98 lines
2.8 KiB
C
98 lines
2.8 KiB
C
/*
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* IP block integration code for the HDQ1W/1-wire IP block
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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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* Based on the I2C reset code in arch/arm/mach-omap2/i2c.c by
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* Avinash.H.M <avinashhm@ti.com>
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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
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* version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* 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/init.h>
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#include <linux/err.h>
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#include <linux/platform_device.h>
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#include <plat/omap_hwmod.h>
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#include <plat/omap_device.h>
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#include "hdq1w.h"
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#include "common.h"
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/* Maximum microseconds to wait for OMAP module to softreset */
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#define MAX_MODULE_SOFTRESET_WAIT 10000
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/**
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* omap_hdq1w_reset - reset the OMAP HDQ1W module
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* @oh: struct omap_hwmod *
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*
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* OCP soft reset the HDQ1W IP block. Section 20.6.1.4 "HDQ1W/1-Wire
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* Software Reset" of the OMAP34xx Technical Reference Manual Revision
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* ZR (SWPU223R) does not include the rather important fact that, for
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* the reset to succeed, the HDQ1W module's internal clock gate must be
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* programmed to allow the clock to propagate to the rest of the
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* module. In this sense, it's rather similar to the I2C custom reset
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* function. Returns 0.
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*/
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int omap_hdq1w_reset(struct omap_hwmod *oh)
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{
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u32 v;
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int c = 0;
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/* Write to the SOFTRESET bit */
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omap_hwmod_softreset(oh);
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/* Enable the module's internal clocks */
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v = omap_hwmod_read(oh, HDQ_CTRL_STATUS_OFFSET);
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v |= 1 << HDQ_CTRL_STATUS_CLOCKENABLE_SHIFT;
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omap_hwmod_write(v, oh, HDQ_CTRL_STATUS_OFFSET);
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/* Poll on RESETDONE bit */
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omap_test_timeout((omap_hwmod_read(oh,
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oh->class->sysc->syss_offs)
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& SYSS_RESETDONE_MASK),
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MAX_MODULE_SOFTRESET_WAIT, c);
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if (c == MAX_MODULE_SOFTRESET_WAIT)
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pr_warning("%s: %s: softreset failed (waited %d usec)\n",
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__func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
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else
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pr_debug("%s: %s: softreset in %d usec\n", __func__,
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oh->name, c);
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return 0;
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}
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static int __init omap_init_hdq(void)
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{
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int id = -1;
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struct platform_device *pdev;
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struct omap_hwmod *oh;
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char *oh_name = "hdq1w";
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char *devname = "omap_hdq";
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oh = omap_hwmod_lookup(oh_name);
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if (!oh)
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return 0;
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pdev = omap_device_build(devname, id, oh, NULL, 0, NULL, 0, 0);
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WARN(IS_ERR(pdev), "Can't build omap_device for %s:%s.\n",
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devname, oh->name);
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return 0;
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}
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arch_initcall(omap_init_hdq);
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