1/*
 2 * IP block integration code for the HDQ1W/1-wire IP block
 3 *
 4 * Copyright (C) 2012 Texas Instruments, Inc.
 5 * Paul Walmsley
 6 *
 7 * Based on the I2C reset code in arch/arm/mach-omap2/i2c.c by
 8 *     Avinash.H.M <avinashhm@ti.com>
 9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * version 2 as published by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22 * 02110-1301 USA
23 */
24
25#include <plat/omap_hwmod.h>
26#include <plat/hdq1w.h>
27
28#include "common.h"
29
30/* Maximum microseconds to wait for OMAP module to softreset */
31#define MAX_MODULE_SOFTRESET_WAIT	10000
32
33/**
34 * omap_hdq1w_reset - reset the OMAP HDQ1W module
35 * @oh: struct omap_hwmod *
36 *
37 * OCP soft reset the HDQ1W IP block.  Section 20.6.1.4 "HDQ1W/1-Wire
38 * Software Reset" of the OMAP34xx Technical Reference Manual Revision
39 * ZR (SWPU223R) does not include the rather important fact that, for
40 * the reset to succeed, the HDQ1W module's internal clock gate must be
41 * programmed to allow the clock to propagate to the rest of the
42 * module.  In this sense, it's rather similar to the I2C custom reset
43 * function.  Returns 0.
44 */
45int omap_hdq1w_reset(struct omap_hwmod *oh)
46{
47	u32 v;
48	int c = 0;
49
50	/* Write to the SOFTRESET bit */
51	omap_hwmod_softreset(oh);
52
53	/* Enable the module's internal clocks */
54	v = omap_hwmod_read(oh, HDQ_CTRL_STATUS_OFFSET);
55	v |= 1 << HDQ_CTRL_STATUS_CLOCKENABLE_SHIFT;
56	omap_hwmod_write(v, oh, HDQ_CTRL_STATUS_OFFSET);
57
58	/* Poll on RESETDONE bit */
59	omap_test_timeout((omap_hwmod_read(oh,
60					   oh->class->sysc->syss_offs)
61			   & SYSS_RESETDONE_MASK),
62			  MAX_MODULE_SOFTRESET_WAIT, c);
63
64	if (c == MAX_MODULE_SOFTRESET_WAIT)
65		pr_warning("%s: %s: softreset failed (waited %d usec)\n",
66			   __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
67	else
68		pr_debug("%s: %s: softreset in %d usec\n", __func__,
69			 oh->name, c);
70
71	return 0;
72}