Hi Adriana,
Chip only gets confused when a SPI signal could simulate a I2C address. Setting the bit tells chip to completely forget about I2C at all. Without setting the bit, it still works. But it might risk of triggering I2C if the SPI signal accidentally simulates an I2C address that matches the chip address and triggers a subsequent action.
Thanks.
Best Regards,
Ge Gao
________________________________________
From: Adriana Reus <adriana.reus@xxxxxxxxx>
Sent: Wednesday, February 3, 2016 1:17 AM
To: Ge Gao; Lucas De Marchi
Cc: jic23@xxxxxxxxxx; linux-iio@xxxxxxxxxxxxxxx; srinivas.pandruvada@xxxxxxxxxxxxxxx
Subject: Re: [PATCH v1 4/4] iio: imu: inv_mpu6050: Add SPI support for MPU6000
Hi Lucas, Ge,
Thanks for pointing that out Lucas, I'm looking into it.
Ge, would it suffice to set the I2C_IF_DIS via an SPI transaction
(spi_write or regmap_write)?
Couldn't the chip get confused during that transaction also?
On 03.02.2016 08:42, Ge Gao wrote:
> That is a good point. That register should be set in case chip get confused if the spi signal mimic a I2C signal
>
> Ge
>
>> On Feb 2, 2016, at 10:31 PM, Lucas De Marchi <lucas.de.marchi@xxxxxxxxx> wrote:
>>
>> Hi Adriana,
>>
>>> On Tue, Feb 2, 2016 at 1:02 PM, Adriana Reus <adriana.reus@xxxxxxxxx> wrote:
>>> The only difference between the MPU6000 and the
>>> MPU6050 is that the first also supports SPI.
>>> Add SPI driver for this chip.
>>>
>>> Signed-off-by: Adriana Reus <adriana.reus@xxxxxxxxx>
>>> ---
>>> Changes since initial version:
>>> * Modified Kconfig so that the SPI component selects the core component
>>> instead of the other way around.
>>>
>>> drivers/iio/imu/inv_mpu6050/Kconfig | 7 +++
>>> drivers/iio/imu/inv_mpu6050/Makefile | 3 ++
>>> drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h | 1 +
>>> drivers/iio/imu/inv_mpu6050/inv_mpu_spi.c | 80 +++++++++++++++++++++++++++++++
>>> 4 files changed, 91 insertions(+)
>>> create mode 100644 drivers/iio/imu/inv_mpu6050/inv_mpu_spi.c
>>>
>>> diff --git a/drivers/iio/imu/inv_mpu6050/Kconfig b/drivers/iio/imu/inv_mpu6050/Kconfig
>>> index 483f52d..6f6a419 100644
>>> --- a/drivers/iio/imu/inv_mpu6050/Kconfig
>>> +++ b/drivers/iio/imu/inv_mpu6050/Kconfig
>>> @@ -25,3 +25,10 @@ config INV_MPU6050_I2C
>>> This driver can be built as a module. The module will be called
>>> inv-mpu6050-i2c.
>>>
>>> +config INV_MPU6050_SPI
>>> + tristate "Invensense MPU6050 devices"
>>> + select INV_MPU6050_IIO
>>> + select REGMAP_SPI
>>> + help
>>> + This driver can be built as a module. The module will be called
>>> + inv-mpu6050-spi.
>>> diff --git a/drivers/iio/imu/inv_mpu6050/Makefile b/drivers/iio/imu/inv_mpu6050/Makefile
>>> index ca4941d..734af5e 100644
>>> --- a/drivers/iio/imu/inv_mpu6050/Makefile
>>> +++ b/drivers/iio/imu/inv_mpu6050/Makefile
>>> @@ -7,3 +7,6 @@ inv-mpu6050-objs := inv_mpu_core.o inv_mpu_ring.o inv_mpu_trigger.o
>>>
>>> obj-$(CONFIG_INV_MPU6050_I2C) += inv-mpu6050-i2c.o
>>> inv-mpu6050-i2c-objs := inv_mpu_i2c.o inv_mpu_acpi.o
>>> +
>>> +obj-$(CONFIG_INV_MPU6050_SPI) += inv-mpu6050-spi.o
>>> +inv-mpu6050-spi-objs := inv_mpu_spi.o
>>> diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
>>> index af406a3..758fe2b 100644
>>> --- a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
>>> +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
>>> @@ -62,6 +62,7 @@ struct inv_mpu6050_reg_map {
>>> enum inv_devices {
>>> INV_MPU6050,
>>> INV_MPU6500,
>>> + INV_MPU6000,
>>> INV_NUM_PARTS
>>> };
>>>
>>> diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_spi.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_spi.c
>>> new file mode 100644
>>> index 0000000..484171e
>>> --- /dev/null
>>> +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_spi.c
>>> @@ -0,0 +1,80 @@
>>> +/*
>>> +* Copyright (C) 2015 Intel Corporation Inc.
>>> +*
>>> +* This software is licensed under the terms of the GNU General Public
>>> +* License version 2, as published by the Free Software Foundation, and
>>> +* may be copied, distributed, and modified under those terms.
>>> +*
>>> +* This program is distributed in the hope that it will be useful,
>>> +* but WITHOUT ANY WARRANTY; without even the implied warranty of
>>> +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>>> +* GNU General Public License for more details.
>>> +*/
>>> +#include <linux/module.h>
>>> +#include <linux/acpi.h>
>>> +#include <linux/spi/spi.h>
>>> +#include <linux/regmap.h>
>>> +#include <linux/iio/iio.h>
>>> +#include "inv_mpu_iio.h"
>>> +
>>> +static const struct regmap_config inv_mpu_regmap_config = {
>>> + .reg_bits = 8,
>>> + .val_bits = 8,
>>> +};
>>> +
>>> +static int inv_mpu_probe(struct spi_device *spi)
>>> +{
>>> + struct regmap *regmap;
>>> + const struct spi_device_id *id = spi_get_device_id(spi);
>>> + const char *name = id ? id->name : NULL;
>>> +
>>> + regmap = devm_regmap_init_spi(spi, &inv_mpu_regmap_config);
>>> + if (IS_ERR(regmap)) {
>>> + dev_err(&spi->dev, "Failed to register spi regmap %d\n",
>>> + (int)PTR_ERR(regmap));
>>> + return PTR_ERR(regmap);
>>> + }
>>> +
>>> + return inv_mpu_core_probe(regmap, spi->irq, name);
>>
>> I think there's still some spi-only initialization missing. As per
>> datasheet we should disable the I2C interface when using the SPI
>> interface.
>>
>> Lucas De Marchi
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