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Subject[RFC PATCH v2 6/8] clk: scmi: Support atomic enable/disable API
Date
Support enable/disable clk_ops instead of prepare/unprepare when the
underlying SCMI transport is configured to support atomic transactions for
synchronous commands.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
drivers/clk/clk-scmi.c | 44 +++++++++++++++++++++++++++++++++---------
1 file changed, 35 insertions(+), 9 deletions(-)

diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
index 1e357d364ca2..a07117d5e5bd 100644
--- a/drivers/clk/clk-scmi.c
+++ b/drivers/clk/clk-scmi.c
@@ -88,21 +88,42 @@ static void scmi_clk_disable(struct clk_hw *hw)
scmi_proto_clk_ops->disable(clk->ph, clk->id);
}

+/*
+ * We can provide enable/disable atomic callbacks only if the underlying SCMI
+ * transport for this SCMI instance is configured to handle synchronous commands
+ * in an atomic manner.
+ *
+ * When no SCMI atomic transport support is available we instead provide the
+ * prepare/unprepare API, as allowed by the clock framework where atomic calls
+ * are not available.
+ *
+ * Note that the provided clk_ops implementations are the same in both cases,
+ * using indeed the same underlying SCMI clock_protocol operations, it's just
+ * that they are assured to act in an atomic manner or not depending on the
+ * actual underlying SCMI transport configuration.
+ *
+ * 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_enable,
+ .disable = scmi_clk_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 +131,7 @@ 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 +166,7 @@ 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;
+ bool is_atomic;

if (!handle)
return -ENODEV;
@@ -168,6 +190,8 @@ static int scmi_clocks_probe(struct scmi_device *sdev)
clk_data->num = count;
hws = clk_data->hws;

+ is_atomic = handle->is_transport_atomic(handle);
+
for (idx = 0; idx < count; idx++) {
struct scmi_clk *sclk;

@@ -184,7 +208,9 @@ 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,
+ is_atomic ? &scmi_atomic_clk_ops :
+ &scmi_clk_ops);
if (err) {
dev_err(dev, "failed to register clock %d\n", idx);
devm_kfree(dev, sclk);
--
2.17.1
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