diff options
Diffstat (limited to 'drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c')
| -rw-r--r-- | drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c b/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c new file mode 100644 index 000000000000..861a453d2a67 --- /dev/null +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/bit.c @@ -0,0 +1,233 @@ +/* + * 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 portions 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 "priv.h" + +#ifdef CONFIG_NOUVEAU_I2C_INTERNAL +#define T_TIMEOUT 2200000 +#define T_RISEFALL 1000 +#define T_HOLD 5000 + +static inline void +i2c_drive_scl(struct nvkm_i2c_port *port, int state) +{ + port->func->drive_scl(port, state); +} + +static inline void +i2c_drive_sda(struct nvkm_i2c_port *port, int state) +{ + port->func->drive_sda(port, state); +} + +static inline int +i2c_sense_scl(struct nvkm_i2c_port *port) +{ + return port->func->sense_scl(port); +} + +static inline int +i2c_sense_sda(struct nvkm_i2c_port *port) +{ + return port->func->sense_sda(port); +} + +static void +i2c_delay(struct nvkm_i2c_port *port, u32 nsec) +{ + udelay((nsec + 500) / 1000); +} + +static bool +i2c_raise_scl(struct nvkm_i2c_port *port) +{ + u32 timeout = T_TIMEOUT / T_RISEFALL; + + i2c_drive_scl(port, 1); + do { + i2c_delay(port, T_RISEFALL); + } while (!i2c_sense_scl(port) && --timeout); + + return timeout != 0; +} + +static int +i2c_start(struct nvkm_i2c_port *port) +{ + int ret = 0; + + if (!i2c_sense_scl(port) || + !i2c_sense_sda(port)) { + i2c_drive_scl(port, 0); + i2c_drive_sda(port, 1); + if (!i2c_raise_scl(port)) + ret = -EBUSY; + } + + i2c_drive_sda(port, 0); + i2c_delay(port, T_HOLD); + i2c_drive_scl(port, 0); + i2c_delay(port, T_HOLD); + return ret; +} + +static void +i2c_stop(struct nvkm_i2c_port *port) +{ + i2c_drive_scl(port, 0); + i2c_drive_sda(port, 0); + i2c_delay(port, T_RISEFALL); + + i2c_drive_scl(port, 1); + i2c_delay(port, T_HOLD); + i2c_drive_sda(port, 1); + i2c_delay(port, T_HOLD); +} + +static int +i2c_bitw(struct nvkm_i2c_port *port, int sda) +{ + i2c_drive_sda(port, sda); + i2c_delay(port, T_RISEFALL); + + if (!i2c_raise_scl(port)) + return -ETIMEDOUT; + i2c_delay(port, T_HOLD); + + i2c_drive_scl(port, 0); + i2c_delay(port, T_HOLD); + return 0; +} + +static int +i2c_bitr(struct nvkm_i2c_port *port) +{ + int sda; + + i2c_drive_sda(port, 1); + i2c_delay(port, T_RISEFALL); + + if (!i2c_raise_scl(port)) + return -ETIMEDOUT; + i2c_delay(port, T_HOLD); + + sda = i2c_sense_sda(port); + + i2c_drive_scl(port, 0); + i2c_delay(port, T_HOLD); + return sda; +} + +static int +i2c_get_byte(struct nvkm_i2c_port *port, u8 *byte, bool last) +{ + int i, bit; + + *byte = 0; + for (i = 7; i >= 0; i--) { + bit = i2c_bitr(port); + if (bit < 0) + return bit; + *byte |= bit << i; + } + + return i2c_bitw(port, last ? 1 : 0); +} + +static int +i2c_put_byte(struct nvkm_i2c_port *port, u8 byte) +{ + int i, ret; + for (i = 7; i >= 0; i--) { + ret = i2c_bitw(port, !!(byte & (1 << i))); + if (ret < 0) + return ret; + } + + ret = i2c_bitr(port); + if (ret == 1) /* nack */ + ret = -EIO; + return ret; +} + +static int +i2c_addr(struct nvkm_i2c_port *port, struct i2c_msg *msg) +{ + u32 addr = msg->addr << 1; + if (msg->flags & I2C_M_RD) + addr |= 1; + return i2c_put_byte(port, addr); +} + +static int +i2c_bit_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) +{ + struct nvkm_i2c_port *port = adap->algo_data; + struct i2c_msg *msg = msgs; + int ret = 0, mcnt = num; + + ret = nvkm_i2c(port)->acquire(port, nsecs_to_jiffies(T_TIMEOUT)); + if (ret) + return ret; + + while (!ret && mcnt--) { + u8 remaining = msg->len; + u8 *ptr = msg->buf; + + ret = i2c_start(port); + if (ret == 0) + ret = i2c_addr(port, msg); + + if (msg->flags & I2C_M_RD) { + while (!ret && remaining--) + ret = i2c_get_byte(port, ptr++, !remaining); + } else { + while (!ret && remaining--) + ret = i2c_put_byte(port, *ptr++); + } + + msg++; + } + + i2c_stop(port); + nvkm_i2c(port)->release(port); + return (ret < 0) ? ret : num; +} +#else +static int +i2c_bit_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) +{ + return -ENODEV; +} +#endif + +static u32 +i2c_bit_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +const struct i2c_algorithm nvkm_i2c_bit_algo = { + .master_xfer = i2c_bit_xfer, + .functionality = i2c_bit_func +}; |