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.

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-clk@vger.kernel.org
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
V5 --> V6
- add concurrent availability of atomic and non atomic reqs
---
 drivers/clk/clk-scmi.c | 56 +++++++++++++++++++++++++++++++++++-------
 1 file changed, 47 insertions(+), 9 deletions(-)

diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
index 1e357d364ca2..50033d873dde 100644
--- a/drivers/clk/clk-scmi.c
+++ b/drivers/clk/clk-scmi.c

@@ -88,21 +88,53 @@ 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,
+       .prepare = scmi_clk_enable,
+       .unprepare = scmi_clk_disable,
+       .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 +142,7 @@ 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,
        };

@@ -145,6 +177,7 @@ static int scmi_clocks_probe(struct scmi_device *sdev)
        struct device_node *np = dev->of_node;
        const struct scmi_handle *handle = sdev->handle;
        struct scmi_protocol_handle *ph;
+       const struct clk_ops *scmi_ops;

        if (!handle)
                return -ENODEV;

@@ -168,6 +201,11 @@ static int scmi_clocks_probe(struct scmi_device *sdev)
        clk_data->num = count;
        hws = clk_data->hws;

+       if (handle->is_transport_atomic(handle))
+               scmi_ops = &scmi_atomic_clk_ops;
+       else
+               scmi_ops = &scmi_clk_ops;
+
        for (idx = 0; idx < count; idx++) {
                struct scmi_clk *sclk;

@@ -184,7 +222,7 @@ static int scmi_clocks_probe(struct scmi_device *sdev)
                sclk->id = idx;
                sclk->ph = ph;

-               err = scmi_clk_ops_init(dev, sclk);
+               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);
--

2.17.1