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@@ -37,6 +37,201 @@
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#include "gma_display.h"
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#include <drm/drm_dp_helper.h>
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+/**
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+ * struct i2c_algo_dp_aux_data - driver interface structure for i2c over dp
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+ * aux algorithm
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+ * @running: set by the algo indicating whether an i2c is ongoing or whether
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+ * the i2c bus is quiescent
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+ * @address: i2c target address for the currently ongoing transfer
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+ * @aux_ch: driver callback to transfer a single byte of the i2c payload
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+ */
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+struct i2c_algo_dp_aux_data {
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+ bool running;
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+ u16 address;
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+ int (*aux_ch) (struct i2c_adapter *adapter,
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+ int mode, uint8_t write_byte,
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+ uint8_t *read_byte);
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+};
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+
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+/* Run a single AUX_CH I2C transaction, writing/reading data as necessary */
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+static int
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+i2c_algo_dp_aux_transaction(struct i2c_adapter *adapter, int mode,
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+ uint8_t write_byte, uint8_t *read_byte)
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+{
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+ struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
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+ int ret;
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+
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+ ret = (*algo_data->aux_ch)(adapter, mode,
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+ write_byte, read_byte);
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+ return ret;
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+}
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+
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+/*
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+ * I2C over AUX CH
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+ */
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+
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+/*
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+ * Send the address. If the I2C link is running, this 'restarts'
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+ * the connection with the new address, this is used for doing
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+ * a write followed by a read (as needed for DDC)
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+ */
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+static int
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+i2c_algo_dp_aux_address(struct i2c_adapter *adapter, u16 address, bool reading)
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+{
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+ struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
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+ int mode = MODE_I2C_START;
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+ int ret;
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+
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+ if (reading)
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+ mode |= MODE_I2C_READ;
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+ else
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+ mode |= MODE_I2C_WRITE;
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+ algo_data->address = address;
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+ algo_data->running = true;
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+ ret = i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
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+ return ret;
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+}
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+
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+/*
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+ * Stop the I2C transaction. This closes out the link, sending
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+ * a bare address packet with the MOT bit turned off
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+ */
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+static void
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+i2c_algo_dp_aux_stop(struct i2c_adapter *adapter, bool reading)
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+{
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+ struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
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+ int mode = MODE_I2C_STOP;
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+
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+ if (reading)
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+ mode |= MODE_I2C_READ;
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+ else
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+ mode |= MODE_I2C_WRITE;
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+ if (algo_data->running) {
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+ (void) i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
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+ algo_data->running = false;
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+ }
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+}
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+
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+/*
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+ * Write a single byte to the current I2C address, the
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+ * the I2C link must be running or this returns -EIO
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+ */
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+static int
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+i2c_algo_dp_aux_put_byte(struct i2c_adapter *adapter, u8 byte)
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+{
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+ struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
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+ int ret;
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+
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+ if (!algo_data->running)
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+ return -EIO;
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+
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+ ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_WRITE, byte, NULL);
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+ return ret;
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+}
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+
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+/*
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+ * Read a single byte from the current I2C address, the
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+ * I2C link must be running or this returns -EIO
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+ */
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+static int
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+i2c_algo_dp_aux_get_byte(struct i2c_adapter *adapter, u8 *byte_ret)
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+{
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+ struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
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+ int ret;
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+
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+ if (!algo_data->running)
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+ return -EIO;
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+
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+ ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_READ, 0, byte_ret);
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+ return ret;
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+}
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+
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+static int
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+i2c_algo_dp_aux_xfer(struct i2c_adapter *adapter,
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+ struct i2c_msg *msgs,
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+ int num)
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+{
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+ int ret = 0;
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+ bool reading = false;
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+ int m;
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+ int b;
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+
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+ for (m = 0; m < num; m++) {
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+ u16 len = msgs[m].len;
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+ u8 *buf = msgs[m].buf;
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+ reading = (msgs[m].flags & I2C_M_RD) != 0;
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+ ret = i2c_algo_dp_aux_address(adapter, msgs[m].addr, reading);
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+ if (ret < 0)
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+ break;
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+ if (reading) {
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+ for (b = 0; b < len; b++) {
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+ ret = i2c_algo_dp_aux_get_byte(adapter, &buf[b]);
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+ if (ret < 0)
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+ break;
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+ }
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+ } else {
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+ for (b = 0; b < len; b++) {
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+ ret = i2c_algo_dp_aux_put_byte(adapter, buf[b]);
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+ if (ret < 0)
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+ break;
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+ }
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+ }
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+ if (ret < 0)
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+ break;
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+ }
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+ if (ret >= 0)
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+ ret = num;
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+ i2c_algo_dp_aux_stop(adapter, reading);
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+ DRM_DEBUG_KMS("dp_aux_xfer return %d\n", ret);
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+ return ret;
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+}
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+
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+static u32
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+i2c_algo_dp_aux_functionality(struct i2c_adapter *adapter)
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+{
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+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
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+ I2C_FUNC_SMBUS_READ_BLOCK_DATA |
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+ I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
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+ I2C_FUNC_10BIT_ADDR;
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+}
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+
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+static const struct i2c_algorithm i2c_dp_aux_algo = {
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+ .master_xfer = i2c_algo_dp_aux_xfer,
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+ .functionality = i2c_algo_dp_aux_functionality,
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+};
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+
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+static void
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+i2c_dp_aux_reset_bus(struct i2c_adapter *adapter)
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+{
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+ (void) i2c_algo_dp_aux_address(adapter, 0, false);
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+ (void) i2c_algo_dp_aux_stop(adapter, false);
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+}
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+
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+static int
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+i2c_dp_aux_prepare_bus(struct i2c_adapter *adapter)
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+{
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+ adapter->algo = &i2c_dp_aux_algo;
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+ adapter->retries = 3;
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+ i2c_dp_aux_reset_bus(adapter);
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+ return 0;
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+}
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+
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+/*
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+ * FIXME: This is the old dp aux helper, gma500 is the last driver that needs to
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+ * be ported over to the new helper code in drm_dp_helper.c like i915 or radeon.
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+ */
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+static int __deprecated
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+i2c_dp_aux_add_bus(struct i2c_adapter *adapter)
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+{
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+ int error;
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+
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+ error = i2c_dp_aux_prepare_bus(adapter);
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+ if (error)
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+ return error;
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+ error = i2c_add_adapter(adapter);
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+ return error;
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+}
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+
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#define _wait_for(COND, MS, W) ({ \
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unsigned long timeout__ = jiffies + msecs_to_jiffies(MS); \
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int ret__ = 0; \
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