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	u64 fmin, fmax, ftmp;
 42	struct scmi_clk *clk = to_scmi_clk(hw);
 43
 44	/*
 45	 * We can't figure out what rate it will be, so just return the
 46	 * rate back to the caller. scmi_clk_recalc_rate() will be called
 47	 * after the rate is set and we'll know what rate the clock is
 48	 * running at then.
 49	 */
 50	if (clk->info->rate_discrete)
 51		return rate;
 52
 53	fmin = clk->info->range.min_rate;
 54	fmax = clk->info->range.max_rate;
 55	if (rate <= fmin)
 56		return fmin;
 57	else if (rate >= fmax)
 58		return fmax;
 59
 60	ftmp = rate - fmin;
 61	ftmp += clk->info->range.step_size - 1; /* to round up */
 62	do_div(ftmp, clk->info->range.step_size);
 63
 64	return ftmp * clk->info->range.step_size + fmin;
 65}
 66
 67static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
 68			     unsigned long parent_rate)
 69{
 70	struct scmi_clk *clk = to_scmi_clk(hw);
 71
 72	return clk->handle->clk_ops->rate_set(clk->handle, clk->id, rate);
 73}
 74
 75static int scmi_clk_enable(struct clk_hw *hw)
 76{
 77	struct scmi_clk *clk = to_scmi_clk(hw);
 78
 79	return clk->handle->clk_ops->enable(clk->handle, clk->id);
 80}
 81
 82static void scmi_clk_disable(struct clk_hw *hw)
 83{
 84	struct scmi_clk *clk = to_scmi_clk(hw);
 85
 86	clk->handle->clk_ops->disable(clk->handle, clk->id);
 87}
 88
 89static const struct clk_ops scmi_clk_ops = {
 90	.recalc_rate = scmi_clk_recalc_rate,
 91	.round_rate = scmi_clk_round_rate,
 92	.set_rate = scmi_clk_set_rate,
 93	/*
 94	 * We can't provide enable/disable callback as we can't perform the same
 95	 * in atomic context. Since the clock framework provides standard API
 96	 * clk_prepare_enable that helps cases using clk_enable in non-atomic
 97	 * context, it should be fine providing prepare/unprepare.
 98	 */
 99	.prepare = scmi_clk_enable,
100	.unprepare = scmi_clk_disable,
101};
102
103static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk)
104{
105	int ret;
106	unsigned long min_rate, max_rate;
107
108	struct clk_init_data init = {
109		.flags = CLK_GET_RATE_NOCACHE,
110		.num_parents = 0,
111		.ops = &scmi_clk_ops,
112		.name = sclk->info->name,
113	};
114
115	sclk->hw.init = &init;
116	ret = devm_clk_hw_register(dev, &sclk->hw);
117	if (ret)
118		return ret;
119
120	if (sclk->info->rate_discrete) {
121		int num_rates = sclk->info->list.num_rates;
122
123		if (num_rates <= 0)
124			return -EINVAL;
125
126		min_rate = sclk->info->list.rates[0];
127		max_rate = sclk->info->list.rates[num_rates - 1];
128	} else {
129		min_rate = sclk->info->range.min_rate;
130		max_rate = sclk->info->range.max_rate;
131	}
132
133	clk_hw_set_rate_range(&sclk->hw, min_rate, max_rate);
134	return ret;
135}
136
137static int scmi_clocks_probe(struct scmi_device *sdev)
138{
139	int idx, count, err;
140	struct clk_hw **hws;
141	struct clk_hw_onecell_data *clk_data;
142	struct device *dev = &sdev->dev;
143	struct device_node *np = dev->of_node;
144	const struct scmi_handle *handle = sdev->handle;
145
146	if (!handle || !handle->clk_ops)
147		return -ENODEV;
148
149	count = handle->clk_ops->count_get(handle);
150	if (count < 0) {
151		dev_err(dev, "%pOFn: invalid clock output count\n", np);
152		return -EINVAL;
153	}
154
155	clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, count),
156				GFP_KERNEL);
157	if (!clk_data)
158		return -ENOMEM;
159
160	clk_data->num = count;
161	hws = clk_data->hws;
162
163	for (idx = 0; idx < count; idx++) {
164		struct scmi_clk *sclk;
165
166		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
167		if (!sclk)
168			return -ENOMEM;
169
170		sclk->info = handle->clk_ops->info_get(handle, idx);
171		if (!sclk->info) {
172			dev_dbg(dev, "invalid clock info for idx %d\n", idx);
173			continue;
174		}
175
176		sclk->id = idx;
177		sclk->handle = handle;
178
179		err = scmi_clk_ops_init(dev, sclk);
180		if (err) {
181			dev_err(dev, "failed to register clock %d\n", idx);
182			devm_kfree(dev, sclk);
183			hws[idx] = NULL;
184		} else {
185			dev_dbg(dev, "Registered clock:%s\n", sclk->info->name);
186			hws[idx] = &sclk->hw;
187		}
188	}
189
190	return devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
191					   clk_data);
192}
193
194static const struct scmi_device_id scmi_id_table[] = {
195	{ SCMI_PROTOCOL_CLOCK, "clocks" },
196	{ },
197};
198MODULE_DEVICE_TABLE(scmi, scmi_id_table);
199
200static struct scmi_driver scmi_clocks_driver = {
201	.name = "scmi-clocks",
202	.probe = scmi_clocks_probe,
203	.id_table = scmi_id_table,
204};
205module_scmi_driver(scmi_clocks_driver);
206
207MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
208MODULE_DESCRIPTION("ARM SCMI clock driver");
209MODULE_LICENSE("GPL v2");