1 /*
2 * arch/arm/mach-lpc32xx/timer.c
3 *
4 * Author: Kevin Wells <kevin.wells@nxp.com>
5 *
6 * Copyright (C) 2009 - 2010 NXP Semiconductors
7 * Copyright (C) 2009 Fontys University of Applied Sciences, Eindhoven
8 * Ed Schouten <e.schouten@fontys.nl>
9 * Laurens Timmermans <l.timmermans@fontys.nl>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 */
21
22 #include <linux/interrupt.h>
23 #include <linux/irq.h>
24 #include <linux/time.h>
25 #include <linux/err.h>
26 #include <linux/clockchips.h>
27
28 #include <asm/mach/time.h>
29
30 #include <mach/hardware.h>
31 #include <mach/platform.h>
32 #include "common.h"
33
lpc32xx_clkevt_next_event(unsigned long delta,struct clock_event_device * dev)34 static int lpc32xx_clkevt_next_event(unsigned long delta,
35 struct clock_event_device *dev)
36 {
37 __raw_writel(LPC32XX_TIMER_CNTR_TCR_RESET,
38 LPC32XX_TIMER_TCR(LPC32XX_TIMER0_BASE));
39 __raw_writel(delta, LPC32XX_TIMER_PR(LPC32XX_TIMER0_BASE));
40 __raw_writel(LPC32XX_TIMER_CNTR_TCR_EN,
41 LPC32XX_TIMER_TCR(LPC32XX_TIMER0_BASE));
42
43 return 0;
44 }
45
lpc32xx_clkevt_mode(enum clock_event_mode mode,struct clock_event_device * dev)46 static void lpc32xx_clkevt_mode(enum clock_event_mode mode,
47 struct clock_event_device *dev)
48 {
49 switch (mode) {
50 case CLOCK_EVT_MODE_PERIODIC:
51 WARN_ON(1);
52 break;
53
54 case CLOCK_EVT_MODE_ONESHOT:
55 case CLOCK_EVT_MODE_SHUTDOWN:
56 /*
57 * Disable the timer. When using oneshot, we must also
58 * disable the timer to wait for the first call to
59 * set_next_event().
60 */
61 __raw_writel(0, LPC32XX_TIMER_TCR(LPC32XX_TIMER0_BASE));
62 break;
63
64 case CLOCK_EVT_MODE_UNUSED:
65 case CLOCK_EVT_MODE_RESUME:
66 break;
67 }
68 }
69
70 static struct clock_event_device lpc32xx_clkevt = {
71 .name = "lpc32xx_clkevt",
72 .features = CLOCK_EVT_FEAT_ONESHOT,
73 .shift = 32,
74 .rating = 300,
75 .set_next_event = lpc32xx_clkevt_next_event,
76 .set_mode = lpc32xx_clkevt_mode,
77 };
78
lpc32xx_timer_interrupt(int irq,void * dev_id)79 static irqreturn_t lpc32xx_timer_interrupt(int irq, void *dev_id)
80 {
81 struct clock_event_device *evt = &lpc32xx_clkevt;
82
83 /* Clear match */
84 __raw_writel(LPC32XX_TIMER_CNTR_MTCH_BIT(0),
85 LPC32XX_TIMER_IR(LPC32XX_TIMER0_BASE));
86
87 evt->event_handler(evt);
88
89 return IRQ_HANDLED;
90 }
91
92 static struct irqaction lpc32xx_timer_irq = {
93 .name = "LPC32XX Timer Tick",
94 .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
95 .handler = lpc32xx_timer_interrupt,
96 };
97
98 /*
99 * The clock management driver isn't initialized at this point, so the
100 * clocks need to be enabled here manually and then tagged as used in
101 * the clock driver initialization
102 */
lpc32xx_timer_init(void)103 static void __init lpc32xx_timer_init(void)
104 {
105 u32 clkrate, pllreg;
106
107 /* Enable timer clock */
108 __raw_writel(LPC32XX_CLKPWR_TMRPWMCLK_TIMER0_EN |
109 LPC32XX_CLKPWR_TMRPWMCLK_TIMER1_EN,
110 LPC32XX_CLKPWR_TIMERS_PWMS_CLK_CTRL_1);
111
112 /*
113 * The clock driver isn't initialized at this point. So determine if
114 * the SYSCLK is driven from the PLL397 or main oscillator and then use
115 * it to compute the PLL frequency and the PCLK divider to get the base
116 * timer rates. This rate is needed to compute the tick rate.
117 */
118 if (clk_is_sysclk_mainosc() != 0)
119 clkrate = LPC32XX_MAIN_OSC_FREQ;
120 else
121 clkrate = 397 * LPC32XX_CLOCK_OSC_FREQ;
122
123 /* Get ARM HCLKPLL register and convert it into a frequency */
124 pllreg = __raw_readl(LPC32XX_CLKPWR_HCLKPLL_CTRL) & 0x1FFFF;
125 clkrate = clk_get_pllrate_from_reg(clkrate, pllreg);
126
127 /* Get PCLK divider and divide ARM PLL clock by it to get timer rate */
128 clkrate = clkrate / clk_get_pclk_div();
129
130 /* Initial timer setup */
131 __raw_writel(0, LPC32XX_TIMER_TCR(LPC32XX_TIMER0_BASE));
132 __raw_writel(LPC32XX_TIMER_CNTR_MTCH_BIT(0),
133 LPC32XX_TIMER_IR(LPC32XX_TIMER0_BASE));
134 __raw_writel(1, LPC32XX_TIMER_MR0(LPC32XX_TIMER0_BASE));
135 __raw_writel(LPC32XX_TIMER_CNTR_MCR_MTCH(0) |
136 LPC32XX_TIMER_CNTR_MCR_STOP(0) |
137 LPC32XX_TIMER_CNTR_MCR_RESET(0),
138 LPC32XX_TIMER_MCR(LPC32XX_TIMER0_BASE));
139
140 /* Setup tick interrupt */
141 setup_irq(IRQ_LPC32XX_TIMER0, &lpc32xx_timer_irq);
142
143 /* Setup the clockevent structure. */
144 lpc32xx_clkevt.mult = div_sc(clkrate, NSEC_PER_SEC,
145 lpc32xx_clkevt.shift);
146 lpc32xx_clkevt.max_delta_ns = clockevent_delta2ns(-1,
147 &lpc32xx_clkevt);
148 lpc32xx_clkevt.min_delta_ns = clockevent_delta2ns(1,
149 &lpc32xx_clkevt) + 1;
150 lpc32xx_clkevt.cpumask = cpumask_of(0);
151 clockevents_register_device(&lpc32xx_clkevt);
152
153 /* Use timer1 as clock source. */
154 __raw_writel(LPC32XX_TIMER_CNTR_TCR_RESET,
155 LPC32XX_TIMER_TCR(LPC32XX_TIMER1_BASE));
156 __raw_writel(0, LPC32XX_TIMER_PR(LPC32XX_TIMER1_BASE));
157 __raw_writel(0, LPC32XX_TIMER_MCR(LPC32XX_TIMER1_BASE));
158 __raw_writel(LPC32XX_TIMER_CNTR_TCR_EN,
159 LPC32XX_TIMER_TCR(LPC32XX_TIMER1_BASE));
160
161 clocksource_mmio_init(LPC32XX_TIMER_TC(LPC32XX_TIMER1_BASE),
162 "lpc32xx_clksrc", clkrate, 300, 32, clocksource_mmio_readl_up);
163 }
164
165 struct sys_timer lpc32xx_timer = {
166 .init = &lpc32xx_timer_init,
167 };
168
169