From 38a0e5b735d6152d334d2f94b925a1c8a93bd7eb Mon Sep 17 00:00:00 2001 From: Cristian Marussi Date: Thu, 17 Feb 2022 13:12:34 +0000 Subject: [PATCH] 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 Cc: Stephen Boyd Cc: linux-clk@vger.kernel.org Acked-by: Stephen Boyd Signed-off-by: Cristian Marussi Signed-off-by: Sudeep Holla --- drivers/clk/clk-scmi.c | 71 +++++++++++++++++++++++++++++++++++------- 1 file changed, 60 insertions(+), 11 deletions(-) diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c index 1e357d364ca2..2c7a830ce308 100644 --- a/drivers/clk/clk-scmi.c +++ b/drivers/clk/clk-scmi.c @@ -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 @@ -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; } }