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