1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * IP block integration code for the HDQ1W/1-wire IP block
4 *
5 * Copyright (C) 2012 Texas Instruments, Inc.
6 * Paul Walmsley
7 *
8 * Based on the I2C reset code in arch/arm/mach-omap2/i2c.c by
9 * Avinash.H.M <avinashhm@ti.com>
10 */
11
12 #include <linux/kernel.h>
13 #include <linux/init.h>
14 #include <linux/err.h>
15 #include <linux/platform_device.h>
16
17 #include "soc.h"
18 #include "omap_hwmod.h"
19 #include "omap_device.h"
20 #include "hdq1w.h"
21
22 #include "prm.h"
23 #include "common.h"
24
25 /**
26 * omap_hdq1w_reset - reset the OMAP HDQ1W module
27 * @oh: struct omap_hwmod *
28 *
29 * OCP soft reset the HDQ1W IP block. Section 20.6.1.4 "HDQ1W/1-Wire
30 * Software Reset" of the OMAP34xx Technical Reference Manual Revision
31 * ZR (SWPU223R) does not include the rather important fact that, for
32 * the reset to succeed, the HDQ1W module's internal clock gate must be
33 * programmed to allow the clock to propagate to the rest of the
34 * module. In this sense, it's rather similar to the I2C custom reset
35 * function. Returns 0.
36 */
37 int omap_hdq1w_reset(struct omap_hwmod *oh)
38 {
39 u32 v;
40 int c = 0;
41
42 /* Write to the SOFTRESET bit */
43 omap_hwmod_softreset(oh);
44
45 /* Enable the module's internal clocks */
46 v = omap_hwmod_read(oh, HDQ_CTRL_STATUS_OFFSET);
47 v |= 1 << HDQ_CTRL_STATUS_CLOCKENABLE_SHIFT;
48 omap_hwmod_write(v, oh, HDQ_CTRL_STATUS_OFFSET);
49
50 /* Poll on RESETDONE bit */
51 omap_test_timeout((omap_hwmod_read(oh,
52 oh->class->sysc->syss_offs)
53 & SYSS_RESETDONE_MASK),
54 MAX_MODULE_SOFTRESET_WAIT, c);
55
56 if (c == MAX_MODULE_SOFTRESET_WAIT)
57 pr_warn("%s: %s: softreset failed (waited %d usec)\n",
58 __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
59 else
60 pr_debug("%s: %s: softreset in %d usec\n", __func__,
61 oh->name, c);
62
63 return 0;
64 }