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 */ 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