arch/arm/mach-omap2/i2c.c

   1 /*
   2  * Helper module for board specific I2C bus registration
   3  *
   4  * Copyright (C) 2009 Nokia Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * version 2 as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  18  * 02110-1301 USA
  19  *
  20  */
  21
  22 #include <plat/cpu.h>
  23 #include <plat/i2c.h>
  24 #include <plat/common.h>
  25 #include <plat/omap_hwmod.h>
  26
  27 #include "mux.h"
  28
  29 /* In register I2C_CON, Bit 15 is the I2C enable bit */
  30 #define I2C_EN                                  BIT(15)
  31 #define OMAP2_I2C_CON_OFFSET                    0x24
  32 #define OMAP4_I2C_CON_OFFSET                    0xA4
  33
  34 /* Maximum microseconds to wait for OMAP module to softreset */
  35 #define MAX_MODULE_SOFTRESET_WAIT       10000
  36
  37 void __init omap2_i2c_mux_pins(int bus_id)
  38 {
  39         char mux_name[sizeof("i2c2_scl.i2c2_scl")];
  40
  41         /* First I2C bus is not muxable */
  42         if (bus_id == 1)
  43                 return;
  44
  45         sprintf(mux_name, "i2c%i_scl.i2c%i_scl", bus_id, bus_id);
  46         omap_mux_init_signal(mux_name, OMAP_PIN_INPUT);
  47         sprintf(mux_name, "i2c%i_sda.i2c%i_sda", bus_id, bus_id);
  48         omap_mux_init_signal(mux_name, OMAP_PIN_INPUT);
  49 }
  50
  51 /**
  52  * omap_i2c_reset - reset the omap i2c module.
  53  * @oh: struct omap_hwmod *
  54  *
  55  * The i2c moudle in omap2, omap3 had a special sequence to reset. The
  56  * sequence is:
  57  * - Disable the I2C.
  58  * - Write to SOFTRESET bit.
  59  * - Enable the I2C.
  60  * - Poll on the RESETDONE bit.
  61  * The sequence is implemented in below function. This is called for 2420,
  62  * 2430 and omap3.
  63  */
  64 int omap_i2c_reset(struct omap_hwmod *oh)
  65 {
  66         u32 v;
  67         u16 i2c_con;
  68         int c = 0;
  69
  70         if (oh->class->rev == OMAP_I2C_IP_VERSION_2) {
  71                 i2c_con = OMAP4_I2C_CON_OFFSET;
  72         } else if (oh->class->rev == OMAP_I2C_IP_VERSION_1) {
  73                 i2c_con = OMAP2_I2C_CON_OFFSET;
  74         } else {
  75                 WARN(1, "Cannot reset I2C block %s: unsupported revision\n",
  76                      oh->name);
  77                 return -EINVAL;
  78         }
  79
  80         /* Disable I2C */
  81         v = omap_hwmod_read(oh, i2c_con);
  82         v &= ~I2C_EN;
  83         omap_hwmod_write(v, oh, i2c_con);
  84
  85         /* Write to the SOFTRESET bit */
  86         omap_hwmod_softreset(oh);
  87
  88         /* Enable I2C */
  89         v = omap_hwmod_read(oh, i2c_con);
  90         v |= I2C_EN;
  91         omap_hwmod_write(v, oh, i2c_con);
  92
  93         /* Poll on RESETDONE bit */
  94         omap_test_timeout((omap_hwmod_read(oh,
  95                                 oh->class->sysc->syss_offs)
  96                                 & SYSS_RESETDONE_MASK),
  97                                 MAX_MODULE_SOFTRESET_WAIT, c);
  98
  99         if (c == MAX_MODULE_SOFTRESET_WAIT)
 100                 pr_warning("%s: %s: softreset failed (waited %d usec)\n",
 101                         __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
 102         else
 103                 pr_debug("%s: %s: softreset in %d usec\n", __func__,
 104                         oh->name, c);
 105
 106         return 0;
 107 }