1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2019 Stephan Gerhold <stephan@gerhold.net>
4 *
5 * Based on arch/arm/cpu/armv7/u8500/timer.c:
6 * Copyright (C) 2010 Linaro Limited
7 * John Rigby <john.rigby@linaro.org>
8 *
9 * Based on Linux kernel source and internal ST-Ericsson U-Boot source:
10 * Copyright (C) 2009 Alessandro Rubini
11 * Copyright (C) 2010 ST-Ericsson
12 * Copyright (C) 2010 Linus Walleij for ST-Ericsson
13 */
14
15 #include <common.h>
16 #include <dm.h>
17 #include <timer.h>
18 #include <asm/io.h>
19 #include <linux/bitops.h>
20
21 #define MTU_NUM_TIMERS 4
22
23 /* The timers */
24 struct nomadik_mtu_timer_regs {
25 u32 lr; /* Load register */
26 u32 cv; /* Current value */
27 u32 cr; /* Control register */
28 u32 bglr; /* Background load register */
29 };
30
31 /* The MTU that contains the timers */
32 struct nomadik_mtu_regs {
33 u32 imsc; /* Interrupt mask set/clear */
34 u32 ris; /* Raw interrupt status */
35 u32 mis; /* Masked interrupt status */
36 u32 icr; /* Interrupt clear register */
37
38 struct nomadik_mtu_timer_regs timers[MTU_NUM_TIMERS];
39 };
40
41 /* Bits for the control register */
42 #define MTU_CR_ONESHOT BIT(0) /* if 0 = wraps reloading from BGLR */
43 #define MTU_CR_32BITS BIT(1) /* if 0 = 16-bit counter */
44
45 #define MTU_CR_PRESCALE_SHIFT 2
46 #define MTU_CR_PRESCALE_1 (0 << MTU_CR_PRESCALE_SHIFT)
47 #define MTU_CR_PRESCALE_16 (1 << MTU_CR_PRESCALE_SHIFT)
48 #define MTU_CR_PRESCALE_256 (2 << MTU_CR_PRESCALE_SHIFT)
49
50 #define MTU_CR_PERIODIC BIT(6) /* if 0 = free-running */
51 #define MTU_CR_ENABLE BIT(7)
52
53 struct nomadik_mtu_priv {
54 struct nomadik_mtu_timer_regs *timer;
55 };
56
nomadik_mtu_get_count(struct udevice * dev)57 static u64 nomadik_mtu_get_count(struct udevice *dev)
58 {
59 struct nomadik_mtu_priv *priv = dev_get_priv(dev);
60
61 /* Decrementing counter: invert the value */
62 return timer_conv_64(~readl(&priv->timer->cv));
63 }
64
nomadik_mtu_probe(struct udevice * dev)65 static int nomadik_mtu_probe(struct udevice *dev)
66 {
67 struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
68 struct nomadik_mtu_priv *priv = dev_get_priv(dev);
69 struct nomadik_mtu_regs *mtu;
70 u32 prescale;
71
72 mtu = dev_read_addr_ptr(dev);
73 if (!mtu)
74 return -EINVAL;
75 priv->timer = mtu->timers; /* Use first timer */
76
77 if (!uc_priv->clock_rate)
78 return -EINVAL;
79
80 /* Use divide-by-16 counter if tick rate is more than 32 MHz */
81 if (uc_priv->clock_rate > 32000000) {
82 uc_priv->clock_rate /= 16;
83 prescale = MTU_CR_PRESCALE_16;
84 } else {
85 prescale = MTU_CR_PRESCALE_1;
86 }
87
88 /* Configure a free-running, auto-wrap counter with selected prescale */
89 writel(MTU_CR_ENABLE | prescale | MTU_CR_32BITS, &priv->timer->cr);
90
91 return 0;
92 }
93
94 static const struct timer_ops nomadik_mtu_ops = {
95 .get_count = nomadik_mtu_get_count,
96 };
97
98 static const struct udevice_id nomadik_mtu_ids[] = {
99 { .compatible = "st,nomadik-mtu" },
100 {}
101 };
102
103 U_BOOT_DRIVER(nomadik_mtu) = {
104 .name = "nomadik_mtu",
105 .id = UCLASS_TIMER,
106 .of_match = nomadik_mtu_ids,
107 .priv_auto = sizeof(struct nomadik_mtu_priv),
108 .probe = nomadik_mtu_probe,
109 .ops = &nomadik_mtu_ops,
110 };
111