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13#define pr_fmt(fmt) "AT91: PIT: " fmt
14
15#include <linux/clk.h>
16#include <linux/clockchips.h>
17#include <linux/interrupt.h>
18#include <linux/irq.h>
19#include <linux/kernel.h>
20#include <linux/of.h>
21#include <linux/of_address.h>
22#include <linux/of_irq.h>
23#include <linux/slab.h>
24
25#define AT91_PIT_MR 0x00
26#define AT91_PIT_PITIEN BIT(25)
27#define AT91_PIT_PITEN BIT(24)
28#define AT91_PIT_PIV GENMASK(19, 0)
29
30#define AT91_PIT_SR 0x04
31#define AT91_PIT_PITS BIT(0)
32
33#define AT91_PIT_PIVR 0x08
34#define AT91_PIT_PIIR 0x0c
35#define AT91_PIT_PICNT GENMASK(31, 20)
36#define AT91_PIT_CPIV GENMASK(19, 0)
37
38#define PIT_CPIV(x) ((x) & AT91_PIT_CPIV)
39#define PIT_PICNT(x) (((x) & AT91_PIT_PICNT) >> 20)
40
41struct pit_data {
42 struct clock_event_device clkevt;
43 struct clocksource clksrc;
44
45 void __iomem *base;
46 u32 cycle;
47 u32 cnt;
48 unsigned int irq;
49 struct clk *mck;
50};
51
52static inline struct pit_data *clksrc_to_pit_data(struct clocksource *clksrc)
53{
54 return container_of(clksrc, struct pit_data, clksrc);
55}
56
57static inline struct pit_data *clkevt_to_pit_data(struct clock_event_device *clkevt)
58{
59 return container_of(clkevt, struct pit_data, clkevt);
60}
61
62static inline unsigned int pit_read(void __iomem *base, unsigned int reg_offset)
63{
64 return readl_relaxed(base + reg_offset);
65}
66
67static inline void pit_write(void __iomem *base, unsigned int reg_offset, unsigned long value)
68{
69 writel_relaxed(value, base + reg_offset);
70}
71
72
73
74
75
76static cycle_t read_pit_clk(struct clocksource *cs)
77{
78 struct pit_data *data = clksrc_to_pit_data(cs);
79 unsigned long flags;
80 u32 elapsed;
81 u32 t;
82
83 raw_local_irq_save(flags);
84 elapsed = data->cnt;
85 t = pit_read(data->base, AT91_PIT_PIIR);
86 raw_local_irq_restore(flags);
87
88 elapsed += PIT_PICNT(t) * data->cycle;
89 elapsed += PIT_CPIV(t);
90 return elapsed;
91}
92
93
94
95
96static void
97pit_clkevt_mode(enum clock_event_mode mode, struct clock_event_device *dev)
98{
99 struct pit_data *data = clkevt_to_pit_data(dev);
100
101 switch (mode) {
102 case CLOCK_EVT_MODE_PERIODIC:
103
104 data->cnt += data->cycle * PIT_PICNT(pit_read(data->base, AT91_PIT_PIVR));
105 pit_write(data->base, AT91_PIT_MR,
106 (data->cycle - 1) | AT91_PIT_PITEN | AT91_PIT_PITIEN);
107 break;
108 case CLOCK_EVT_MODE_ONESHOT:
109 BUG();
110
111 case CLOCK_EVT_MODE_SHUTDOWN:
112 case CLOCK_EVT_MODE_UNUSED:
113
114 pit_write(data->base, AT91_PIT_MR,
115 (data->cycle - 1) | AT91_PIT_PITEN);
116 break;
117 case CLOCK_EVT_MODE_RESUME:
118 break;
119 }
120}
121
122static void at91sam926x_pit_suspend(struct clock_event_device *cedev)
123{
124 struct pit_data *data = clkevt_to_pit_data(cedev);
125
126
127 pit_write(data->base, AT91_PIT_MR, 0);
128}
129
130static void at91sam926x_pit_reset(struct pit_data *data)
131{
132
133 pit_write(data->base, AT91_PIT_MR, 0);
134
135
136 while (PIT_CPIV(pit_read(data->base, AT91_PIT_PIVR)) != 0)
137 cpu_relax();
138
139
140 pit_write(data->base, AT91_PIT_MR,
141 (data->cycle - 1) | AT91_PIT_PITEN);
142}
143
144static void at91sam926x_pit_resume(struct clock_event_device *cedev)
145{
146 struct pit_data *data = clkevt_to_pit_data(cedev);
147
148 at91sam926x_pit_reset(data);
149}
150
151
152
153
154static irqreturn_t at91sam926x_pit_interrupt(int irq, void *dev_id)
155{
156 struct pit_data *data = dev_id;
157
158
159
160
161
162 WARN_ON_ONCE(!irqs_disabled());
163
164
165 if ((data->clkevt.mode == CLOCK_EVT_MODE_PERIODIC) &&
166 (pit_read(data->base, AT91_PIT_SR) & AT91_PIT_PITS)) {
167 unsigned nr_ticks;
168
169
170 nr_ticks = PIT_PICNT(pit_read(data->base, AT91_PIT_PIVR));
171 do {
172 data->cnt += data->cycle;
173 data->clkevt.event_handler(&data->clkevt);
174 nr_ticks--;
175 } while (nr_ticks);
176
177 return IRQ_HANDLED;
178 }
179
180 return IRQ_NONE;
181}
182
183
184
185
186static void __init at91sam926x_pit_common_init(struct pit_data *data)
187{
188 unsigned long pit_rate;
189 unsigned bits;
190 int ret;
191
192
193
194
195
196 pit_rate = clk_get_rate(data->mck) / 16;
197 data->cycle = DIV_ROUND_CLOSEST(pit_rate, HZ);
198 WARN_ON(((data->cycle - 1) & ~AT91_PIT_PIV) != 0);
199
200
201 at91sam926x_pit_reset(data);
202
203
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205
206
207 bits = 12 + ilog2(data->cycle) ;
208 data->clksrc.mask = CLOCKSOURCE_MASK(bits);
209 data->clksrc.name = "pit";
210 data->clksrc.rating = 175;
211 data->clksrc.read = read_pit_clk,
212 data->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS,
213 clocksource_register_hz(&data->clksrc, pit_rate);
214
215
216 ret = request_irq(data->irq, at91sam926x_pit_interrupt,
217 IRQF_SHARED | IRQF_TIMER | IRQF_IRQPOLL,
218 "at91_tick", data);
219 if (ret)
220 panic(pr_fmt("Unable to setup IRQ\n"));
221
222
223 data->clkevt.name = "pit";
224 data->clkevt.features = CLOCK_EVT_FEAT_PERIODIC;
225 data->clkevt.shift = 32;
226 data->clkevt.mult = div_sc(pit_rate, NSEC_PER_SEC, data->clkevt.shift);
227 data->clkevt.rating = 100;
228 data->clkevt.cpumask = cpumask_of(0);
229
230 data->clkevt.set_mode = pit_clkevt_mode;
231 data->clkevt.resume = at91sam926x_pit_resume;
232 data->clkevt.suspend = at91sam926x_pit_suspend;
233 clockevents_register_device(&data->clkevt);
234}
235
236static void __init at91sam926x_pit_dt_init(struct device_node *node)
237{
238 struct pit_data *data;
239
240 data = kzalloc(sizeof(*data), GFP_KERNEL);
241 if (!data)
242 panic(pr_fmt("Unable to allocate memory\n"));
243
244 data->base = of_iomap(node, 0);
245 if (!data->base)
246 panic(pr_fmt("Could not map PIT address\n"));
247
248 data->mck = of_clk_get(node, 0);
249 if (IS_ERR(data->mck))
250
251 data->mck = clk_get(NULL, "mck");
252
253 if (IS_ERR(data->mck))
254 panic(pr_fmt("Unable to get mck clk\n"));
255
256
257 data->irq = irq_of_parse_and_map(node, 0);
258 if (!data->irq)
259 panic(pr_fmt("Unable to get IRQ from DT\n"));
260
261 at91sam926x_pit_common_init(data);
262}
263CLOCKSOURCE_OF_DECLARE(at91sam926x_pit, "atmel,at91sam9260-pit",
264 at91sam926x_pit_dt_init);
265