1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * OMAP2+ MPU WD_TIMER-specific code
4 *
5 * Copyright (C) 2012 Texas Instruments, Inc.
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/io.h>
10 #include <linux/err.h>
11
12 #include <linux/platform_data/omap-wd-timer.h>
13
14 #include "omap_hwmod.h"
15 #include "omap_device.h"
16 #include "wd_timer.h"
17 #include "common.h"
18 #include "prm.h"
19 #include "soc.h"
20
21 /*
22 * In order to avoid any assumptions from bootloader regarding WDT
23 * settings, WDT module is reset during init. This enables the watchdog
24 * timer. Hence it is required to disable the watchdog after the WDT reset
25 * during init. Otherwise the system would reboot as per the default
26 * watchdog timer registers settings.
27 */
28 #define OMAP_WDT_WPS 0x34
29 #define OMAP_WDT_SPR 0x48
30
31 int omap2_wd_timer_disable(struct omap_hwmod *oh)
32 {
33 void __iomem *base;
34
35 if (!oh) {
36 pr_err("%s: Could not look up wdtimer_hwmod\n", __func__);
37 return -EINVAL;
38 }
39
40 base = omap_hwmod_get_mpu_rt_va(oh);
41 if (!base) {
42 pr_err("%s: Could not get the base address for %s\n",
43 oh->name, __func__);
44 return -EINVAL;
45 }
46
47 /* sequence required to disable watchdog */
48 writel_relaxed(0xAAAA, base + OMAP_WDT_SPR);
49 while (readl_relaxed(base + OMAP_WDT_WPS) & 0x10)
50 cpu_relax();
51
52 writel_relaxed(0x5555, base + OMAP_WDT_SPR);
53 while (readl_relaxed(base + OMAP_WDT_WPS) & 0x10)
54 cpu_relax();
55
56 return 0;
57 }
58
59 /**
60 * omap2_wdtimer_reset - reset and disable the WDTIMER IP block
61 * @oh: struct omap_hwmod *
62 *
63 * After the WDTIMER IP blocks are reset on OMAP2/3, we must also take
64 * care to execute the special watchdog disable sequence. This is
65 * because the watchdog is re-armed upon OCP softreset. (On OMAP4,
66 * this behavior was apparently changed and the watchdog is no longer
67 * re-armed after an OCP soft-reset.) Returns -ETIMEDOUT if the reset
68 * did not complete, or 0 upon success.
69 *
70 * XXX Most of this code should be moved to the omap_hwmod.c layer
71 * during a normal merge window. omap_hwmod_softreset() should be
72 * renamed to omap_hwmod_set_ocp_softreset(), and omap_hwmod_softreset()
73 * should call the hwmod _ocp_softreset() code.
74 */
75 int omap2_wd_timer_reset(struct omap_hwmod *oh)
76 {
77 int c = 0;
78
79 /* Write to the SOFTRESET bit */
80 omap_hwmod_softreset(oh);
81
82 /* Poll on RESETDONE bit */
83 omap_test_timeout((omap_hwmod_read(oh,
84 oh->class->sysc->syss_offs)
85 & SYSS_RESETDONE_MASK),
86 MAX_MODULE_SOFTRESET_WAIT, c);
87
88 if (oh->class->sysc->srst_udelay)
89 udelay(oh->class->sysc->srst_udelay);
90
91 if (c == MAX_MODULE_SOFTRESET_WAIT)
92 pr_warn("%s: %s: softreset failed (waited %d usec)\n",
93 __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
94 else
95 pr_debug("%s: %s: softreset in %d usec\n", __func__,
96 oh->name, c);
97
98 return (c == MAX_MODULE_SOFTRESET_WAIT) ? -ETIMEDOUT :
99 omap2_wd_timer_disable(oh);
100 }