Due to the electrical design of the A/DC circuits on LEGO MINDSTORMS EV3,
if we are reading analog values as fast as possible (i.e. using DMA to
service the SPI) the A/DC chip will read incorrect values - as much as
0.1V off when the SPI is running at 10MHz. (This has to do with the
capacitor charge time when channels are muxed in the A/DC.)
This patch slows down the SPI as much as possible (if CPU is at 456MHz,
SPI runs at 1/2 of that, so 228MHz and has a max prescalar of 256, so
we could get ~891kHz, but we're just rounding it to 1MHz). We also use
the max allowable value for WDELAY to slow things down even more.
These changes reduce the error of the analog values to about 5mV, which
is tolerable.
Commits a3762b13a5 ("spi: spi-davinci: Add support for SPI_CS_WORD")
and e2540da86e ("iio: adc: ti-ads7950: use SPI_CS_WORD to reduce
CPU usage") introduce changes that allow DMA transfers to be used, so
this slow down is needed now.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This adds nodes for describing the Bluetooth chip and connections on
LEGO MINDSTORMS EV3 to da850-lego-ev3.dts.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This adds clock provider nodes for da850 and wires them up to all of the
devices.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This removes the #address-cells and #size-cells properties from the
gpio-keys node in the da850-lego-ev3 device tree. These properties are
not needed since the child nodes don't have a reg property.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This makes use of the gpio-ranges feature that connects GPIO
controllers and PINMUX controllers.
In da850.dtsi, pinctrl-single,gpio-range is added to the pinmux node
and gpio-ranges is added to the GPIO node. Unfortunately, the way the
pinctrl-single driver enumerates the pins (starting with LSB) causes
them to be in reverse order compared to the way the gpios are assigned.
As a result, we have to declare the mapping for each GPIO individually.
This also lets us remove all of the GPIO pinmuxes from
da850-lego-ev3.dts. (Other da850 boards do not currently have any
GPIO pinmuxes declared.)
Acked-by: Linus Walleij <linus.wallei@linaro.org>
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
We now require all at24 users to use the "atmel,<model>" fallback in
device tree for different manufacturers.
Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This adds a new node for reboot modes on LEGO MINDSTORMS EV3. The EV3's
bootloader looks for a magic number in the ARM local RAM and if found,
it will boot into a special firmware update mode where the flash memory
can be written via USB.
This has been testing working using the command:
# systemctl reboot loader
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This fixes the battery voltage monitoring gpio-hog settings.
When the gpio is low, it turns off the battery voltage to the ADC chip.
However, this needs to be on all of the time so that we can monitor
battery voltage.
Also, there was a typo that prevented pinmuxing from working correctly.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This adds a new node for the LEGO MINDSTORMS EV3 LCD display.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This adds a new node to the LEGO MINDSTORMS EV3 device tree for the battery.
Signed-off-by: David Lechner <david@lechnology.com>
[nsekhar@ti.com: minor headline fix]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This moves the spi0_cs3_pin pinconf node from the LEGO EV3 file to the
common DA850 include file. This node is applicable to any board, and
therefore belongs in the common file.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This adds a device tree node for sound on LEGO MINDSTORMS EV3. The EV3
uses one of the SoC PWMs connected to an amplifier to create sound from
a speaker.
The PWM is passed through a low-pass filter, so it is actually possible
to do PCM playback, but there is no existing driver, so just using
pwm-beeper for now, since it is also a compatible mode of operation.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This adds a node for the TI ADS7957 analog/digital converter on LEGO
MINDSTORMS EV3 as well as a regulator node that is used by the A/DC node.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
This adds a device tree definition file for LEGO MINDSTORMS EV3.
What is working:
* Pin muxing
* Pinconf
* GPIOs
* MicroSD card reader
* UART on input port 1
* Buttons
* LEDs
* Poweroff/reset
* Flash memory
* EEPROM
* USB host port
* USB peripheral port
What is not working/to be added later:
* Speaker - have patch submitted to get pwm-beeper working - maybe someday
it will have a real sound driver that uses PRU
* A/DC chip - have driver submitted and accepted - waiting for ack on
device tree bindings
* Display - waiting for "simple DRM" to be mainlined
* Bluetooth - needs new driver for sequencing power/enable/clock
* Input and output ports - need some sort of new phy or extcon driver as
well as PRU UART and PRU I2C drivers
* Battery indication - needs new power supply driver
Note on flash partitions:
These partitions are based on the official EV3 firmware from LEGO. It is
expected that most users of the mainline kernel on EV3 will be booting from
an SD card while retaining the official firmware in the flash memory.
Furthermore, the official firmware uses an ancient U-Boot (2009) that has
no device tree support. So, it makes sense to have this partition table in
the EV3 device tree file. In the unlikely case that anyone does create
their own firmware image with different partitioning, they can use a modern
U-Boot in their own firmware image that modifies the device tree with the
custom partitions.
Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
