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
ftm_readl(void __iomem * addr)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
ftm_writel(u32 val,void __iomem * addr)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
ftm_counter_enable(void __iomem * base)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
ftm_counter_disable(void __iomem * base)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
ftm_irq_acknowledge(void __iomem * base)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
ftm_irq_enable(void __iomem * base)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
ftm_irq_disable(void __iomem * base)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
ftm_reset_counter(void __iomem * base)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
ftm_read_sched_clock(void)106 static u64 notrace ftm_read_sched_clock(void)
107 {
108 return ftm_readl(priv->clksrc_base + FTM_CNT);
109 }
110
ftm_set_next_event(unsigned long delta,struct clock_event_device * unused)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 diabled.
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
ftm_set_oneshot(struct clock_event_device * evt)141 static int ftm_set_oneshot(struct clock_event_device *evt)
142 {
143 ftm_counter_disable(priv->clkevt_base);
144 return 0;
145 }
146
ftm_set_periodic(struct clock_event_device * evt)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
ftm_evt_interrupt(int irq,void * dev_id)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
ftm_clockevent_init(unsigned long freq,int irq)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
ftm_clocksource_init(unsigned long freq)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
__ftm_clk_init(struct device_node * np,char * cnt_name,char * ftm_name)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
ftm_clk_init(struct device_node * np)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
ftm_calc_closest_round_cyc(unsigned long freq)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
ftm_timer_init(struct device_node * np)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
