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-rw-r--r--drivers/clk/clk-scmi.c267
1 files changed, 267 insertions, 0 deletions
diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
new file mode 100644
index 000000000..fdec715c9
--- /dev/null
+++ b/drivers/clk/clk-scmi.c
@@ -0,0 +1,267 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Power Interface (SCMI) Protocol based clock driver
+ *
+ * Copyright (C) 2018-2022 ARM Ltd.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/module.h>
+#include <linux/scmi_protocol.h>
+#include <asm/div64.h>
+
+static const struct scmi_clk_proto_ops *scmi_proto_clk_ops;
+
+struct scmi_clk {
+ u32 id;
+ struct clk_hw hw;
+ const struct scmi_clock_info *info;
+ const struct scmi_protocol_handle *ph;
+};
+
+#define to_scmi_clk(clk) container_of(clk, struct scmi_clk, hw)
+
+static unsigned long scmi_clk_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ int ret;
+ u64 rate;
+ struct scmi_clk *clk = to_scmi_clk(hw);
+
+ ret = scmi_proto_clk_ops->rate_get(clk->ph, clk->id, &rate);
+ if (ret)
+ return 0;
+ return rate;
+}
+
+static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *parent_rate)
+{
+ u64 fmin, fmax, ftmp;
+ struct scmi_clk *clk = to_scmi_clk(hw);
+
+ /*
+ * We can't figure out what rate it will be, so just return the
+ * rate back to the caller. scmi_clk_recalc_rate() will be called
+ * after the rate is set and we'll know what rate the clock is
+ * running at then.
+ */
+ if (clk->info->rate_discrete)
+ return rate;
+
+ fmin = clk->info->range.min_rate;
+ fmax = clk->info->range.max_rate;
+ if (rate <= fmin)
+ return fmin;
+ else if (rate >= fmax)
+ return fmax;
+
+ ftmp = rate - fmin;
+ ftmp += clk->info->range.step_size - 1; /* to round up */
+ do_div(ftmp, clk->info->range.step_size);
+
+ return ftmp * clk->info->range.step_size + fmin;
+}
+
+static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct scmi_clk *clk = to_scmi_clk(hw);
+
+ return scmi_proto_clk_ops->rate_set(clk->ph, clk->id, rate);
+}
+
+static int scmi_clk_enable(struct clk_hw *hw)
+{
+ struct scmi_clk *clk = to_scmi_clk(hw);
+
+ return scmi_proto_clk_ops->enable(clk->ph, clk->id);
+}
+
+static void scmi_clk_disable(struct clk_hw *hw)
+{
+ struct scmi_clk *clk = to_scmi_clk(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,
+ .prepare = scmi_clk_enable,
+ .unprepare = scmi_clk_disable,
+};
+
+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;
+
+ struct clk_init_data init = {
+ .flags = CLK_GET_RATE_NOCACHE,
+ .num_parents = 0,
+ .ops = scmi_ops,
+ .name = sclk->info->name,
+ };
+
+ sclk->hw.init = &init;
+ ret = devm_clk_hw_register(dev, &sclk->hw);
+ if (ret)
+ return ret;
+
+ if (sclk->info->rate_discrete) {
+ int num_rates = sclk->info->list.num_rates;
+
+ if (num_rates <= 0)
+ return -EINVAL;
+
+ min_rate = sclk->info->list.rates[0];
+ max_rate = sclk->info->list.rates[num_rates - 1];
+ } else {
+ min_rate = sclk->info->range.min_rate;
+ max_rate = sclk->info->range.max_rate;
+ }
+
+ clk_hw_set_rate_range(&sclk->hw, min_rate, max_rate);
+ return ret;
+}
+
+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;
+ struct device_node *np = dev->of_node;
+ const struct scmi_handle *handle = sdev->handle;
+ struct scmi_protocol_handle *ph;
+
+ if (!handle)
+ return -ENODEV;
+
+ scmi_proto_clk_ops =
+ handle->devm_protocol_get(sdev, SCMI_PROTOCOL_CLOCK, &ph);
+ if (IS_ERR(scmi_proto_clk_ops))
+ return PTR_ERR(scmi_proto_clk_ops);
+
+ count = scmi_proto_clk_ops->count_get(ph);
+ if (count < 0) {
+ dev_err(dev, "%pOFn: invalid clock output count\n", np);
+ return -EINVAL;
+ }
+
+ clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, count),
+ GFP_KERNEL);
+ if (!clk_data)
+ return -ENOMEM;
+
+ 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)
+ return -ENOMEM;
+
+ sclk->info = scmi_proto_clk_ops->info_get(ph, idx);
+ if (!sclk->info) {
+ dev_dbg(dev, "invalid clock info for idx %d\n", idx);
+ devm_kfree(dev, sclk);
+ continue;
+ }
+
+ sclk->id = idx;
+ sclk->ph = ph;
+
+ /*
+ * 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%s\n",
+ sclk->info->name,
+ scmi_ops == &scmi_atomic_clk_ops ?
+ " (atomic ops)" : "");
+ hws[idx] = &sclk->hw;
+ }
+ }
+
+ return devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
+ clk_data);
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+ { SCMI_PROTOCOL_CLOCK, "clocks" },
+ { },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_clocks_driver = {
+ .name = "scmi-clocks",
+ .probe = scmi_clocks_probe,
+ .id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_clocks_driver);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI clock driver");
+MODULE_LICENSE("GPL v2");