Commit 38a0e5b7 authored by Cristian Marussi's avatar Cristian Marussi Committed by Sudeep Holla
Browse files

clk: scmi: Support atomic clock enable/disable API 

Support also atomic enable/disable clk_ops beside the bare non-atomic one
(prepare/unprepare) when the underlying SCMI transport is configured to
support atomic transactions for synchronous commands.

Compare the SCMI system-wide configured atomic threshold latency time and
the per-clock advertised enable latency (if any) to choose whether to
provide sleeping prepare/unprepare vs atomic enable/disable.

Link: https://lore.kernel.org/r/20220217131234.50328-9-cristian.marussi@arm.com


Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-clk@vger.kernel.org
Acked-by: default avatarStephen Boyd <sboyd@kernel.org>
Signed-off-by: default avatarCristian Marussi <cristian.marussi@arm.com>
Signed-off-by: default avatarSudeep Holla <sudeep.holla@arm.com>
parent 18f295b7

drivers/clk/clk-scmi.c

+60 −11
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
/*

 * System Control and Power Interface (SCMI) Protocol based clock driver

 *

 * Copyright (C) 2018-2021 ARM Ltd.

 * Copyright (C) 2018-2022 ARM Ltd.

 */



#include <linux/clk-provider.h>
@@ -88,21 +88,51 @@ static void scmi_clk_disable(struct clk_hw *hw) 
	scmi_proto_clk_ops->disable(clk->ph, clk->id);

}



static int scmi_clk_atomic_enable(struct clk_hw *hw)

{

	struct scmi_clk *clk = to_scmi_clk(hw);



	return scmi_proto_clk_ops->enable_atomic(clk->ph, clk->id);

}



static void scmi_clk_atomic_disable(struct clk_hw *hw)

{

	struct scmi_clk *clk = to_scmi_clk(hw);



	scmi_proto_clk_ops->disable_atomic(clk->ph, clk->id);

}



/*

 * We can provide enable/disable atomic callbacks only if the underlying SCMI

 * transport for an SCMI instance is configured to handle SCMI commands in an

 * atomic manner.

 *

 * When no SCMI atomic transport support is available we instead provide only

 * the prepare/unprepare API, as allowed by the clock framework when atomic

 * calls are not available.

 *

 * Two distinct sets of clk_ops are provided since we could have multiple SCMI

 * instances with different underlying transport quality, so they cannot be

 * shared.

 */

static const struct clk_ops scmi_clk_ops = {

	.recalc_rate = scmi_clk_recalc_rate,

	.round_rate = scmi_clk_round_rate,

	.set_rate = scmi_clk_set_rate,

	/*

	 * We can't provide enable/disable callback as we can't perform the same

	 * in atomic context. Since the clock framework provides standard API

	 * clk_prepare_enable that helps cases using clk_enable in non-atomic

	 * context, it should be fine providing prepare/unprepare.

	 */

	.prepare = scmi_clk_enable,

	.unprepare = scmi_clk_disable,

};



static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk)

static const struct clk_ops scmi_atomic_clk_ops = {

	.recalc_rate = scmi_clk_recalc_rate,

	.round_rate = scmi_clk_round_rate,

	.set_rate = scmi_clk_set_rate,

	.enable = scmi_clk_atomic_enable,

	.disable = scmi_clk_atomic_disable,

};



static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk,

			     const struct clk_ops *scmi_ops)

{

	int ret;

	unsigned long min_rate, max_rate;
@@ -110,7 +140,7 @@ static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk) 
	struct clk_init_data init = {

		.flags = CLK_GET_RATE_NOCACHE,

		.num_parents = 0,

		.ops = &scmi_clk_ops,

		.ops = scmi_ops,

		.name = sclk->info->name,

	};
@@ -139,6 +169,8 @@ static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk) 
static int scmi_clocks_probe(struct scmi_device *sdev)

{

	int idx, count, err;

	unsigned int atomic_threshold;

	bool is_atomic;

	struct clk_hw **hws;

	struct clk_hw_onecell_data *clk_data;

	struct device *dev = &sdev->dev;
@@ -168,8 +200,11 @@ static int scmi_clocks_probe(struct scmi_device *sdev) 
	clk_data->num = count;

	hws = clk_data->hws;



	is_atomic = handle->is_transport_atomic(handle, &atomic_threshold);



	for (idx = 0; idx < count; idx++) {

		struct scmi_clk *sclk;

		const struct clk_ops *scmi_ops;



		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);

		if (!sclk)
@@ -184,13 +219,27 @@ static int scmi_clocks_probe(struct scmi_device *sdev) 
		sclk->id = idx;

		sclk->ph = ph;



		err = scmi_clk_ops_init(dev, sclk);

		/*

		 * Note that when transport is atomic but SCMI protocol did not

		 * specify (or support) an enable_latency associated with a

		 * clock, we default to use atomic operations mode.

		 */

		if (is_atomic &&

		    sclk->info->enable_latency <= atomic_threshold)

			scmi_ops = &scmi_atomic_clk_ops;

		else

			scmi_ops = &scmi_clk_ops;



		err = scmi_clk_ops_init(dev, sclk, scmi_ops);

		if (err) {

			dev_err(dev, "failed to register clock %d\n", idx);

			devm_kfree(dev, sclk);

			hws[idx] = NULL;

		} else {

			dev_dbg(dev, "Registered clock:%s\n", sclk->info->name);

			dev_dbg(dev, "Registered clock:%s%s\n",

				sclk->info->name,

				scmi_ops == &scmi_atomic_clk_ops ?

				" (atomic ops)" : "");

			hws[idx] = &sclk->hw;

		}

	}