[RESEND] New driver for TLV493D-A1B6 I2C chip, input and hwmon class device.
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Message ID 966f09b8-0936-6d90-2ec8-bcb1b94c81aa@volny.cz
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  • [RESEND] New driver for TLV493D-A1B6 I2C chip, input and hwmon class device.
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Commit Message

Jakub Ladman Oct. 18, 2019, 8:10 p.m. UTC
Dear maintainers.

As a linux-patch newbie i made some mistakes in my first attempt to send 
this patch.
This patch contains a new driver for i2c connected chip, Infineon 
TLV493D-A1B6.
The chip is 3D hall-effect sensor with thermometer.

This particular driver senses magnetic field rotation in X/Y plane with 
1 degree resolution and +/- 1 degree error.

Input device is created for the angle sensing part.
Hwmon device is created for the thermometer part.

Input device axis must be configured by device-tree. There are also 
optional parameters regarding absolute/relative mode switching, minimum 
step in relative mode, filtering and thermometer calibration.

We are using that device as high reliability rotary encoder.

Signed-off-by: Jakub Ladman <ladmanj@volny.cz>
---
.../bindings/input/tlv493d-a1b6_rotenc.txt | 70 ++
drivers/input/misc/Kconfig | 9 +
drivers/input/misc/Makefile | 2 +-
drivers/input/misc/tlv493d-a1b6_rotenc.c | 675 ++++++++++++++++++
4 files changed, 755 insertions(+), 1 deletion(-)
create mode 100644 
Documentation/devicetree/bindings/input/tlv493d-a1b6_rotenc.txt
create mode 100644 drivers/input/misc/tlv493d-a1b6_rotenc.c

+MODULE_LICENSE("GPL v2");
+MODULE_VERSION("0.0.3");
--

Comments

Dmitry Torokhov Oct. 18, 2019, 8:56 p.m. UTC | #1
Hi Jakub,

On Fri, Oct 18, 2019 at 10:10:19PM +0200, Jakub Ladman wrote:
> Dear maintainers.
> 
> As a linux-patch newbie i made some mistakes in my first attempt to send
> this patch.
> This patch contains a new driver for i2c connected chip, Infineon
> TLV493D-A1B6.
> The chip is 3D hall-effect sensor with thermometer.
> 
> This particular driver senses magnetic field rotation in X/Y plane with 1
> degree resolution and +/- 1 degree error.
> 
> Input device is created for the angle sensing part.
> Hwmon device is created for the thermometer part.
> 
> Input device axis must be configured by device-tree. There are also optional
> parameters regarding absolute/relative mode switching, minimum step in
> relative mode, filtering and thermometer calibration.
> 
> We are using that device as high reliability rotary encoder.

I wonder if IIO subsystem that support s magnetometers and temperature
sensors would not be a better hone for this.

CC-ing Jonathan.

Also, your mailer mangled your patch pretty badly, please consider using
git send-email next time.

Thanks.
Jonathan Cameron Oct. 28, 2019, 1:05 p.m. UTC | #2
On Fri, 18 Oct 2019 13:56:37 -0700
Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:

> Hi Jakub,
> 
> On Fri, Oct 18, 2019 at 10:10:19PM +0200, Jakub Ladman wrote:
> > Dear maintainers.
> > 
> > As a linux-patch newbie i made some mistakes in my first attempt to send
> > this patch.
> > This patch contains a new driver for i2c connected chip, Infineon
> > TLV493D-A1B6.
> > The chip is 3D hall-effect sensor with thermometer.
> > 
> > This particular driver senses magnetic field rotation in X/Y plane with 1
> > degree resolution and +/- 1 degree error.
> > 
> > Input device is created for the angle sensing part.
> > Hwmon device is created for the thermometer part.
> > 
> > Input device axis must be configured by device-tree. There are also optional
> > parameters regarding absolute/relative mode switching, minimum step in
> > relative mode, filtering and thermometer calibration.
> > 
> > We are using that device as high reliability rotary encoder.  
> 
> I wonder if IIO subsystem that support s magnetometers and temperature
> sensors would not be a better hone for this.
> 
> CC-ing Jonathan.
> 
Hi Jakub, Dmitry,

Sorry for slow reply, was on vacation.

Anyhow, from a quick glance at the datasheet this looks like a fairly standard
magnetometer, be it one designed for use with an associated magnet, rather than
intended for use to measure the earths magnetic field (compass type chips).

These devices only become an 'input device' once the relative positioning relative
to the magnet is known.  We should probably figure out a way to represent that
in DT etc for devices where it is known.  Whether we then do a bridge to input
using that info in kernel or pass it all up to userspace to deal with is a
separate issue, that position information needs to be described first.  My suspicion
is that it would be hard to handle the maths in kernel, but I've not tried
working it out!

So this would fit in IIO, even if the eventual 'use case' is classic input
(I'm guessing a rotary dial).

We have a driver for a part with similar support undergoing revisions at the
moment:

https://www.azoteq.com/images/stories/pdf/iqs624_datasheet.pdf

There might be other hall effect devices like this in IIO, I can't recall but
I certainly have one in my todo pile.

+CC linux-iio

Thanks,

Jonathan


> Also, your mailer mangled your patch pretty badly, please consider using
> git send-email next time.


> 
> Thanks.
>

Patch
diff mbox series

diff --git 
a/Documentation/devicetree/bindings/input/tlv493d-a1b6_rotenc.txt 
b/Documentation/devicetree/bindings/input/tlv493d-a1b6_rotenc.txt
new file mode 100644
index 000000000000..0f7dac615dc1
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/tlv493d-a1b6_rotenc.txt
@@ -0,0 +1,70 @@ 
+This is driver of Infineon TLV493D-1AB6 chip, acting like rotary encoder.
+TLV493-A1B6 is I2C slave.
+
+Example of usage (for raspberry-pi):
+
+/dts-v1/;
+/plugin/;
+
+/ {
+ compatible = "brcm,bcm2708";
+
+ fragment@0 {
+ target = <&i2c0>;
+ __overlay__ {
+ status = "okay";
+
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ tlv493da1b6@1f {
+ compatible = "infineon,tlv493da1b6";
+ reg = <0x1f>;
+ relative_step = <12>;
+ filter = <1>;
+ temp_filter = <6>;
+ temp_base = <340>;
+ refresh_rate_ms = <15>;
+ linux,axis = <8>; /* REL_WHEEL */
+ };
+
+ };
+ };
+};
+
+reg is the only mandatory parameter, for the others defaults will be 
used if not specified.
+
+reg = <0x1f> - set to alternate address
+Can be switched to <0x5f>, the primary address, but this is unavailable 
at for some +i2c controllers.
+For example 0x1f must be used for NXP IMx6 SOC.
+This may change in future with its i2c-controller driver updates.
+
+0x5f is the device's default address, but we need to preserve the 
address after device
+periodical reset and it's impossible to reset it to primary address on 
some i2c controllers.
+Raspberry Pi 3B+ is proven to work with both addresses.
+
+See driver source code for more details.
+
+relative_step can be:
+ zero -> absolute output 0-359 deg
+ non-zero -> relative tick if change > step
+
+
+filter:
+ coefficient of first order IIR filter
+ - set to balance speed and noise of magnetic vector components
+
+temp_filter:
+ coefficient of first order IIR filter
+ - set to transform temperature sensor noise to additional resolution
+
+temp_base:
+ raw binary value for 25 deg C, typical value is 340, but it differs 
device to device. See datasheet.
+
+refresh_rate:
+ hardware starts new measurement 12 ms after last readout
+ set the refresh rate to T > 12 ms
+ +linux,axis:
+ set to appropriate input event
diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 7d9ae394e597..91a36a632f62 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -894,4 +894,13 @@  config INPUT_STPMIC1_ONKEY
To compile this driver as a module, choose M here: the
module will be called stpmic1_onkey.
+config INPUT_TLV493D_A1B6_ROTENC
+ tristate "Infineon TLV493D-A1B6 Rotary Encoder"
+ depends on I2C
+ help
+ Say Y to enable support of TLV493D-A1B6 as rotary encoder.
+
+ To compile this driver as a module, choose M here. The
+ module will be called tlv493d-a1b6_rotenc.
+
endif
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index 8fd187f314bd..071fb506475f 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -85,4 +85,4 @@  obj-$(CONFIG_INPUT_WM831X_ON) += wm831x-on.o
obj-$(CONFIG_INPUT_XEN_KBDDEV_FRONTEND) += xen-kbdfront.o
obj-$(CONFIG_INPUT_YEALINK) += yealink.o
obj-$(CONFIG_INPUT_IDEAPAD_SLIDEBAR) += ideapad_slidebar.o
-
+obj-$(CONFIG_INPUT_TLV493D_A1B6_ROTENC) += tlv493d-a1b6_rotenc.o
diff --git a/drivers/input/misc/tlv493d-a1b6_rotenc.c 
b/drivers/input/misc/tlv493d-a1b6_rotenc.c
new file mode 100644
index 000000000000..33e53fd30fb0
--- /dev/null
+++ b/drivers/input/misc/tlv493d-a1b6_rotenc.c
@@ -0,0 +1,675 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TLV493D-A1B6 three axis magnetic sensor acting as rotary encoder.
+ * Rotation in X/Y plane is reported, Z-axis is ignored.
+ * Temperature is reported.
+ *
+ * Copyright (C) 2019 Jakub Ladman <ladmanj@volny.cz>
+ *
+ * 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/slab.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/workqueue.h>
+
+#include <linux/input.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+
+#include <linux/of.h>
+#include <linux/types.h>
+
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+
+#define TLV493DA1B6_ROTENC_NAME "tlv493da1b6_rotenc"
+
+#define TLV_BITS_PAR (1<<7)
+#define TLV_BITS_ADR (1<<5)
+#define TLV_BITS_INT (1<<2)
+#define TLV_BITS_FST (1<<1)
+#define TLV_BITS_LOW (1<<0)
+#define TLV_BITS_TEM (1<<7)
+#define TLV_BITS_LPP (1<<6)
+#define TLV_BITS_PTE (1<<5)
+
+#define TLV_BITS_FRM(a) (((a) >> 2) & 0b11) /* frame counter */
+#define TLV_BITS_CHA(a) (((a) >> 0) & 0b11) /* ongoing conversion */
+
+struct tlv493da1b6_rotenc_data {
+ struct i2c_client *client;
+ struct input_dev *input_dev;
+ struct timer_list i2c_timer;
+ struct work_struct offload;
+
+ struct device *hwmon_dev;
+ struct attribute_group attr_group;
+ const struct attribute_group *groups[2];
+ struct attribute **attrs;
+ struct sensor_device_attribute *attr;
+
+ u32 refresh_rate_ms;
+ u32 filter_bits;
+ u32 temp_filter_bits;
+ u32 temp_base;
+ u32 axis;
+ u32 relative_step;
+
+/* private */
+ s32 x_filter;
+ s32 y_filter;
+ s32 t_filter;
+ u32 frame_cnt;
+ int lastabs;
+ int temperature;
+};
+
+static uint8_t parity(uint32_t x)
+{
+ x ^= x >> 16;
+ x ^= x >> 8;
+ x ^= x >> 4;
+ x ^= x >> 2;
+ x ^= x >> 1;
+ return (~x << 7); /* returns parity at seventh bit possition! */
+}
+
+/**********************************************************************
+ * input values filter (https://electronics.stackexchange.com/a/34426)
+ **********************************************************************/
+
+/*
+ * @details Implement a first order IIR filter to approximate a K sample
+ * moving average. This function implements the equation:
+ *
+ * y[n] = alpha * x[n] + (1 - alpha) * y[n-1]
+ *
+ * @param *filter - a Signed 15.16 fixed-point value.
+ * @param sample - the 16-bit value of the current sample.
+ * @param bits - this is roughly = log2( 1 / alpha ).
+ */
+
+int16_t IIR_Filter(int32_t *filter, int32_t sample, uint32_t bits)
+{
+ int32_t local_sample = (int32_t) sample << 16;
+ *filter += (local_sample - *filter) >> bits;
+ return (int16_t) ((*filter + 0x8000) >> 16);
+}
+
+/**********************************************************************
+ * angle computation
+ **********************************************************************/
+
+/*
+ * Original copyright notice:
+ * This algorithm and code examples on this page are open-source,
+ * use them as you like but please mention www.RomanBlack.com.
+ *
+ * Fast XY vector to integer degree algorithm - Jan 2011 www.RomanBlack.com
+ * Converts any XY values including 0 to a degree value that should be
+ * within +/- 1 degree of the accurate value without needing
+ * large slow trig functions like ArcTan() or ArcCos().
+ * NOTE! at least one of the X or Y values must be non-zero!
+ * This is the full version, for all 4 quadrants and will generate
+ * the angle in integer degrees from 0-359.
+ * Any values of X and Y are usable including negative values provided
+ * they are between -95443717 and 95443717
+ * so the 32bit multiply does not overflow.
+ *
+ * modified to 32bit and corrected to 0-359 degrees output by Jakub Ladman
+ */
+
+int angle(int32_t y, int32_t x)
+{
+
+ uint32_t negflag;
+ uint32_t comp;
+ int32_t degree; /* this will hold the result */
+ int32_t ux;
+ int32_t uy;
+
+ /* preventing div by zero, in hardware fault condition */
+ if (!(x && y))
+ return -1;
+
+ /* Save the sign flags then remove signs and get XY as unsigned ints */
+ negflag = 0;
+ if (x < 0) {
+ negflag |= 0x01; /* x flag bit */
+ x = (0 - x); /* is now + */
+ }
+ ux = x; /* copy to unsigned var before multiply */
+ if (y < 0) {
+ negflag |= 0x02; /* y flag bit */
+ y = (0 - y); /* is now + */
+ }
+ uy = y; /* copy to unsigned var before multiply */
+
+ /* 1. Calc the scaled "degrees" */
+ if (ux > uy) {
+ degree = (uy * 45) / ux; /* degree result will be 0-45 range */
+ negflag |= 0x10; /* octant flag bit */
+ } else {
+ degree = (ux * 45) / uy; /* degree result will be 0-45 range */
+ }
+
+ /* 2. Compensate for the 4 degree error curve */
+ comp = 0;
+ if (degree > 22) { /* if top half of range */
+ if (degree <= 44)
+ comp++;
+ if (degree <= 41)
+ comp++;
+ if (degree <= 37)
+ comp++;
+ if (degree <= 32)
+ comp++; /* max is 4 degrees compensated */
+ } else { /* else is lower half of range */
+ if (degree >= 2)
+ comp++;
+ if (degree >= 6)
+ comp++;
+ if (degree >= 10)
+ comp++;
+ if (degree >= 15)
+ comp++; /* max is 4 degrees compensated */
+ }
+ degree += comp; /* degree is now accurate to +/- 1 degree! */
+
+ /* Invert degree if it was X>Y octant, makes 0-45 into 90-45 */
+ if (negflag & 0x10)
+ degree = (90 - degree);
+
+ /* 3. Degree is now 0-90 range for this quadrant,
+ * need to invert it for whichever quadrant it was in
+ */
+ if (negflag & 0x02) { /* if -Y */
+ if (negflag & 0x01) /* if -Y -X */
+ degree = (180 + degree);
+ else /* else is -Y +X */
+ degree = (180 - degree);
+ } else { /* else is +Y */
+ if (negflag & 0x01) { /* if +Y -X */
+ degree = (359 - degree);
+ if (negflag & 0x10)
+ degree += 1;
+ }
+ }
+ return degree;
+}
+
+/*
+ * TLV493D-A1B6 device reset
+ * Reset is needed to set up secondary address and to unlock the device
+ * if the measurement stalls.
+ * From time to time the device freezes, returning the same old data again
+ * and again.
+ * This behavior is documented in official documentation from the
+ * manufacturer.
+ * The stalled state is detectable observing the frame counter,
+ * if it stops incrementing and overflowing the device must be reset.
+ * See the detection part in work handler function.
+ *
+ * The device is reset if i2c address 0x00 is called in write mode.
+ * The new device address is set by the state (voltage) of the SDA line
+ * from 4 us to 14 us after address ACK is sent.
+ * This is done in this driver by sending 0x00 or 0xff byte according
+ * to requested address. This behavior was tested on bare metal MCU,
+ * before implemented here.
+ *
+ * Unfortunately at least in case of IMx6 SOC, there is impossible
+ * to send the 0xff byte in that time limit.
+ * This leads to practical limitation of single TLV493D-A1B6 chip at 0x1f
+ * on single i2c bus.
+ *
+ * On Raspberry PI 3B+ is possible to use both addresses.
+ *
+ * Another limitation is that if there were two (or more) these chips on
+ * the same bus, both will respond to reset command in the same way and
+ * thus it will lead to address confilct.
+ *
+ * This has to be solved by additional hardware and driver modification.
+ * I.e. disconnect clock and/or data signal from the unrelated chip
+ * during reset.
+ *
+ * In the datasheet and user manual is also described a possibility
+ * to select up to 8 different addresses and then share a single bus
+ * by these 8 devices.
+ * Without help of additional hardware and driver modification,
+ * unable to maintain these further addresses which are to be set
+ * by power sequencing. This driver doesn't support power sequencing.
+ *
+ * After the reset, the configuration is sent to the device.
+ */
+
+static int i2c_device_reset(struct i2c_client *client)
+{
+ struct i2c_msg tlv493_reset_msg[1];
+ int result = 0;
+ u8 buf[10];
+
+ buf[0] = 0x00; /* Reset the device to the alternate address 0x1f. */
+
+ tlv493_reset_msg[0].addr = 0;
+ tlv493_reset_msg[0].flags = 0;
+ tlv493_reset_msg[0].len = 1;
+ tlv493_reset_msg[0].buf = buf;
+
+ /* If MSB of the address is high, default address 0x5e is used. */
+ /* It does not work if the controller is pulling SDA line low */
+ /* after ACK. Only the alternate address is then usable. */
+ if (client->addr & 0x40)
+ buf[0] = 0xff;
+
+
+ result = i2c_transfer(client->adapter, tlv493_reset_msg, 1);
+
+ udelay(10);
+
+ /*
+ * The initialization part:
+ * There is a strange request in the datasheet to not change some bits.
+ * Original values has to be read from registers 6..9, then modified
+ * and written back to registers 0..3.
+ *
+ * There is also need to set the parity so the parity of
+ * all the 32 bits of configuration will be odd.
+ *
+ * The parity checking can be disabled, but the first configuration
+ * has to be "secured" anyway.
+ *
+ * This driver exploits master controlled low power mode, in which
+ * the measurement is started 12 ms after the last readout.
+ * If faster refresh rate needed, the low power bit must be
+ * switched off. Then the refresh rate can be as low as 300 us.
+ *
+ * This version of the driver doesn't support these refresh rates,
+ * because it is assumed to be unpractical on the non-realtime os.
+ */
+
+ /* Read all registers to get the default values for write registers */
+ result = i2c_master_recv(client, buf, 10);
+ if (result < 0) {
+ dev_info(&client->dev, "FAIL: i2c can't read data: %d", result);
+ return result;
+ }
+
+ udelay(20);
+
+ /* Prepare config data, use the read values in buffer[6..9] */
+ buf[6] = 0x00;
+
+ buf[7] |= TLV_BITS_FST | TLV_BITS_LOW;
+ /* Other bits must correspond to bits from read register 7. */
+
+ /* All bits must correspond to bits 7:0 from read register 8. */
+
+ buf[9] |= TLV_BITS_LPP | TLV_BITS_PTE;
+ /* Other bits must correspond to bits from read register 9. */
+
+ /* Update parity bit according to actual content of buf[6..9] */
+ buf[7] ^= parity(*((uint32_t *) (buf + 6)));
+
+ /* Send configuration data */
+ result = i2c_master_send(client, buf + 6, 4);
+ if (result < 0)
+ dev_info(&client->dev,
+ "FAIL: i2c can't write data: %d", result);
+
+ return result;
+}
+
+static void i2c_work_handler(struct work_struct *work)
+{
+ struct tlv493da1b6_rotenc_data *rotenc =
+ container_of(work, struct tlv493da1b6_rotenc_data, offload);
+ struct input_dev *input_dev = rotenc->input_dev;
+ struct {
+ signed int val:12;
+ } tmp;
+
+ u8 buf[10];
+ s16 x, y;
+ u8 attempt = 1;
+ int curabs;
+
+ do {
+ if (attempt < 10) { /* try it ten times */
+ i2c_master_recv(rotenc->client, buf, 7);
+ attempt++;
+ } else { /* give up */
+ dev_info(&rotenc->client->dev,
+ "FAIL: tlv493 read failed, attempt %d\n",
+ attempt);
+ return;
+ }
+
+ /* zero if all three axes consistent */
+ if (TLV_BITS_CHA(buf[3])) {
+ dev_info(&rotenc->client->dev,
+ "tlv493 read inconsistent, attempt %d\n",
+ attempt);
+ continue; /* read again if not */
+ }
+
+ /* if the frame was already received */
+ if (rotenc->frame_cnt == TLV_BITS_FRM(buf[3])) {
+ dev_info(&rotenc->client->dev,
+ "FAIL: tlv493 stalled %d, resetting\n",
+ TLV_BITS_FRM(buf[3]));
+ if (i2c_device_reset(rotenc->client) < 0) {
+ dev_err(&rotenc->client->dev,
+ "FAIL: i2c device doesn't respond to reset.");
+ /* Device permanent error, the hw dissappeared from bus or so. */
+ /* I would like to stop and exit module here, but don't know how to. */
+ }
+ /* reinit with unseen frame number again */
+ rotenc->frame_cnt = 0xff;
+ /* discard data and wait for next timer event */
+ return;
+ }
+ rotenc->frame_cnt = TLV_BITS_FRM(buf[3]);
+
+ } while (TLV_BITS_CHA(buf[3]));
+
+ /* Magnetic axis X data */
+ tmp.val = buf[0] << 4;
+ tmp.val |= buf[4] >> 4;
+
+ x = IIR_Filter(&rotenc->x_filter, tmp.val, rotenc->filter_bits);
+
+ /* Magnetic axis Y data */
+ tmp.val = buf[1] << 4;
+ tmp.val |= buf[4] & 0xf;
+
+ y = IIR_Filter(&rotenc->y_filter, tmp.val, rotenc->filter_bits);
+
+ /* Temperature data */
+ tmp.val = buf[6];
+ tmp.val |= (buf[3] << 4) & 0xf00;
+
+ /*
+ * subtracting typical offset of 340 LSB's
+ * converting to degC by 1.1C/LSB
+ * adding reference temperature of 25C
+ */
+
+ rotenc->temperature = 25000
+ + IIR_Filter(&rotenc->t_filter,
+ 1100 * (tmp.val - rotenc->temp_base),
+ rotenc->temp_filter_bits); /* TEMP: 0.001C/bit */
+
+ /* compute current angle */
+ curabs = angle(y, x);
+
+ if (curabs < 0)
+ return; /* invalid values aren't reported */
+
+ /* non-zero -> relative, zero -> absolute */
+ if (rotenc->relative_step) {
+
+ int diff = (curabs - rotenc->lastabs);
+
+ if (diff > 180)
+ diff -= 360;
+ else if (diff < -180)
+ diff += 360;
+
+ if (abs(diff) > rotenc->relative_step) {
+ diff /= abs(diff);
+ input_report_rel(input_dev, rotenc->axis, diff);
+ rotenc->lastabs = curabs;
+ }
+ } else {
+ input_report_abs(input_dev, rotenc->axis, curabs);
+ }
+
+ input_sync(input_dev);
+}
+
+static ssize_t show_temperature(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct tlv493da1b6_rotenc_data *rotenc = dev_get_drvdata(dev);
+
+ return sprintf(buf, "%d\n", rotenc->temperature);
+}
+
+static void i2c_timer_callback(struct timer_list *t)
+{
+
+ struct tlv493da1b6_rotenc_data *rotenc =
+ from_timer(rotenc, t, i2c_timer);
+ schedule_work(&rotenc->offload);
+
+ mod_timer(&rotenc->i2c_timer,
+ jiffies + msecs_to_jiffies(rotenc->refresh_rate_ms));
+}
+
+static void tlv493da1b6_rotenc_power(struct tlv493da1b6_rotenc_data 
*rotenc,
+ bool poweron)
+{
+}
+
+static int tlv493da1b6_rotenc_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct tlv493da1b6_rotenc_data *rotenc;
+ struct device_node *np = client->dev.of_node;
+ struct input_dev *input_dev;
+ int error;
+ char *sname;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+ dev_err(&client->dev, "need I2C_FUNC_I2C\n");
+ return -EIO;
+ }
+
+ rotenc = devm_kzalloc(&client->dev, sizeof(*rotenc), GFP_KERNEL);
+ if (!rotenc)
+ return -ENOMEM;
+
+ input_dev = devm_input_allocate_device(&client->dev);
+ if (!input_dev)
+ return -ENOMEM;
+
+ rotenc->client = client;
+ rotenc->input_dev = input_dev;
+
+ tlv493da1b6_rotenc_power(rotenc, true);
+
+ input_dev->name = TLV493DA1B6_ROTENC_NAME;
+ input_dev->id.bustype = BUS_I2C;
+ input_dev->dev.parent = &client->dev;
+
+ i2c_set_clientdata(client, rotenc);
+ device_init_wakeup(&client->dev, 1);
+
+ error = i2c_device_reset(rotenc->client);
+ if (error < 0) {
+ dev_err(&client->dev, "Unable to reset %s\n", input_dev->name);
+ return error;
+ }
+
+ if (of_property_read_u32(np, "relative_step", &rotenc->relative_step))
+ rotenc->relative_step = 0;
+
+ dev_info(&client->dev, "relative_step %d\n", rotenc->relative_step);
+
+ /* if zero, absolute value reported */
+ if (of_property_read_u32(np, "linux,axis", &rotenc->axis)) {
+ if (rotenc->relative_step)
+ rotenc->axis = REL_WHEEL;
+ else
+ rotenc->axis = ABS_WHEEL;
+ }
+ dev_info(&client->dev, "axis %d\n", rotenc->axis);
+
+ if (rotenc->relative_step) {
+ __set_bit(EV_REL, input_dev->evbit);
+ input_set_capability(input_dev, EV_REL, rotenc->axis);
+ } else {
+ __set_bit(EV_ABS, input_dev->evbit);
+ input_set_abs_params(input_dev, rotenc->axis, 0, 359, 0, 0);
+ }
+
+ error = input_register_device(rotenc->input_dev);
+ if (error) {
+ dev_err(&client->dev, "Unable to register %s input device\n",
+ input_dev->name);
+ return error;
+ }
+
+ rotenc->attrs =
+ devm_kzalloc(&client->dev, sizeof(*rotenc->attrs) * 2, GFP_KERNEL);
+ if (rotenc->attrs == NULL) {
+ error = -ENOMEM;
+ goto err2;
+ }
+
+ rotenc->attr =
+ devm_kzalloc(&client->dev, sizeof(*rotenc->attr), GFP_KERNEL);
+ if (rotenc->attr == NULL) {
+ error = -ENOMEM;
+ goto err2;
+ }
+
+ sysfs_attr_init(&rotenc->attr->dev_attr.attr);
+
+ rotenc->attr->dev_attr.attr.name =
+ devm_kasprintf(&client->dev, GFP_KERNEL, "temp1_input");
+ if (rotenc->attr->dev_attr.attr.name == NULL) {
+ error = -ENOMEM;
+ goto err2;
+ }
+
+ rotenc->attr->dev_attr.show = show_temperature;
+ rotenc->attr->dev_attr.attr.mode = 0444;
+ rotenc->attr->index = 0;
+
+ rotenc->attrs[0] = &rotenc->attr->dev_attr.attr;
+
+ rotenc->attr_group.attrs = rotenc->attrs;
+ rotenc->groups[0] = &rotenc->attr_group;
+
+ sname = devm_kstrdup(&client->dev, input_dev->name, GFP_KERNEL);
+ if (!sname) {
+ error = -ENOMEM;
+ goto err2;
+ }
+
+ strreplace(sname, '-', '_');
+ rotenc->hwmon_dev =
+ hwmon_device_register_with_groups(&client->dev, sname, rotenc,
+ rotenc->groups);
+ if (IS_ERR(rotenc->hwmon_dev)) {
+ error = PTR_ERR(rotenc->hwmon_dev);
+ goto err2;
+ }
+
+ rotenc->x_filter = 0;
+ rotenc->y_filter = 0;
+ rotenc->t_filter = 0;
+ rotenc->frame_cnt = 0xff; /* received frame nr. will differ for sure */
+
+ if (of_property_read_u32(np, "filter", &rotenc->filter_bits))
+ rotenc->filter_bits = 3;
+
+ dev_info(&client->dev, "filter %d\n", rotenc->filter_bits);
+
+ if (of_property_read_u32(np, "temp_filter", &rotenc->temp_filter_bits))
+ rotenc->temp_filter_bits = 8;
+
+ dev_info(&client->dev, "temp_filter %d\n", rotenc->temp_filter_bits);
+
+ if (of_property_read_u32(np, "temp_base", &rotenc->temp_base))
+ rotenc->temp_base = 340;
+
+ dev_info(&client->dev, "temp_base %d\n", rotenc->temp_base);
+
+ if (of_property_read_u32
+ (np, "refresh_rate_ms", &rotenc->refresh_rate_ms)) {
+ rotenc->refresh_rate_ms = 20;
+ }
+/* measurement is started by hw 12ms after last readout */
+ if (rotenc->refresh_rate_ms < 12)
+ rotenc->refresh_rate_ms = 20;
+ dev_info(&client->dev, "refresh_rate_ms %d\n", rotenc->refresh_rate_ms);
+
+ INIT_WORK(&rotenc->offload, i2c_work_handler);
+ timer_setup(&rotenc->i2c_timer, i2c_timer_callback, 0);
+ error =
+ mod_timer(&rotenc->i2c_timer,
+ jiffies + msecs_to_jiffies(rotenc->refresh_rate_ms));
+
+ if (error) {
+ dev_err(&client->dev, "Unable to register %s timer\n",
+ input_dev->name);
+ goto err1;
+ }
+
+ return 0;
+
+err1: del_timer(&rotenc->i2c_timer);
+ hwmon_device_unregister(rotenc->hwmon_dev);
+err2: input_unregister_device(rotenc->input_dev);
+
+ return error;
+}
+
+static int tlv493da1b6_rotenc_remove(struct i2c_client *client)
+{
+ struct tlv493da1b6_rotenc_data *rotenc = i2c_get_clientdata(client);
+
+ del_timer(&rotenc->i2c_timer);
+ hwmon_device_unregister(rotenc->hwmon_dev);
+ input_unregister_device(rotenc->input_dev);
+ tlv493da1b6_rotenc_power(rotenc, false);
+
+ return 0;
+}
+
+
+static const struct i2c_device_id tlv493da1b6_rotenc_id[] = {
+ { TLV493DA1B6_ROTENC_NAME, 0 },
+ { }
+};
+
+MODULE_DEVICE_TABLE(i2c, tlv493da1b6_rotenc_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id tlv493da1b6_rotenc_dt_ids[] = {
+ {.compatible = "infineon,tlv493da1b6", },
+ { }
+};
+
+MODULE_DEVICE_TABLE(of, tlv493da1b6_rotenc_dt_ids);
+#endif
+
+static struct i2c_driver tlv493da1b6_rotenc_driver = {
+ .probe = tlv493da1b6_rotenc_probe,
+ .remove = tlv493da1b6_rotenc_remove,
+ .id_table = tlv493da1b6_rotenc_id,
+ .driver = {
+ .name = TLV493DA1B6_ROTENC_NAME,
+ .of_match_table = of_match_ptr(tlv493da1b6_rotenc_dt_ids),
+ },
+};
+
+module_i2c_driver(tlv493da1b6_rotenc_driver);
+
+MODULE_ALIAS(TLV493DA1B6_ROTENC_NAME);
+MODULE_DESCRIPTION("Infineon TLV493D-A1B6 magnetic sensor as rotary 
encoder");
+MODULE_AUTHOR("Jakub Ladman <ladmanj@volny.cz>");