arch/arm/mach-omap2/omap_hwmod_reset.c

   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  */
  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  */
  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  */
  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 }