arch/arm/mach-omap2/msdi.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * MSDI IP block reset
   4  *
   5  * Copyright (C) 2012 Texas Instruments, Inc.
   6  * Paul Walmsley
   7  *
   8  * XXX What about pad muxing?
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/err.h>
  13
  14 #include "prm.h"
  15 #include "common.h"
  16 #include "control.h"
  17 #include "omap_hwmod.h"
  18 #include "omap_device.h"
  19 #include "mmc.h"
  20
  21 /*
  22  * MSDI_CON_OFFSET: offset in bytes of the MSDI IP block's CON register
  23  *     from the IP block's base address
  24  */
  25 #define MSDI_CON_OFFSET                         0x0c
  26
  27 /* Register bitfields in the CON register */
  28 #define MSDI_CON_POW_MASK                       BIT(11)
  29 #define MSDI_CON_CLKD_MASK                      (0x3f << 0)
  30 #define MSDI_CON_CLKD_SHIFT                     0
  31
  32 /* MSDI_TARGET_RESET_CLKD: clock divisor to use throughout the reset */
  33 #define MSDI_TARGET_RESET_CLKD          0x3ff
  34
  35 /**
  36  * omap_msdi_reset - reset the MSDI IP block
  37  * @oh: struct omap_hwmod *
  38  *
  39  * The MSDI IP block on OMAP2420 has to have both the POW and CLKD
  40  * fields set inside its CON register for a reset to complete
  41  * successfully.  This is not documented in the TRM.  For CLKD, we use
  42  * the value that results in the lowest possible clock rate, to attempt
  43  * to avoid disturbing any cards.
  44  */
  45 int omap_msdi_reset(struct omap_hwmod *oh)
  46 {
  47         u16 v = 0;
  48         int c = 0;
  49
  50         /* Write to the SOFTRESET bit */
  51         omap_hwmod_softreset(oh);
  52
  53         /* Enable the MSDI core and internal clock */
  54         v |= MSDI_CON_POW_MASK;
  55         v |= MSDI_TARGET_RESET_CLKD << MSDI_CON_CLKD_SHIFT;
  56         omap_hwmod_write(v, oh, MSDI_CON_OFFSET);
  57
  58         /* Poll on RESETDONE bit */
  59         omap_test_timeout((omap_hwmod_read(oh, oh->class->sysc->syss_offs)
  60                            & SYSS_RESETDONE_MASK),
  61                           MAX_MODULE_SOFTRESET_WAIT, c);
  62
  63         if (c == MAX_MODULE_SOFTRESET_WAIT)
  64                 pr_warn("%s: %s: softreset failed (waited %d usec)\n",
  65                         __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
  66         else
  67                 pr_debug("%s: %s: softreset in %d usec\n", __func__,
  68                          oh->name, c);
  69
  70         /* Disable the MSDI internal clock */
  71         v &= ~MSDI_CON_CLKD_MASK;
  72         omap_hwmod_write(v, oh, MSDI_CON_OFFSET);
  73
  74         return 0;
  75 }