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SubjectRe: [RFC PATCH v5 2/6] interconnect: Add generic interconnect driver for Exynos SoCs
On Fri, May 29, 2020 at 06:31:56PM +0200, Sylwester Nawrocki 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);

I think of_node_put() should happen after of_icc_get_from_provider().

Best regards,
Krzysztof

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