1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Freescale i.MX28 timer driver
4  *
5  * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com>
6  * on behalf of DENX Software Engineering GmbH
7  *
8  * Based on code from LTIB:
9  * (C) Copyright 2009-2010 Freescale Semiconductor, Inc.
10  */
11 
12 #include <common.h>
13 #include <init.h>
14 #include <time.h>
15 #include <asm/global_data.h>
16 #include <asm/io.h>
17 #include <asm/arch/imx-regs.h>
18 #include <asm/arch/sys_proto.h>
19 #include <linux/delay.h>
20 
21 /* Maximum fixed count */
22 #if defined(CONFIG_MX23)
23 #define TIMER_LOAD_VAL 0xffff
24 #elif defined(CONFIG_MX28)
25 #define TIMER_LOAD_VAL 0xffffffff
26 #endif
27 
28 DECLARE_GLOBAL_DATA_PTR;
29 
30 #define timestamp (gd->arch.tbl)
31 #define lastdec (gd->arch.lastinc)
32 
33 /*
34  * This driver uses 1kHz clock source.
35  */
36 #define	MXS_INCREMENTER_HZ		1000
37 
tick_to_time(unsigned long tick)38 static inline unsigned long tick_to_time(unsigned long tick)
39 {
40 	return tick / (MXS_INCREMENTER_HZ / CONFIG_SYS_HZ);
41 }
42 
time_to_tick(unsigned long time)43 static inline unsigned long time_to_tick(unsigned long time)
44 {
45 	return time * (MXS_INCREMENTER_HZ / CONFIG_SYS_HZ);
46 }
47 
48 /* Calculate how many ticks happen in "us" microseconds */
us_to_tick(unsigned long us)49 static inline unsigned long us_to_tick(unsigned long us)
50 {
51 	return (us * MXS_INCREMENTER_HZ) / 1000000;
52 }
53 
timer_init(void)54 int timer_init(void)
55 {
56 	struct mxs_timrot_regs *timrot_regs =
57 		(struct mxs_timrot_regs *)MXS_TIMROT_BASE;
58 
59 	/* Reset Timers and Rotary Encoder module */
60 	mxs_reset_block(&timrot_regs->hw_timrot_rotctrl_reg);
61 
62 	/* Set fixed_count to 0 */
63 #if defined(CONFIG_MX23)
64 	writel(0, &timrot_regs->hw_timrot_timcount0);
65 #elif defined(CONFIG_MX28)
66 	writel(0, &timrot_regs->hw_timrot_fixed_count0);
67 #endif
68 
69 	/* Set UPDATE bit and 1Khz frequency */
70 	writel(TIMROT_TIMCTRLn_UPDATE | TIMROT_TIMCTRLn_RELOAD |
71 		TIMROT_TIMCTRLn_SELECT_1KHZ_XTAL,
72 		&timrot_regs->hw_timrot_timctrl0);
73 
74 	/* Set fixed_count to maximal value */
75 #if defined(CONFIG_MX23)
76 	writel(TIMER_LOAD_VAL - 1, &timrot_regs->hw_timrot_timcount0);
77 #elif defined(CONFIG_MX28)
78 	writel(TIMER_LOAD_VAL, &timrot_regs->hw_timrot_fixed_count0);
79 #endif
80 
81 	return 0;
82 }
83 
get_ticks(void)84 unsigned long long get_ticks(void)
85 {
86 	struct mxs_timrot_regs *timrot_regs =
87 		(struct mxs_timrot_regs *)MXS_TIMROT_BASE;
88 	uint32_t now;
89 
90 	/* Current tick value */
91 #if defined(CONFIG_MX23)
92 	/* Upper bits are the valid ones. */
93 	now = readl(&timrot_regs->hw_timrot_timcount0) >>
94 		TIMROT_RUNNING_COUNTn_RUNNING_COUNT_OFFSET;
95 #elif defined(CONFIG_MX28)
96 	now = readl(&timrot_regs->hw_timrot_running_count0);
97 #else
98 #error "Don't know how to read timrot_regs"
99 #endif
100 
101 	if (lastdec >= now) {
102 		/*
103 		 * normal mode (non roll)
104 		 * move stamp forward with absolut diff ticks
105 		 */
106 		timestamp += (lastdec - now);
107 	} else {
108 		/* we have rollover of decrementer */
109 		timestamp += (TIMER_LOAD_VAL - now) + lastdec;
110 
111 	}
112 	lastdec = now;
113 
114 	return timestamp;
115 }
116 
get_timer(ulong base)117 ulong get_timer(ulong base)
118 {
119 	return tick_to_time(get_ticks()) - base;
120 }
121 
122 /* We use the HW_DIGCTL_MICROSECONDS register for sub-millisecond timer. */
123 #define	MXS_HW_DIGCTL_MICROSECONDS	0x8001c0c0
124 
__udelay(unsigned long usec)125 void __udelay(unsigned long usec)
126 {
127 	uint32_t old, new, incr;
128 	uint32_t counter = 0;
129 
130 	old = readl(MXS_HW_DIGCTL_MICROSECONDS);
131 
132 	while (counter < usec) {
133 		new = readl(MXS_HW_DIGCTL_MICROSECONDS);
134 
135 		/* Check if the timer wrapped. */
136 		if (new < old) {
137 			incr = 0xffffffff - old;
138 			incr += new;
139 		} else {
140 			incr = new - old;
141 		}
142 
143 		/*
144 		 * Check if we are close to the maximum time and the counter
145 		 * would wrap if incremented. If that's the case, break out
146 		 * from the loop as the requested delay time passed.
147 		 */
148 		if (counter + incr < counter)
149 			break;
150 
151 		counter += incr;
152 		old = new;
153 	}
154 }
155 
get_tbclk(void)156 ulong get_tbclk(void)
157 {
158 	return MXS_INCREMENTER_HZ;
159 }
160