xref: /openbmc/linux/drivers/clk/renesas/clk-mstp.c (revision 1a59d1b8) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * R-Car MSTP clocks
4  *
5  * Copyright (C) 2013 Ideas On Board SPRL
6  * Copyright (C) 2015 Glider bvba
7  *
8  * Contact: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
9  */
10 
11 #include <linux/clk.h>
12 #include <linux/clk-provider.h>
13 #include <linux/clkdev.h>
14 #include <linux/clk/renesas.h>
15 #include <linux/device.h>
16 #include <linux/io.h>
17 #include <linux/of.h>
18 #include <linux/of_address.h>
19 #include <linux/pm_clock.h>
20 #include <linux/pm_domain.h>
21 #include <linux/spinlock.h>
22 
23 /*
24  * MSTP clocks. We can't use standard gate clocks as we need to poll on the
25  * status register when enabling the clock.
26  */
27 
28 #define MSTP_MAX_CLOCKS		32
29 
30 /**
31  * struct mstp_clock_group - MSTP gating clocks group
32  *
33  * @data: clocks in this group
34  * @smstpcr: module stop control register
35  * @mstpsr: module stop status register (optional)
36  * @lock: protects writes to SMSTPCR
37  * @width_8bit: registers are 8-bit, not 32-bit
38  */
39 struct mstp_clock_group {
40 	struct clk_onecell_data data;
41 	void __iomem *smstpcr;
42 	void __iomem *mstpsr;
43 	spinlock_t lock;
44 	bool width_8bit;
45 };
46 
47 /**
48  * struct mstp_clock - MSTP gating clock
49  * @hw: handle between common and hardware-specific interfaces
50  * @bit_index: control bit index
51  * @group: MSTP clocks group
52  */
53 struct mstp_clock {
54 	struct clk_hw hw;
55 	u32 bit_index;
56 	struct mstp_clock_group *group;
57 };
58 
59 #define to_mstp_clock(_hw) container_of(_hw, struct mstp_clock, hw)
60 
61 static inline u32 cpg_mstp_read(struct mstp_clock_group *group,
62 				u32 __iomem *reg)
63 {
64 	return group->width_8bit ? readb(reg) : readl(reg);
65 }
66 
67 static inline void cpg_mstp_write(struct mstp_clock_group *group, u32 val,
68 				  u32 __iomem *reg)
69 {
70 	group->width_8bit ? writeb(val, reg) : writel(val, reg);
71 }
72 
73 static int cpg_mstp_clock_endisable(struct clk_hw *hw, bool enable)
74 {
75 	struct mstp_clock *clock = to_mstp_clock(hw);
76 	struct mstp_clock_group *group = clock->group;
77 	u32 bitmask = BIT(clock->bit_index);
78 	unsigned long flags;
79 	unsigned int i;
80 	u32 value;
81 
82 	spin_lock_irqsave(&group->lock, flags);
83 
84 	value = cpg_mstp_read(group, group->smstpcr);
85 	if (enable)
86 		value &= ~bitmask;
87 	else
88 		value |= bitmask;
89 	cpg_mstp_write(group, value, group->smstpcr);
90 
91 	if (!group->mstpsr) {
92 		/* dummy read to ensure write has completed */
93 		cpg_mstp_read(group, group->smstpcr);
94 		barrier_data(group->smstpcr);
95 	}
96 
97 	spin_unlock_irqrestore(&group->lock, flags);
98 
99 	if (!enable || !group->mstpsr)
100 		return 0;
101 
102 	for (i = 1000; i > 0; --i) {
103 		if (!(cpg_mstp_read(group, group->mstpsr) & bitmask))
104 			break;
105 		cpu_relax();
106 	}
107 
108 	if (!i) {
109 		pr_err("%s: failed to enable %p[%d]\n", __func__,
110 		       group->smstpcr, clock->bit_index);
111 		return -ETIMEDOUT;
112 	}
113 
114 	return 0;
115 }
116 
117 static int cpg_mstp_clock_enable(struct clk_hw *hw)
118 {
119 	return cpg_mstp_clock_endisable(hw, true);
120 }
121 
122 static void cpg_mstp_clock_disable(struct clk_hw *hw)
123 {
124 	cpg_mstp_clock_endisable(hw, false);
125 }
126 
127 static int cpg_mstp_clock_is_enabled(struct clk_hw *hw)
128 {
129 	struct mstp_clock *clock = to_mstp_clock(hw);
130 	struct mstp_clock_group *group = clock->group;
131 	u32 value;
132 
133 	if (group->mstpsr)
134 		value = cpg_mstp_read(group, group->mstpsr);
135 	else
136 		value = cpg_mstp_read(group, group->smstpcr);
137 
138 	return !(value & BIT(clock->bit_index));
139 }
140 
141 static const struct clk_ops cpg_mstp_clock_ops = {
142 	.enable = cpg_mstp_clock_enable,
143 	.disable = cpg_mstp_clock_disable,
144 	.is_enabled = cpg_mstp_clock_is_enabled,
145 };
146 
147 static struct clk * __init cpg_mstp_clock_register(const char *name,
148 	const char *parent_name, unsigned int index,
149 	struct mstp_clock_group *group)
150 {
151 	struct clk_init_data init;
152 	struct mstp_clock *clock;
153 	struct clk *clk;
154 
155 	clock = kzalloc(sizeof(*clock), GFP_KERNEL);
156 	if (!clock)
157 		return ERR_PTR(-ENOMEM);
158 
159 	init.name = name;
160 	init.ops = &cpg_mstp_clock_ops;
161 	init.flags = CLK_SET_RATE_PARENT;
162 	/* INTC-SYS is the module clock of the GIC, and must not be disabled */
163 	if (!strcmp(name, "intc-sys")) {
164 		pr_debug("MSTP %s setting CLK_IS_CRITICAL\n", name);
165 		init.flags |= CLK_IS_CRITICAL;
166 	}
167 	init.parent_names = &parent_name;
168 	init.num_parents = 1;
169 
170 	clock->bit_index = index;
171 	clock->group = group;
172 	clock->hw.init = &init;
173 
174 	clk = clk_register(NULL, &clock->hw);
175 
176 	if (IS_ERR(clk))
177 		kfree(clock);
178 
179 	return clk;
180 }
181 
182 static void __init cpg_mstp_clocks_init(struct device_node *np)
183 {
184 	struct mstp_clock_group *group;
185 	const char *idxname;
186 	struct clk **clks;
187 	unsigned int i;
188 
189 	group = kzalloc(sizeof(*group), GFP_KERNEL);
190 	clks = kmalloc_array(MSTP_MAX_CLOCKS, sizeof(*clks), GFP_KERNEL);
191 	if (group == NULL || clks == NULL) {
192 		kfree(group);
193 		kfree(clks);
194 		return;
195 	}
196 
197 	spin_lock_init(&group->lock);
198 	group->data.clks = clks;
199 
200 	group->smstpcr = of_iomap(np, 0);
201 	group->mstpsr = of_iomap(np, 1);
202 
203 	if (group->smstpcr == NULL) {
204 		pr_err("%s: failed to remap SMSTPCR\n", __func__);
205 		kfree(group);
206 		kfree(clks);
207 		return;
208 	}
209 
210 	if (of_device_is_compatible(np, "renesas,r7s72100-mstp-clocks"))
211 		group->width_8bit = true;
212 
213 	for (i = 0; i < MSTP_MAX_CLOCKS; ++i)
214 		clks[i] = ERR_PTR(-ENOENT);
215 
216 	if (of_find_property(np, "clock-indices", &i))
217 		idxname = "clock-indices";
218 	else
219 		idxname = "renesas,clock-indices";
220 
221 	for (i = 0; i < MSTP_MAX_CLOCKS; ++i) {
222 		const char *parent_name;
223 		const char *name;
224 		u32 clkidx;
225 		int ret;
226 
227 		/* Skip clocks with no name. */
228 		ret = of_property_read_string_index(np, "clock-output-names",
229 						    i, &name);
230 		if (ret < 0 || strlen(name) == 0)
231 			continue;
232 
233 		parent_name = of_clk_get_parent_name(np, i);
234 		ret = of_property_read_u32_index(np, idxname, i, &clkidx);
235 		if (parent_name == NULL || ret < 0)
236 			break;
237 
238 		if (clkidx >= MSTP_MAX_CLOCKS) {
239 			pr_err("%s: invalid clock %pOFn %s index %u\n",
240 			       __func__, np, name, clkidx);
241 			continue;
242 		}
243 
244 		clks[clkidx] = cpg_mstp_clock_register(name, parent_name,
245 						       clkidx, group);
246 		if (!IS_ERR(clks[clkidx])) {
247 			group->data.clk_num = max(group->data.clk_num,
248 						  clkidx + 1);
249 			/*
250 			 * Register a clkdev to let board code retrieve the
251 			 * clock by name and register aliases for non-DT
252 			 * devices.
253 			 *
254 			 * FIXME: Remove this when all devices that require a
255 			 * clock will be instantiated from DT.
256 			 */
257 			clk_register_clkdev(clks[clkidx], name, NULL);
258 		} else {
259 			pr_err("%s: failed to register %pOFn %s clock (%ld)\n",
260 			       __func__, np, name, PTR_ERR(clks[clkidx]));
261 		}
262 	}
263 
264 	of_clk_add_provider(np, of_clk_src_onecell_get, &group->data);
265 }
266 CLK_OF_DECLARE(cpg_mstp_clks, "renesas,cpg-mstp-clocks", cpg_mstp_clocks_init);
267 
268 int cpg_mstp_attach_dev(struct generic_pm_domain *unused, struct device *dev)
269 {
270 	struct device_node *np = dev->of_node;
271 	struct of_phandle_args clkspec;
272 	struct clk *clk;
273 	int i = 0;
274 	int error;
275 
276 	while (!of_parse_phandle_with_args(np, "clocks", "#clock-cells", i,
277 					   &clkspec)) {
278 		if (of_device_is_compatible(clkspec.np,
279 					    "renesas,cpg-mstp-clocks"))
280 			goto found;
281 
282 		/* BSC on r8a73a4/sh73a0 uses zb_clk instead of an mstp clock */
283 		if (of_node_name_eq(clkspec.np, "zb_clk"))
284 			goto found;
285 
286 		of_node_put(clkspec.np);
287 		i++;
288 	}
289 
290 	return 0;
291 
292 found:
293 	clk = of_clk_get_from_provider(&clkspec);
294 	of_node_put(clkspec.np);
295 
296 	if (IS_ERR(clk))
297 		return PTR_ERR(clk);
298 
299 	error = pm_clk_create(dev);
300 	if (error) {
301 		dev_err(dev, "pm_clk_create failed %d\n", error);
302 		goto fail_put;
303 	}
304 
305 	error = pm_clk_add_clk(dev, clk);
306 	if (error) {
307 		dev_err(dev, "pm_clk_add_clk %pC failed %d\n", clk, error);
308 		goto fail_destroy;
309 	}
310 
311 	return 0;
312 
313 fail_destroy:
314 	pm_clk_destroy(dev);
315 fail_put:
316 	clk_put(clk);
317 	return error;
318 }
319 
320 void cpg_mstp_detach_dev(struct generic_pm_domain *unused, struct device *dev)
321 {
322 	if (!pm_clk_no_clocks(dev))
323 		pm_clk_destroy(dev);
324 }
325 
326 void __init cpg_mstp_add_clk_domain(struct device_node *np)
327 {
328 	struct generic_pm_domain *pd;
329 	u32 ncells;
330 
331 	if (of_property_read_u32(np, "#power-domain-cells", &ncells)) {
332 		pr_warn("%pOF lacks #power-domain-cells\n", np);
333 		return;
334 	}
335 
336 	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
337 	if (!pd)
338 		return;
339 
340 	pd->name = np->name;
341 	pd->flags = GENPD_FLAG_PM_CLK | GENPD_FLAG_ACTIVE_WAKEUP;
342 	pd->attach_dev = cpg_mstp_attach_dev;
343 	pd->detach_dev = cpg_mstp_detach_dev;
344 	pm_genpd_init(pd, &pm_domain_always_on_gov, false);
345 
346 	of_genpd_add_provider_simple(np, pd);
347 }
348