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"Das U-Boot" Source Tree
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright (C) 2022 Svyatoslav Ryhel <clamor95@gmail.com>
4 */
5
6#include <dm.h>
7#include <errno.h>
8#include <timer.h>
9
10#include <asm/io.h>
11#include <asm/arch/clock.h>
12#include <asm/arch/tegra.h>
13
14#define TEGRA_OSC_CLK_ENB_L_SET (NV_PA_CLK_RST_BASE + 0x320)
15#define TEGRA_OSC_SET_CLK_ENB_TMR BIT(5)
16
17#define TEGRA_TIMER_USEC_CNTR (NV_PA_TMRUS_BASE + 0)
18#define TEGRA_TIMER_USEC_CFG (NV_PA_TMRUS_BASE + 4)
19
20#define TEGRA_TIMER_RATE 1000000 /* 1 MHz */
21
22/*
23 * On pre-DM stage timer should be left configured by
24 * previous bootloader for correct 1MHz clock.
25 * In the case of reset default value is set to 1/13 of
26 * CLK_M which should be decent enough to safely
27 * get to DM stage.
28 */
29u64 notrace timer_early_get_count(void)
30{
31 /* At this stage raw timer is used */
32 return readl(TEGRA_TIMER_USEC_CNTR);
33}
34
35unsigned long notrace timer_early_get_rate(void)
36{
37 return TEGRA_TIMER_RATE;
38}
39
40ulong timer_get_boot_us(void)
41{
42 return timer_early_get_count();
43}
44
45/*
46 * At moment of calling get_count, timer driver is already
47 * probed and is configured to have precise 1MHz clock.
48 * Tegra timer has a step of 1 microsecond which removes
49 * need of using adjusments involving uc_priv->clock_rate.
50 */
51static notrace u64 tegra_timer_get_count(struct udevice *dev)
52{
53 u32 val = timer_early_get_count();
54 return timer_conv_64(val);
55}
56
57static int tegra_timer_probe(struct udevice *dev)
58{
59 struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
60 u32 usec_config, value;
61
62 /* Timer rate has to be set unconditionally */
63 uc_priv->clock_rate = TEGRA_TIMER_RATE;
64
65 /*
66 * Configure microsecond timers to have 1MHz clock
67 * Config register is 0xqqww, where qq is "dividend", ww is "divisor"
68 * Uses n+1 scheme
69 */
70 switch (clock_get_rate(CLOCK_ID_CLK_M)) {
71 case 12000000:
72 usec_config = 0x000b; /* (11+1)/(0+1) */
73 break;
74 case 12800000:
75 usec_config = 0x043f; /* (63+1)/(4+1) */
76 break;
77 case 13000000:
78 usec_config = 0x000c; /* (12+1)/(0+1) */
79 break;
80 case 16800000:
81 usec_config = 0x0453; /* (83+1)/(4+1) */
82 break;
83 case 19200000:
84 usec_config = 0x045f; /* (95+1)/(4+1) */
85 break;
86 case 26000000:
87 usec_config = 0x0019; /* (25+1)/(0+1) */
88 break;
89 case 38400000:
90 usec_config = 0x04bf; /* (191+1)/(4+1) */
91 break;
92 case 48000000:
93 usec_config = 0x002f; /* (47+1)/(0+1) */
94 break;
95 default:
96 return -EINVAL;
97 }
98
99 /* Enable clock to timer hardware */
100 value = readl_relaxed(TEGRA_OSC_CLK_ENB_L_SET);
101 writel_relaxed(value | TEGRA_OSC_SET_CLK_ENB_TMR,
102 TEGRA_OSC_CLK_ENB_L_SET);
103
104 writel_relaxed(usec_config, TEGRA_TIMER_USEC_CFG);
105
106 return 0;
107}
108
109static const struct timer_ops tegra_timer_ops = {
110 .get_count = tegra_timer_get_count,
111};
112
113static const struct udevice_id tegra_timer_ids[] = {
114 { .compatible = "nvidia,tegra20-timer" },
115 { .compatible = "nvidia,tegra30-timer" },
116 { .compatible = "nvidia,tegra114-timer" },
117 { .compatible = "nvidia,tegra124-timer" },
118 { .compatible = "nvidia,tegra210-timer" },
119 { }
120};
121
122U_BOOT_DRIVER(tegra_timer) = {
123 .name = "tegra_timer",
124 .id = UCLASS_TIMER,
125 .of_match = tegra_timer_ids,
126 .probe = tegra_timer_probe,
127 .ops = &tegra_timer_ops,
128 .flags = DM_FLAG_PRE_RELOC,
129};