[v4,2/4] iterconnect: add clk-based icc provider support

For some devices it is useful to export clocks as interconect providers,
if the clock corresponds to bus bandwidth.

For example, on MSM8996 the cluster interconnect clock should be scaled
according to the cluster frequencies. Exporting it as an interconnect
allows one to properly describe this as the cluster bandwidth
requirements.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/interconnect/Kconfig     |   6 ++
 drivers/interconnect/Makefile    |   2 +
 drivers/interconnect/icc-clk.c   | 168 +++++++++++++++++++++++++++++++
 include/linux/interconnect-clk.h |  22 ++++
 4 files changed, 198 insertions(+)
 create mode 100644 drivers/interconnect/icc-clk.c
 create mode 100644 include/linux/interconnect-clk.h

On 09/04/2023 01:49, Dmitry Baryshkov wrote:
> For some devices it is useful to export clocks as interconect providers,

typo

> if the clock corresponds to bus bandwidth.
> 
> For example, on MSM8996 the cluster interconnect clock should be scaled
> according to the cluster frequencies. Exporting it as an interconnect
> allows one to properly describe this as the cluster bandwidth
> requirements.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Subject: also typo

Best regards,
Krzysztof

On 9.04.2023 01:49, Dmitry Baryshkov wrote:
> For some devices it is useful to export clocks as interconect providers,
> if the clock corresponds to bus bandwidth.
> 
> For example, on MSM8996 the cluster interconnect clock should be scaled
> according to the cluster frequencies. Exporting it as an interconnect
> allows one to properly describe this as the cluster bandwidth
> requirements.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  drivers/interconnect/Kconfig     |   6 ++
>  drivers/interconnect/Makefile    |   2 +
>  drivers/interconnect/icc-clk.c   | 168 +++++++++++++++++++++++++++++++
>  include/linux/interconnect-clk.h |  22 ++++
>  4 files changed, 198 insertions(+)
>  create mode 100644 drivers/interconnect/icc-clk.c
>  create mode 100644 include/linux/interconnect-clk.h
> 
> diff --git a/drivers/interconnect/Kconfig b/drivers/interconnect/Kconfig
> index d637a89d4695..5faa8d2aecff 100644
> --- a/drivers/interconnect/Kconfig
> +++ b/drivers/interconnect/Kconfig
> @@ -15,4 +15,10 @@ source "drivers/interconnect/imx/Kconfig"
>  source "drivers/interconnect/qcom/Kconfig"
>  source "drivers/interconnect/samsung/Kconfig"
>  
> +config INTERCONNECT_CLK
> +	tristate
> +	depends on COMMON_CLK
> +	help
> +	  Support for wrapping clocks into the interconnect nodes.
> +
>  endif
> diff --git a/drivers/interconnect/Makefile b/drivers/interconnect/Makefile
> index 97d393fd638d..5604ce351a9f 100644
> --- a/drivers/interconnect/Makefile
> +++ b/drivers/interconnect/Makefile
> @@ -7,3 +7,5 @@ obj-$(CONFIG_INTERCONNECT)		+= icc-core.o
>  obj-$(CONFIG_INTERCONNECT_IMX)		+= imx/
>  obj-$(CONFIG_INTERCONNECT_QCOM)		+= qcom/
>  obj-$(CONFIG_INTERCONNECT_SAMSUNG)	+= samsung/
> +
> +obj-$(CONFIG_INTERCONNECT_CLK)		+= icc-clk.o
> diff --git a/drivers/interconnect/icc-clk.c b/drivers/interconnect/icc-clk.c
> new file mode 100644
> index 000000000000..0db3b654548b
> --- /dev/null
> +++ b/drivers/interconnect/icc-clk.c
> @@ -0,0 +1,168 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2023, Linaro Ltd.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/interconnect-clk.h>
> +#include <linux/interconnect-provider.h>
> +
> +struct icc_clk_node {
> +	struct clk *clk;
> +	bool enabled;
> +};
> +
> +struct icc_clk_provider {
> +	struct icc_provider provider;
> +	int num_clocks;
> +	struct icc_clk_node clocks[];
> +};
> +
> +#define to_icc_clk_provider(_provider) \
> +	container_of(_provider, struct icc_clk_provider, provider)
> +
> +static int icc_clk_set(struct icc_node *src, struct icc_node *dst)
> +{
> +	struct icc_clk_node *qn = src->data;
"qn" is used in qc drivers for "qcom node", the generic code should
probably use "n" for "node" or "cn" for "clock node".

> +	int ret;
> +
> +	if (!qn || !qn->clk)
> +		return 0;
Shouldn't this be an error?

> +
> +	if (!src->peak_bw) {
> +		if (qn->enabled)
> +			clk_disable_unprepare(qn->clk);
> +		qn->enabled = false;
> +
> +		return 0;
> +	}
> +
> +	if (!qn->enabled) {
> +		ret = clk_prepare_enable(qn->clk);
> +		if (ret)
> +			return ret;
> +		qn->enabled = true;
> +	}
> +
> +	return clk_set_rate(qn->clk, icc_units_to_bps(src->peak_bw));
> +}
> +
> +static int icc_clk_get_bw(struct icc_node *node, u32 *avg, u32 *peak)
> +{
> +	struct icc_clk_node *qn = node->data;
> +
> +	if (!qn || !qn->clk)
> +		*peak = INT_MAX;
> +	else
> +		*peak = Bps_to_icc(clk_get_rate(qn->clk));
clk_get_rate can return 0 if the rate is actually 0 or when
there's some sort of an error. Not sure how/whether we wanna
throw some warning there based on qp->enabled.


> +
> +	return 0;
> +}
> +
> +/**
> + * icc_clk_register() - register a new clk-based interconnect provider
> + * @dev: device supporting this provider
> + * @first_id: an ID of the first provider's node
> + * @num_clocks: number of instances of struct icc_clk_data
> + * @data: data for the provider
> + *
> + * Registers and returns a clk-based interconnect provider. It is a simple
> + * wrapper around COMMON_CLK framework, allowing other devices to vote on the
> + * clock rate.
> + *
> + * Return: 0 on success, or an error code otherwise
> + */
> +struct icc_provider *icc_clk_register(struct device *dev,
> +				      unsigned int first_id,
> +				      unsigned int num_clocks,
> +				      const struct icc_clk_data *data)
Misaligned

> +{
> +	struct icc_clk_provider *qp;
Similarly to before, "qp" was for "qcom provider".

> +	struct icc_provider *provider;
> +	struct icc_onecell_data *onecell;
> +	struct icc_node *node;
> +	int ret, i, j;
> +
> +	onecell = devm_kzalloc(dev, struct_size(onecell, nodes, 2 * num_clocks), GFP_KERNEL);
> +	if (!onecell)
> +		return ERR_PTR(-ENOMEM);
> +
> +	qp = devm_kzalloc(dev, struct_size(qp, clocks, num_clocks), GFP_KERNEL);
> +	if (!qp)
> +		return ERR_PTR(-ENOMEM);
> +
> +	qp->num_clocks = num_clocks;
> +
> +	provider = &qp->provider;
> +	provider->dev = dev;
> +	provider->get_bw = icc_clk_get_bw;
> +	provider->set = icc_clk_set;
> +	provider->aggregate = icc_std_aggregate;
> +	provider->xlate = of_icc_xlate_onecell;
> +	INIT_LIST_HEAD(&provider->nodes);
> +	provider->data = onecell;
> +
> +	icc_provider_init(provider);
> +
> +	for (i = 0, j = 0; i < num_clocks; i++) {
> +		qp->clocks[i].clk = data[i].clk;
> +
> +		node = icc_node_create(first_id + j);
Remove j altogether and use 2*i / 2*i + 1?

> +		if (IS_ERR(node)) {
> +			ret = PTR_ERR(node);
> +			goto err;
> +		}
> +
> +		node->name = devm_kasprintf(dev, GFP_KERNEL, "%s_master", data[i].name);
> +		node->data = &qp->clocks[i];
> +		icc_node_add(node, provider);
> +		/* link to the next node, slave */
> +		icc_link_create(node, first_id + j + 1);
> +		onecell->nodes[j++] = node;
> +
> +		node = icc_node_create(first_id + j);
> +		if (IS_ERR(node)) {
> +			ret = PTR_ERR(node);
> +			goto err;
> +		}
> +
> +		node->name = devm_kasprintf(dev, GFP_KERNEL, "%s_slave", data[i].name);
> +		/* no data for slave node */
> +		icc_node_add(node, provider);
> +		onecell->nodes[j++] = node;
> +	}
> +
> +	onecell->num_nodes = j> +
> +	ret = icc_provider_register(provider);
> +	if (ret)
> +		goto err;
> +
> +	return provider;
> +
> +err:
> +	icc_nodes_remove(provider);
> +
> +	return ERR_PTR(ret);
> +}
> +
> +/**
> + * icc_clk_unregister() - unregister a previously registered clk interconnect provider
> + * @provider: provider returned by icc_clk_register()
> + */
> +void icc_clk_unregister(struct icc_provider *provider)
> +{
> +	struct icc_clk_provider *qp = container_of(provider, struct icc_clk_provider, provider);
to_icc_clk_provider?

> +	int i;
> +
> +	icc_provider_deregister(&qp->provider);
> +	icc_nodes_remove(&qp->provider);
> +
> +	for (i = 0; i < qp->num_clocks; i++) {
> +		struct icc_clk_node *qn = &qp->clocks[i];
> +
> +		if (qn->enabled)
> +			clk_disable_unprepare(qn->clk);
> +	}
> +}
> diff --git a/include/linux/interconnect-clk.h b/include/linux/interconnect-clk.h
> new file mode 100644
> index 000000000000..0cd80112bea5
> --- /dev/null
> +++ b/include/linux/interconnect-clk.h
> @@ -0,0 +1,22 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2023, Linaro Ltd.
> + */
> +
> +#ifndef __LINUX_INTERCONNECT_CLK_H
> +#define __LINUX_INTERCONNECT_CLK_H
> +
> +struct device;
> +
> +struct icc_clk_data {
> +	struct clk *clk;
> +	const char *name;
> +};
> +
> +struct icc_provider *icc_clk_register(struct device *dev,
> +				      unsigned int first_id,
> +				      unsigned int num_clocks,
> +				      const struct icc_clk_data *data);
Misaligned

Konrad
> +void icc_clk_unregister(struct icc_provider *provider);
> +
> +#endif