7f4f1096d5
After the result of the previous conversion is read the chip
automatically starts a new conversion and doesn't accept new i2c
transfers until this conversion is completed which makes the function
return failure.
So add an early return iff the programming of the new address isn't
needed. Note this will not fix the problem in general, but all cases
that are currently used. Once this changes we get the failure back, but
this can be addressed when the need arises.
Fixes: 69548b7c2c ("iio: adc: ltc2497: split protocol independent part in a separate module ")
Reported-by: Meng Li <Meng.Li@windriver.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Tested-by: Denys Zagorui <dzagorui@cisco.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220815091647.1523532-1-dzagorui@cisco.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
125 lines
3.2 KiB
C
125 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
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*
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* Copyright (C) 2017 Analog Devices Inc.
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*
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* Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
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*/
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#include <linux/i2c.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/driver.h>
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include "ltc2497.h"
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struct ltc2497_driverdata {
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/* this must be the first member */
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struct ltc2497core_driverdata common_ddata;
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struct i2c_client *client;
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/*
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* DMA (thus cache coherency maintenance) may require the
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* transfer buffers to live in their own cache lines.
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*/
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__be32 buf __aligned(IIO_DMA_MINALIGN);
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};
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static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
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u8 address, int *val)
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{
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struct ltc2497_driverdata *st =
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container_of(ddata, struct ltc2497_driverdata, common_ddata);
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int ret;
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if (val) {
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ret = i2c_master_recv(st->client, (char *)&st->buf, 3);
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if (ret < 0) {
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dev_err(&st->client->dev, "i2c_master_recv failed\n");
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return ret;
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}
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*val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
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/*
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* The part started a new conversion at the end of the above i2c
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* transfer, so if the address didn't change since the last call
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* everything is fine and we can return early.
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* If not (which should only happen when some sort of bulk
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* conversion is implemented) we have to program the new
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* address. Note that this probably fails as the conversion that
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* was triggered above is like not complete yet and the two
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* operations have to be done in a single transfer.
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*/
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if (ddata->addr_prev == address)
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return 0;
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}
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ret = i2c_smbus_write_byte(st->client,
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LTC2497_ENABLE | address);
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if (ret)
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dev_err(&st->client->dev, "i2c transfer failed: %pe\n",
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ERR_PTR(ret));
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return ret;
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}
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static int ltc2497_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct iio_dev *indio_dev;
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struct ltc2497_driverdata *st;
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struct device *dev = &client->dev;
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
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I2C_FUNC_SMBUS_WRITE_BYTE))
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return -EOPNOTSUPP;
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indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
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if (!indio_dev)
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return -ENOMEM;
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st = iio_priv(indio_dev);
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i2c_set_clientdata(client, indio_dev);
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st->client = client;
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st->common_ddata.result_and_measure = ltc2497_result_and_measure;
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return ltc2497core_probe(dev, indio_dev);
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}
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static int ltc2497_remove(struct i2c_client *client)
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{
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struct iio_dev *indio_dev = i2c_get_clientdata(client);
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ltc2497core_remove(indio_dev);
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return 0;
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}
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static const struct i2c_device_id ltc2497_id[] = {
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{ "ltc2497", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, ltc2497_id);
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static const struct of_device_id ltc2497_of_match[] = {
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{ .compatible = "lltc,ltc2497", },
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{},
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};
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MODULE_DEVICE_TABLE(of, ltc2497_of_match);
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static struct i2c_driver ltc2497_driver = {
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.driver = {
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.name = "ltc2497",
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.of_match_table = ltc2497_of_match,
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},
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.probe = ltc2497_probe,
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.remove = ltc2497_remove,
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.id_table = ltc2497_id,
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};
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module_i2c_driver(ltc2497_driver);
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MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
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MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
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MODULE_LICENSE("GPL v2");
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