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Subject: Re: [v6 2/3] interconnect: qcom: Add EPSS L3 support on SC7280
To:     Odelu Kukatla <okukatla@codeaurora.org>, georgi.djakov@linaro.org,
        bjorn.andersson@linaro.org, evgreen@google.com,
        Andy Gross <agross@kernel.org>,
        Georgi Djakov <djakov@kernel.org>,
        linux-arm-msm@vger.kernel.org, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     sboyd@kernel.org, mdtipton@codeaurora.org, sibis@codeaurora.org,
        saravanak@google.com, seansw@qti.qualcomm.com,
        linux-arm-msm-owner@vger.kernel.org
References: <1628577962-3995-1-git-send-email-okukatla@codeaurora.org>
 <1628577962-3995-3-git-send-email-okukatla@codeaurora.org>
From:   Alex Elder <elder@linaro.org>
Message-ID: <8c046ac4-27c8-d858-941b-80f1509dbb61@linaro.org>
Date:   Tue, 10 Aug 2021 07:46:14 -0500
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On 8/10/21 1:46 AM, Odelu Kukatla wrote:
> Add Epoch Subsystem (EPSS) L3 interconnect provider support on
> SC7280 SoCs.
> 
> Signed-off-by: Odelu Kukatla <okukatla@codeaurora.org>

I don't have much to say about what this is doing but I
have a few suggestions.

					-Alex

> ---
>   drivers/interconnect/qcom/osm-l3.c | 136 +++++++++++++++++++++++++++++++------
>   drivers/interconnect/qcom/sc7280.h |  10 +++
>   2 files changed, 125 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/interconnect/qcom/osm-l3.c b/drivers/interconnect/qcom/osm-l3.c
> index c7af143..3b16e73 100644
> --- a/drivers/interconnect/qcom/osm-l3.c
> +++ b/drivers/interconnect/qcom/osm-l3.c
> @@ -9,12 +9,14 @@
>   #include <linux/io.h>
>   #include <linux/kernel.h>
>   #include <linux/module.h>
> +#include <linux/of_address.h>
>   #include <linux/of_device.h>
>   #include <linux/platform_device.h>
>   
>   #include <dt-bindings/interconnect/qcom,osm-l3.h>
>   
>   #include "sc7180.h"
> +#include "sc7280.h"
>   #include "sc8180x.h"
>   #include "sdm845.h"
>   #include "sm8150.h"
> @@ -33,17 +35,33 @@
>   
>   /* EPSS Register offsets */
>   #define EPSS_LUT_ROW_SIZE		4
> +#define EPSS_REG_L3_VOTE		0x90
>   #define EPSS_REG_FREQ_LUT		0x100
>   #define EPSS_REG_PERF_STATE		0x320
> +#define EPSS_CORE_OFFSET		0x4
> +#define EPSS_L3_VOTE_REG(base, cpu)\
> +			(((base) + EPSS_REG_L3_VOTE) +\
> +			((cpu) * EPSS_CORE_OFFSET))
>   
> -#define OSM_L3_MAX_LINKS		1
> +#define L3_DOMAIN_CNT		4
> +#define L3_MAX_LINKS		9

It may not matter much, but if you specified the
qcom_osm_l3_node->links[] field as the last field
in the structure, I think it could be a flexible
array and you wouldn't have to specify the maximum
number of links.  (You are already using the actual
array size to set ->num_links in __DEFINE_QNODE().)

>   #define to_osm_l3_provider(_provider) \
>   	container_of(_provider, struct qcom_osm_l3_icc_provider, provider)
>   
> +/**
> + * @domain_base: an array of base address for each clock domain
> + * @max_state: max supported frequency level
> + * @per_core_dcvs: flag used to indicate whether the frequency scaling
> + * for each core is enabled
> + * @reg_perf_state: requested frequency level
> + * @lut_tables: an array of supported frequency levels
> + * @provider: interconnect provider of this node
> + */

Run this to check your kernel doc validity:
     scripts/kernel-doc -none <file> [<file>...]

>   struct qcom_osm_l3_icc_provider {
> -	void __iomem *base;
> +	void __iomem *domain_base[L3_DOMAIN_CNT];
>   	unsigned int max_state;
> +	bool per_core_dcvs;
>   	unsigned int reg_perf_state;
>   	unsigned long lut_tables[LUT_MAX_ENTRIES];
>   	struct icc_provider provider;

. . .

> @@ -235,12 +322,17 @@ static int qcom_osm_l3_probe(struct platform_device *pdev)
>   	if (!qp)
>   		return -ENOMEM;
>   
> -	qp->base = devm_platform_ioremap_resource(pdev, 0);
> -	if (IS_ERR(qp->base))
> -		return PTR_ERR(qp->base);
> +	while (of_get_address(pdev->dev.of_node, i++, NULL, NULL))
> +		nr_domain_bases++;

Maybe you could combine these two loops by counting as you go.
I.e.:

     i = 0;
     while (true) {
	void __iomem *base;

	if (of_get_address(pdev->dev.of_node, i, NULL, NULL))
		break;
	base = devm_platform_ioremap_resource(pdev, i);
	if (IS_ERR(base))
	    return PTR_ERR(base);
	qp->domain_base[i++] = base
     }
     nr_domain_bases = i;

> +
> +	for (i = 0; i < nr_domain_bases ; i++) {
> +		qp->domain_base[i] = devm_platform_ioremap_resource(pdev, i);
> +		if (IS_ERR(qp->domain_base[i]))
> +			return PTR_ERR(qp->domain_base[i]);
> +	}
>   
>   	/* HW should be in enabled state to proceed */
> -	if (!(readl_relaxed(qp->base + REG_ENABLE) & 0x1)) {
> +	if (!(readl_relaxed(qp->domain_base[0] + REG_ENABLE) & 0x1)) {
>   		dev_err(&pdev->dev, "error hardware not enabled\n");
>   		return -ENODEV;
>   	}
> @@ -252,7 +344,7 @@ static int qcom_osm_l3_probe(struct platform_device *pdev)
>   	qp->reg_perf_state = desc->reg_perf_state;
>   
>   	for (i = 0; i < LUT_MAX_ENTRIES; i++) {
> -		info = readl_relaxed(qp->base + desc->reg_freq_lut +
> +		info = readl_relaxed(qp->domain_base[0] + desc->reg_freq_lut +
>   				     i * desc->lut_row_size);

Maybe you could define a macro to encapsulate computing this
register offset, along the lines of EPSS_L3_VOTE_REG().  (Here
and elsewhere.)

>   		src = FIELD_GET(LUT_SRC, info);
>   		lval = FIELD_GET(LUT_L_VAL, info);
> @@ -271,6 +363,7 @@ static int qcom_osm_l3_probe(struct platform_device *pdev)
>   		prev_freq = freq;
>   	}
>   	qp->max_state = i;
> +	qp->per_core_dcvs = desc->per_core_dcvs;
>   
>   	qnodes = desc->nodes;
>   	num_nodes = desc->num_nodes;
> @@ -326,6 +419,7 @@ static int qcom_osm_l3_probe(struct platform_device *pdev)
>   
>   static const struct of_device_id osm_l3_of_match[] = {
>   	{ .compatible = "qcom,sc7180-osm-l3", .data = &sc7180_icc_osm_l3 },
> +	{ .compatible = "qcom,sc7280-epss-l3", .data = &sc7280_icc_epss_l3 },
>   	{ .compatible = "qcom,sdm845-osm-l3", .data = &sdm845_icc_osm_l3 },
>   	{ .compatible = "qcom,sm8150-osm-l3", .data = &sm8150_icc_osm_l3 },
>   	{ .compatible = "qcom,sc8180x-osm-l3", .data = &sc8180x_icc_osm_l3 },
> diff --git a/drivers/interconnect/qcom/sc7280.h b/drivers/interconnect/qcom/sc7280.h
> index 175e400..5df7600 100644
> --- a/drivers/interconnect/qcom/sc7280.h
> +++ b/drivers/interconnect/qcom/sc7280.h
> @@ -150,5 +150,15 @@
>   #define SC7280_SLAVE_PCIE_1			139
>   #define SC7280_SLAVE_QDSS_STM			140
>   #define SC7280_SLAVE_TCU			141
> +#define SC7280_MASTER_EPSS_L3_APPS			142
> +#define SC7280_SLAVE_EPSS_L3_SHARED			143
> +#define SC7280_SLAVE_EPSS_L3_CPU0			144
> +#define SC7280_SLAVE_EPSS_L3_CPU1			145
> +#define SC7280_SLAVE_EPSS_L3_CPU2			146
> +#define SC7280_SLAVE_EPSS_L3_CPU3			147
> +#define SC7280_SLAVE_EPSS_L3_CPU4			148
> +#define SC7280_SLAVE_EPSS_L3_CPU5			149
> +#define SC7280_SLAVE_EPSS_L3_CPU6			150
> +#define SC7280_SLAVE_EPSS_L3_CPU7			151
>   
>   #endif
>