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SubjectRe: [RFC PATCH v5 2/6] interconnect: Add generic interconnect driver for Exynos SoCs
Hi Sylwester,

On Sat, May 30, 2020 at 1:34 AM Sylwester Nawrocki
<s.nawrocki@samsung.com> wrote:
>
> This patch adds a generic interconnect driver for Exynos SoCs in order
> to provide interconnect functionality for each "samsung,exynos-bus"
> compatible device.
>
> The SoC topology is a graph (or more specifically, a tree) and its
> edges are specified using the 'samsung,interconnect-parent' in the
> DT. Due to unspecified relative probing order, -EPROBE_DEFER may be
> propagated to ensure that the parent is probed before its children.
>
> Each bus is now an interconnect provider and an interconnect node as
> well (cf. Documentation/interconnect/interconnect.rst), i.e. every bus
> registers itself as a node. Node IDs are not hardcoded but rather
> assigned dynamically at runtime. This approach allows for using this
> driver with various Exynos SoCs.
>
> Frequencies requested via the interconnect API for a given node are
> propagated to devfreq using dev_pm_qos_update_request(). Please note
> that it is not an error when CONFIG_INTERCONNECT is 'n', in which
> case all interconnect API functions are no-op.
>
> Signed-off-by: Artur Świgoń <a.swigon@samsung.com>
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
>
> Changes for v5:
> - adjust to renamed exynos,interconnect-parent-node property,
> - use automatically generated platform device id as the interconect
> node id instead of a now unavailable devfreq->id field,
> - add icc_ prefix to some variables to make the code more self-commenting,
> - use icc_nodes_remove() instead of icc_node_del() + icc_node_destroy(),
> - adjust to exynos,interconnect-parent-node property rename to
> samsung,interconnect-parent,
> - converted to a separate platform driver in drivers/interconnect.
> ---
> drivers/interconnect/Kconfig | 1 +
> drivers/interconnect/Makefile | 1 +
> drivers/interconnect/exynos/Kconfig | 6 ++
> drivers/interconnect/exynos/Makefile | 4 +
> drivers/interconnect/exynos/exynos.c | 185 +++++++++++++++++++++++++++++++++++
> 5 files changed, 197 insertions(+)
> create mode 100644 drivers/interconnect/exynos/Kconfig
> create mode 100644 drivers/interconnect/exynos/Makefile
> create mode 100644 drivers/interconnect/exynos/exynos.c
>
> diff --git a/drivers/interconnect/Kconfig b/drivers/interconnect/Kconfig
> index 5b7204e..eca6eda 100644
> --- a/drivers/interconnect/Kconfig
> +++ b/drivers/interconnect/Kconfig
> @@ -11,6 +11,7 @@ menuconfig INTERCONNECT
>
> if INTERCONNECT
>
> +source "drivers/interconnect/exynos/Kconfig"
> source "drivers/interconnect/imx/Kconfig"
> source "drivers/interconnect/qcom/Kconfig"
>
> diff --git a/drivers/interconnect/Makefile b/drivers/interconnect/Makefile
> index 4825c28..2ba1de6 100644
> --- a/drivers/interconnect/Makefile
> +++ b/drivers/interconnect/Makefile
> @@ -4,5 +4,6 @@ CFLAGS_core.o := -I$(src)
> icc-core-objs := core.o
>
> obj-$(CONFIG_INTERCONNECT) += icc-core.o
> +obj-$(CONFIG_INTERCONNECT_EXYNOS) += exynos/
> obj-$(CONFIG_INTERCONNECT_IMX) += imx/
> obj-$(CONFIG_INTERCONNECT_QCOM) += qcom/
> diff --git a/drivers/interconnect/exynos/Kconfig b/drivers/interconnect/exynos/Kconfig
> new file mode 100644
> index 0000000..e51e52e
> --- /dev/null
> +++ b/drivers/interconnect/exynos/Kconfig
> @@ -0,0 +1,6 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +config INTERCONNECT_EXYNOS
> + tristate "Exynos generic interconnect driver"
> + depends on ARCH_EXYNOS || COMPILE_TEST
> + help
> + Generic interconnect driver for Exynos SoCs.
> diff --git a/drivers/interconnect/exynos/Makefile b/drivers/interconnect/exynos/Makefile
> new file mode 100644
> index 0000000..e19d1df
> --- /dev/null
> +++ b/drivers/interconnect/exynos/Makefile
> @@ -0,0 +1,4 @@
> +# SPDX-License-Identifier: GPL-2.0
> +exynos-interconnect-objs := exynos.o
> +
> +obj-$(CONFIG_INTERCONNECT_EXYNOS) += exynos-interconnect.o
> diff --git a/drivers/interconnect/exynos/exynos.c b/drivers/interconnect/exynos/exynos.c
> new file mode 100644
> index 0000000..8278194
> --- /dev/null
> +++ b/drivers/interconnect/exynos/exynos.c
> @@ -0,0 +1,185 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Exynos generic interconnect provider driver
> + *
> + * Copyright (c) 2020 Samsung Electronics Co., Ltd.
> + *
> + * Authors: Artur Świgoń <a.swigon@samsung.com>
> + * Sylwester Nawrocki <s.nawrocki@samsung.com>
> + */
> +#include <linux/device.h>
> +#include <linux/interconnect-provider.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_qos.h>
> +
> +#define kbps_to_khz(x) ((x) / 8)
> +
> +struct exynos_icc_priv {
> + struct device *dev;
> +
> + /* One interconnect node per provider */
> + struct icc_provider provider;
> + struct icc_node *node;
> +
> + struct dev_pm_qos_request qos_req;
> +};
> +
> +static struct icc_node *exynos_icc_get_parent(struct device_node *np)
> +{
> + struct of_phandle_args args;
> + int num, ret;
> +
> + num = of_count_phandle_with_args(np, "samsung,interconnect-parent",
> + "#interconnect-cells");
> + if (num != 1)
> + return NULL; /* parent nodes are optional */
> +
> + ret = of_parse_phandle_with_args(np, "samsung,interconnect-parent",
> + "#interconnect-cells", 0, &args);
> + if (ret < 0)
> + return ERR_PTR(ret);
> +
> + of_node_put(args.np);
> +
> + return of_icc_get_from_provider(&args);
> +}
> +
> +
> +static int exynos_generic_icc_set(struct icc_node *src, struct icc_node *dst)
> +{
> + struct exynos_icc_priv *src_priv = src->data, *dst_priv = dst->data;
> + s32 src_freq = kbps_to_khz(max(src->avg_bw, src->peak_bw));
> + s32 dst_freq = kbps_to_khz(max(dst->avg_bw, dst->peak_bw));
> + int ret;
> +
> + ret = dev_pm_qos_update_request(&src_priv->qos_req, src_freq);
> + if (ret < 0) {
> + dev_err(src_priv->dev, "failed to update PM QoS of %s\n",
> + src->name);
> + return ret;
> + }
> +
> + ret = dev_pm_qos_update_request(&dst_priv->qos_req, dst_freq);
> + if (ret < 0) {
> + dev_err(dst_priv->dev, "failed to update PM QoS of %s\n",
> + dst->name);
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static struct icc_node *exynos_generic_icc_xlate(struct of_phandle_args *spec,
> + void *data)
> +{
> + struct exynos_icc_priv *priv = data;
> +
> + if (spec->np != priv->dev->parent->of_node)
> + return ERR_PTR(-EINVAL);
> +
> + return priv->node;
> +}
> +
> +static int exynos_generic_icc_remove(struct platform_device *pdev)
> +{
> + struct exynos_icc_priv *priv = platform_get_drvdata(pdev);
> + struct icc_node *parent_node, *node = priv->node;
> +
> + parent_node = exynos_icc_get_parent(priv->dev->parent->of_node);
> + if (parent_node && !IS_ERR(parent_node))
> + icc_link_destroy(node, parent_node);
> +
> + icc_nodes_remove(&priv->provider);
> + icc_provider_del(&priv->provider);
> +
> + return 0;
> +}
> +
> +static int exynos_generic_icc_probe(struct platform_device *pdev)
> +{
> + struct device *bus_dev = pdev->dev.parent;
> + struct exynos_icc_priv *priv;
> + struct icc_provider *provider;
> + struct icc_node *icc_node, *icc_parent_node;
> + int ret;
> +
> + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + priv->dev = &pdev->dev;
> + platform_set_drvdata(pdev, priv);
> +
> + provider = &priv->provider;
> +
> + provider->set = exynos_generic_icc_set;
> + provider->aggregate = icc_std_aggregate;
> + provider->xlate = exynos_generic_icc_xlate;
> + provider->dev = bus_dev;
> + provider->inter_set = true;
> + provider->data = priv;
> +
> + ret = icc_provider_add(provider);
> + if (ret < 0)
> + return ret;
> +
> + icc_node = icc_node_create(pdev->id);
> + if (IS_ERR(icc_node)) {
> + ret = PTR_ERR(icc_node);
> + goto err_prov_del;
> + }
> +
> + priv->node = icc_node;
> + icc_node->name = bus_dev->of_node->name;
> + icc_node->data = priv;
> + icc_node_add(icc_node, provider);
> +
> + icc_parent_node = exynos_icc_get_parent(bus_dev->of_node);
> + if (IS_ERR(icc_parent_node)) {
> + ret = PTR_ERR(icc_parent_node);
> + goto err_node_del;
> + }
> + if (icc_parent_node) {
> + ret = icc_link_create(icc_node, icc_parent_node->id);
> + if (ret < 0)
> + goto err_node_del;
> + }
> +
> + /*
> + * Register a PM QoS request for the bus device for which also devfreq
> + * functionality is registered.
> + */
> + ret = dev_pm_qos_add_request(bus_dev, &priv->qos_req,
> + DEV_PM_QOS_MIN_FREQUENCY, 0);
> + if (ret < 0)
> + goto err_link_destroy;
> +
> + return 0;
> +
> +err_link_destroy:
> + if (icc_parent_node)
> + icc_link_destroy(icc_node, icc_parent_node);
> +err_node_del:
> + icc_nodes_remove(provider);
> +err_prov_del:
> + icc_provider_del(provider);
> +
> + return ret;
> +}
> +
> +static struct platform_driver exynos_generic_icc_driver = {
> + .driver = {
> + .name = "exynos-generic-icc",
> + },
> + .probe = exynos_generic_icc_probe,
> + .remove = exynos_generic_icc_remove,
> +};
> +module_platform_driver(exynos_generic_icc_driver);
> +
> +MODULE_DESCRIPTION("Exynos generic interconnect driver");
> +MODULE_AUTHOR("Artur Świgoń <a.swigon@samsung.com>");
> +MODULE_AUTHOR("Sylwester Nawrocki <s.nawrocki@samsung.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:exynos-generic-icc");
> --
> 2.7.4
>

Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>

As I commented, How about changing the compatible name 'exynos-icc'
without 'generic'?
The 'exynos-icc' doesn't have the any specific version of Exynos SoC,
it think that it already contain the 'generic' meaning for Exynos SoC.

--
Best Regards,
Chanwoo Choi
Samsung Electronics

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