1/*
 2 * OMAP IP block custom reset and preprogramming stubs
 3 *
 4 * Copyright (C) 2012 Texas Instruments, Inc.
 5 * Paul Walmsley
 6 *
 7 * A small number of IP blocks need custom reset and preprogramming
 8 * functions.  The stubs in this file provide a standard way for the
 9 * hwmod code to call these functions, which are to be located under
10 * drivers/.
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License as
14 * published by the Free Software Foundation version 2.
15 *
16 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
17 * kind, whether express or implied; without even the implied warranty
18 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
24 * 02110-1301 USA
25 */
26#include <linux/kernel.h>
27#include <linux/errno.h>
28
29#include "omap_hwmod.h"
30#include "common.h"
31
32#define OMAP_RTC_STATUS_REG	0x44
33#define OMAP_RTC_KICK0_REG	0x6c
34#define OMAP_RTC_KICK1_REG	0x70
35
36#define OMAP_RTC_KICK0_VALUE	0x83E70B13
37#define OMAP_RTC_KICK1_VALUE	0x95A4F1E0
38#define OMAP_RTC_STATUS_BUSY	BIT(0)
39#define OMAP_RTC_MAX_READY_TIME	50
40
41/**
42 * omap_rtc_wait_not_busy - Wait for the RTC BUSY flag
43 * @oh: struct omap_hwmod *
44 *
45 * For updating certain RTC registers, the MPU must wait
46 * for the BUSY status in OMAP_RTC_STATUS_REG to become zero.
47 * Once the BUSY status is zero, there is a 15 microseconds access
48 * period in which the MPU can program.
49 */
50static void omap_rtc_wait_not_busy(struct omap_hwmod *oh)
51{
52	int i;
53
54	/* BUSY may stay active for 1/32768 second (~30 usec) */
55	omap_test_timeout(omap_hwmod_read(oh, OMAP_RTC_STATUS_REG)
56			  & OMAP_RTC_STATUS_BUSY, OMAP_RTC_MAX_READY_TIME, i);
57	/* now we have ~15 microseconds to read/write various registers */
58}
59
60/**
61 * omap_hwmod_rtc_unlock - Unlock the Kicker mechanism.
62 * @oh: struct omap_hwmod *
63 *
64 * RTC IP have kicker feature. This prevents spurious writes to its registers.
65 * In order to write into any of the RTC registers, KICK values has te be
66 * written in respective KICK registers. This is needed for hwmod to write into
67 * sysconfig register.
68 */
69void omap_hwmod_rtc_unlock(struct omap_hwmod *oh)
70{
71	unsigned long flags;
72
73	local_irq_save(flags);
74	omap_rtc_wait_not_busy(oh);
75	omap_hwmod_write(OMAP_RTC_KICK0_VALUE, oh, OMAP_RTC_KICK0_REG);
76	omap_hwmod_write(OMAP_RTC_KICK1_VALUE, oh, OMAP_RTC_KICK1_REG);
77	local_irq_restore(flags);
78}
79
80/**
81 * omap_hwmod_rtc_lock - Lock the Kicker mechanism.
82 * @oh: struct omap_hwmod *
83 *
84 * RTC IP have kicker feature. This prevents spurious writes to its registers.
85 * Once the RTC registers are written, KICK mechanism needs to be locked,
86 * in order to prevent any spurious writes. This function locks back the RTC
87 * registers once hwmod completes its write into sysconfig register.
88 */
89void omap_hwmod_rtc_lock(struct omap_hwmod *oh)
90{
91	unsigned long flags;
92
93	local_irq_save(flags);
94	omap_rtc_wait_not_busy(oh);
95	omap_hwmod_write(0x0, oh, OMAP_RTC_KICK0_REG);
96	omap_hwmod_write(0x0, oh, OMAP_RTC_KICK1_REG);
97	local_irq_restore(flags);
98}