-l2",
> +		.of_match_table = krait_l2_match_table,
> +		.sync_state = icc_sync_state,
> +	},
> +};
> +
> +module_platform_driver(krait_l2_driver);
> +
> +MODULE_DESCRIPTION("Qualcomm Krait L2 scaling driver");
> +MODULE_LICENSE("GPL v2");