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/*
* Copyright 2012 Red Hat Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial busions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Authors: Ben Skeggs
*/
#include "bus.h"
#ifdef CONFIG_NOUVEAU_I2C_INTERNAL
#define T_TIMEOUT 2200000
#define T_RISEFALL 1000
#define T_HOLD 5000
static inline void
nvkm_i2c_drive_scl(struct nvkm_i2c_bus *bus, int state)
{
bus->func->drive_scl(bus, state);
}
static inline void
nvkm_i2c_drive_sda(struct nvkm_i2c_bus *bus, int state)
{
bus->func->drive_sda(bus, state);
}
static inline int
nvkm_i2c_sense_scl(struct nvkm_i2c_bus *bus)
{
return bus->func->sense_scl(bus);
}
static inline int
nvkm_i2c_sense_sda(struct nvkm_i2c_bus *bus)
{
return bus->func->sense_sda(bus);
}
static void
nvkm_i2c_delay(struct nvkm_i2c_bus *bus, u32 nsec)
{
udelay((nsec + 500) / 1000);
}
static bool
nvkm_i2c_raise_scl(struct nvkm_i2c_bus *bus)
{
u32 timeout = T_TIMEOUT / T_RISEFALL;
nvkm_i2c_drive_scl(bus, 1);
do {
nvkm_i2c_delay(bus, T_RISEFALL);
} while (!nvkm_i2c_sense_scl(bus) && --timeout);
return timeout != 0;
}
static int
i2c_start(struct nvkm_i2c_bus *bus)
{
int ret = 0;
if (!nvkm_i2c_sense_scl(bus) ||
!nvkm_i2c_sense_sda(bus)) {
nvkm_i2c_drive_scl(bus, 0);
nvkm_i2c_drive_sda(bus, 1);
if (!nvkm_i2c_raise_scl(bus))
ret = -EBUSY;
}
nvkm_i2c_drive_sda(bus, 0);
nvkm_i2c_delay(bus, T_HOLD);
nvkm_i2c_drive_scl(bus, 0);
nvkm_i2c_delay(bus, T_HOLD);
return ret;
}
static void
i2c_stop(struct nvkm_i2c_bus *bus)
{
nvkm_i2c_drive_scl(bus, 0);
nvkm_i2c_drive_sda(bus, 0);
nvkm_i2c_delay(bus, T_RISEFALL);
nvkm_i2c_drive_scl(bus, 1);
nvkm_i2c_delay(bus, T_HOLD);
nvkm_i2c_drive_sda(bus, 1);
nvkm_i2c_delay(bus, T_HOLD);
}
static int
i2c_bitw(struct nvkm_i2c_bus *bus, int sda)
{
nvkm_i2c_drive_sda(bus, sda);
nvkm_i2c_delay(bus, T_RISEFALL);
if (!nvkm_i2c_raise_scl(bus))
return -ETIMEDOUT;
nvkm_i2c_delay(bus, T_HOLD);
nvkm_i2c_drive_scl(bus, 0);
nvkm_i2c_delay(bus, T_HOLD);
return 0;
}
static int
i2c_bitr(struct nvkm_i2c_bus *bus)
{
int sda;
nvkm_i2c_drive_sda(bus, 1);
nvkm_i2c_delay(bus, T_RISEFALL);
if (!nvkm_i2c_raise_scl(bus))
return -ETIMEDOUT;
nvkm_i2c_delay(bus, T_HOLD);
sda = nvkm_i2c_sense_sda(bus);
nvkm_i2c_drive_scl(bus, 0);
nvkm_i2c_delay(bus, T_HOLD);
return sda;
}
static int
nvkm_i2c_get_byte(struct nvkm_i2c_bus *bus, u8 *byte, bool last)
{
int i, bit;
*byte = 0;
for (i = 7; i >= 0; i--) {
bit = i2c_bitr(bus);
if (bit < 0)
return bit;
*byte |= bit << i;
}
return i2c_bitw(bus, last ? 1 : 0);
}
static int
nvkm_i2c_put_byte(struct nvkm_i2c_bus *bus, u8 byte)
{
int i, ret;
for (i = 7; i >= 0; i--) {
ret = i2c_bitw(bus, !!(byte & (1 << i)));
if (ret < 0)
return ret;
}
ret = i2c_bitr(bus);
if (ret == 1) /* nack */
ret = -EIO;
return ret;
}
static int
i2c_addr(struct nvkm_i2c_bus *bus, struct i2c_msg *msg)
{
u32 addr = msg->addr << 1;
if (msg->flags & I2C_M_RD)
addr |= 1;
return nvkm_i2c_put_byte(bus, addr);
}
int
nvkm_i2c_bit_xfer(struct nvkm_i2c_bus *bus, struct i2c_msg *msgs, int num)
{
struct i2c_msg *msg = msgs;
int ret = 0, mcnt = num;
while (!ret && mcnt--) {
u8 remaining = msg->len;
u8 *ptr = msg->buf;
ret = i2c_start(bus);
if (ret == 0)
ret = i2c_addr(bus, msg);
if (msg->flags & I2C_M_RD) {
while (!ret && remaining--)
ret = nvkm_i2c_get_byte(bus, ptr++, !remaining);
} else {
while (!ret && remaining--)
ret = nvkm_i2c_put_byte(bus, *ptr++);
}
msg++;
}
i2c_stop(bus);
return (ret < 0) ? ret : num;
}
#else
int
nvkm_i2c_bit_xfer(struct nvkm_i2c_bus *bus, struct i2c_msg *msgs, int num)
{
return -ENODEV;
}
#endif
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