Linux Kernel  3.7.1
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i2c.c
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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/i2c.h>
23 #include "common.h"
24 #include <plat/omap_hwmod.h>
25 
26 #include "mux.h"
27 
28 /* In register I2C_CON, Bit 15 is the I2C enable bit */
29 #define I2C_EN BIT(15)
30 #define OMAP2_I2C_CON_OFFSET 0x24
31 #define OMAP4_I2C_CON_OFFSET 0xA4
32 
33 /* Maximum microseconds to wait for OMAP module to softreset */
34 #define MAX_MODULE_SOFTRESET_WAIT 10000
35 
36 void __init omap2_i2c_mux_pins(int bus_id)
37 {
38  char mux_name[sizeof("i2c2_scl.i2c2_scl")];
39 
40  /* First I2C bus is not muxable */
41  if (bus_id == 1)
42  return;
43 
44  sprintf(mux_name, "i2c%i_scl.i2c%i_scl", bus_id, bus_id);
45  omap_mux_init_signal(mux_name, OMAP_PIN_INPUT);
46  sprintf(mux_name, "i2c%i_sda.i2c%i_sda", bus_id, bus_id);
47  omap_mux_init_signal(mux_name, OMAP_PIN_INPUT);
48 }
49 
63 int omap_i2c_reset(struct omap_hwmod *oh)
64 {
65  u32 v;
66  u16 i2c_con;
67  int c = 0;
68 
69  if (oh->class->rev == OMAP_I2C_IP_VERSION_2) {
70  i2c_con = OMAP4_I2C_CON_OFFSET;
71  } else if (oh->class->rev == OMAP_I2C_IP_VERSION_1) {
72  i2c_con = OMAP2_I2C_CON_OFFSET;
73  } else {
74  WARN(1, "Cannot reset I2C block %s: unsupported revision\n",
75  oh->name);
76  return -EINVAL;
77  }
78 
79  /* Disable I2C */
80  v = omap_hwmod_read(oh, i2c_con);
81  v &= ~I2C_EN;
82  omap_hwmod_write(v, oh, i2c_con);
83 
84  /* Write to the SOFTRESET bit */
86 
87  /* Enable I2C */
88  v = omap_hwmod_read(oh, i2c_con);
89  v |= I2C_EN;
90  omap_hwmod_write(v, oh, i2c_con);
91 
92  /* Poll on RESETDONE bit */
93  omap_test_timeout((omap_hwmod_read(oh,
94  oh->class->sysc->syss_offs)
97 
99  pr_warning("%s: %s: softreset failed (waited %d usec)\n",
100  __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
101  else
102  pr_debug("%s: %s: softreset in %d usec\n", __func__,
103  oh->name, c);
104 
105  return 0;
106 }