arch/arm/mach-omap2/msdi.c

   1 /*
   2  * MSDI IP block reset
   3  *
   4  * Copyright (C) 2012 Texas Instruments, Inc.
   5  * Paul Walmsley
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * version 2 as published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  19  * 02110-1301 USA
  20  *
  21  * XXX What about pad muxing?
  22  */
  23
  24 #include <linux/kernel.h>
  25
  26 #include <plat/omap_hwmod.h>
  27 #include <plat/mmc.h>
  28
  29 #include "common.h"
  30
  31 /*
  32  * MSDI_CON_OFFSET: offset in bytes of the MSDI IP block's CON register
  33  *     from the IP block's base address
  34  */
  35 #define MSDI_CON_OFFSET                         0x0c
  36
  37 /* Register bitfields in the CON register */
  38 #define MSDI_CON_POW_MASK                       BIT(11)
  39 #define MSDI_CON_CLKD_MASK                      (0x3f << 0)
  40 #define MSDI_CON_CLKD_SHIFT                     0
  41
  42 /* Maximum microseconds to wait for OMAP module to softreset */
  43 #define MAX_MODULE_SOFTRESET_WAIT       10000
  44
  45 /* MSDI_TARGET_RESET_CLKD: clock divisor to use throughout the reset */
  46 #define MSDI_TARGET_RESET_CLKD          0x3ff
  47
  48 /**
  49  * omap_msdi_reset - reset the MSDI IP block
  50  * @oh: struct omap_hwmod *
  51  *
  52  * The MSDI IP block on OMAP2420 has to have both the POW and CLKD
  53  * fields set inside its CON register for a reset to complete
  54  * successfully.  This is not documented in the TRM.  For CLKD, we use
  55  * the value that results in the lowest possible clock rate, to attempt
  56  * to avoid disturbing any cards.
  57  */
  58 int omap_msdi_reset(struct omap_hwmod *oh)
  59 {
  60         u16 v = 0;
  61         int c = 0;
  62
  63         /* Write to the SOFTRESET bit */
  64         omap_hwmod_softreset(oh);
  65
  66         /* Enable the MSDI core and internal clock */
  67         v |= MSDI_CON_POW_MASK;
  68         v |= MSDI_TARGET_RESET_CLKD << MSDI_CON_CLKD_SHIFT;
  69         omap_hwmod_write(v, oh, MSDI_CON_OFFSET);
  70
  71         /* Poll on RESETDONE bit */
  72         omap_test_timeout((omap_hwmod_read(oh, oh->class->sysc->syss_offs)
  73                            & SYSS_RESETDONE_MASK),
  74                           MAX_MODULE_SOFTRESET_WAIT, c);
  75
  76         if (c == MAX_MODULE_SOFTRESET_WAIT)
  77                 pr_warning("%s: %s: softreset failed (waited %d usec)\n",
  78                            __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
  79         else
  80                 pr_debug("%s: %s: softreset in %d usec\n", __func__,
  81                          oh->name, c);
  82
  83         /* Disable the MSDI internal clock */
  84         v &= ~MSDI_CON_CLKD_MASK;
  85         omap_hwmod_write(v, oh, MSDI_CON_OFFSET);
  86
  87         return 0;
  88 }