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1/*2 * Copyright 2012 Red Hat Inc.3 *4 * Permission is hereby granted, free of charge, to any person obtaining a5 * copy of this software and associated documentation files (the "Software"),6 * to deal in the Software without restriction, including without limitation7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,8 * and/or sell copies of the Software, and to permit persons to whom the9 * Software is furnished to do so, subject to the following conditions:10 *11 * The above copyright notice and this permission notice shall be included in12 * all copies or substantial busions of the Software.13 *14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL17 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR18 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR20 * OTHER DEALINGS IN THE SOFTWARE.21 *22 * Authors: Ben Skeggs23 */24#include "bus.h"25 26#ifdef CONFIG_NOUVEAU_I2C_INTERNAL27#define T_TIMEOUT 220000028#define T_RISEFALL 100029#define T_HOLD 500030 31static inline void32nvkm_i2c_drive_scl(struct nvkm_i2c_bus *bus, int state)33{34 bus->func->drive_scl(bus, state);35}36 37static inline void38nvkm_i2c_drive_sda(struct nvkm_i2c_bus *bus, int state)39{40 bus->func->drive_sda(bus, state);41}42 43static inline int44nvkm_i2c_sense_scl(struct nvkm_i2c_bus *bus)45{46 return bus->func->sense_scl(bus);47}48 49static inline int50nvkm_i2c_sense_sda(struct nvkm_i2c_bus *bus)51{52 return bus->func->sense_sda(bus);53}54 55static void56nvkm_i2c_delay(struct nvkm_i2c_bus *bus, u32 nsec)57{58 udelay((nsec + 500) / 1000);59}60 61static bool62nvkm_i2c_raise_scl(struct nvkm_i2c_bus *bus)63{64 u32 timeout = T_TIMEOUT / T_RISEFALL;65 66 nvkm_i2c_drive_scl(bus, 1);67 do {68 nvkm_i2c_delay(bus, T_RISEFALL);69 } while (!nvkm_i2c_sense_scl(bus) && --timeout);70 71 return timeout != 0;72}73 74static int75i2c_start(struct nvkm_i2c_bus *bus)76{77 int ret = 0;78 79 if (!nvkm_i2c_sense_scl(bus) ||80 !nvkm_i2c_sense_sda(bus)) {81 nvkm_i2c_drive_scl(bus, 0);82 nvkm_i2c_drive_sda(bus, 1);83 if (!nvkm_i2c_raise_scl(bus))84 ret = -EBUSY;85 }86 87 nvkm_i2c_drive_sda(bus, 0);88 nvkm_i2c_delay(bus, T_HOLD);89 nvkm_i2c_drive_scl(bus, 0);90 nvkm_i2c_delay(bus, T_HOLD);91 return ret;92}93 94static void95i2c_stop(struct nvkm_i2c_bus *bus)96{97 nvkm_i2c_drive_scl(bus, 0);98 nvkm_i2c_drive_sda(bus, 0);99 nvkm_i2c_delay(bus, T_RISEFALL);100 101 nvkm_i2c_drive_scl(bus, 1);102 nvkm_i2c_delay(bus, T_HOLD);103 nvkm_i2c_drive_sda(bus, 1);104 nvkm_i2c_delay(bus, T_HOLD);105}106 107static int108i2c_bitw(struct nvkm_i2c_bus *bus, int sda)109{110 nvkm_i2c_drive_sda(bus, sda);111 nvkm_i2c_delay(bus, T_RISEFALL);112 113 if (!nvkm_i2c_raise_scl(bus))114 return -ETIMEDOUT;115 nvkm_i2c_delay(bus, T_HOLD);116 117 nvkm_i2c_drive_scl(bus, 0);118 nvkm_i2c_delay(bus, T_HOLD);119 return 0;120}121 122static int123i2c_bitr(struct nvkm_i2c_bus *bus)124{125 int sda;126 127 nvkm_i2c_drive_sda(bus, 1);128 nvkm_i2c_delay(bus, T_RISEFALL);129 130 if (!nvkm_i2c_raise_scl(bus))131 return -ETIMEDOUT;132 nvkm_i2c_delay(bus, T_HOLD);133 134 sda = nvkm_i2c_sense_sda(bus);135 136 nvkm_i2c_drive_scl(bus, 0);137 nvkm_i2c_delay(bus, T_HOLD);138 return sda;139}140 141static int142nvkm_i2c_get_byte(struct nvkm_i2c_bus *bus, u8 *byte, bool last)143{144 int i, bit;145 146 *byte = 0;147 for (i = 7; i >= 0; i--) {148 bit = i2c_bitr(bus);149 if (bit < 0)150 return bit;151 *byte |= bit << i;152 }153 154 return i2c_bitw(bus, last ? 1 : 0);155}156 157static int158nvkm_i2c_put_byte(struct nvkm_i2c_bus *bus, u8 byte)159{160 int i, ret;161 for (i = 7; i >= 0; i--) {162 ret = i2c_bitw(bus, !!(byte & (1 << i)));163 if (ret < 0)164 return ret;165 }166 167 ret = i2c_bitr(bus);168 if (ret == 1) /* nack */169 ret = -EIO;170 return ret;171}172 173static int174i2c_addr(struct nvkm_i2c_bus *bus, struct i2c_msg *msg)175{176 u32 addr = msg->addr << 1;177 if (msg->flags & I2C_M_RD)178 addr |= 1;179 return nvkm_i2c_put_byte(bus, addr);180}181 182int183nvkm_i2c_bit_xfer(struct nvkm_i2c_bus *bus, struct i2c_msg *msgs, int num)184{185 struct i2c_msg *msg = msgs;186 int ret = 0, mcnt = num;187 188 while (!ret && mcnt--) {189 u8 remaining = msg->len;190 u8 *ptr = msg->buf;191 192 ret = i2c_start(bus);193 if (ret == 0)194 ret = i2c_addr(bus, msg);195 196 if (msg->flags & I2C_M_RD) {197 while (!ret && remaining--)198 ret = nvkm_i2c_get_byte(bus, ptr++, !remaining);199 } else {200 while (!ret && remaining--)201 ret = nvkm_i2c_put_byte(bus, *ptr++);202 }203 204 msg++;205 }206 207 i2c_stop(bus);208 return (ret < 0) ? ret : num;209}210#else211int212nvkm_i2c_bit_xfer(struct nvkm_i2c_bus *bus, struct i2c_msg *msgs, int num)213{214 return -ENODEV;215}216#endif217