1 /*
2 * Copyright (C) 2008 Scientific-Atlanta, Inc.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 */
18 /*
19 * The file comes from kernel/csrc-r4k.c
20 */
21 #include <linux/clocksource.h>
22 #include <linux/init.h>
23
24 #include <asm/time.h> /* Not included in linux/time.h */
25
26 #include <asm/mach-powertv/asic_regs.h>
27 #include "powertv-clock.h"
28
29 /* MIPS PLL Register Definitions */
30 #define PLL_GET_M(x) (((x) >> 8) & 0x000000FF)
31 #define PLL_GET_N(x) (((x) >> 16) & 0x000000FF)
32 #define PLL_GET_P(x) (((x) >> 24) & 0x00000007)
33
34 /*
35 * returns: Clock frequency in kHz
36 */
mips_get_pll_freq(void)37 unsigned int __init mips_get_pll_freq(void)
38 {
39 unsigned int pll_reg, m, n, p;
40 unsigned int fin = 54000; /* Base frequency in kHz */
41 unsigned int fout;
42
43 /* Read PLL register setting */
44 pll_reg = asic_read(mips_pll_setup);
45 m = PLL_GET_M(pll_reg);
46 n = PLL_GET_N(pll_reg);
47 p = PLL_GET_P(pll_reg);
48 pr_info("MIPS PLL Register:0x%x M=%d N=%d P=%d\n", pll_reg, m, n, p);
49
50 /* Calculate clock frequency = (2 * N * 54MHz) / (M * (2**P)) */
51 fout = ((2 * n * fin) / (m * (0x01 << p)));
52
53 pr_info("MIPS Clock Freq=%d kHz\n", fout);
54
55 return fout;
56 }
57
c0_hpt_read(struct clocksource * cs)58 static cycle_t c0_hpt_read(struct clocksource *cs)
59 {
60 return read_c0_count();
61 }
62
63 static struct clocksource clocksource_mips = {
64 .name = "powertv-counter",
65 .read = c0_hpt_read,
66 .mask = CLOCKSOURCE_MASK(32),
67 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
68 };
69
powertv_c0_hpt_clocksource_init(void)70 static void __init powertv_c0_hpt_clocksource_init(void)
71 {
72 unsigned int pll_freq = mips_get_pll_freq();
73
74 pr_info("CPU frequency %d.%02d MHz\n", pll_freq / 1000,
75 (pll_freq % 1000) * 100 / 1000);
76
77 mips_hpt_frequency = pll_freq / 2 * 1000;
78
79 clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
80
81 clocksource_register_hz(&clocksource_mips, mips_hpt_frequency);
82 }
83
84 /**
85 * struct tim_c - free running counter
86 * @hi: High 16 bits of the counter
87 * @lo: Low 32 bits of the counter
88 *
89 * Lays out the structure of the free running counter in memory. This counter
90 * increments at a rate of 27 MHz/8 on all platforms.
91 */
92 struct tim_c {
93 unsigned int hi;
94 unsigned int lo;
95 };
96
97 static struct tim_c *tim_c;
98
tim_c_read(struct clocksource * cs)99 static cycle_t tim_c_read(struct clocksource *cs)
100 {
101 unsigned int hi;
102 unsigned int next_hi;
103 unsigned int lo;
104
105 hi = readl(&tim_c->hi);
106
107 for (;;) {
108 lo = readl(&tim_c->lo);
109 next_hi = readl(&tim_c->hi);
110 if (next_hi == hi)
111 break;
112 hi = next_hi;
113 }
114
115 pr_crit("%s: read %llx\n", __func__, ((u64) hi << 32) | lo);
116 return ((u64) hi << 32) | lo;
117 }
118
119 #define TIM_C_SIZE 48 /* # bits in the timer */
120
121 static struct clocksource clocksource_tim_c = {
122 .name = "powertv-tim_c",
123 .read = tim_c_read,
124 .mask = CLOCKSOURCE_MASK(TIM_C_SIZE),
125 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
126 };
127
128 /**
129 * powertv_tim_c_clocksource_init - set up a clock source for the TIM_C clock
130 *
131 * We know that TIM_C counts at 27 MHz/8, so each cycle corresponds to
132 * 1 / (27,000,000/8) seconds.
133 */
powertv_tim_c_clocksource_init(void)134 static void __init powertv_tim_c_clocksource_init(void)
135 {
136 const unsigned long counts_per_second = 27000000 / 8;
137
138 clocksource_tim_c.rating = 200;
139
140 clocksource_register_hz(&clocksource_tim_c, counts_per_second);
141 tim_c = (struct tim_c *) asic_reg_addr(tim_ch);
142 }
143
144 /**
145 powertv_clocksource_init - initialize all clocksources
146 */
powertv_clocksource_init(void)147 void __init powertv_clocksource_init(void)
148 {
149 powertv_c0_hpt_clocksource_init();
150 powertv_tim_c_clocksource_init();
151 }
152