1 /*
2  * Copyright (C) 2009 Samsung Electronics
3  * Heungjun Kim <riverful.kim@samsung.com>
4  * Inki Dae <inki.dae@samsung.com>
5  * Minkyu Kang <mk7.kang@samsung.com>
6  *
7  * See file CREDITS for list of people who contributed to this
8  * project.
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public License as
12  * published by the Free Software Foundation; either version 2 of
13  * the License, or (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
18  * GNU General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
23  * MA 02111-1307 USA
24  */
25 
26 #include <common.h>
27 #include <asm/io.h>
28 #include <asm/arch/pwm.h>
29 #include <asm/arch/clk.h>
30 
31 #define PRESCALER_1		(16 - 1)	/* prescaler of timer 2, 3, 4 */
32 #define MUX_DIV_2		1		/* 1/2 period */
33 #define MUX_DIV_4		2		/* 1/4 period */
34 #define MUX_DIV_8		3		/* 1/8 period */
35 #define MUX_DIV_16		4		/* 1/16 period */
36 #define MUX4_DIV_SHIFT		16
37 
38 #define TCON_TIMER4_SHIFT	20
39 
40 static unsigned long count_value;
41 
42 /* Internal tick units */
43 static unsigned long long timestamp;	/* Monotonic incrementing timer */
44 static unsigned long lastdec;		/* Last decremneter snapshot */
45 
46 /* macro to read the 16 bit timer */
47 static inline struct s5p_timer *s5p_get_base_timer(void)
48 {
49 	return (struct s5p_timer *)samsung_get_base_timer();
50 }
51 
52 int timer_init(void)
53 {
54 	struct s5p_timer *const timer = s5p_get_base_timer();
55 	u32 val;
56 
57 	/*
58 	 * @ PWM Timer 4
59 	 * Timer Freq(HZ) =
60 	 *	PWM_CLK / { (prescaler_value + 1) * (divider_value) }
61 	 */
62 
63 	/* set prescaler : 16 */
64 	/* set divider : 2 */
65 	writel((PRESCALER_1 & 0xff) << 8, &timer->tcfg0);
66 	writel((MUX_DIV_2 & 0xf) << MUX4_DIV_SHIFT, &timer->tcfg1);
67 
68 	/* count_value = 2085937.5(HZ) (per 1 sec)*/
69 	count_value = get_pwm_clk() / ((PRESCALER_1 + 1) *
70 			(MUX_DIV_2 + 1));
71 
72 	/* count_value / 100 = 20859.375(HZ) (per 10 msec) */
73 	count_value = count_value / 100;
74 
75 	/* set count value */
76 	writel(count_value, &timer->tcntb4);
77 	lastdec = count_value;
78 
79 	val = (readl(&timer->tcon) & ~(0x07 << TCON_TIMER4_SHIFT)) |
80 		TCON4_AUTO_RELOAD;
81 
82 	/* auto reload & manual update */
83 	writel(val | TCON4_UPDATE, &timer->tcon);
84 
85 	/* start PWM timer 4 */
86 	writel(val | TCON4_START, &timer->tcon);
87 
88 	timestamp = 0;
89 
90 	return 0;
91 }
92 
93 /*
94  * timer without interrupts
95  */
96 void reset_timer(void)
97 {
98 	reset_timer_masked();
99 }
100 
101 unsigned long get_timer(unsigned long base)
102 {
103 	return get_timer_masked() - base;
104 }
105 
106 void set_timer(unsigned long t)
107 {
108 	timestamp = t;
109 }
110 
111 /* delay x useconds */
112 void __udelay(unsigned long usec)
113 {
114 	struct s5p_timer *const timer = s5p_get_base_timer();
115 	unsigned long tmo, tmp;
116 
117 	count_value = readl(&timer->tcntb4);
118 
119 	if (usec >= 1000) {
120 		/*
121 		 * if "big" number, spread normalization
122 		 * to seconds
123 		 * 1. start to normalize for usec to ticks per sec
124 		 * 2. find number of "ticks" to wait to achieve target
125 		 * 3. finish normalize.
126 		 */
127 		tmo = usec / 1000;
128 		tmo *= (CONFIG_SYS_HZ * count_value / 10);
129 		tmo /= 1000;
130 	} else {
131 		/* else small number, don't kill it prior to HZ multiply */
132 		tmo = usec * CONFIG_SYS_HZ * count_value / 10;
133 		tmo /= (1000 * 1000);
134 	}
135 
136 	/* get current timestamp */
137 	tmp = get_timer(0);
138 
139 	/* if setting this fordward will roll time stamp */
140 	/* reset "advancing" timestamp to 0, set lastdec value */
141 	/* else, set advancing stamp wake up time */
142 	if ((tmo + tmp + 1) < tmp)
143 		reset_timer_masked();
144 	else
145 		tmo += tmp;
146 
147 	/* loop till event */
148 	while (get_timer_masked() < tmo)
149 		;	/* nop */
150 }
151 
152 void reset_timer_masked(void)
153 {
154 	struct s5p_timer *const timer = s5p_get_base_timer();
155 
156 	/* reset time */
157 	lastdec = readl(&timer->tcnto4);
158 	timestamp = 0;
159 }
160 
161 unsigned long get_timer_masked(void)
162 {
163 	struct s5p_timer *const timer = s5p_get_base_timer();
164 	unsigned long now = readl(&timer->tcnto4);
165 
166 	if (lastdec >= now)
167 		timestamp += lastdec - now;
168 	else
169 		timestamp += lastdec + count_value - now;
170 
171 	lastdec = now;
172 
173 	return timestamp;
174 }
175 
176 /*
177  * This function is derived from PowerPC code (read timebase as long long).
178  * On ARM it just returns the timer value.
179  */
180 unsigned long long get_ticks(void)
181 {
182 	return get_timer(0);
183 }
184 
185 /*
186  * This function is derived from PowerPC code (timebase clock frequency).
187  * On ARM it returns the number of timer ticks per second.
188  */
189 unsigned long get_tbclk(void)
190 {
191 	return CONFIG_SYS_HZ;
192 }
193