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 "soc.h"
23 #include "omap_hwmod.h"
24 #include "omap_device.h"
25
26 #include "prm.h"
27 #include "common.h"
28 #include "i2c.h"
29
30 /* In register I2C_CON, Bit 15 is the I2C enable bit */
31 #define I2C_EN BIT(15)
32 #define OMAP2_I2C_CON_OFFSET 0x24
33 #define OMAP4_I2C_CON_OFFSET 0xA4
34
35 #define MAX_OMAP_I2C_HWMOD_NAME_LEN 16
36
37 /**
38 * omap_i2c_reset - reset the omap i2c module.
39 * @oh: struct omap_hwmod *
40 *
41 * The i2c moudle in omap2, omap3 had a special sequence to reset. The
42 * sequence is:
43 * - Disable the I2C.
44 * - Write to SOFTRESET bit.
45 * - Enable the I2C.
46 * - Poll on the RESETDONE bit.
47 * The sequence is implemented in below function. This is called for 2420,
48 * 2430 and omap3.
49 */
omap_i2c_reset(struct omap_hwmod * oh)50 int omap_i2c_reset(struct omap_hwmod *oh)
51 {
52 u32 v;
53 u16 i2c_con;
54 int c = 0;
55
56 if (oh->class->rev == OMAP_I2C_IP_VERSION_2) {
57 i2c_con = OMAP4_I2C_CON_OFFSET;
58 } else if (oh->class->rev == OMAP_I2C_IP_VERSION_1) {
59 i2c_con = OMAP2_I2C_CON_OFFSET;
60 } else {
61 WARN(1, "Cannot reset I2C block %s: unsupported revision\n",
62 oh->name);
63 return -EINVAL;
64 }
65
66 /* Disable I2C */
67 v = omap_hwmod_read(oh, i2c_con);
68 v &= ~I2C_EN;
69 omap_hwmod_write(v, oh, i2c_con);
70
71 /* Write to the SOFTRESET bit */
72 omap_hwmod_softreset(oh);
73
74 /* Enable I2C */
75 v = omap_hwmod_read(oh, i2c_con);
76 v |= I2C_EN;
77 omap_hwmod_write(v, oh, i2c_con);
78
79 /* Poll on RESETDONE bit */
80 omap_test_timeout((omap_hwmod_read(oh,
81 oh->class->sysc->syss_offs)
82 & SYSS_RESETDONE_MASK),
83 MAX_MODULE_SOFTRESET_WAIT, c);
84
85 if (c == MAX_MODULE_SOFTRESET_WAIT)
86 pr_warn("%s: %s: softreset failed (waited %d usec)\n",
87 __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
88 else
89 pr_debug("%s: %s: softreset in %d usec\n", __func__,
90 oh->name, c);
91
92 return 0;
93 }
94
