linux/drivers/clk/clk-scmi.c
Cristian Marussi 38a0e5b735 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: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
2022-02-21 10:37:00 +00:00

267 lines
6.5 KiB
C

// 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);
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");