1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2016-17 Synopsys, Inc. (www.synopsys.com)
4 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
5 */
6
7 /* ARC700 has two 32bit independent prog Timers: TIMER0 and TIMER1, Each can be
8 * programmed to go from @count to @limit and optionally interrupt.
9 * We've designated TIMER0 for clockevents and TIMER1 for clocksource
10 *
11 * ARCv2 based HS38 cores have RTC (in-core) and GFRC (inside ARConnect/MCIP)
12 * which are suitable for UP and SMP based clocksources respectively
13 */
14
15 #include <linux/interrupt.h>
16 #include <linux/bits.h>
17 #include <linux/clk.h>
18 #include <linux/clk-provider.h>
19 #include <linux/clocksource.h>
20 #include <linux/clockchips.h>
21 #include <linux/cpu.h>
22 #include <linux/of.h>
23 #include <linux/of_irq.h>
24 #include <linux/sched_clock.h>
25
26 #include <soc/arc/timers.h>
27 #include <soc/arc/mcip.h>
28
29
30 static unsigned long arc_timer_freq;
31
arc_get_timer_clk(struct device_node * node)32 static int noinline arc_get_timer_clk(struct device_node *node)
33 {
34 struct clk *clk;
35 int ret;
36
37 clk = of_clk_get(node, 0);
38 if (IS_ERR(clk)) {
39 pr_err("timer missing clk\n");
40 return PTR_ERR(clk);
41 }
42
43 ret = clk_prepare_enable(clk);
44 if (ret) {
45 pr_err("Couldn't enable parent clk\n");
46 return ret;
47 }
48
49 arc_timer_freq = clk_get_rate(clk);
50
51 return 0;
52 }
53
54 /********** Clock Source Device *********/
55
56 #ifdef CONFIG_ARC_TIMERS_64BIT
57
arc_read_gfrc(struct clocksource * cs)58 static u64 arc_read_gfrc(struct clocksource *cs)
59 {
60 unsigned long flags;
61 u32 l, h;
62
63 /*
64 * From a programming model pov, there seems to be just one instance of
65 * MCIP_CMD/MCIP_READBACK however micro-architecturally there's
66 * an instance PER ARC CORE (not per cluster), and there are dedicated
67 * hardware decode logic (per core) inside ARConnect to handle
68 * simultaneous read/write accesses from cores via those two registers.
69 * So several concurrent commands to ARConnect are OK if they are
70 * trying to access two different sub-components (like GFRC,
71 * inter-core interrupt, etc...). HW also supports simultaneously
72 * accessing GFRC by multiple cores.
73 * That's why it is safe to disable hard interrupts on the local CPU
74 * before access to GFRC instead of taking global MCIP spinlock
75 * defined in arch/arc/kernel/mcip.c
76 */
77 local_irq_save(flags);
78
79 __mcip_cmd(CMD_GFRC_READ_LO, 0);
80 l = read_aux_reg(ARC_REG_MCIP_READBACK);
81
82 __mcip_cmd(CMD_GFRC_READ_HI, 0);
83 h = read_aux_reg(ARC_REG_MCIP_READBACK);
84
85 local_irq_restore(flags);
86
87 return (((u64)h) << 32) | l;
88 }
89
arc_gfrc_clock_read(void)90 static notrace u64 arc_gfrc_clock_read(void)
91 {
92 return arc_read_gfrc(NULL);
93 }
94
95 static struct clocksource arc_counter_gfrc = {
96 .name = "ARConnect GFRC",
97 .rating = 400,
98 .read = arc_read_gfrc,
99 .mask = CLOCKSOURCE_MASK(64),
100 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
101 };
102
arc_cs_setup_gfrc(struct device_node * node)103 static int __init arc_cs_setup_gfrc(struct device_node *node)
104 {
105 struct mcip_bcr mp;
106 int ret;
107
108 READ_BCR(ARC_REG_MCIP_BCR, mp);
109 if (!mp.gfrc) {
110 pr_warn("Global-64-bit-Ctr clocksource not detected\n");
111 return -ENXIO;
112 }
113
114 ret = arc_get_timer_clk(node);
115 if (ret)
116 return ret;
117
118 sched_clock_register(arc_gfrc_clock_read, 64, arc_timer_freq);
119
120 return clocksource_register_hz(&arc_counter_gfrc, arc_timer_freq);
121 }
122 TIMER_OF_DECLARE(arc_gfrc, "snps,archs-timer-gfrc", arc_cs_setup_gfrc);
123
124 #define AUX_RTC_CTRL 0x103
125 #define AUX_RTC_LOW 0x104
126 #define AUX_RTC_HIGH 0x105
127
arc_read_rtc(struct clocksource * cs)128 static u64 arc_read_rtc(struct clocksource *cs)
129 {
130 unsigned long status;
131 u32 l, h;
132
133 /*
134 * hardware has an internal state machine which tracks readout of
135 * low/high and updates the CTRL.status if
136 * - interrupt/exception taken between the two reads
137 * - high increments after low has been read
138 */
139 do {
140 l = read_aux_reg(AUX_RTC_LOW);
141 h = read_aux_reg(AUX_RTC_HIGH);
142 status = read_aux_reg(AUX_RTC_CTRL);
143 } while (!(status & BIT(31)));
144
145 return (((u64)h) << 32) | l;
146 }
147
arc_rtc_clock_read(void)148 static notrace u64 arc_rtc_clock_read(void)
149 {
150 return arc_read_rtc(NULL);
151 }
152
153 static struct clocksource arc_counter_rtc = {
154 .name = "ARCv2 RTC",
155 .rating = 350,
156 .read = arc_read_rtc,
157 .mask = CLOCKSOURCE_MASK(64),
158 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
159 };
160
arc_cs_setup_rtc(struct device_node * node)161 static int __init arc_cs_setup_rtc(struct device_node *node)
162 {
163 struct bcr_timer timer;
164 int ret;
165
166 READ_BCR(ARC_REG_TIMERS_BCR, timer);
167 if (!timer.rtc) {
168 pr_warn("Local-64-bit-Ctr clocksource not detected\n");
169 return -ENXIO;
170 }
171
172 /* Local to CPU hence not usable in SMP */
173 if (IS_ENABLED(CONFIG_SMP)) {
174 pr_warn("Local-64-bit-Ctr not usable in SMP\n");
175 return -EINVAL;
176 }
177
178 ret = arc_get_timer_clk(node);
179 if (ret)
180 return ret;
181
182 write_aux_reg(AUX_RTC_CTRL, 1);
183
184 sched_clock_register(arc_rtc_clock_read, 64, arc_timer_freq);
185
186 return clocksource_register_hz(&arc_counter_rtc, arc_timer_freq);
187 }
188 TIMER_OF_DECLARE(arc_rtc, "snps,archs-timer-rtc", arc_cs_setup_rtc);
189
190 #endif
191
192 /*
193 * 32bit TIMER1 to keep counting monotonically and wraparound
194 */
195
arc_read_timer1(struct clocksource * cs)196 static u64 arc_read_timer1(struct clocksource *cs)
197 {
198 return (u64) read_aux_reg(ARC_REG_TIMER1_CNT);
199 }
200
arc_timer1_clock_read(void)201 static notrace u64 arc_timer1_clock_read(void)
202 {
203 return arc_read_timer1(NULL);
204 }
205
206 static struct clocksource arc_counter_timer1 = {
207 .name = "ARC Timer1",
208 .rating = 300,
209 .read = arc_read_timer1,
210 .mask = CLOCKSOURCE_MASK(32),
211 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
212 };
213
arc_cs_setup_timer1(struct device_node * node)214 static int __init arc_cs_setup_timer1(struct device_node *node)
215 {
216 int ret;
217
218 /* Local to CPU hence not usable in SMP */
219 if (IS_ENABLED(CONFIG_SMP))
220 return -EINVAL;
221
222 ret = arc_get_timer_clk(node);
223 if (ret)
224 return ret;
225
226 write_aux_reg(ARC_REG_TIMER1_LIMIT, ARC_TIMERN_MAX);
227 write_aux_reg(ARC_REG_TIMER1_CNT, 0);
228 write_aux_reg(ARC_REG_TIMER1_CTRL, ARC_TIMER_CTRL_NH);
229
230 sched_clock_register(arc_timer1_clock_read, 32, arc_timer_freq);
231
232 return clocksource_register_hz(&arc_counter_timer1, arc_timer_freq);
233 }
234
235 /********** Clock Event Device *********/
236
237 static int arc_timer_irq;
238
239 /*
240 * Arm the timer to interrupt after @cycles
241 * The distinction for oneshot/periodic is done in arc_event_timer_ack() below
242 */
arc_timer_event_setup(unsigned int cycles)243 static void arc_timer_event_setup(unsigned int cycles)
244 {
245 write_aux_reg(ARC_REG_TIMER0_LIMIT, cycles);
246 write_aux_reg(ARC_REG_TIMER0_CNT, 0); /* start from 0 */
247
248 write_aux_reg(ARC_REG_TIMER0_CTRL, ARC_TIMER_CTRL_IE | ARC_TIMER_CTRL_NH);
249 }
250
251
arc_clkevent_set_next_event(unsigned long delta,struct clock_event_device * dev)252 static int arc_clkevent_set_next_event(unsigned long delta,
253 struct clock_event_device *dev)
254 {
255 arc_timer_event_setup(delta);
256 return 0;
257 }
258
arc_clkevent_set_periodic(struct clock_event_device * dev)259 static int arc_clkevent_set_periodic(struct clock_event_device *dev)
260 {
261 /*
262 * At X Hz, 1 sec = 1000ms -> X cycles;
263 * 10ms -> X / 100 cycles
264 */
265 arc_timer_event_setup(arc_timer_freq / HZ);
266 return 0;
267 }
268
269 static DEFINE_PER_CPU(struct clock_event_device, arc_clockevent_device) = {
270 .name = "ARC Timer0",
271 .features = CLOCK_EVT_FEAT_ONESHOT |
272 CLOCK_EVT_FEAT_PERIODIC,
273 .rating = 300,
274 .set_next_event = arc_clkevent_set_next_event,
275 .set_state_periodic = arc_clkevent_set_periodic,
276 };
277
timer_irq_handler(int irq,void * dev_id)278 static irqreturn_t timer_irq_handler(int irq, void *dev_id)
279 {
280 /*
281 * Note that generic IRQ core could have passed @evt for @dev_id if
282 * irq_set_chip_and_handler() asked for handle_percpu_devid_irq()
283 */
284 struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
285 int irq_reenable = clockevent_state_periodic(evt);
286
287 /*
288 * 1. ACK the interrupt
289 * - For ARC700, any write to CTRL reg ACKs it, so just rewrite
290 * Count when [N]ot [H]alted bit.
291 * - For HS3x, it is a bit subtle. On taken count-down interrupt,
292 * IP bit [3] is set, which needs to be cleared for ACK'ing.
293 * The write below can only update the other two bits, hence
294 * explicitly clears IP bit
295 * 2. Re-arm interrupt if periodic by writing to IE bit [0]
296 */
297 write_aux_reg(ARC_REG_TIMER0_CTRL, irq_reenable | ARC_TIMER_CTRL_NH);
298
299 evt->event_handler(evt);
300
301 return IRQ_HANDLED;
302 }
303
304
arc_timer_starting_cpu(unsigned int cpu)305 static int arc_timer_starting_cpu(unsigned int cpu)
306 {
307 struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
308
309 evt->cpumask = cpumask_of(smp_processor_id());
310
311 clockevents_config_and_register(evt, arc_timer_freq, 0, ARC_TIMERN_MAX);
312 enable_percpu_irq(arc_timer_irq, 0);
313 return 0;
314 }
315
arc_timer_dying_cpu(unsigned int cpu)316 static int arc_timer_dying_cpu(unsigned int cpu)
317 {
318 disable_percpu_irq(arc_timer_irq);
319 return 0;
320 }
321
322 /*
323 * clockevent setup for boot CPU
324 */
arc_clockevent_setup(struct device_node * node)325 static int __init arc_clockevent_setup(struct device_node *node)
326 {
327 struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
328 int ret;
329
330 arc_timer_irq = irq_of_parse_and_map(node, 0);
331 if (arc_timer_irq <= 0) {
332 pr_err("clockevent: missing irq\n");
333 return -EINVAL;
334 }
335
336 ret = arc_get_timer_clk(node);
337 if (ret)
338 return ret;
339
340 /* Needs apriori irq_set_percpu_devid() done in intc map function */
341 ret = request_percpu_irq(arc_timer_irq, timer_irq_handler,
342 "Timer0 (per-cpu-tick)", evt);
343 if (ret) {
344 pr_err("clockevent: unable to request irq\n");
345 return ret;
346 }
347
348 ret = cpuhp_setup_state(CPUHP_AP_ARC_TIMER_STARTING,
349 "clockevents/arc/timer:starting",
350 arc_timer_starting_cpu,
351 arc_timer_dying_cpu);
352 if (ret) {
353 pr_err("Failed to setup hotplug state\n");
354 return ret;
355 }
356 return 0;
357 }
358
arc_of_timer_init(struct device_node * np)359 static int __init arc_of_timer_init(struct device_node *np)
360 {
361 static int init_count = 0;
362 int ret;
363
364 if (!init_count) {
365 init_count = 1;
366 ret = arc_clockevent_setup(np);
367 } else {
368 ret = arc_cs_setup_timer1(np);
369 }
370
371 return ret;
372 }
373 TIMER_OF_DECLARE(arc_clkevt, "snps,arc-timer", arc_of_timer_init);
374
