1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Freescale FlexTimer Module (FTM) timer driver.
4  *
5  * Copyright 2014 Freescale Semiconductor, Inc.
6  */
7 
8 #include <linux/clk.h>
9 #include <linux/clockchips.h>
10 #include <linux/clocksource.h>
11 #include <linux/err.h>
12 #include <linux/interrupt.h>
13 #include <linux/io.h>
14 #include <linux/of_address.h>
15 #include <linux/of_irq.h>
16 #include <linux/sched_clock.h>
17 #include <linux/slab.h>
18 #include <linux/fsl/ftm.h>
19 
20 #define FTM_SC_CLK(c)	((c) << FTM_SC_CLK_MASK_SHIFT)
21 
22 struct ftm_clock_device {
23 	void __iomem *clksrc_base;
24 	void __iomem *clkevt_base;
25 	unsigned long periodic_cyc;
26 	unsigned long ps;
27 	bool big_endian;
28 };
29 
30 static struct ftm_clock_device *priv;
31 
32 static inline u32 ftm_readl(void __iomem *addr)
33 {
34 	if (priv->big_endian)
35 		return ioread32be(addr);
36 	else
37 		return ioread32(addr);
38 }
39 
40 static inline void ftm_writel(u32 val, void __iomem *addr)
41 {
42 	if (priv->big_endian)
43 		iowrite32be(val, addr);
44 	else
45 		iowrite32(val, addr);
46 }
47 
48 static inline void ftm_counter_enable(void __iomem *base)
49 {
50 	u32 val;
51 
52 	/* select and enable counter clock source */
53 	val = ftm_readl(base + FTM_SC);
54 	val &= ~(FTM_SC_PS_MASK | FTM_SC_CLK_MASK);
55 	val |= priv->ps | FTM_SC_CLK(1);
56 	ftm_writel(val, base + FTM_SC);
57 }
58 
59 static inline void ftm_counter_disable(void __iomem *base)
60 {
61 	u32 val;
62 
63 	/* disable counter clock source */
64 	val = ftm_readl(base + FTM_SC);
65 	val &= ~(FTM_SC_PS_MASK | FTM_SC_CLK_MASK);
66 	ftm_writel(val, base + FTM_SC);
67 }
68 
69 static inline void ftm_irq_acknowledge(void __iomem *base)
70 {
71 	u32 val;
72 
73 	val = ftm_readl(base + FTM_SC);
74 	val &= ~FTM_SC_TOF;
75 	ftm_writel(val, base + FTM_SC);
76 }
77 
78 static inline void ftm_irq_enable(void __iomem *base)
79 {
80 	u32 val;
81 
82 	val = ftm_readl(base + FTM_SC);
83 	val |= FTM_SC_TOIE;
84 	ftm_writel(val, base + FTM_SC);
85 }
86 
87 static inline void ftm_irq_disable(void __iomem *base)
88 {
89 	u32 val;
90 
91 	val = ftm_readl(base + FTM_SC);
92 	val &= ~FTM_SC_TOIE;
93 	ftm_writel(val, base + FTM_SC);
94 }
95 
96 static inline void ftm_reset_counter(void __iomem *base)
97 {
98 	/*
99 	 * The CNT register contains the FTM counter value.
100 	 * Reset clears the CNT register. Writing any value to COUNT
101 	 * updates the counter with its initial value, CNTIN.
102 	 */
103 	ftm_writel(0x00, base + FTM_CNT);
104 }
105 
106 static u64 notrace ftm_read_sched_clock(void)
107 {
108 	return ftm_readl(priv->clksrc_base + FTM_CNT);
109 }
110 
111 static int ftm_set_next_event(unsigned long delta,
112 				struct clock_event_device *unused)
113 {
114 	/*
115 	 * The CNNIN and MOD are all double buffer registers, writing
116 	 * to the MOD register latches the value into a buffer. The MOD
117 	 * register is updated with the value of its write buffer with
118 	 * the following scenario:
119 	 * a, the counter source clock is disabled.
120 	 */
121 	ftm_counter_disable(priv->clkevt_base);
122 
123 	/* Force the value of CNTIN to be loaded into the FTM counter */
124 	ftm_reset_counter(priv->clkevt_base);
125 
126 	/*
127 	 * The counter increments until the value of MOD is reached,
128 	 * at which point the counter is reloaded with the value of CNTIN.
129 	 * The TOF (the overflow flag) bit is set when the FTM counter
130 	 * changes from MOD to CNTIN. So we should using the delta - 1.
131 	 */
132 	ftm_writel(delta - 1, priv->clkevt_base + FTM_MOD);
133 
134 	ftm_counter_enable(priv->clkevt_base);
135 
136 	ftm_irq_enable(priv->clkevt_base);
137 
138 	return 0;
139 }
140 
141 static int ftm_set_oneshot(struct clock_event_device *evt)
142 {
143 	ftm_counter_disable(priv->clkevt_base);
144 	return 0;
145 }
146 
147 static int ftm_set_periodic(struct clock_event_device *evt)
148 {
149 	ftm_set_next_event(priv->periodic_cyc, evt);
150 	return 0;
151 }
152 
153 static irqreturn_t ftm_evt_interrupt(int irq, void *dev_id)
154 {
155 	struct clock_event_device *evt = dev_id;
156 
157 	ftm_irq_acknowledge(priv->clkevt_base);
158 
159 	if (likely(clockevent_state_oneshot(evt))) {
160 		ftm_irq_disable(priv->clkevt_base);
161 		ftm_counter_disable(priv->clkevt_base);
162 	}
163 
164 	evt->event_handler(evt);
165 
166 	return IRQ_HANDLED;
167 }
168 
169 static struct clock_event_device ftm_clockevent = {
170 	.name			= "Freescale ftm timer",
171 	.features		= CLOCK_EVT_FEAT_PERIODIC |
172 				  CLOCK_EVT_FEAT_ONESHOT,
173 	.set_state_periodic	= ftm_set_periodic,
174 	.set_state_oneshot	= ftm_set_oneshot,
175 	.set_next_event		= ftm_set_next_event,
176 	.rating			= 300,
177 };
178 
179 static int __init ftm_clockevent_init(unsigned long freq, int irq)
180 {
181 	int err;
182 
183 	ftm_writel(0x00, priv->clkevt_base + FTM_CNTIN);
184 	ftm_writel(~0u, priv->clkevt_base + FTM_MOD);
185 
186 	ftm_reset_counter(priv->clkevt_base);
187 
188 	err = request_irq(irq, ftm_evt_interrupt, IRQF_TIMER | IRQF_IRQPOLL,
189 			  "Freescale ftm timer", &ftm_clockevent);
190 	if (err) {
191 		pr_err("ftm: setup irq failed: %d\n", err);
192 		return err;
193 	}
194 
195 	ftm_clockevent.cpumask = cpumask_of(0);
196 	ftm_clockevent.irq = irq;
197 
198 	clockevents_config_and_register(&ftm_clockevent,
199 					freq / (1 << priv->ps),
200 					1, 0xffff);
201 
202 	ftm_counter_enable(priv->clkevt_base);
203 
204 	return 0;
205 }
206 
207 static int __init ftm_clocksource_init(unsigned long freq)
208 {
209 	int err;
210 
211 	ftm_writel(0x00, priv->clksrc_base + FTM_CNTIN);
212 	ftm_writel(~0u, priv->clksrc_base + FTM_MOD);
213 
214 	ftm_reset_counter(priv->clksrc_base);
215 
216 	sched_clock_register(ftm_read_sched_clock, 16, freq / (1 << priv->ps));
217 	err = clocksource_mmio_init(priv->clksrc_base + FTM_CNT, "fsl-ftm",
218 				    freq / (1 << priv->ps), 300, 16,
219 				    clocksource_mmio_readl_up);
220 	if (err) {
221 		pr_err("ftm: init clock source mmio failed: %d\n", err);
222 		return err;
223 	}
224 
225 	ftm_counter_enable(priv->clksrc_base);
226 
227 	return 0;
228 }
229 
230 static int __init __ftm_clk_init(struct device_node *np, char *cnt_name,
231 				 char *ftm_name)
232 {
233 	struct clk *clk;
234 	int err;
235 
236 	clk = of_clk_get_by_name(np, cnt_name);
237 	if (IS_ERR(clk)) {
238 		pr_err("ftm: Cannot get \"%s\": %ld\n", cnt_name, PTR_ERR(clk));
239 		return PTR_ERR(clk);
240 	}
241 	err = clk_prepare_enable(clk);
242 	if (err) {
243 		pr_err("ftm: clock failed to prepare+enable \"%s\": %d\n",
244 			cnt_name, err);
245 		return err;
246 	}
247 
248 	clk = of_clk_get_by_name(np, ftm_name);
249 	if (IS_ERR(clk)) {
250 		pr_err("ftm: Cannot get \"%s\": %ld\n", ftm_name, PTR_ERR(clk));
251 		return PTR_ERR(clk);
252 	}
253 	err = clk_prepare_enable(clk);
254 	if (err)
255 		pr_err("ftm: clock failed to prepare+enable \"%s\": %d\n",
256 			ftm_name, err);
257 
258 	return clk_get_rate(clk);
259 }
260 
261 static unsigned long __init ftm_clk_init(struct device_node *np)
262 {
263 	long freq;
264 
265 	freq = __ftm_clk_init(np, "ftm-evt-counter-en", "ftm-evt");
266 	if (freq <= 0)
267 		return 0;
268 
269 	freq = __ftm_clk_init(np, "ftm-src-counter-en", "ftm-src");
270 	if (freq <= 0)
271 		return 0;
272 
273 	return freq;
274 }
275 
276 static int __init ftm_calc_closest_round_cyc(unsigned long freq)
277 {
278 	priv->ps = 0;
279 
280 	/* The counter register is only using the lower 16 bits, and
281 	 * if the 'freq' value is to big here, then the periodic_cyc
282 	 * may exceed 0xFFFF.
283 	 */
284 	do {
285 		priv->periodic_cyc = DIV_ROUND_CLOSEST(freq,
286 						HZ * (1 << priv->ps++));
287 	} while (priv->periodic_cyc > 0xFFFF);
288 
289 	if (priv->ps > FTM_PS_MAX) {
290 		pr_err("ftm: the prescaler is %lu > %d\n",
291 				priv->ps, FTM_PS_MAX);
292 		return -EINVAL;
293 	}
294 
295 	return 0;
296 }
297 
298 static int __init ftm_timer_init(struct device_node *np)
299 {
300 	unsigned long freq;
301 	int ret, irq;
302 
303 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
304 	if (!priv)
305 		return -ENOMEM;
306 
307 	ret = -ENXIO;
308 	priv->clkevt_base = of_iomap(np, 0);
309 	if (!priv->clkevt_base) {
310 		pr_err("ftm: unable to map event timer registers\n");
311 		goto err_clkevt;
312 	}
313 
314 	priv->clksrc_base = of_iomap(np, 1);
315 	if (!priv->clksrc_base) {
316 		pr_err("ftm: unable to map source timer registers\n");
317 		goto err_clksrc;
318 	}
319 
320 	ret = -EINVAL;
321 	irq = irq_of_parse_and_map(np, 0);
322 	if (irq <= 0) {
323 		pr_err("ftm: unable to get IRQ from DT, %d\n", irq);
324 		goto err;
325 	}
326 
327 	priv->big_endian = of_property_read_bool(np, "big-endian");
328 
329 	freq = ftm_clk_init(np);
330 	if (!freq)
331 		goto err;
332 
333 	ret = ftm_calc_closest_round_cyc(freq);
334 	if (ret)
335 		goto err;
336 
337 	ret = ftm_clocksource_init(freq);
338 	if (ret)
339 		goto err;
340 
341 	ret = ftm_clockevent_init(freq, irq);
342 	if (ret)
343 		goto err;
344 
345 	return 0;
346 
347 err:
348 	iounmap(priv->clksrc_base);
349 err_clksrc:
350 	iounmap(priv->clkevt_base);
351 err_clkevt:
352 	kfree(priv);
353 	return ret;
354 }
355 TIMER_OF_DECLARE(flextimer, "fsl,ftm-timer", ftm_timer_init);
356