/* * Copyright © 2009 Keith Packard * * Permission to use, copy, modify, distribute, and sell this software and its * documentation for any purpose is hereby granted without fee, provided that * the above copyright notice appear in all copies and that both that copyright * notice and this permission notice appear in supporting documentation, and * that the name of the copyright holders not be used in advertising or * publicity pertaining to distribution of the software without specific, * written prior permission. The copyright holders make no representations * about the suitability of this software for any purpose. It is provided "as * is" without express or implied warranty. * * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE * OF THIS SOFTWARE. */ #include <linux/kernel.h> #include <linux/module.h> //#include <linux/delay.h> //#include <linux/init.h> #include <linux/errno.h> #include <linux/sched.h> #include <linux/i2c.h> #include "drm_dp_helper.h" #include "drmP.h" /* Run a single AUX_CH I2C transaction, writing/reading data as necessary */ static int i2c_algo_dp_aux_transaction(struct i2c_adapter *adapter, int mode, uint8_t write_byte, uint8_t *read_byte) { struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data; int ret; ret = (*algo_data->aux_ch)(adapter, mode, write_byte, read_byte); return ret; } /* * I2C over AUX CH */ /* * Send the address. If the I2C link is running, this 'restarts' * the connection with the new address, this is used for doing * a write followed by a read (as needed for DDC) */ static int i2c_algo_dp_aux_address(struct i2c_adapter *adapter, u16 address, bool reading) { struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data; int mode = MODE_I2C_START; int ret; if (reading) mode |= MODE_I2C_READ; else mode |= MODE_I2C_WRITE; algo_data->address = address; algo_data->running = true; ret = i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL); return ret; } /* * Stop the I2C transaction. This closes out the link, sending * a bare address packet with the MOT bit turned off */ static void i2c_algo_dp_aux_stop(struct i2c_adapter *adapter, bool reading) { struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data; int mode = MODE_I2C_STOP; if (reading) mode |= MODE_I2C_READ; else mode |= MODE_I2C_WRITE; if (algo_data->running) { (void) i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL); algo_data->running = false; } } /* * Write a single byte to the current I2C address, the * the I2C link must be running or this returns -EIO */ static int i2c_algo_dp_aux_put_byte(struct i2c_adapter *adapter, u8 byte) { struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data; int ret; if (!algo_data->running) return -EIO; ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_WRITE, byte, NULL); return ret; } /* * Read a single byte from the current I2C address, the * I2C link must be running or this returns -EIO */ static int i2c_algo_dp_aux_get_byte(struct i2c_adapter *adapter, u8 *byte_ret) { struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data; int ret; if (!algo_data->running) return -EIO; ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_READ, 0, byte_ret); return ret; } static int i2c_algo_dp_aux_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num) { int ret = 0; bool reading = false; int m; int b; for (m = 0; m < num; m++) { u16 len = msgs[m].len; u8 *buf = msgs[m].buf; reading = (msgs[m].flags & I2C_M_RD) != 0; ret = i2c_algo_dp_aux_address(adapter, msgs[m].addr, reading); if (ret < 0) break; if (reading) { for (b = 0; b < len; b++) { ret = i2c_algo_dp_aux_get_byte(adapter, &buf[b]); if (ret < 0) break; } } else { for (b = 0; b < len; b++) { ret = i2c_algo_dp_aux_put_byte(adapter, buf[b]); if (ret < 0) break; } } if (ret < 0) break; } if (ret >= 0) ret = num; i2c_algo_dp_aux_stop(adapter, reading); DRM_DEBUG_KMS("dp_aux_xfer return %d\n", ret); return ret; } static u32 i2c_algo_dp_aux_functionality(struct i2c_adapter *adapter) { return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL | I2C_FUNC_10BIT_ADDR; } static const struct i2c_algorithm i2c_dp_aux_algo = { .master_xfer = i2c_algo_dp_aux_xfer, .functionality = i2c_algo_dp_aux_functionality, }; static void i2c_dp_aux_reset_bus(struct i2c_adapter *adapter) { (void) i2c_algo_dp_aux_address(adapter, 0, false); (void) i2c_algo_dp_aux_stop(adapter, false); } static int i2c_dp_aux_prepare_bus(struct i2c_adapter *adapter) { adapter->algo = &i2c_dp_aux_algo; adapter->retries = 3; i2c_dp_aux_reset_bus(adapter); return 0; } int i2c_dp_aux_add_bus(struct i2c_adapter *adapter) { int error; error = i2c_dp_aux_prepare_bus(adapter); if (error) return error; // error = i2c_add_adapter(adapter); return error; } EXPORT_SYMBOL(i2c_dp_aux_add_bus);