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 */
omap_rtc_wait_not_busy(struct omap_hwmod * oh)50 static 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 */
omap_hwmod_rtc_unlock(struct omap_hwmod * oh)69 void 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 */
omap_hwmod_rtc_lock(struct omap_hwmod * oh)89 void 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 }
99