99 lines
3.2 KiB
C
99 lines
3.2 KiB
C
/*
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* OMAP IP block custom reset and preprogramming stubs
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*
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* Copyright (C) 2012 Texas Instruments, Inc.
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* Paul Walmsley
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*
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* A small number of IP blocks need custom reset and preprogramming
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* functions. The stubs in this file provide a standard way for the
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* hwmod code to call these functions, which are to be located under
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* drivers/.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation version 2.
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*
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* This program is distributed "as is" WITHOUT ANY WARRANTY of any
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* kind, whether express or implied; without even the implied warranty
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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* 02110-1301 USA
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*/
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include "omap_hwmod.h"
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#include "common.h"
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#define OMAP_RTC_STATUS_REG 0x44
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#define OMAP_RTC_KICK0_REG 0x6c
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#define OMAP_RTC_KICK1_REG 0x70
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#define OMAP_RTC_KICK0_VALUE 0x83E70B13
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#define OMAP_RTC_KICK1_VALUE 0x95A4F1E0
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#define OMAP_RTC_STATUS_BUSY BIT(0)
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#define OMAP_RTC_MAX_READY_TIME 50
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/**
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* omap_rtc_wait_not_busy - Wait for the RTC BUSY flag
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* @oh: struct omap_hwmod *
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*
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* For updating certain RTC registers, the MPU must wait
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* for the BUSY status in OMAP_RTC_STATUS_REG to become zero.
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* Once the BUSY status is zero, there is a 15 microseconds access
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* period in which the MPU can program.
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*/
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static void omap_rtc_wait_not_busy(struct omap_hwmod *oh)
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{
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int i;
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/* BUSY may stay active for 1/32768 second (~30 usec) */
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omap_test_timeout(omap_hwmod_read(oh, OMAP_RTC_STATUS_REG)
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& OMAP_RTC_STATUS_BUSY, OMAP_RTC_MAX_READY_TIME, i);
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/* now we have ~15 microseconds to read/write various registers */
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}
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/**
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* omap_hwmod_rtc_unlock - Unlock the Kicker mechanism.
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* @oh: struct omap_hwmod *
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*
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* RTC IP have kicker feature. This prevents spurious writes to its registers.
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* In order to write into any of the RTC registers, KICK values has te be
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* written in respective KICK registers. This is needed for hwmod to write into
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* sysconfig register.
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*/
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void omap_hwmod_rtc_unlock(struct omap_hwmod *oh)
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{
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unsigned long flags;
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local_irq_save(flags);
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omap_rtc_wait_not_busy(oh);
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omap_hwmod_write(OMAP_RTC_KICK0_VALUE, oh, OMAP_RTC_KICK0_REG);
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omap_hwmod_write(OMAP_RTC_KICK1_VALUE, oh, OMAP_RTC_KICK1_REG);
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local_irq_restore(flags);
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}
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/**
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* omap_hwmod_rtc_lock - Lock the Kicker mechanism.
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* @oh: struct omap_hwmod *
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*
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* RTC IP have kicker feature. This prevents spurious writes to its registers.
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* Once the RTC registers are written, KICK mechanism needs to be locked,
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* in order to prevent any spurious writes. This function locks back the RTC
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* registers once hwmod completes its write into sysconfig register.
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*/
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void omap_hwmod_rtc_lock(struct omap_hwmod *oh)
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{
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unsigned long flags;
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local_irq_save(flags);
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omap_rtc_wait_not_busy(oh);
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omap_hwmod_write(0x0, oh, OMAP_RTC_KICK0_REG);
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omap_hwmod_write(0x0, oh, OMAP_RTC_KICK1_REG);
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local_irq_restore(flags);
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}
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