diff options
Diffstat (limited to 'drivers/gpu/drm/drm_dp_helper.c')
| -rw-r--r-- | drivers/gpu/drm/drm_dp_helper.c | 348 |
1 files changed, 348 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c new file mode 100644 index 0000000..89e1966 --- /dev/null +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -0,0 +1,348 @@ +/* + * 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/drm_dp_helper.h> +#include <drm/drmP.h> + +/** + * DOC: dp helpers + * + * These functions contain some common logic and helpers at various abstraction + * levels to deal with Display Port sink devices and related things like DP aux + * channel transfers, EDID reading over DP aux channels, decoding certain DPCD + * blocks, ... + */ + +/* 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; +} + +/** + * i2c_dp_aux_add_bus() - register an i2c adapter using the aux ch helper + * @adapter: i2c adapter to register + * + * This registers an i2c adapater that uses dp aux channel as it's underlaying + * transport. The driver needs to fill out the &i2c_algo_dp_aux_data structure + * and store it in the algo_data member of the @adapter argument. This will be + * used by the i2c over dp aux algorithm to drive the hardware. + * + * RETURNS: + * 0 on success, -ERRNO on failure. + */ +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); + +/* Helpers for DP link training */ +static u8 dp_link_status(u8 link_status[DP_LINK_STATUS_SIZE], int r) +{ + return link_status[r - DP_LANE0_1_STATUS]; +} + +static u8 dp_get_lane_status(u8 link_status[DP_LINK_STATUS_SIZE], + int lane) +{ + int i = DP_LANE0_1_STATUS + (lane >> 1); + int s = (lane & 1) * 4; + u8 l = dp_link_status(link_status, i); + return (l >> s) & 0xf; +} + +bool drm_dp_channel_eq_ok(u8 link_status[DP_LINK_STATUS_SIZE], + int lane_count) +{ + u8 lane_align; + u8 lane_status; + int lane; + + lane_align = dp_link_status(link_status, + DP_LANE_ALIGN_STATUS_UPDATED); + if ((lane_align & DP_INTERLANE_ALIGN_DONE) == 0) + return false; + for (lane = 0; lane < lane_count; lane++) { + lane_status = dp_get_lane_status(link_status, lane); + if ((lane_status & DP_CHANNEL_EQ_BITS) != DP_CHANNEL_EQ_BITS) + return false; + } + return true; +} +EXPORT_SYMBOL(drm_dp_channel_eq_ok); + +bool drm_dp_clock_recovery_ok(u8 link_status[DP_LINK_STATUS_SIZE], + int lane_count) +{ + int lane; + u8 lane_status; + + for (lane = 0; lane < lane_count; lane++) { + lane_status = dp_get_lane_status(link_status, lane); + if ((lane_status & DP_LANE_CR_DONE) == 0) + return false; + } + return true; +} +EXPORT_SYMBOL(drm_dp_clock_recovery_ok); + +u8 drm_dp_get_adjust_request_voltage(u8 link_status[DP_LINK_STATUS_SIZE], + int lane) +{ + int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1); + int s = ((lane & 1) ? + DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT : + DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT); + u8 l = dp_link_status(link_status, i); + + return ((l >> s) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT; +} +EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage); + +u8 drm_dp_get_adjust_request_pre_emphasis(u8 link_status[DP_LINK_STATUS_SIZE], + int lane) +{ + int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1); + int s = ((lane & 1) ? + DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT : + DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT); + u8 l = dp_link_status(link_status, i); + + return ((l >> s) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT; +} +EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis); + +void drm_dp_link_train_clock_recovery_delay(u8 dpcd[DP_RECEIVER_CAP_SIZE]) { + if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0) + udelay(100); + else + mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4); +} +EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay); + +void drm_dp_link_train_channel_eq_delay(u8 dpcd[DP_RECEIVER_CAP_SIZE]) { + if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0) + udelay(400); + else + mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4); +} +EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay); + +u8 drm_dp_link_rate_to_bw_code(int link_rate) +{ + switch (link_rate) { + case 162000: + default: + return DP_LINK_BW_1_62; + case 270000: + return DP_LINK_BW_2_7; + case 540000: + return DP_LINK_BW_5_4; + } +} +EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code); + +int drm_dp_bw_code_to_link_rate(u8 link_bw) +{ + switch (link_bw) { + case DP_LINK_BW_1_62: + default: + return 162000; + case DP_LINK_BW_2_7: + return 270000; + case DP_LINK_BW_5_4: + return 540000; + } +} +EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate); |