xref: /openbmc/linux/arch/arm/mach-omap2/i2c.c (revision 2b27bdcc)
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  */
omap_i2c_reset(struct omap_hwmod * oh)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 }
75