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4d243f92 DB |
1 | #include <linux/init.h> |
2 | #include <linux/clocksource.h> | |
3 | #include <linux/clockchips.h> | |
4 | #include <linux/interrupt.h> | |
5 | #include <linux/irq.h> | |
6 | ||
7 | #include <linux/clk.h> | |
8 | #include <linux/err.h> | |
9 | #include <linux/ioport.h> | |
10 | #include <linux/io.h> | |
11 | #include <linux/platform_device.h> | |
12 | #include <linux/atmel_tc.h> | |
13 | ||
14 | ||
15 | /* | |
16 | * We're configured to use a specific TC block, one that's not hooked | |
17 | * up to external hardware, to provide a time solution: | |
18 | * | |
19 | * - Two channels combine to create a free-running 32 bit counter | |
20 | * with a base rate of 5+ MHz, packaged as a clocksource (with | |
21 | * resolution better than 200 nsec). | |
8e315a7b NF |
22 | * - Some chips support 32 bit counter. A single channel is used for |
23 | * this 32 bit free-running counter. the second channel is not used. | |
4d243f92 DB |
24 | * |
25 | * - The third channel may be used to provide a 16-bit clockevent | |
26 | * source, used in either periodic or oneshot mode. This runs | |
27 | * at 32 KiHZ, and can handle delays of up to two seconds. | |
28 | * | |
29 | * A boot clocksource and clockevent source are also currently needed, | |
30 | * unless the relevant platforms (ARM/AT91, AVR32/AT32) are changed so | |
31 | * this code can be used when init_timers() is called, well before most | |
32 | * devices are set up. (Some low end AT91 parts, which can run uClinux, | |
33 | * have only the timers in one TC block... they currently don't support | |
34 | * the tclib code, because of that initialization issue.) | |
35 | * | |
36 | * REVISIT behavior during system suspend states... we should disable | |
37 | * all clocks and save the power. Easily done for clockevent devices, | |
38 | * but clocksources won't necessarily get the needed notifications. | |
39 | * For deeper system sleep states, this will be mandatory... | |
40 | */ | |
41 | ||
42 | static void __iomem *tcaddr; | |
43 | ||
8e19608e | 44 | static cycle_t tc_get_cycles(struct clocksource *cs) |
4d243f92 DB |
45 | { |
46 | unsigned long flags; | |
47 | u32 lower, upper; | |
48 | ||
49 | raw_local_irq_save(flags); | |
50 | do { | |
51 | upper = __raw_readl(tcaddr + ATMEL_TC_REG(1, CV)); | |
52 | lower = __raw_readl(tcaddr + ATMEL_TC_REG(0, CV)); | |
53 | } while (upper != __raw_readl(tcaddr + ATMEL_TC_REG(1, CV))); | |
54 | ||
55 | raw_local_irq_restore(flags); | |
56 | return (upper << 16) | lower; | |
57 | } | |
58 | ||
8e315a7b NF |
59 | static cycle_t tc_get_cycles32(struct clocksource *cs) |
60 | { | |
61 | return __raw_readl(tcaddr + ATMEL_TC_REG(0, CV)); | |
62 | } | |
63 | ||
4d243f92 DB |
64 | static struct clocksource clksrc = { |
65 | .name = "tcb_clksrc", | |
66 | .rating = 200, | |
67 | .read = tc_get_cycles, | |
68 | .mask = CLOCKSOURCE_MASK(32), | |
4d243f92 DB |
69 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
70 | }; | |
71 | ||
72 | #ifdef CONFIG_GENERIC_CLOCKEVENTS | |
73 | ||
74 | struct tc_clkevt_device { | |
75 | struct clock_event_device clkevt; | |
76 | struct clk *clk; | |
77 | void __iomem *regs; | |
78 | }; | |
79 | ||
80 | static struct tc_clkevt_device *to_tc_clkevt(struct clock_event_device *clkevt) | |
81 | { | |
82 | return container_of(clkevt, struct tc_clkevt_device, clkevt); | |
83 | } | |
84 | ||
85 | /* For now, we always use the 32K clock ... this optimizes for NO_HZ, | |
86 | * because using one of the divided clocks would usually mean the | |
87 | * tick rate can never be less than several dozen Hz (vs 0.5 Hz). | |
88 | * | |
89 | * A divided clock could be good for high resolution timers, since | |
90 | * 30.5 usec resolution can seem "low". | |
91 | */ | |
92 | static u32 timer_clock; | |
93 | ||
94 | static void tc_mode(enum clock_event_mode m, struct clock_event_device *d) | |
95 | { | |
96 | struct tc_clkevt_device *tcd = to_tc_clkevt(d); | |
97 | void __iomem *regs = tcd->regs; | |
98 | ||
99 | if (tcd->clkevt.mode == CLOCK_EVT_MODE_PERIODIC | |
100 | || tcd->clkevt.mode == CLOCK_EVT_MODE_ONESHOT) { | |
101 | __raw_writel(0xff, regs + ATMEL_TC_REG(2, IDR)); | |
102 | __raw_writel(ATMEL_TC_CLKDIS, regs + ATMEL_TC_REG(2, CCR)); | |
103 | clk_disable(tcd->clk); | |
104 | } | |
105 | ||
106 | switch (m) { | |
107 | ||
108 | /* By not making the gentime core emulate periodic mode on top | |
109 | * of oneshot, we get lower overhead and improved accuracy. | |
110 | */ | |
111 | case CLOCK_EVT_MODE_PERIODIC: | |
112 | clk_enable(tcd->clk); | |
113 | ||
114 | /* slow clock, count up to RC, then irq and restart */ | |
115 | __raw_writel(timer_clock | |
116 | | ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO, | |
117 | regs + ATMEL_TC_REG(2, CMR)); | |
118 | __raw_writel((32768 + HZ/2) / HZ, tcaddr + ATMEL_TC_REG(2, RC)); | |
119 | ||
120 | /* Enable clock and interrupts on RC compare */ | |
121 | __raw_writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER)); | |
122 | ||
123 | /* go go gadget! */ | |
124 | __raw_writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG, | |
125 | regs + ATMEL_TC_REG(2, CCR)); | |
126 | break; | |
127 | ||
128 | case CLOCK_EVT_MODE_ONESHOT: | |
129 | clk_enable(tcd->clk); | |
130 | ||
131 | /* slow clock, count up to RC, then irq and stop */ | |
132 | __raw_writel(timer_clock | ATMEL_TC_CPCSTOP | |
133 | | ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO, | |
134 | regs + ATMEL_TC_REG(2, CMR)); | |
135 | __raw_writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER)); | |
136 | ||
137 | /* set_next_event() configures and starts the timer */ | |
138 | break; | |
139 | ||
140 | default: | |
141 | break; | |
142 | } | |
143 | } | |
144 | ||
145 | static int tc_next_event(unsigned long delta, struct clock_event_device *d) | |
146 | { | |
147 | __raw_writel(delta, tcaddr + ATMEL_TC_REG(2, RC)); | |
148 | ||
149 | /* go go gadget! */ | |
150 | __raw_writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG, | |
151 | tcaddr + ATMEL_TC_REG(2, CCR)); | |
152 | return 0; | |
153 | } | |
154 | ||
155 | static struct tc_clkevt_device clkevt = { | |
156 | .clkevt = { | |
157 | .name = "tc_clkevt", | |
158 | .features = CLOCK_EVT_FEAT_PERIODIC | |
159 | | CLOCK_EVT_FEAT_ONESHOT, | |
4d243f92 DB |
160 | /* Should be lower than at91rm9200's system timer */ |
161 | .rating = 125, | |
4d243f92 DB |
162 | .set_next_event = tc_next_event, |
163 | .set_mode = tc_mode, | |
164 | }, | |
165 | }; | |
166 | ||
167 | static irqreturn_t ch2_irq(int irq, void *handle) | |
168 | { | |
169 | struct tc_clkevt_device *dev = handle; | |
170 | unsigned int sr; | |
171 | ||
172 | sr = __raw_readl(dev->regs + ATMEL_TC_REG(2, SR)); | |
173 | if (sr & ATMEL_TC_CPCS) { | |
174 | dev->clkevt.event_handler(&dev->clkevt); | |
175 | return IRQ_HANDLED; | |
176 | } | |
177 | ||
178 | return IRQ_NONE; | |
179 | } | |
180 | ||
181 | static struct irqaction tc_irqaction = { | |
182 | .name = "tc_clkevt", | |
183 | .flags = IRQF_TIMER | IRQF_DISABLED, | |
184 | .handler = ch2_irq, | |
185 | }; | |
186 | ||
3ee08aea | 187 | static void __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx) |
4d243f92 | 188 | { |
4d243f92 DB |
189 | struct clk *t2_clk = tc->clk[2]; |
190 | int irq = tc->irq[2]; | |
191 | ||
192 | clkevt.regs = tc->regs; | |
193 | clkevt.clk = t2_clk; | |
194 | tc_irqaction.dev_id = &clkevt; | |
195 | ||
196 | timer_clock = clk32k_divisor_idx; | |
197 | ||
320ab2b0 | 198 | clkevt.clkevt.cpumask = cpumask_of(0); |
4d243f92 | 199 | |
77cc982f | 200 | clockevents_config_and_register(&clkevt.clkevt, 32768, 1, 0xffff); |
1817dc03 VN |
201 | |
202 | setup_irq(irq, &tc_irqaction); | |
4d243f92 DB |
203 | } |
204 | ||
205 | #else /* !CONFIG_GENERIC_CLOCKEVENTS */ | |
206 | ||
3ee08aea | 207 | static void __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx) |
4d243f92 DB |
208 | { |
209 | /* NOTHING */ | |
210 | } | |
211 | ||
212 | #endif | |
213 | ||
8e315a7b NF |
214 | static void __init tcb_setup_dual_chan(struct atmel_tc *tc, int mck_divisor_idx) |
215 | { | |
216 | /* channel 0: waveform mode, input mclk/8, clock TIOA0 on overflow */ | |
217 | __raw_writel(mck_divisor_idx /* likely divide-by-8 */ | |
218 | | ATMEL_TC_WAVE | |
219 | | ATMEL_TC_WAVESEL_UP /* free-run */ | |
220 | | ATMEL_TC_ACPA_SET /* TIOA0 rises at 0 */ | |
221 | | ATMEL_TC_ACPC_CLEAR, /* (duty cycle 50%) */ | |
222 | tcaddr + ATMEL_TC_REG(0, CMR)); | |
223 | __raw_writel(0x0000, tcaddr + ATMEL_TC_REG(0, RA)); | |
224 | __raw_writel(0x8000, tcaddr + ATMEL_TC_REG(0, RC)); | |
225 | __raw_writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR)); /* no irqs */ | |
226 | __raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR)); | |
227 | ||
228 | /* channel 1: waveform mode, input TIOA0 */ | |
229 | __raw_writel(ATMEL_TC_XC1 /* input: TIOA0 */ | |
230 | | ATMEL_TC_WAVE | |
231 | | ATMEL_TC_WAVESEL_UP, /* free-run */ | |
232 | tcaddr + ATMEL_TC_REG(1, CMR)); | |
233 | __raw_writel(0xff, tcaddr + ATMEL_TC_REG(1, IDR)); /* no irqs */ | |
234 | __raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(1, CCR)); | |
235 | ||
236 | /* chain channel 0 to channel 1*/ | |
237 | __raw_writel(ATMEL_TC_TC1XC1S_TIOA0, tcaddr + ATMEL_TC_BMR); | |
238 | /* then reset all the timers */ | |
239 | __raw_writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR); | |
240 | } | |
241 | ||
242 | static void __init tcb_setup_single_chan(struct atmel_tc *tc, int mck_divisor_idx) | |
243 | { | |
244 | /* channel 0: waveform mode, input mclk/8 */ | |
245 | __raw_writel(mck_divisor_idx /* likely divide-by-8 */ | |
246 | | ATMEL_TC_WAVE | |
247 | | ATMEL_TC_WAVESEL_UP, /* free-run */ | |
248 | tcaddr + ATMEL_TC_REG(0, CMR)); | |
249 | __raw_writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR)); /* no irqs */ | |
250 | __raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR)); | |
251 | ||
252 | /* then reset all the timers */ | |
253 | __raw_writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR); | |
254 | } | |
255 | ||
4d243f92 DB |
256 | static int __init tcb_clksrc_init(void) |
257 | { | |
258 | static char bootinfo[] __initdata | |
259 | = KERN_DEBUG "%s: tc%d at %d.%03d MHz\n"; | |
260 | ||
261 | struct platform_device *pdev; | |
262 | struct atmel_tc *tc; | |
3ee08aea | 263 | struct clk *t0_clk; |
4d243f92 DB |
264 | u32 rate, divided_rate = 0; |
265 | int best_divisor_idx = -1; | |
266 | int clk32k_divisor_idx = -1; | |
267 | int i; | |
268 | ||
269 | tc = atmel_tc_alloc(CONFIG_ATMEL_TCB_CLKSRC_BLOCK, clksrc.name); | |
270 | if (!tc) { | |
271 | pr_debug("can't alloc TC for clocksource\n"); | |
272 | return -ENODEV; | |
273 | } | |
274 | tcaddr = tc->regs; | |
275 | pdev = tc->pdev; | |
276 | ||
277 | t0_clk = tc->clk[0]; | |
278 | clk_enable(t0_clk); | |
279 | ||
280 | /* How fast will we be counting? Pick something over 5 MHz. */ | |
281 | rate = (u32) clk_get_rate(t0_clk); | |
282 | for (i = 0; i < 5; i++) { | |
283 | unsigned divisor = atmel_tc_divisors[i]; | |
284 | unsigned tmp; | |
285 | ||
286 | /* remember 32 KiHz clock for later */ | |
287 | if (!divisor) { | |
288 | clk32k_divisor_idx = i; | |
289 | continue; | |
290 | } | |
291 | ||
292 | tmp = rate / divisor; | |
293 | pr_debug("TC: %u / %-3u [%d] --> %u\n", rate, divisor, i, tmp); | |
294 | if (best_divisor_idx > 0) { | |
295 | if (tmp < 5 * 1000 * 1000) | |
296 | continue; | |
297 | } | |
298 | divided_rate = tmp; | |
299 | best_divisor_idx = i; | |
300 | } | |
301 | ||
4d243f92 DB |
302 | |
303 | printk(bootinfo, clksrc.name, CONFIG_ATMEL_TCB_CLKSRC_BLOCK, | |
304 | divided_rate / 1000000, | |
305 | ((divided_rate + 500000) % 1000000) / 1000); | |
306 | ||
8e315a7b NF |
307 | if (tc->tcb_config && tc->tcb_config->counter_width == 32) { |
308 | /* use apropriate function to read 32 bit counter */ | |
309 | clksrc.read = tc_get_cycles32; | |
310 | /* setup ony channel 0 */ | |
311 | tcb_setup_single_chan(tc, best_divisor_idx); | |
312 | } else { | |
313 | /* tclib will give us three clocks no matter what the | |
314 | * underlying platform supports. | |
315 | */ | |
316 | clk_enable(tc->clk[1]); | |
317 | /* setup both channel 0 & 1 */ | |
318 | tcb_setup_dual_chan(tc, best_divisor_idx); | |
319 | } | |
4d243f92 DB |
320 | |
321 | /* and away we go! */ | |
f5a54dd7 | 322 | clocksource_register_hz(&clksrc, divided_rate); |
4d243f92 DB |
323 | |
324 | /* channel 2: periodic and oneshot timer support */ | |
3ee08aea | 325 | setup_clkevents(tc, clk32k_divisor_idx); |
4d243f92 DB |
326 | |
327 | return 0; | |
328 | } | |
329 | arch_initcall(tcb_clksrc_init); |