1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * System Control and Power Interface (SCMI) Protocol based clock driver
  4 *
  5 * Copyright (C) 2018 ARM Ltd.
  6 */
  7
  8#include <linux/clk-provider.h>
  9#include <linux/device.h>
 10#include <linux/err.h>
 11#include <linux/of.h>
 12#include <linux/module.h>
 13#include <linux/scmi_protocol.h>
 14#include <asm/div64.h>
 15
 16struct scmi_clk {
 17	u32 id;
 18	struct clk_hw hw;
 19	const struct scmi_clock_info *info;
 20	const struct scmi_handle *handle;
 21};
 22
 23#define to_scmi_clk(clk) container_of(clk, struct scmi_clk, hw)
 24
 25static unsigned long scmi_clk_recalc_rate(struct clk_hw *hw,
 26					  unsigned long parent_rate)
 27{
 28	int ret;
 29	u64 rate;
 30	struct scmi_clk *clk = to_scmi_clk(hw);
 31
 32	ret = clk->handle->clk_ops->rate_get(clk->handle, clk->id, &rate);
 33	if (ret)
 34		return 0;
 35	return rate;
 36}
 37
 38static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
 39				unsigned long *parent_rate)
 40{
 41	int step;
 42	u64 fmin, fmax, ftmp;
 43	struct scmi_clk *clk = to_scmi_clk(hw);
 44
 45	/*
 46	 * We can't figure out what rate it will be, so just return the
 47	 * rate back to the caller. scmi_clk_recalc_rate() will be called
 48	 * after the rate is set and we'll know what rate the clock is
 49	 * running at then.
 50	 */
 51	if (clk->info->rate_discrete)
 52		return rate;
 53
 54	fmin = clk->info->range.min_rate;
 55	fmax = clk->info->range.max_rate;
 56	if (rate <= fmin)
 57		return fmin;
 58	else if (rate >= fmax)
 59		return fmax;
 60
 61	ftmp = rate - fmin;
 62	ftmp += clk->info->range.step_size - 1; /* to round up */
 63	step = do_div(ftmp, clk->info->range.step_size);
 64
 65	return step * clk->info->range.step_size + fmin;
 66}
 67
 68static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
 69			     unsigned long parent_rate)
 70{
 71	struct scmi_clk *clk = to_scmi_clk(hw);
 72
 73	return clk->handle->clk_ops->rate_set(clk->handle, clk->id, 0, rate);
 74}
 75
 76static int scmi_clk_enable(struct clk_hw *hw)
 77{
 78	struct scmi_clk *clk = to_scmi_clk(hw);
 79
 80	return clk->handle->clk_ops->enable(clk->handle, clk->id);
 81}
 82
 83static void scmi_clk_disable(struct clk_hw *hw)
 84{
 85	struct scmi_clk *clk = to_scmi_clk(hw);
 86
 87	clk->handle->clk_ops->disable(clk->handle, clk->id);
 88}
 89
 90static const struct clk_ops scmi_clk_ops = {
 91	.recalc_rate = scmi_clk_recalc_rate,
 92	.round_rate = scmi_clk_round_rate,
 93	.set_rate = scmi_clk_set_rate,
 94	/*
 95	 * We can't provide enable/disable callback as we can't perform the same
 96	 * in atomic context. Since the clock framework provides standard API
 97	 * clk_prepare_enable that helps cases using clk_enable in non-atomic
 98	 * context, it should be fine providing prepare/unprepare.
 99	 */
100	.prepare = scmi_clk_enable,
101	.unprepare = scmi_clk_disable,
102};
103
104static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk)
105{
106	int ret;
107	struct clk_init_data init = {
108		.flags = CLK_GET_RATE_NOCACHE,
109		.num_parents = 0,
110		.ops = &scmi_clk_ops,
111		.name = sclk->info->name,
112	};
113
114	sclk->hw.init = &init;
115	ret = devm_clk_hw_register(dev, &sclk->hw);
116	if (!ret)
117		clk_hw_set_rate_range(&sclk->hw, sclk->info->range.min_rate,
118				      sclk->info->range.max_rate);
119	return ret;
120}
121
122static int scmi_clocks_probe(struct scmi_device *sdev)
123{
124	int idx, count, err;
125	struct clk_hw **hws;
126	struct clk_hw_onecell_data *clk_data;
127	struct device *dev = &sdev->dev;
128	struct device_node *np = dev->of_node;
129	const struct scmi_handle *handle = sdev->handle;
130
131	if (!handle || !handle->clk_ops)
132		return -ENODEV;
133
134	count = handle->clk_ops->count_get(handle);
135	if (count < 0) {
136		dev_err(dev, "%s: invalid clock output count\n", np->name);
137		return -EINVAL;
138	}
139
140	clk_data = devm_kzalloc(dev, sizeof(*clk_data) +
141				sizeof(*clk_data->hws) * count, GFP_KERNEL);
142	if (!clk_data)
143		return -ENOMEM;
144
145	clk_data->num = count;
146	hws = clk_data->hws;
147
148	for (idx = 0; idx < count; idx++) {
149		struct scmi_clk *sclk;
150
151		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
152		if (!sclk)
153			return -ENOMEM;
154
155		sclk->info = handle->clk_ops->info_get(handle, idx);
156		if (!sclk->info) {
157			dev_dbg(dev, "invalid clock info for idx %d\n", idx);
158			continue;
159		}
160
161		sclk->id = idx;
162		sclk->handle = handle;
163
164		err = scmi_clk_ops_init(dev, sclk);
165		if (err) {
166			dev_err(dev, "failed to register clock %d\n", idx);
167			devm_kfree(dev, sclk);
168			hws[idx] = NULL;
169		} else {
170			dev_dbg(dev, "Registered clock:%s\n", sclk->info->name);
171			hws[idx] = &sclk->hw;
172		}
173	}
174
175	return devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
176					   clk_data);
177}
178
179static const struct scmi_device_id scmi_id_table[] = {
180	{ SCMI_PROTOCOL_CLOCK },
181	{ },
182};
183MODULE_DEVICE_TABLE(scmi, scmi_id_table);
184
185static struct scmi_driver scmi_clocks_driver = {
186	.name = "scmi-clocks",
187	.probe = scmi_clocks_probe,
188	.id_table = scmi_id_table,
189};
190module_scmi_driver(scmi_clocks_driver);
191
192MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
193MODULE_DESCRIPTION("ARM SCMI clock driver");
194MODULE_LICENSE("GPL v2");