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1 | /* | |
2 | * Copyright (C) 2008 STMicroelectronics | |
3 | * Copyright (C) 2010 Alessandro Rubini | |
4 | * Copyright (C) 2010 Linus Walleij for ST-Ericsson | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2, as | |
8 | * published by the Free Software Foundation. | |
9 | */ | |
10 | #include <linux/init.h> | |
11 | #include <linux/interrupt.h> | |
12 | #include <linux/irq.h> | |
13 | #include <linux/io.h> | |
14 | #include <linux/clockchips.h> | |
15 | #include <linux/clocksource.h> | |
16 | #include <linux/of_address.h> | |
17 | #include <linux/of_irq.h> | |
18 | #include <linux/of_platform.h> | |
19 | #include <linux/clk.h> | |
20 | #include <linux/jiffies.h> | |
21 | #include <linux/delay.h> | |
22 | #include <linux/err.h> | |
23 | #include <linux/platform_data/clocksource-nomadik-mtu.h> | |
24 | #include <linux/sched_clock.h> | |
25 | #include <asm/mach/time.h> | |
26 | ||
27 | /* | |
28 | * The MTU device hosts four different counters, with 4 set of | |
29 | * registers. These are register names. | |
30 | */ | |
31 | ||
32 | #define MTU_IMSC 0x00 /* Interrupt mask set/clear */ | |
33 | #define MTU_RIS 0x04 /* Raw interrupt status */ | |
34 | #define MTU_MIS 0x08 /* Masked interrupt status */ | |
35 | #define MTU_ICR 0x0C /* Interrupt clear register */ | |
36 | ||
37 | /* per-timer registers take 0..3 as argument */ | |
38 | #define MTU_LR(x) (0x10 + 0x10 * (x) + 0x00) /* Load value */ | |
39 | #define MTU_VAL(x) (0x10 + 0x10 * (x) + 0x04) /* Current value */ | |
40 | #define MTU_CR(x) (0x10 + 0x10 * (x) + 0x08) /* Control reg */ | |
41 | #define MTU_BGLR(x) (0x10 + 0x10 * (x) + 0x0c) /* At next overflow */ | |
42 | ||
43 | /* bits for the control register */ | |
44 | #define MTU_CRn_ENA 0x80 | |
45 | #define MTU_CRn_PERIODIC 0x40 /* if 0 = free-running */ | |
46 | #define MTU_CRn_PRESCALE_MASK 0x0c | |
47 | #define MTU_CRn_PRESCALE_1 0x00 | |
48 | #define MTU_CRn_PRESCALE_16 0x04 | |
49 | #define MTU_CRn_PRESCALE_256 0x08 | |
50 | #define MTU_CRn_32BITS 0x02 | |
51 | #define MTU_CRn_ONESHOT 0x01 /* if 0 = wraps reloading from BGLR*/ | |
52 | ||
53 | /* Other registers are usual amba/primecell registers, currently not used */ | |
54 | #define MTU_ITCR 0xff0 | |
55 | #define MTU_ITOP 0xff4 | |
56 | ||
57 | #define MTU_PERIPH_ID0 0xfe0 | |
58 | #define MTU_PERIPH_ID1 0xfe4 | |
59 | #define MTU_PERIPH_ID2 0xfe8 | |
60 | #define MTU_PERIPH_ID3 0xfeC | |
61 | ||
62 | #define MTU_PCELL0 0xff0 | |
63 | #define MTU_PCELL1 0xff4 | |
64 | #define MTU_PCELL2 0xff8 | |
65 | #define MTU_PCELL3 0xffC | |
66 | ||
67 | static void __iomem *mtu_base; | |
68 | static bool clkevt_periodic; | |
69 | static u32 clk_prescale; | |
70 | static u32 nmdk_cycle; /* write-once */ | |
71 | static struct delay_timer mtu_delay_timer; | |
72 | ||
73 | #ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK | |
74 | /* | |
75 | * Override the global weak sched_clock symbol with this | |
76 | * local implementation which uses the clocksource to get some | |
77 | * better resolution when scheduling the kernel. | |
78 | */ | |
79 | static u64 notrace nomadik_read_sched_clock(void) | |
80 | { | |
81 | if (unlikely(!mtu_base)) | |
82 | return 0; | |
83 | ||
84 | return -readl(mtu_base + MTU_VAL(0)); | |
85 | } | |
86 | #endif | |
87 | ||
88 | static unsigned long nmdk_timer_read_current_timer(void) | |
89 | { | |
90 | return ~readl_relaxed(mtu_base + MTU_VAL(0)); | |
91 | } | |
92 | ||
93 | /* Clockevent device: use one-shot mode */ | |
94 | static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev) | |
95 | { | |
96 | writel(1 << 1, mtu_base + MTU_IMSC); | |
97 | writel(evt, mtu_base + MTU_LR(1)); | |
98 | /* Load highest value, enable device, enable interrupts */ | |
99 | writel(MTU_CRn_ONESHOT | clk_prescale | | |
100 | MTU_CRn_32BITS | MTU_CRn_ENA, | |
101 | mtu_base + MTU_CR(1)); | |
102 | ||
103 | return 0; | |
104 | } | |
105 | ||
106 | void nmdk_clkevt_reset(void) | |
107 | { | |
108 | if (clkevt_periodic) { | |
109 | /* Timer: configure load and background-load, and fire it up */ | |
110 | writel(nmdk_cycle, mtu_base + MTU_LR(1)); | |
111 | writel(nmdk_cycle, mtu_base + MTU_BGLR(1)); | |
112 | ||
113 | writel(MTU_CRn_PERIODIC | clk_prescale | | |
114 | MTU_CRn_32BITS | MTU_CRn_ENA, | |
115 | mtu_base + MTU_CR(1)); | |
116 | writel(1 << 1, mtu_base + MTU_IMSC); | |
117 | } else { | |
118 | /* Generate an interrupt to start the clockevent again */ | |
119 | (void) nmdk_clkevt_next(nmdk_cycle, NULL); | |
120 | } | |
121 | } | |
122 | ||
123 | static void nmdk_clkevt_mode(enum clock_event_mode mode, | |
124 | struct clock_event_device *dev) | |
125 | { | |
126 | switch (mode) { | |
127 | case CLOCK_EVT_MODE_PERIODIC: | |
128 | clkevt_periodic = true; | |
129 | nmdk_clkevt_reset(); | |
130 | break; | |
131 | case CLOCK_EVT_MODE_ONESHOT: | |
132 | clkevt_periodic = false; | |
133 | break; | |
134 | case CLOCK_EVT_MODE_SHUTDOWN: | |
135 | case CLOCK_EVT_MODE_UNUSED: | |
136 | writel(0, mtu_base + MTU_IMSC); | |
137 | /* disable timer */ | |
138 | writel(0, mtu_base + MTU_CR(1)); | |
139 | /* load some high default value */ | |
140 | writel(0xffffffff, mtu_base + MTU_LR(1)); | |
141 | break; | |
142 | case CLOCK_EVT_MODE_RESUME: | |
143 | break; | |
144 | } | |
145 | } | |
146 | ||
147 | void nmdk_clksrc_reset(void) | |
148 | { | |
149 | /* Disable */ | |
150 | writel(0, mtu_base + MTU_CR(0)); | |
151 | ||
152 | /* ClockSource: configure load and background-load, and fire it up */ | |
153 | writel(nmdk_cycle, mtu_base + MTU_LR(0)); | |
154 | writel(nmdk_cycle, mtu_base + MTU_BGLR(0)); | |
155 | ||
156 | writel(clk_prescale | MTU_CRn_32BITS | MTU_CRn_ENA, | |
157 | mtu_base + MTU_CR(0)); | |
158 | } | |
159 | ||
160 | static void nmdk_clkevt_resume(struct clock_event_device *cedev) | |
161 | { | |
162 | nmdk_clkevt_reset(); | |
163 | nmdk_clksrc_reset(); | |
164 | } | |
165 | ||
166 | static struct clock_event_device nmdk_clkevt = { | |
167 | .name = "mtu_1", | |
168 | .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC | | |
169 | CLOCK_EVT_FEAT_DYNIRQ, | |
170 | .rating = 200, | |
171 | .set_mode = nmdk_clkevt_mode, | |
172 | .set_next_event = nmdk_clkevt_next, | |
173 | .resume = nmdk_clkevt_resume, | |
174 | }; | |
175 | ||
176 | /* | |
177 | * IRQ Handler for timer 1 of the MTU block. | |
178 | */ | |
179 | static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id) | |
180 | { | |
181 | struct clock_event_device *evdev = dev_id; | |
182 | ||
183 | writel(1 << 1, mtu_base + MTU_ICR); /* Interrupt clear reg */ | |
184 | evdev->event_handler(evdev); | |
185 | return IRQ_HANDLED; | |
186 | } | |
187 | ||
188 | static struct irqaction nmdk_timer_irq = { | |
189 | .name = "Nomadik Timer Tick", | |
190 | .flags = IRQF_DISABLED | IRQF_TIMER, | |
191 | .handler = nmdk_timer_interrupt, | |
192 | .dev_id = &nmdk_clkevt, | |
193 | }; | |
194 | ||
195 | static void __init __nmdk_timer_init(void __iomem *base, int irq, | |
196 | struct clk *pclk, struct clk *clk) | |
197 | { | |
198 | unsigned long rate; | |
199 | ||
200 | mtu_base = base; | |
201 | ||
202 | BUG_ON(clk_prepare_enable(pclk)); | |
203 | BUG_ON(clk_prepare_enable(clk)); | |
204 | ||
205 | /* | |
206 | * Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz | |
207 | * for ux500. | |
208 | * Use a divide-by-16 counter if the tick rate is more than 32MHz. | |
209 | * At 32 MHz, the timer (with 32 bit counter) can be programmed | |
210 | * to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer | |
211 | * with 16 gives too low timer resolution. | |
212 | */ | |
213 | rate = clk_get_rate(clk); | |
214 | if (rate > 32000000) { | |
215 | rate /= 16; | |
216 | clk_prescale = MTU_CRn_PRESCALE_16; | |
217 | } else { | |
218 | clk_prescale = MTU_CRn_PRESCALE_1; | |
219 | } | |
220 | ||
221 | /* Cycles for periodic mode */ | |
222 | nmdk_cycle = DIV_ROUND_CLOSEST(rate, HZ); | |
223 | ||
224 | ||
225 | /* Timer 0 is the free running clocksource */ | |
226 | nmdk_clksrc_reset(); | |
227 | ||
228 | if (clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0", | |
229 | rate, 200, 32, clocksource_mmio_readl_down)) | |
230 | pr_err("timer: failed to initialize clock source %s\n", | |
231 | "mtu_0"); | |
232 | ||
233 | #ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK | |
234 | sched_clock_register(nomadik_read_sched_clock, 32, rate); | |
235 | #endif | |
236 | ||
237 | /* Timer 1 is used for events, register irq and clockevents */ | |
238 | setup_irq(irq, &nmdk_timer_irq); | |
239 | nmdk_clkevt.cpumask = cpumask_of(0); | |
240 | nmdk_clkevt.irq = irq; | |
241 | clockevents_config_and_register(&nmdk_clkevt, rate, 2, 0xffffffffU); | |
242 | ||
243 | mtu_delay_timer.read_current_timer = &nmdk_timer_read_current_timer; | |
244 | mtu_delay_timer.freq = rate; | |
245 | register_current_timer_delay(&mtu_delay_timer); | |
246 | } | |
247 | ||
248 | void __init nmdk_timer_init(void __iomem *base, int irq) | |
249 | { | |
250 | struct clk *clk0, *pclk0; | |
251 | ||
252 | pclk0 = clk_get_sys("mtu0", "apb_pclk"); | |
253 | BUG_ON(IS_ERR(pclk0)); | |
254 | clk0 = clk_get_sys("mtu0", NULL); | |
255 | BUG_ON(IS_ERR(clk0)); | |
256 | ||
257 | __nmdk_timer_init(base, irq, pclk0, clk0); | |
258 | } | |
259 | ||
260 | static void __init nmdk_timer_of_init(struct device_node *node) | |
261 | { | |
262 | struct clk *pclk; | |
263 | struct clk *clk; | |
264 | void __iomem *base; | |
265 | int irq; | |
266 | ||
267 | base = of_iomap(node, 0); | |
268 | if (!base) | |
269 | panic("Can't remap registers"); | |
270 | ||
271 | pclk = of_clk_get_by_name(node, "apb_pclk"); | |
272 | if (IS_ERR(pclk)) | |
273 | panic("could not get apb_pclk"); | |
274 | ||
275 | clk = of_clk_get_by_name(node, "timclk"); | |
276 | if (IS_ERR(clk)) | |
277 | panic("could not get timclk"); | |
278 | ||
279 | irq = irq_of_parse_and_map(node, 0); | |
280 | if (irq <= 0) | |
281 | panic("Can't parse IRQ"); | |
282 | ||
283 | __nmdk_timer_init(base, irq, pclk, clk); | |
284 | } | |
285 | CLOCKSOURCE_OF_DECLARE(nomadik_mtu, "st,nomadik-mtu", | |
286 | nmdk_timer_of_init); |