arch/arm/mach-omap2/i2c.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Helper module for board specific I2C bus registration
   4  *
   5  * Copyright (C) 2009 Nokia Corporation.
   6  */
   7
   8 #include "soc.h"
   9 #include "omap_hwmod.h"
  10 #include "omap_device.h"
  11
  12 #include "prm.h"
  13 #include "common.h"
  14 #include "i2c.h"
  15
  16 /* In register I2C_CON, Bit 15 is the I2C enable bit */
  17 #define I2C_EN                                  BIT(15)
  18 #define OMAP2_I2C_CON_OFFSET                    0x24
  19 #define OMAP4_I2C_CON_OFFSET                    0xA4
  20
  21 #define MAX_OMAP_I2C_HWMOD_NAME_LEN     16
  22
  23 /**
  24  * omap_i2c_reset - reset the omap i2c module.
  25  * @oh: struct omap_hwmod *
  26  *
  27  * The i2c moudle in omap2, omap3 had a special sequence to reset. The
  28  * sequence is:
  29  * - Disable the I2C.
  30  * - Write to SOFTRESET bit.
  31  * - Enable the I2C.
  32  * - Poll on the RESETDONE bit.
  33  * The sequence is implemented in below function. This is called for 2420,
  34  * 2430 and omap3.
  35  */
  36 int omap_i2c_reset(struct omap_hwmod *oh)
  37 {
  38         u32 v;
  39         u16 i2c_con;
  40         int c = 0;
  41
  42         if (soc_is_omap24xx() || soc_is_omap34xx() || soc_is_am35xx())
  43                 i2c_con = OMAP2_I2C_CON_OFFSET;
  44         else
  45                 i2c_con = OMAP4_I2C_CON_OFFSET;
  46
  47         /* Disable I2C */
  48         v = omap_hwmod_read(oh, i2c_con);
  49         v &= ~I2C_EN;
  50         omap_hwmod_write(v, oh, i2c_con);
  51
  52         /* Write to the SOFTRESET bit */
  53         omap_hwmod_softreset(oh);
  54
  55         /* Enable I2C */
  56         v = omap_hwmod_read(oh, i2c_con);
  57         v |= I2C_EN;
  58         omap_hwmod_write(v, oh, i2c_con);
  59
  60         /* Poll on RESETDONE bit */
  61         omap_test_timeout((omap_hwmod_read(oh,
  62                                 oh->class->sysc->syss_offs)
  63                                 & SYSS_RESETDONE_MASK),
  64                                 MAX_MODULE_SOFTRESET_WAIT, c);
  65
  66         if (c == MAX_MODULE_SOFTRESET_WAIT)
  67                 pr_warn("%s: %s: softreset failed (waited %d usec)\n",
  68                         __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
  69         else
  70                 pr_debug("%s: %s: softreset in %d usec\n", __func__,
  71                         oh->name, c);
  72
  73         return 0;
  74 }