[PATCH v6 0/3] Input: Add TouchNetix axiom touchscreen driver

[PATCH v6 0/3] Input: Add TouchNetix axiom touchscreen driver

[Kamel Bouhara]

Add a new driver for the TouchNetix's axiom family of touchscreen
controller. This driver only support i2c and can be later adapted for
SPI and USB support.

---
Changes in v2:
 - Add device tree binding documentation
 - Move core functions in axiom_i2c as we only care about i2c support now
 - Use static function when required
 - Use syntax dev_err_probe()
 - Add an hardware based reset

Changes in v3:
 - Remove irq-gpios property in dt-binding
 - Use a generic node name
 - Fix issues reported in https://lore.kernel.org/oe-kbuild-all/202310100300.oAC2M62R-lkp@intel.com/

Changes in v4:
 - Cleanup unused headers and macros
 - Use standard kernel type
 - Namespace structures and functions
 - Use packed struct when possible to avoid bitfield operators
 - Fix missing break when address is found in axiom_populate_target_address()
 - Split reads in two steps for the reports, first length then report
   itself so we only read required bytes
 - Get poll-interval from devicetree
 - Add VDDI/VDDA regulators
 - Add a startup delay of 110 ms required after VDDA/VDDI is applied
 - Remove axiom_i2c_write() as it is no more used

Changes in v5:
 - Fix wrong message constructed in axiom_i2c_read
 - Delay required between i2c reads is >= 250us
 - Do not split report reading in two phases as we'll
   have to wait 500us
 - Use lower-case in properties names
 - Make regulators properties are required in dt-binding
 - Fix bug report: https://lore.kernel.org/lkml/202312051457.y3N1q3sZ-lkp@intel.com/
 - Fix bug report: https://lore.kernel.org/lkml/6f8e3b64-5b21-4a50-8680-063ef7a93bdb@suswa.mountain/

Changes in v6:
 - Fix missing unevaluatedProperties.in dt-binding
 - Use __le16 to correctly deal with device endianness
 - Use standart kernel types s/char/u8/
 - Use regmap api as driver might support spi later
 - Use get_unaligned_le16() for the sake of clarity
 - Use devm_regulator_enable_optional()

Kamel Bouhara (3):
  dt-bindings: vendor-prefixes: Add TouchNetix AS
  dt-bindings: input: Add TouchNetix axiom touchscreen
  Input: Add TouchNetix axiom i2c touchscreen driver

 .../input/touchscreen/touchnetix,ax54a.yaml   |  67 ++
 .../devicetree/bindings/vendor-prefixes.yaml  |   2 +
 MAINTAINERS                                   |   7 +
 drivers/input/touchscreen/Kconfig             |  12 +
 drivers/input/touchscreen/Makefile            |   1 +
 drivers/input/touchscreen/touchnetix_axiom.c  | 664 ++++++++++++++++++
 6 files changed, 753 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/touchnetix,ax54a.yaml
 create mode 100644 drivers/input/touchscreen/touchnetix_axiom.c

--
2.25.1

[PATCH v6 1/3] dt-bindings: vendor-prefixes: Add TouchNetix AS

[Kamel Bouhara]

Add vendor prefix for TouchNetix AS (https://www.touchnetix.com/products/).

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
 Documentation/devicetree/bindings/vendor-prefixes.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/vendor-prefixes.yaml b/Documentation/devicetree/bindings/vendor-prefixes.yaml
index 573578db9509..78581001a79c 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
+++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
@@ -1400,6 +1400,8 @@ patternProperties:
     description: Toradex AG
   "^toshiba,.*":
     description: Toshiba Corporation
+  "^touchnetix,.*":
+    description: TouchNetix AS
   "^toumaz,.*":
     description: Toumaz
   "^tpk,.*":
-- 
2.25.1

[PATCH v6 2/3] dt-bindings: input: Add TouchNetix axiom touchscreen

[Kamel Bouhara]

Add the TouchNetix axiom I2C touchscreen device tree bindings
documentation.

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
---
 .../input/touchscreen/touchnetix,ax54a.yaml   | 67 +++++++++++++++++++
 MAINTAINERS                                   |  6 ++
 2 files changed, 73 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/touchnetix,ax54a.yaml

diff --git a/Documentation/devicetree/bindings/input/touchscreen/touchnetix,ax54a.yaml b/Documentation/devicetree/bindings/input/touchscreen/touchnetix,ax54a.yaml
new file mode 100644
index 000000000000..7b3997457fa5
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/touchnetix,ax54a.yaml
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/touchscreen/touchnetix,ax54a.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TouchNetix Axiom series touchscreen controller
+
+maintainers:
+  - Kamel Bouhara <kamel.bouhara@bootlin.com>
+
+allOf:
+  - $ref: /schemas/input/touchscreen/touchscreen.yaml#
+  - $ref: /schemas/input/input.yaml#
+
+properties:
+  compatible:
+    const: touchnetix,ax54a
+
+  reg:
+    const: 0x66
+
+  interrupts:
+    maxItems: 1
+
+  reset-gpios:
+    maxItems: 1
+
+  vdda-supply:
+    description: Analog power supply regulator on VDDA pin
+
+  vddi-supply:
+    description: I/O power supply regulator on VDDI pin
+
+  startup-time-ms:
+    description: delay after power supply regulator is applied in ms
+
+required:
+  - compatible
+  - reg
+  - vdda-supply
+  - vddi-supply
+  - startup-time-ms
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      touchscreen@66 {
+        compatible = "touchnetix,ax54a";
+        reg = <0x66>;
+        interrupt-parent = <&gpio2>;
+        interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
+        reset-gpios = <&gpio1 1 GPIO_ACTIVE_HIGH>;
+        vdda-supply = <&vdda_reg>;
+        vddi-supply = <&vddi_reg>;
+        poll-interval = <20>;
+        startup-time-ms = <100>;
+      };
+    };
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 7608b714653f..4752d8436dbb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21431,6 +21431,12 @@ S:	Maintained
 F:	Documentation/ABI/testing/sysfs-class-firmware-attributes
 F:	drivers/platform/x86/think-lmi.?
 
+TOUCHNETIX AXIOM I2C TOUCHSCREEN DRIVER
+M:	Kamel Bouhara <kamel.bouhara@bootlin.com>
+L:	linux-input@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/input/touchscreen/touchnetix,ax54a.yaml
+
 THUNDERBOLT DMA TRAFFIC TEST DRIVER
 M:	Isaac Hazan <isaac.hazan@intel.com>
 L:	linux-usb@vger.kernel.org
-- 
2.25.1

Re: [PATCH v6 2/3] dt-bindings: input: Add TouchNetix axiom touchscreen

[Krzysztof Kozlowski]

On 25/01/2024 17:58, Kamel Bouhara wrote:
> +  reset-gpios:
> +    maxItems: 1
> +
> +  vdda-supply:
> +    description: Analog power supply regulator on VDDA pin
> +
> +  vddi-supply:
> +    description: I/O power supply regulator on VDDI pin
> +
> +  startup-time-ms:
> +    description: delay after power supply regulator is applied in ms

That's a regulator property - ramp up time.

Best regards,
Krzysztof

Re: [PATCH v6 2/3] dt-bindings: input: Add TouchNetix axiom touchscreen

[Rob Herring]

On Fri, Jan 26, 2024 at 12:46:16PM +0100, Krzysztof Kozlowski wrote:
> On 25/01/2024 17:58, Kamel Bouhara wrote:
> > +  reset-gpios:
> > +    maxItems: 1
> > +
> > +  vdda-supply:
> > +    description: Analog power supply regulator on VDDA pin
> > +
> > +  vddi-supply:
> > +    description: I/O power supply regulator on VDDI pin
> > +
> > +  startup-time-ms:
> > +    description: delay after power supply regulator is applied in ms
> 
> That's a regulator property - ramp up time.

I'm sure there's an existing property name that could be used.

But why is it needed? Is it variable per board with the same device? If 
not, it should be implied by the compatible.

Rob

Re: [PATCH v6 2/3] dt-bindings: input: Add TouchNetix axiom touchscreen

[Krzysztof Kozlowski]

On 30/01/2024 23:28, Rob Herring wrote:
> On Fri, Jan 26, 2024 at 12:46:16PM +0100, Krzysztof Kozlowski wrote:
>> On 25/01/2024 17:58, Kamel Bouhara wrote:
>>> +  reset-gpios:
>>> +    maxItems: 1
>>> +
>>> +  vdda-supply:
>>> +    description: Analog power supply regulator on VDDA pin
>>> +
>>> +  vddi-supply:
>>> +    description: I/O power supply regulator on VDDI pin
>>> +
>>> +  startup-time-ms:
>>> +    description: delay after power supply regulator is applied in ms
>>
>> That's a regulator property - ramp up time.
> 
> I'm sure there's an existing property name that could be used.
> 
> But why is it needed? Is it variable per board with the same device? If 
> not, it should be implied by the compatible.

I meant, that regulators have such property. Unless this is coming from
the device needs, not from the regulator?

Best regards,
Krzysztof

Re: [PATCH v6 2/3] dt-bindings: input: Add TouchNetix axiom touchscreen

[Kamel Bouhara]

Hello,

On Wed, Jan 31, 2024 at 08:28:43AM +0100, Krzysztof Kozlowski wrote:
> On 30/01/2024 23:28, Rob Herring wrote:
> > On Fri, Jan 26, 2024 at 12:46:16PM +0100, Krzysztof Kozlowski wrote:
> >> On 25/01/2024 17:58, Kamel Bouhara wrote:
> >>> +  reset-gpios:
> >>> +    maxItems: 1
> >>> +
> >>> +  vdda-supply:
> >>> +    description: Analog power supply regulator on VDDA pin
> >>> +
> >>> +  vddi-supply:
> >>> +    description: I/O power supply regulator on VDDI pin
> >>> +
> >>> +  startup-time-ms:
> >>> +    description: delay after power supply regulator is applied in ms
> >>
> >> That's a regulator property - ramp up time.
> >
> > I'm sure there's an existing property name that could be used.
> >
> > But why is it needed? Is it variable per board with the same device? If
> > not, it should be implied by the compatible.
>
> I meant, that regulators have such property. Unless this is coming from
> the device needs, not from the regulator?
>

After looking again into the device's datasheet [1], the delay (startup
time) is not really optional and it shouldn't be set through devicetree.

IIUC, it have to be set unconditionally after a device reset or
a vdda assertion.

[1]: https://www.touchnetix.com/media/dgnjohor/tnxd00394-a3-axiom_ax54a_2d_touch_controller_datasheet.pdf
--
Kamel Bouhara, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

Re: [PATCH v6 2/3] dt-bindings: input: Add TouchNetix axiom touchscreen

[Krzysztof Kozlowski]

On 31/01/2024 10:06, Kamel Bouhara wrote:
> Hello,
> 
> On Wed, Jan 31, 2024 at 08:28:43AM +0100, Krzysztof Kozlowski wrote:
>> On 30/01/2024 23:28, Rob Herring wrote:
>>> On Fri, Jan 26, 2024 at 12:46:16PM +0100, Krzysztof Kozlowski wrote:
>>>> On 25/01/2024 17:58, Kamel Bouhara wrote:
>>>>> +  reset-gpios:
>>>>> +    maxItems: 1
>>>>> +
>>>>> +  vdda-supply:
>>>>> +    description: Analog power supply regulator on VDDA pin
>>>>> +
>>>>> +  vddi-supply:
>>>>> +    description: I/O power supply regulator on VDDI pin
>>>>> +
>>>>> +  startup-time-ms:
>>>>> +    description: delay after power supply regulator is applied in ms
>>>>
>>>> That's a regulator property - ramp up time.
>>>
>>> I'm sure there's an existing property name that could be used.
>>>
>>> But why is it needed? Is it variable per board with the same device? If
>>> not, it should be implied by the compatible.
>>
>> I meant, that regulators have such property. Unless this is coming from
>> the device needs, not from the regulator?
>>
> 
> After looking again into the device's datasheet [1], the delay (startup
> time) is not really optional and it shouldn't be set through devicetree.
> 
> IIUC, it have to be set unconditionally after a device reset or
> a vdda assertion.
> 
> [1]: https://www.touchnetix.com/media/dgnjohor/tnxd00394-a3-axiom_ax54a_2d_touch_controller_datasheet.pdf
> --

OK, then it's not a regulator ramp up, but rather part of device driver
(deduced from compatible).

Best regards,
Krzysztof

[PATCH v6 3/3] Input: Add TouchNetix axiom i2c touchscreen driver

[Kamel Bouhara]

Add a new driver for the TouchNetix's axiom family of
touchscreen controllers. This driver only supports i2c
and can be later adapted for SPI and USB support.

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
---
 MAINTAINERS                                  |   1 +
 drivers/input/touchscreen/Kconfig            |  12 +
 drivers/input/touchscreen/Makefile           |   1 +
 drivers/input/touchscreen/touchnetix_axiom.c | 664 +++++++++++++++++++
 4 files changed, 678 insertions(+)
 create mode 100644 drivers/input/touchscreen/touchnetix_axiom.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 4752d8436dbb..337ddac6c74b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21436,6 +21436,7 @@ M:	Kamel Bouhara <kamel.bouhara@bootlin.com>
 L:	linux-input@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/input/touchscreen/touchnetix,ax54a.yaml
+F:	drivers/input/touchscreen/touchnetix_axiom.c
 
 THUNDERBOLT DMA TRAFFIC TEST DRIVER
 M:	Isaac Hazan <isaac.hazan@intel.com>
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index e3e2324547b9..f36bee8d8696 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -803,6 +803,18 @@ config TOUCHSCREEN_MIGOR
 	  To compile this driver as a module, choose M here: the
 	  module will be called migor_ts.
 
+config TOUCHSCREEN_TOUCHNETIX_AXIOM
+	tristate "TouchNetix AXIOM based touchscreen controllers"
+	depends on I2C
+	help
+	  Say Y here if you have a axiom touchscreen connected to
+	  your system.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called axiom.
+
 config TOUCHSCREEN_TOUCHRIGHT
 	tristate "Touchright serial touchscreen"
 	select SERIO
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 62bd24f3ac8e..8e32a2df5e18 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -88,6 +88,7 @@ obj-$(CONFIG_TOUCHSCREEN_SUR40)		+= sur40.o
 obj-$(CONFIG_TOUCHSCREEN_SURFACE3_SPI)	+= surface3_spi.o
 obj-$(CONFIG_TOUCHSCREEN_TI_AM335X_TSC)	+= ti_am335x_tsc.o
 obj-$(CONFIG_TOUCHSCREEN_TOUCHIT213)	+= touchit213.o
+obj-$(CONFIG_TOUCHSCREEN_TOUCHNETIX_AXIOM)	+= touchnetix_axiom.o
 obj-$(CONFIG_TOUCHSCREEN_TOUCHRIGHT)	+= touchright.o
 obj-$(CONFIG_TOUCHSCREEN_TOUCHWIN)	+= touchwin.o
 obj-$(CONFIG_TOUCHSCREEN_TS4800)	+= ts4800-ts.o
diff --git a/drivers/input/touchscreen/touchnetix_axiom.c b/drivers/input/touchscreen/touchnetix_axiom.c
new file mode 100644
index 000000000000..cbb5525b83f5
--- /dev/null
+++ b/drivers/input/touchscreen/touchnetix_axiom.c
@@ -0,0 +1,664 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TouchNetix axiom Touchscreen Driver
+ *
+ * Copyright (C) 2020-2023 TouchNetix Ltd.
+ *
+ * Author(s): Bart Prescott <bartp@baasheep.co.uk>
+ *            Pedro Torruella <pedro.torruella@touchnetix.com>
+ *            Mark Satterthwaite <mark.satterthwaite@touchnetix.com>
+ *            Hannah Rossiter <hannah.rossiter@touchnetix.com>
+ *            Kamel Bouhara <kamel.bouhara@bootlin.com>
+ *
+ */
+#include <linux/bitfield.h>
+#include <linux/crc16.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/regmap.h>
+
+#include <asm/unaligned.h>
+#define AXIOM_PROX_LEVEL		-128
+#define AXIOM_DMA_OPS_DELAY_USEC	250
+/*
+ * Register group u31 has 2 pages for usage table entries.
+ */
+#define AXIOM_U31_MAX_USAGES		0xff
+#define AXIOM_U31_BYTES_PER_USAGE	6
+#define AXIOM_U31_PAGE0_LENGTH		0x0C
+#define AXIOM_U31_BOOTMODE_MASK		BIT(7)
+#define AXIOM_U31_DEVID_MASK		GENMASK(14, 0)
+
+#define AXIOM_MAX_REPORT_LEN		0x7f
+
+#define AXIOM_CMD_HEADER_READ_MASK	BIT(15)
+#define AXIOM_U41_MAX_TARGETS		10
+
+#define AXIOM_U46_AUX_CHANNELS		4
+#define AXIOM_U46_AUX_MASK		GENMASK(11, 0)
+
+#define AXIOM_COMMS_MAX_USAGE_PAGES	3
+#define AXIOM_COMMS_PAGE_SIZE		256
+#define AXIOM_COMMS_REPORT_LEN_MASK	GENMASK(6, 0)
+
+#define AXIOM_REPORT_USAGE_ID		0x34
+#define AXIOM_DEVINFO_USAGE_ID		0x31
+#define AXIOM_USAGE_2HB_REPORT_ID	0x01
+#define AXIOM_USAGE_2AUX_REPORT_ID	0x46
+#define AXIOM_USAGE_2DCTS_REPORT_ID	0x41
+
+#define AXIOM_PAGE_OFFSET_MASK		GENMASK(6, 0)
+
+struct axiom_devinfo {
+	__le16 device_id;
+	u8 fw_minor;
+	u8 fw_major;
+	u8 fw_info_extra;
+	u8 tcp_revision;
+	u8 bootloader_fw_minor;
+	u8 bootloader_fw_major;
+	__le16 jedec_id;
+	u8 num_usages;
+} __packed;
+
+/*
+ * Describes parameters of a specific usage, essentially a single element of
+ * the "Usage Table"
+ */
+struct axiom_usage_entry {
+	u8 id;
+	u8 is_report;
+	u8 start_page;
+	u8 num_pages;
+};
+
+/*
+ * Represents state of a touch or target when detected prior to a touch (eg.
+ * hover or proximity events).
+ */
+enum axiom_target_state {
+	AXIOM_TARGET_STATE_NOT_PRESENT = 0,
+	AXIOM_TARGET_STATE_PROX = 1,
+	AXIOM_TARGET_STATE_HOVER = 2,
+	AXIOM_TARGET_STATE_TOUCHING = 3,
+};
+
+struct axiom_u41_target {
+	enum axiom_target_state state;
+	u16 x;
+	u16 y;
+	s8 z;
+	bool insert;
+	bool touch;
+};
+
+struct axiom_target_report {
+	u8 index;
+	u8 present;
+	u16 x;
+	u16 y;
+	s8 z;
+};
+
+struct axiom_cmd_header {
+	__le16 target_address;
+	__le16 length;
+} __packed;
+
+struct axiom_data {
+	struct axiom_devinfo devinfo;
+	struct device *dev;
+	struct gpio_desc *reset_gpio;
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	u32 max_report_len;
+	u8 rx_buf[AXIOM_COMMS_MAX_USAGE_PAGES * AXIOM_COMMS_PAGE_SIZE];
+	struct axiom_u41_target targets[AXIOM_U41_MAX_TARGETS];
+	struct axiom_usage_entry usage_table[AXIOM_U31_MAX_USAGES];
+	bool usage_table_populated;
+	struct regulator *vdda;
+	struct regulator *vddi;
+	struct regmap *regmap;
+	struct touchscreen_properties	prop;
+};
+
+static const struct regmap_config axiom_i2c_regmap_config = {
+	.reg_bits = 32,
+	.reg_format_endian = REGMAP_ENDIAN_LITTLE,
+	.val_bits = 8,
+	.val_format_endian = REGMAP_ENDIAN_LITTLE,
+};
+
+/*
+ * axiom devices are typically configured to report touches at a rate
+ * of 100Hz (10ms) for systems that require polling for reports.
+ * When reports are polled, it will be expected to occasionally
+ * observe the overflow bit being set in the reports.
+ * This indicates that reports are not being read fast enough.
+ */
+#define POLL_INTERVAL_DEFAULT_MS 10
+
+/* Translate usage/page/offset triplet into physical address. */
+static u16 axiom_usage_to_target_address(struct axiom_data *ts, u8 usage, u8 page,
+					 char offset)
+{
+	/* At the moment the convention is that u31 is always at physical address 0x0 */
+	if (!ts->usage_table_populated) {
+		if (usage == AXIOM_DEVINFO_USAGE_ID)
+			return ((page << 8) + offset);
+		else
+			return 0xffff;
+	}
+
+	if (page >= ts->usage_table[usage].num_pages) {
+		dev_err(ts->dev, "Invalid usage table! usage: u%02x, page: %02x, offset: %02x\n",
+			usage, page, offset);
+		return 0xffff;
+	}
+
+	return ((ts->usage_table[usage].start_page + page) << 8) + offset;
+}
+
+static int axiom_read(struct axiom_data *ts, u8 usage, u8 page, void *buf, u16 len)
+{
+	struct axiom_cmd_header cmd_header;
+	int ret;
+
+	cmd_header.target_address = cpu_to_le16(axiom_usage_to_target_address(ts, usage, page, 0));
+	cmd_header.length = cpu_to_le16(len | AXIOM_CMD_HEADER_READ_MASK);
+
+	__le32 preamble = get_unaligned_le32((u8 *)&cmd_header);
+
+	ret = regmap_write(ts->regmap, preamble, 0);
+	if (ret) {
+		dev_err(ts->dev, "failed to write preamble, error %d\n", ret);
+		return ret;
+	}
+
+	ret = regmap_raw_read(ts->regmap, 0, buf, len);
+	if (ret) {
+		dev_err(ts->dev, "failed to read target address %04x, error %d\n",
+			cmd_header.target_address, ret);
+		return ret;
+	}
+
+	/* Wait device's DMA operations */
+	usleep_range(AXIOM_DMA_OPS_DELAY_USEC, AXIOM_DMA_OPS_DELAY_USEC + 50);
+
+	return 0;
+}
+
+/*
+ * One of the main purposes for reading the usage table is to identify
+ * which usages reside at which target address.
+ * When performing subsequent reads or writes to AXIOM, the target address
+ * is used to specify which usage is being accessed.
+ * Consider the following discovery code which will build up the usage table.
+ */
+static u32 axiom_populate_usage_table(struct axiom_data *ts)
+{
+	struct axiom_usage_entry *usage_table;
+	u8 *rx_data = ts->rx_buf;
+	u32 max_report_len;
+	u32 usage_id;
+	int error;
+
+	usage_table = ts->usage_table;
+
+	/* Read the second page of usage u31 to get the usage table */
+	error = axiom_read(ts, AXIOM_DEVINFO_USAGE_ID, 1, rx_data,
+			   (AXIOM_U31_BYTES_PER_USAGE * ts->devinfo.num_usages));
+
+	if (error)
+		return error;
+
+	for (usage_id = 1; usage_id < AXIOM_U31_MAX_USAGES; usage_id++) {
+		u16 offset = (usage_id * AXIOM_U31_BYTES_PER_USAGE);
+		u8 id = rx_data[offset + 0];
+		u8 start_page = rx_data[offset + 1];
+		u8 num_pages = rx_data[offset + 2];
+		u32 max_offset = ((rx_data[offset + 3] & AXIOM_PAGE_OFFSET_MASK) + 1) * 2;
+
+		if (!num_pages)
+			usage_table[id].is_report = true;
+
+		/* Store the entry into the usage table */
+		usage_table[id].id = id;
+		usage_table[id].start_page = start_page;
+		usage_table[id].num_pages = num_pages;
+
+		dev_dbg(ts->dev, "Usage u%02x Info: %*ph\n", id, AXIOM_U31_BYTES_PER_USAGE,
+			&rx_data[offset]);
+
+		/* Identify the max report length the module will receive */
+		if (usage_table[id].is_report && max_offset > max_report_len)
+			max_report_len = max_offset;
+	}
+
+	ts->usage_table_populated = true;
+
+	return max_report_len;
+}
+
+static int axiom_discover(struct axiom_data *ts)
+{
+	int error;
+
+	/*
+	 * Fetch the first page of usage u31 to get the
+	 * device information and the number of usages
+	 */
+	error = axiom_read(ts, AXIOM_DEVINFO_USAGE_ID, 0, &ts->devinfo, AXIOM_U31_PAGE0_LENGTH);
+	if (error)
+		return error;
+
+	dev_dbg(ts->dev, "  Boot Mode      : %s\n",
+		FIELD_GET(AXIOM_U31_BOOTMODE_MASK,
+			  le16_to_cpu(ts->devinfo.device_id)) ? "BLP" : "TCP");
+	dev_dbg(ts->dev, "  Device ID      : %04lx\n",
+		FIELD_GET(AXIOM_U31_DEVID_MASK, le16_to_cpu(ts->devinfo.device_id)));
+	dev_dbg(ts->dev, "  Firmware Rev   : %02x.%02x\n", ts->devinfo.fw_major,
+		ts->devinfo.fw_minor);
+	dev_dbg(ts->dev, "  Bootloader Rev : %02x.%02x\n", ts->devinfo.bootloader_fw_major,
+		ts->devinfo.bootloader_fw_minor);
+	dev_dbg(ts->dev, "  FW Extra Info  : %04x\n", ts->devinfo.fw_info_extra);
+	dev_dbg(ts->dev, "  Silicon        : %04x\n", le16_to_cpu(ts->devinfo.jedec_id));
+	dev_dbg(ts->dev, "  Number usages        : %04x\n", ts->devinfo.num_usages);
+
+	ts->max_report_len = axiom_populate_usage_table(ts);
+	if (!ts->max_report_len || !ts->devinfo.num_usages ||
+	    ts->max_report_len > AXIOM_MAX_REPORT_LEN) {
+		dev_err(ts->dev, "Invalid report length or usages number");
+		return -EINVAL;
+	}
+
+	dev_dbg(ts->dev, "Max Report Length: %u\n", ts->max_report_len);
+
+	return 0;
+}
+
+/*
+ * Support function to axiom_process_u41_report.
+ * Generates input-subsystem events for every target.
+ * After calling this function the caller shall issue
+ * a Sync to the input sub-system.
+ */
+static bool axiom_process_u41_report_target(struct axiom_data *ts,
+					    struct axiom_target_report *target)
+{
+	struct input_dev *input_dev = ts->input_dev;
+	struct axiom_u41_target *target_prev_state;
+	enum axiom_target_state current_state;
+	int slot;
+
+	/* Verify the target index */
+	if (target->index >= AXIOM_U41_MAX_TARGETS) {
+		dev_err(ts->dev, "Invalid target index! %u\n", target->index);
+		return false;
+	}
+
+	target_prev_state = &ts->targets[target->index];
+
+	current_state = AXIOM_TARGET_STATE_NOT_PRESENT;
+
+	if (target->present) {
+		if (target->z >= 0)
+			current_state = AXIOM_TARGET_STATE_TOUCHING;
+		else if (target->z > AXIOM_PROX_LEVEL && target->z < 0)
+			current_state = AXIOM_TARGET_STATE_HOVER;
+		else if (target->z == AXIOM_PROX_LEVEL)
+			current_state = AXIOM_TARGET_STATE_PROX;
+	}
+
+	if (target_prev_state->state == current_state &&
+	    target_prev_state->x == target->x &&
+	    target_prev_state->y == target->y &&
+	    target_prev_state->z == target->z)
+		return false;
+
+	slot = target->index;
+
+	dev_dbg(ts->dev, "U41 Target T%u, slot:%u present:%u, x:%u, y:%u, z:%d\n",
+		target->index, slot, target->present,
+		target->x, target->y, target->z);
+
+	switch (current_state) {
+	case AXIOM_TARGET_STATE_NOT_PRESENT:
+	case AXIOM_TARGET_STATE_PROX:
+		if (!target_prev_state->insert)
+			break;
+		target_prev_state->insert = false;
+		input_mt_slot(input_dev, slot);
+
+		if (!slot)
+			input_report_key(input_dev, BTN_TOUCH, 0);
+
+		input_mt_report_slot_inactive(input_dev);
+		/*
+		 * make sure the previous coordinates are
+		 * all off screen when the finger comes back
+		 */
+		target->x = 65535;
+		target->y = 65535;
+		target->z = AXIOM_PROX_LEVEL;
+		break;
+	case AXIOM_TARGET_STATE_HOVER:
+	case AXIOM_TARGET_STATE_TOUCHING:
+		target_prev_state->insert = true;
+		input_mt_slot(input_dev, slot);
+		input_report_abs(input_dev, ABS_MT_TRACKING_ID, slot);
+		input_report_abs(input_dev, ABS_MT_POSITION_X, target->x);
+		input_report_abs(input_dev, ABS_MT_POSITION_Y, target->y);
+
+		if (current_state == AXIOM_TARGET_STATE_TOUCHING) {
+			input_report_abs(input_dev, ABS_MT_DISTANCE, 0);
+			input_report_abs(input_dev, ABS_DISTANCE, 0);
+			input_report_abs(input_dev, ABS_MT_PRESSURE, target->z);
+			input_report_abs(input_dev, ABS_PRESSURE, target->z);
+		} else {
+			input_report_abs(input_dev, ABS_MT_DISTANCE, -target->z);
+			input_report_abs(input_dev, ABS_DISTANCE, -target->z);
+			input_report_abs(input_dev, ABS_MT_PRESSURE, 0);
+			input_report_abs(input_dev, ABS_PRESSURE, 0);
+		}
+
+		if (!slot)
+			input_report_key(input_dev, BTN_TOUCH, (current_state ==
+					 AXIOM_TARGET_STATE_TOUCHING));
+		break;
+	default:
+		break;
+	}
+
+	target_prev_state->state = current_state;
+	target_prev_state->x = target->x;
+	target_prev_state->y = target->y;
+	target_prev_state->z = target->z;
+
+	return true;
+}
+
+/*
+ * U41 is the output report of the 2D CTS and contains the status of targets
+ * (including contacts and pre-contacts) along with their X,Y,Z values.
+ * When a target has been removed (no longer detected),
+ * the corresponding X,Y,Z values will be zeroed.
+ */
+static bool axiom_process_u41_report(struct axiom_data *ts, u8 *rx_buf)
+{
+	struct axiom_target_report target;
+	bool update_done = false;
+	u16 target_status;
+	int i;
+
+	target_status = get_unaligned_le16(rx_buf + 1);
+
+	for (i = 0; i < AXIOM_U41_MAX_TARGETS; i++) {
+		u8 *target_step = &rx_buf[i * 4];
+
+		target.index = i;
+		target.present = ((target_status & (1 << i)) != 0) ? 1 : 0;
+		target.x = get_unaligned_le16(target_step + 3);
+		target.y = get_unaligned_le16(target_step + 5);
+		target.z = (s8)(rx_buf[i + 43]);
+		update_done |= axiom_process_u41_report_target(ts, &target);
+	}
+
+	return update_done;
+}
+
+/*
+ * U46 report contains a low level measurement data generated by the capacitive
+ * displacement sensor (CDS) algorithms from the auxiliary channels.
+ * This information is useful when tuning multi-press to assess mechanical
+ * consistency in the unit's construction.
+ */
+static void axiom_process_u46_report(struct axiom_data *ts, u8 *rx_buf)
+{
+	struct input_dev *input_dev = ts->input_dev;
+	u32 event_value;
+	u16 aux_value;
+	int i;
+
+	for (i = 0; i < AXIOM_U46_AUX_CHANNELS; i++) {
+		u8 *target_step = &rx_buf[i * 2];
+
+		aux_value = get_unaligned_le16(target_step + 1) & AXIOM_U46_AUX_MASK;
+		event_value = (i << 16) | (aux_value);
+		input_event(input_dev, EV_MSC, MSC_RAW, event_value);
+	}
+}
+
+/*
+ * Validates the crc and demultiplexes the axiom reports to the appropriate
+ * report handler
+ */
+static int axiom_handle_events(struct axiom_data *ts)
+{
+	struct input_dev *input_dev = ts->input_dev;
+	u8 *report_data = ts->rx_buf;
+	struct device *dev = ts->dev;
+	u16 crc_report;
+	u16 crc_calc;
+	int error;
+	u8 len;
+
+	error = axiom_read(ts, AXIOM_REPORT_USAGE_ID, 0, report_data, ts->max_report_len);
+	if (error)
+		return error;
+
+	len = (report_data[0] & AXIOM_COMMS_REPORT_LEN_MASK) << 1;
+	if (len <= 2) {
+		dev_err(dev, "Zero length report discarded.\n");
+		return -ENODATA;
+	}
+
+	/* Validate the report CRC */
+	u8 *crc_bytes = &report_data[len];
+
+	crc_report = get_unaligned_le16(crc_bytes - 2);
+	/* Length is in 16 bit words and remove the size of the CRC16 itself */
+	crc_calc = crc16(0, report_data, (len - 2));
+
+	if (crc_calc != crc_report) {
+		dev_err(dev,
+			"CRC mismatch! Expected: %#x, Calculated CRC: %#x.\n",
+			crc_report, crc_calc);
+		return -EINVAL;
+	}
+
+	switch (report_data[1]) {
+	case AXIOM_USAGE_2DCTS_REPORT_ID:
+		if (axiom_process_u41_report(ts, &report_data[1])) {
+			input_mt_sync_frame(input_dev);
+			input_sync(input_dev);
+		}
+		break;
+
+	case AXIOM_USAGE_2AUX_REPORT_ID:
+		/* This is an aux report (force) */
+		axiom_process_u46_report(ts, &report_data[1]);
+		input_mt_sync(input_dev);
+		input_sync(input_dev);
+		break;
+
+	case AXIOM_USAGE_2HB_REPORT_ID:
+		/* This is a heartbeat report */
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void axiom_i2c_poll(struct input_dev *input_dev)
+{
+	struct axiom_data *ts = input_get_drvdata(input_dev);
+
+	axiom_handle_events(ts);
+}
+
+static irqreturn_t axiom_irq(int irq, void *dev_id)
+{
+	struct axiom_data *ts = dev_id;
+
+	axiom_handle_events(ts);
+
+	return IRQ_HANDLED;
+}
+
+static void axiom_reset(struct gpio_desc *reset_gpio)
+{
+	gpiod_set_value_cansleep(reset_gpio, 1);
+	usleep_range(1000, 2000);
+	gpiod_set_value_cansleep(reset_gpio, 0);
+	msleep(110);
+}
+
+static int axiom_i2c_probe(struct i2c_client *client)
+{
+	u32 poll_interval = POLL_INTERVAL_DEFAULT_MS;
+	struct device *dev = &client->dev;
+	struct input_dev *input_dev;
+	struct axiom_data *ts;
+	u32 startup_delay_ms;
+	int target;
+	int error;
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, ts);
+	ts->client = client;
+	ts->dev = dev;
+
+	ts->regmap = devm_regmap_init_i2c(client, &axiom_i2c_regmap_config);
+	error = PTR_ERR_OR_ZERO(ts->regmap);
+	if (error) {
+		dev_err(dev, "Failed to initialize regmap: %d\n", error);
+		return error;
+	}
+
+	ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(ts->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(ts->reset_gpio), "failed to get reset GPIO\n");
+
+	if (ts->reset_gpio)
+		axiom_reset(ts->reset_gpio);
+
+	ts->vddi = devm_regulator_get_optional(dev, "vddi");
+	if (!IS_ERR(ts->vddi)) {
+		error = devm_regulator_get_enable(dev, "vddi");
+		if (error)
+			return dev_err_probe(&client->dev, error,
+					     "Failed to enable vddi regulator\n");
+	}
+
+	ts->vdda = devm_regulator_get_optional(dev, "vdda");
+	if (!IS_ERR(ts->vdda)) {
+		error = devm_regulator_get_enable(dev, "vdda");
+		if (error)
+			return dev_err_probe(&client->dev, error,
+					     "Failed to enable vdda regulator\n");
+		if (!device_property_read_u32(dev, "startup-time-ms", &startup_delay_ms))
+			msleep(startup_delay_ms);
+	}
+
+	error = axiom_discover(ts);
+	if (error)
+		return dev_err_probe(dev, error, "Failed touchscreen discover\n");
+
+	input_dev = devm_input_allocate_device(ts->dev);
+	if (!input_dev)
+		return -ENOMEM;
+
+	input_dev->name = "TouchNetix axiom Touchscreen";
+	input_dev->phys = "input/axiom_ts";
+
+	input_set_abs_params(input_dev, ABS_MT_POSITION_X, 0, 65535, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_POSITION_Y, 0, 65535, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_TOOL_TYPE, 0, MT_TOOL_MAX, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_DISTANCE, 0, 127, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_PRESSURE, 0, 127, 0, 0);
+
+	touchscreen_parse_properties(input_dev, true, &ts->prop);
+
+	/* Registers the axiom device as a touchscreen instead of a mouse pointer */
+	error = input_mt_init_slots(input_dev, AXIOM_U41_MAX_TARGETS, INPUT_MT_DIRECT);
+	if (error)
+		return error;
+
+	/* Enables the raw data for up to 4 force channels to be sent to the input subsystem */
+	set_bit(EV_REL, input_dev->evbit);
+	set_bit(EV_MSC, input_dev->evbit);
+	/* Declare that we support "RAW" Miscellaneous events */
+	set_bit(MSC_RAW, input_dev->mscbit);
+
+	ts->input_dev = input_dev;
+	input_set_drvdata(ts->input_dev, ts);
+
+	/* Ensure that all reports are initialised to not be present. */
+	for (target = 0; target < AXIOM_U41_MAX_TARGETS; target++)
+		ts->targets[target].state = AXIOM_TARGET_STATE_NOT_PRESENT;
+
+	error = input_register_device(input_dev);
+	if (error)
+		return dev_err_probe(ts->dev, error,
+				     "Could not register with Input Sub-system.\n");
+
+	error = devm_request_threaded_irq(dev, client->irq, NULL,
+					  axiom_irq, IRQF_ONESHOT, dev_name(dev), ts);
+	if (error) {
+		dev_info(dev, "Request irq failed, falling back to polling mode");
+
+		error = input_setup_polling(input_dev, axiom_i2c_poll);
+		if (error)
+			return dev_err_probe(ts->dev, error, "Unable to set up polling mode\n");
+
+		if (!device_property_read_u32(ts->dev, "poll-interval", &poll_interval))
+			input_set_poll_interval(input_dev, poll_interval);
+	}
+
+	return 0;
+}
+
+static const struct i2c_device_id axiom_i2c_id_table[] = {
+	{ "ax54a" },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, axiom_i2c_id_table);
+
+static const struct of_device_id axiom_i2c_of_match[] = {
+	{ .compatible = "touchnetix,ax54a", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, axiom_i2c_of_match);
+
+static struct i2c_driver axiom_i2c_driver = {
+	.driver = {
+		   .name = "axiom",
+		   .of_match_table = axiom_i2c_of_match,
+	},
+	.id_table = axiom_i2c_id_table,
+	.probe = axiom_i2c_probe,
+};
+module_i2c_driver(axiom_i2c_driver);
+
+MODULE_AUTHOR("Bart Prescott <bartp@baasheep.co.uk>");
+MODULE_AUTHOR("Pedro Torruella <pedro.torruella@touchnetix.com>");
+MODULE_AUTHOR("Mark Satterthwaite <mark.satterthwaite@touchnetix.com>");
+MODULE_AUTHOR("Hannah Rossiter <hannah.rossiter@touchnetix.com>");
+MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
+MODULE_DESCRIPTION("TouchNetix axiom touchscreen I2C bus driver");
+MODULE_LICENSE("GPL");
-- 
2.25.1

Re: [PATCH v6 3/3] Input: Add TouchNetix axiom i2c touchscreen driver

[POPESCU Catalin]

Hi Kamel,

I have a few remarks regarding the population of the usage table 
function, see inline.

On 25.01.24 17:58, Kamel Bouhara wrote:
> [Some people who received this message don't often get email from kamel.bouhara@bootlin.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> This email is not from Hexagon’s Office 365 instance. Please be careful while clicking links, opening attachments, or replying to this email.
>
>
> Add a new driver for the TouchNetix's axiom family of
> touchscreen controllers. This driver only supports i2c
> and can be later adapted for SPI and USB support.
>
> Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
> ---
>   MAINTAINERS                                  |   1 +
>   drivers/input/touchscreen/Kconfig            |  12 +
>   drivers/input/touchscreen/Makefile           |   1 +
>   drivers/input/touchscreen/touchnetix_axiom.c | 664 +++++++++++++++++++
>   4 files changed, 678 insertions(+)
>   create mode 100644 drivers/input/touchscreen/touchnetix_axiom.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 4752d8436dbb..337ddac6c74b 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21436,6 +21436,7 @@ M:      Kamel Bouhara <kamel.bouhara@bootlin.com>
>   L:     linux-input@vger.kernel.org
>   S:     Maintained
>   F:     Documentation/devicetree/bindings/input/touchscreen/touchnetix,ax54a.yaml
> +F:     drivers/input/touchscreen/touchnetix_axiom.c
>
>   THUNDERBOLT DMA TRAFFIC TEST DRIVER
>   M:     Isaac Hazan <isaac.hazan@intel.com>
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index e3e2324547b9..f36bee8d8696 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -803,6 +803,18 @@ config TOUCHSCREEN_MIGOR
>            To compile this driver as a module, choose M here: the
>            module will be called migor_ts.
>
> +config TOUCHSCREEN_TOUCHNETIX_AXIOM
> +       tristate "TouchNetix AXIOM based touchscreen controllers"
> +       depends on I2C
> +       help
> +         Say Y here if you have a axiom touchscreen connected to
> +         your system.
> +
> +         If unsure, say N.
> +
> +         To compile this driver as a module, choose M here: the
> +         module will be called axiom.
> +
>   config TOUCHSCREEN_TOUCHRIGHT
>          tristate "Touchright serial touchscreen"
>          select SERIO
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 62bd24f3ac8e..8e32a2df5e18 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -88,6 +88,7 @@ obj-$(CONFIG_TOUCHSCREEN_SUR40)               += sur40.o
>   obj-$(CONFIG_TOUCHSCREEN_SURFACE3_SPI) += surface3_spi.o
>   obj-$(CONFIG_TOUCHSCREEN_TI_AM335X_TSC)        += ti_am335x_tsc.o
>   obj-$(CONFIG_TOUCHSCREEN_TOUCHIT213)   += touchit213.o
> +obj-$(CONFIG_TOUCHSCREEN_TOUCHNETIX_AXIOM)     += touchnetix_axiom.o
>   obj-$(CONFIG_TOUCHSCREEN_TOUCHRIGHT)   += touchright.o
>   obj-$(CONFIG_TOUCHSCREEN_TOUCHWIN)     += touchwin.o
>   obj-$(CONFIG_TOUCHSCREEN_TS4800)       += ts4800-ts.o
> diff --git a/drivers/input/touchscreen/touchnetix_axiom.c b/drivers/input/touchscreen/touchnetix_axiom.c
> new file mode 100644
> index 000000000000..cbb5525b83f5
> --- /dev/null
> +++ b/drivers/input/touchscreen/touchnetix_axiom.c
> @@ -0,0 +1,664 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * TouchNetix axiom Touchscreen Driver
> + *
> + * Copyright (C) 2020-2023 TouchNetix Ltd.
> + *
> + * Author(s): Bart Prescott <bartp@baasheep.co.uk>
> + *            Pedro Torruella <pedro.torruella@touchnetix.com>
> + *            Mark Satterthwaite <mark.satterthwaite@touchnetix.com>
> + *            Hannah Rossiter <hannah.rossiter@touchnetix.com>
> + *            Kamel Bouhara <kamel.bouhara@bootlin.com>
> + *
> + */
> +#include <linux/bitfield.h>
> +#include <linux/crc16.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/input.h>
> +#include <linux/input/mt.h>
> +#include <linux/input/touchscreen.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/regmap.h>
> +
> +#include <asm/unaligned.h>
> +#define AXIOM_PROX_LEVEL               -128
> +#define AXIOM_DMA_OPS_DELAY_USEC       250
> +/*
> + * Register group u31 has 2 pages for usage table entries.
> + */
> +#define AXIOM_U31_MAX_USAGES           0xff
> +#define AXIOM_U31_BYTES_PER_USAGE      6
> +#define AXIOM_U31_PAGE0_LENGTH         0x0C
> +#define AXIOM_U31_BOOTMODE_MASK                BIT(7)
> +#define AXIOM_U31_DEVID_MASK           GENMASK(14, 0)
> +
> +#define AXIOM_MAX_REPORT_LEN           0x7f
> +
> +#define AXIOM_CMD_HEADER_READ_MASK     BIT(15)
> +#define AXIOM_U41_MAX_TARGETS          10
> +
> +#define AXIOM_U46_AUX_CHANNELS         4
> +#define AXIOM_U46_AUX_MASK             GENMASK(11, 0)
> +
> +#define AXIOM_COMMS_MAX_USAGE_PAGES    3
> +#define AXIOM_COMMS_PAGE_SIZE          256
> +#define AXIOM_COMMS_REPORT_LEN_MASK    GENMASK(6, 0)
> +
> +#define AXIOM_REPORT_USAGE_ID          0x34
> +#define AXIOM_DEVINFO_USAGE_ID         0x31
> +#define AXIOM_USAGE_2HB_REPORT_ID      0x01
> +#define AXIOM_USAGE_2AUX_REPORT_ID     0x46
> +#define AXIOM_USAGE_2DCTS_REPORT_ID    0x41
> +
> +#define AXIOM_PAGE_OFFSET_MASK         GENMASK(6, 0)
> +
> +struct axiom_devinfo {
> +       __le16 device_id;
> +       u8 fw_minor;
> +       u8 fw_major;
> +       u8 fw_info_extra;
> +       u8 tcp_revision;
> +       u8 bootloader_fw_minor;
> +       u8 bootloader_fw_major;
> +       __le16 jedec_id;
> +       u8 num_usages;
> +} __packed;
> +
> +/*
> + * Describes parameters of a specific usage, essentially a single element of
> + * the "Usage Table"
> + */
> +struct axiom_usage_entry {
> +       u8 id;
> +       u8 is_report;
> +       u8 start_page;
> +       u8 num_pages;
> +};
> +
> +/*
> + * Represents state of a touch or target when detected prior to a touch (eg.
> + * hover or proximity events).
> + */
> +enum axiom_target_state {
> +       AXIOM_TARGET_STATE_NOT_PRESENT = 0,
> +       AXIOM_TARGET_STATE_PROX = 1,
> +       AXIOM_TARGET_STATE_HOVER = 2,
> +       AXIOM_TARGET_STATE_TOUCHING = 3,
> +};
> +
> +struct axiom_u41_target {
> +       enum axiom_target_state state;
> +       u16 x;
> +       u16 y;
> +       s8 z;
> +       bool insert;
> +       bool touch;
> +};
> +
> +struct axiom_target_report {
> +       u8 index;
> +       u8 present;
> +       u16 x;
> +       u16 y;
> +       s8 z;
> +};
> +
> +struct axiom_cmd_header {
> +       __le16 target_address;
> +       __le16 length;
> +} __packed;
> +
> +struct axiom_data {
> +       struct axiom_devinfo devinfo;
> +       struct device *dev;
> +       struct gpio_desc *reset_gpio;
> +       struct i2c_client *client;
> +       struct input_dev *input_dev;
> +       u32 max_report_len;
> +       u8 rx_buf[AXIOM_COMMS_MAX_USAGE_PAGES * AXIOM_COMMS_PAGE_SIZE];
> +       struct axiom_u41_target targets[AXIOM_U41_MAX_TARGETS];
> +       struct axiom_usage_entry usage_table[AXIOM_U31_MAX_USAGES];
> +       bool usage_table_populated;
> +       struct regulator *vdda;
> +       struct regulator *vddi;
> +       struct regmap *regmap;
> +       struct touchscreen_properties   prop;
> +};
> +
> +static const struct regmap_config axiom_i2c_regmap_config = {
> +       .reg_bits = 32,
> +       .reg_format_endian = REGMAP_ENDIAN_LITTLE,
> +       .val_bits = 8,
> +       .val_format_endian = REGMAP_ENDIAN_LITTLE,
> +};
> +
> +/*
> + * axiom devices are typically configured to report touches at a rate
> + * of 100Hz (10ms) for systems that require polling for reports.
> + * When reports are polled, it will be expected to occasionally
> + * observe the overflow bit being set in the reports.
> + * This indicates that reports are not being read fast enough.
> + */
> +#define POLL_INTERVAL_DEFAULT_MS 10
> +
> +/* Translate usage/page/offset triplet into physical address. */
> +static u16 axiom_usage_to_target_address(struct axiom_data *ts, u8 usage, u8 page,
> +                                        char offset)
> +{
> +       /* At the moment the convention is that u31 is always at physical address 0x0 */
> +       if (!ts->usage_table_populated) {
> +               if (usage == AXIOM_DEVINFO_USAGE_ID)
> +                       return ((page << 8) + offset);
> +               else
> +                       return 0xffff;
> +       }
> +
> +       if (page >= ts->usage_table[usage].num_pages) {
> +               dev_err(ts->dev, "Invalid usage table! usage: u%02x, page: %02x, offset: %02x\n",
> +                       usage, page, offset);
> +               return 0xffff;
> +       }
> +
> +       return ((ts->usage_table[usage].start_page + page) << 8) + offset;
> +}
> +
> +static int axiom_read(struct axiom_data *ts, u8 usage, u8 page, void *buf, u16 len)
> +{
> +       struct axiom_cmd_header cmd_header;
> +       int ret;
> +
> +       cmd_header.target_address = cpu_to_le16(axiom_usage_to_target_address(ts, usage, page, 0));
> +       cmd_header.length = cpu_to_le16(len | AXIOM_CMD_HEADER_READ_MASK);
> +
> +       __le32 preamble = get_unaligned_le32((u8 *)&cmd_header);
> +
> +       ret = regmap_write(ts->regmap, preamble, 0);
> +       if (ret) {
> +               dev_err(ts->dev, "failed to write preamble, error %d\n", ret);
> +               return ret;
> +       }
> +
> +       ret = regmap_raw_read(ts->regmap, 0, buf, len);
> +       if (ret) {
> +               dev_err(ts->dev, "failed to read target address %04x, error %d\n",
> +                       cmd_header.target_address, ret);
> +               return ret;
> +       }
> +
> +       /* Wait device's DMA operations */
> +       usleep_range(AXIOM_DMA_OPS_DELAY_USEC, AXIOM_DMA_OPS_DELAY_USEC + 50);
> +
> +       return 0;
> +}
> +
> +/*
> + * One of the main purposes for reading the usage table is to identify
> + * which usages reside at which target address.
> + * When performing subsequent reads or writes to AXIOM, the target address
> + * is used to specify which usage is being accessed.
> + * Consider the following discovery code which will build up the usage table.
> + */
> +static u32 axiom_populate_usage_table(struct axiom_data *ts)
> +{
> +       struct axiom_usage_entry *usage_table;
> +       u8 *rx_data = ts->rx_buf;
> +       u32 max_report_len;
please force initialization of max_report_len to 0.
> +       u32 usage_id;
> +       int error;
> +
> +       usage_table = ts->usage_table;
> +
> +       /* Read the second page of usage u31 to get the usage table */
> +       error = axiom_read(ts, AXIOM_DEVINFO_USAGE_ID, 1, rx_data,
> +                          (AXIOM_U31_BYTES_PER_USAGE * ts->devinfo.num_usages));
> +
> +       if (error)
> +               return error;
> +
> +       for (usage_id = 1; usage_id < AXIOM_U31_MAX_USAGES; usage_id++) {

usage_id should start at 0, since it's used to compute the offset in the 
page 1 of u31.
if you start with usage_id=1, then whatever is the 1st usage of the 
usage table gets jumped out...
also, you should stop the loop at num_usages, otherwise you're going to 
read garbage after the end of rx_data buffer...
this garbage would end up in wrong computation of max_report_len then in 
failure of reading any touch report.

> +               u16 offset = (usage_id * AXIOM_U31_BYTES_PER_USAGE);
> +               u8 id = rx_data[offset + 0];
> +               u8 start_page = rx_data[offset + 1];
> +               u8 num_pages = rx_data[offset + 2];
> +               u32 max_offset = ((rx_data[offset + 3] & AXIOM_PAGE_OFFSET_MASK) + 1) * 2;
> +
> +               if (!num_pages)
> +                       usage_table[id].is_report = true;
please add an else statement to set is_report to false.
> +
> +               /* Store the entry into the usage table */
> +               usage_table[id].id = id;
> +               usage_table[id].start_page = start_page;
> +               usage_table[id].num_pages = num_pages;
> +
> +               dev_dbg(ts->dev, "Usage u%02x Info: %*ph\n", id, AXIOM_U31_BYTES_PER_USAGE,
> +                       &rx_data[offset]);
> +
> +               /* Identify the max report length the module will receive */
> +               if (usage_table[id].is_report && max_offset > max_report_len)
> +                       max_report_len = max_offset;
> +       }
> +
> +       ts->usage_table_populated = true;
> +
> +       return max_report_len;
> +}
> +
> +static int axiom_discover(struct axiom_data *ts)
> +{
> +       int error;
> +
> +       /*
> +        * Fetch the first page of usage u31 to get the
> +        * device information and the number of usages
> +        */
> +       error = axiom_read(ts, AXIOM_DEVINFO_USAGE_ID, 0, &ts->devinfo, AXIOM_U31_PAGE0_LENGTH);
> +       if (error)
> +               return error;
> +
> +       dev_dbg(ts->dev, "  Boot Mode      : %s\n",
> +               FIELD_GET(AXIOM_U31_BOOTMODE_MASK,
> +                         le16_to_cpu(ts->devinfo.device_id)) ? "BLP" : "TCP");
> +       dev_dbg(ts->dev, "  Device ID      : %04lx\n",
> +               FIELD_GET(AXIOM_U31_DEVID_MASK, le16_to_cpu(ts->devinfo.device_id)));
> +       dev_dbg(ts->dev, "  Firmware Rev   : %02x.%02x\n", ts->devinfo.fw_major,
> +               ts->devinfo.fw_minor);
> +       dev_dbg(ts->dev, "  Bootloader Rev : %02x.%02x\n", ts->devinfo.bootloader_fw_major,
> +               ts->devinfo.bootloader_fw_minor);
> +       dev_dbg(ts->dev, "  FW Extra Info  : %04x\n", ts->devinfo.fw_info_extra);
> +       dev_dbg(ts->dev, "  Silicon        : %04x\n", le16_to_cpu(ts->devinfo.jedec_id));
> +       dev_dbg(ts->dev, "  Number usages        : %04x\n", ts->devinfo.num_usages);
> +
> +       ts->max_report_len = axiom_populate_usage_table(ts);
> +       if (!ts->max_report_len || !ts->devinfo.num_usages ||
> +           ts->max_report_len > AXIOM_MAX_REPORT_LEN) {
> +               dev_err(ts->dev, "Invalid report length or usages number");
> +               return -EINVAL;
> +       }
> +
> +       dev_dbg(ts->dev, "Max Report Length: %u\n", ts->max_report_len);
> +
> +       return 0;
> +}
> +
> +/*
> + * Support function to axiom_process_u41_report.
> + * Generates input-subsystem events for every target.
> + * After calling this function the caller shall issue
> + * a Sync to the input sub-system.
> + */
> +static bool axiom_process_u41_report_target(struct axiom_data *ts,
> +                                           struct axiom_target_report *target)
> +{
> +       struct input_dev *input_dev = ts->input_dev;
> +       struct axiom_u41_target *target_prev_state;
> +       enum axiom_target_state current_state;
> +       int slot;
> +
> +       /* Verify the target index */
> +       if (target->index >= AXIOM_U41_MAX_TARGETS) {
> +               dev_err(ts->dev, "Invalid target index! %u\n", target->index);
> +               return false;
> +       }
> +
> +       target_prev_state = &ts->targets[target->index];
> +
> +       current_state = AXIOM_TARGET_STATE_NOT_PRESENT;
> +
> +       if (target->present) {
> +               if (target->z >= 0)
> +                       current_state = AXIOM_TARGET_STATE_TOUCHING;
> +               else if (target->z > AXIOM_PROX_LEVEL && target->z < 0)
> +                       current_state = AXIOM_TARGET_STATE_HOVER;
> +               else if (target->z == AXIOM_PROX_LEVEL)
> +                       current_state = AXIOM_TARGET_STATE_PROX;
> +       }
> +
> +       if (target_prev_state->state == current_state &&
> +           target_prev_state->x == target->x &&
> +           target_prev_state->y == target->y &&
> +           target_prev_state->z == target->z)
> +               return false;
> +
> +       slot = target->index;
> +
> +       dev_dbg(ts->dev, "U41 Target T%u, slot:%u present:%u, x:%u, y:%u, z:%d\n",
> +               target->index, slot, target->present,
> +               target->x, target->y, target->z);
> +
> +       switch (current_state) {
> +       case AXIOM_TARGET_STATE_NOT_PRESENT:
> +       case AXIOM_TARGET_STATE_PROX:
> +               if (!target_prev_state->insert)
> +                       break;
> +               target_prev_state->insert = false;
> +               input_mt_slot(input_dev, slot);
> +
> +               if (!slot)
> +                       input_report_key(input_dev, BTN_TOUCH, 0);
> +
> +               input_mt_report_slot_inactive(input_dev);
> +               /*
> +                * make sure the previous coordinates are
> +                * all off screen when the finger comes back
> +                */
> +               target->x = 65535;
> +               target->y = 65535;
> +               target->z = AXIOM_PROX_LEVEL;
> +               break;
> +       case AXIOM_TARGET_STATE_HOVER:
> +       case AXIOM_TARGET_STATE_TOUCHING:
> +               target_prev_state->insert = true;
> +               input_mt_slot(input_dev, slot);
> +               input_report_abs(input_dev, ABS_MT_TRACKING_ID, slot);
> +               input_report_abs(input_dev, ABS_MT_POSITION_X, target->x);
> +               input_report_abs(input_dev, ABS_MT_POSITION_Y, target->y);
> +
> +               if (current_state == AXIOM_TARGET_STATE_TOUCHING) {
> +                       input_report_abs(input_dev, ABS_MT_DISTANCE, 0);
> +                       input_report_abs(input_dev, ABS_DISTANCE, 0);
> +                       input_report_abs(input_dev, ABS_MT_PRESSURE, target->z);
> +                       input_report_abs(input_dev, ABS_PRESSURE, target->z);
> +               } else {
> +                       input_report_abs(input_dev, ABS_MT_DISTANCE, -target->z);
> +                       input_report_abs(input_dev, ABS_DISTANCE, -target->z);
> +                       input_report_abs(input_dev, ABS_MT_PRESSURE, 0);
> +                       input_report_abs(input_dev, ABS_PRESSURE, 0);
> +               }
> +
> +               if (!slot)
> +                       input_report_key(input_dev, BTN_TOUCH, (current_state ==
> +                                        AXIOM_TARGET_STATE_TOUCHING));
> +               break;
> +       default:
> +               break;
> +       }
> +
> +       target_prev_state->state = current_state;
> +       target_prev_state->x = target->x;
> +       target_prev_state->y = target->y;
> +       target_prev_state->z = target->z;
> +
> +       return true;
> +}
> +
> +/*
> + * U41 is the output report of the 2D CTS and contains the status of targets
> + * (including contacts and pre-contacts) along with their X,Y,Z values.
> + * When a target has been removed (no longer detected),
> + * the corresponding X,Y,Z values will be zeroed.
> + */
> +static bool axiom_process_u41_report(struct axiom_data *ts, u8 *rx_buf)
> +{
> +       struct axiom_target_report target;
> +       bool update_done = false;
> +       u16 target_status;
> +       int i;
> +
> +       target_status = get_unaligned_le16(rx_buf + 1);
> +
> +       for (i = 0; i < AXIOM_U41_MAX_TARGETS; i++) {
> +               u8 *target_step = &rx_buf[i * 4];
> +
> +               target.index = i;
> +               target.present = ((target_status & (1 << i)) != 0) ? 1 : 0;
> +               target.x = get_unaligned_le16(target_step + 3);
> +               target.y = get_unaligned_le16(target_step + 5);
> +               target.z = (s8)(rx_buf[i + 43]);
> +               update_done |= axiom_process_u41_report_target(ts, &target);
> +       }
> +
> +       return update_done;
> +}
> +
> +/*
> + * U46 report contains a low level measurement data generated by the capacitive
> + * displacement sensor (CDS) algorithms from the auxiliary channels.
> + * This information is useful when tuning multi-press to assess mechanical
> + * consistency in the unit's construction.
> + */
> +static void axiom_process_u46_report(struct axiom_data *ts, u8 *rx_buf)
> +{
> +       struct input_dev *input_dev = ts->input_dev;
> +       u32 event_value;
> +       u16 aux_value;
> +       int i;
> +
> +       for (i = 0; i < AXIOM_U46_AUX_CHANNELS; i++) {
> +               u8 *target_step = &rx_buf[i * 2];
> +
> +               aux_value = get_unaligned_le16(target_step + 1) & AXIOM_U46_AUX_MASK;
> +               event_value = (i << 16) | (aux_value);
> +               input_event(input_dev, EV_MSC, MSC_RAW, event_value);
> +       }
> +}
> +
> +/*
> + * Validates the crc and demultiplexes the axiom reports to the appropriate
> + * report handler
> + */
> +static int axiom_handle_events(struct axiom_data *ts)
> +{
> +       struct input_dev *input_dev = ts->input_dev;
> +       u8 *report_data = ts->rx_buf;
> +       struct device *dev = ts->dev;
> +       u16 crc_report;
> +       u16 crc_calc;
> +       int error;
> +       u8 len;
> +
> +       error = axiom_read(ts, AXIOM_REPORT_USAGE_ID, 0, report_data, ts->max_report_len);
> +       if (error)
> +               return error;
> +
> +       len = (report_data[0] & AXIOM_COMMS_REPORT_LEN_MASK) << 1;
> +       if (len <= 2) {
> +               dev_err(dev, "Zero length report discarded.\n");
> +               return -ENODATA;
> +       }
> +
> +       /* Validate the report CRC */
> +       u8 *crc_bytes = &report_data[len];
> +
> +       crc_report = get_unaligned_le16(crc_bytes - 2);
> +       /* Length is in 16 bit words and remove the size of the CRC16 itself */
> +       crc_calc = crc16(0, report_data, (len - 2));
> +
> +       if (crc_calc != crc_report) {
> +               dev_err(dev,
> +                       "CRC mismatch! Expected: %#x, Calculated CRC: %#x.\n",
> +                       crc_report, crc_calc);
> +               return -EINVAL;
> +       }
> +
> +       switch (report_data[1]) {
> +       case AXIOM_USAGE_2DCTS_REPORT_ID:
> +               if (axiom_process_u41_report(ts, &report_data[1])) {
> +                       input_mt_sync_frame(input_dev);
> +                       input_sync(input_dev);
> +               }
> +               break;
> +
> +       case AXIOM_USAGE_2AUX_REPORT_ID:
> +               /* This is an aux report (force) */
> +               axiom_process_u46_report(ts, &report_data[1]);
> +               input_mt_sync(input_dev);
> +               input_sync(input_dev);
> +               break;
> +
> +       case AXIOM_USAGE_2HB_REPORT_ID:
> +               /* This is a heartbeat report */
> +               break;
> +       default:
> +               return -EINVAL;
> +       }
> +
> +       return 0;
> +}
> +
> +static void axiom_i2c_poll(struct input_dev *input_dev)
> +{
> +       struct axiom_data *ts = input_get_drvdata(input_dev);
> +
> +       axiom_handle_events(ts);
> +}
> +
> +static irqreturn_t axiom_irq(int irq, void *dev_id)
> +{
> +       struct axiom_data *ts = dev_id;
> +
> +       axiom_handle_events(ts);
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static void axiom_reset(struct gpio_desc *reset_gpio)
> +{
> +       gpiod_set_value_cansleep(reset_gpio, 1);
> +       usleep_range(1000, 2000);
> +       gpiod_set_value_cansleep(reset_gpio, 0);
> +       msleep(110);
> +}
> +
> +static int axiom_i2c_probe(struct i2c_client *client)
> +{
> +       u32 poll_interval = POLL_INTERVAL_DEFAULT_MS;
> +       struct device *dev = &client->dev;
> +       struct input_dev *input_dev;
> +       struct axiom_data *ts;
> +       u32 startup_delay_ms;
> +       int target;
> +       int error;
> +
> +       ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
> +       if (!ts)
> +               return -ENOMEM;
> +
> +       i2c_set_clientdata(client, ts);
> +       ts->client = client;
> +       ts->dev = dev;
> +
> +       ts->regmap = devm_regmap_init_i2c(client, &axiom_i2c_regmap_config);
> +       error = PTR_ERR_OR_ZERO(ts->regmap);
> +       if (error) {
> +               dev_err(dev, "Failed to initialize regmap: %d\n", error);
> +               return error;
> +       }
> +
> +       ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> +       if (IS_ERR(ts->reset_gpio))
> +               return dev_err_probe(dev, PTR_ERR(ts->reset_gpio), "failed to get reset GPIO\n");
> +
> +       if (ts->reset_gpio)
> +               axiom_reset(ts->reset_gpio);
> +
> +       ts->vddi = devm_regulator_get_optional(dev, "vddi");
> +       if (!IS_ERR(ts->vddi)) {
> +               error = devm_regulator_get_enable(dev, "vddi");
> +               if (error)
> +                       return dev_err_probe(&client->dev, error,
> +                                            "Failed to enable vddi regulator\n");
> +       }
> +
> +       ts->vdda = devm_regulator_get_optional(dev, "vdda");
> +       if (!IS_ERR(ts->vdda)) {
> +               error = devm_regulator_get_enable(dev, "vdda");
> +               if (error)
> +                       return dev_err_probe(&client->dev, error,
> +                                            "Failed to enable vdda regulator\n");
> +               if (!device_property_read_u32(dev, "startup-time-ms", &startup_delay_ms))
> +                       msleep(startup_delay_ms);
> +       }
> +
> +       error = axiom_discover(ts);
> +       if (error)
> +               return dev_err_probe(dev, error, "Failed touchscreen discover\n");
> +
> +       input_dev = devm_input_allocate_device(ts->dev);
> +       if (!input_dev)
> +               return -ENOMEM;
> +
> +       input_dev->name = "TouchNetix axiom Touchscreen";
> +       input_dev->phys = "input/axiom_ts";
> +
> +       input_set_abs_params(input_dev, ABS_MT_POSITION_X, 0, 65535, 0, 0);
> +       input_set_abs_params(input_dev, ABS_MT_POSITION_Y, 0, 65535, 0, 0);
> +       input_set_abs_params(input_dev, ABS_MT_TOOL_TYPE, 0, MT_TOOL_MAX, 0, 0);
> +       input_set_abs_params(input_dev, ABS_MT_DISTANCE, 0, 127, 0, 0);
> +       input_set_abs_params(input_dev, ABS_MT_PRESSURE, 0, 127, 0, 0);
> +
> +       touchscreen_parse_properties(input_dev, true, &ts->prop);
> +
> +       /* Registers the axiom device as a touchscreen instead of a mouse pointer */
> +       error = input_mt_init_slots(input_dev, AXIOM_U41_MAX_TARGETS, INPUT_MT_DIRECT);
> +       if (error)
> +               return error;
> +
> +       /* Enables the raw data for up to 4 force channels to be sent to the input subsystem */
> +       set_bit(EV_REL, input_dev->evbit);
> +       set_bit(EV_MSC, input_dev->evbit);
> +       /* Declare that we support "RAW" Miscellaneous events */
> +       set_bit(MSC_RAW, input_dev->mscbit);
> +
> +       ts->input_dev = input_dev;
> +       input_set_drvdata(ts->input_dev, ts);
> +
> +       /* Ensure that all reports are initialised to not be present. */
> +       for (target = 0; target < AXIOM_U41_MAX_TARGETS; target++)
> +               ts->targets[target].state = AXIOM_TARGET_STATE_NOT_PRESENT;
> +
> +       error = input_register_device(input_dev);
> +       if (error)
> +               return dev_err_probe(ts->dev, error,
> +                                    "Could not register with Input Sub-system.\n");
> +
> +       error = devm_request_threaded_irq(dev, client->irq, NULL,
> +                                         axiom_irq, IRQF_ONESHOT, dev_name(dev), ts);
> +       if (error) {
> +               dev_info(dev, "Request irq failed, falling back to polling mode");
> +
> +               error = input_setup_polling(input_dev, axiom_i2c_poll);
> +               if (error)
> +                       return dev_err_probe(ts->dev, error, "Unable to set up polling mode\n");
> +
> +               if (!device_property_read_u32(ts->dev, "poll-interval", &poll_interval))
> +                       input_set_poll_interval(input_dev, poll_interval);
> +       }
> +
> +       return 0;
> +}
> +
> +static const struct i2c_device_id axiom_i2c_id_table[] = {
> +       { "ax54a" },
> +       { },
> +};
> +MODULE_DEVICE_TABLE(i2c, axiom_i2c_id_table);
> +
> +static const struct of_device_id axiom_i2c_of_match[] = {
> +       { .compatible = "touchnetix,ax54a", },
> +       { }
> +};
> +MODULE_DEVICE_TABLE(of, axiom_i2c_of_match);
> +
> +static struct i2c_driver axiom_i2c_driver = {
> +       .driver = {
> +                  .name = "axiom",
> +                  .of_match_table = axiom_i2c_of_match,
> +       },
> +       .id_table = axiom_i2c_id_table,
> +       .probe = axiom_i2c_probe,
> +};
> +module_i2c_driver(axiom_i2c_driver);
> +
> +MODULE_AUTHOR("Bart Prescott <bartp@baasheep.co.uk>");
> +MODULE_AUTHOR("Pedro Torruella <pedro.torruella@touchnetix.com>");
> +MODULE_AUTHOR("Mark Satterthwaite <mark.satterthwaite@touchnetix.com>");
> +MODULE_AUTHOR("Hannah Rossiter <hannah.rossiter@touchnetix.com>");
> +MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
> +MODULE_DESCRIPTION("TouchNetix axiom touchscreen I2C bus driver");
> +MODULE_LICENSE("GPL");
> --
> 2.25.1
>

Re: [PATCH v6 3/3] Input: Add TouchNetix axiom i2c touchscreen driver

[Dmitry Torokhov]

On Tue, Jan 30, 2024 at 05:32:54PM +0000, POPESCU Catalin wrote:
> On 25.01.24 17:58, Kamel Bouhara wrote:

> > +               u16 offset = (usage_id * AXIOM_U31_BYTES_PER_USAGE);
> > +               u8 id = rx_data[offset + 0];
> > +               u8 start_page = rx_data[offset + 1];
> > +               u8 num_pages = rx_data[offset + 2];
> > +               u32 max_offset = ((rx_data[offset + 3] & AXIOM_PAGE_OFFSET_MASK) + 1) * 2;
> > +
> > +               if (!num_pages)
> > +                       usage_table[id].is_report = true;
> please add an else statement to set is_report to false.

Better written as:

		usage_table[id].is_report = num_pages == 0;

or

		usage_table[id].is_report = !num_pages;

Thanks.

-- 
Dmitry

Re: [PATCH v6 3/3] Input: Add TouchNetix axiom i2c touchscreen driver

[Kamel Bouhara]

On Tue, Jan 30, 2024 at 05:32:54PM +0000, POPESCU Catalin wrote:
> Hi Kamel,
>

Hi,

> I have a few remarks regarding the population of the usage table
> function, see inline.
>
> On 25.01.24 17:58, Kamel Bouhara wrote:
> > [Some people who received this message don't often get email from kamel.bouhara@bootlin.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> >
> > This email is not from Hexagon’s Office 365 instance. Please be careful while clicking links, opening attachments, or replying to this email.
> >
> >
> > Add a new driver for the TouchNetix's axiom family of
> > touchscreen controllers. This driver only supports i2c
> > and can be later adapted for SPI and USB support.
> >
> > Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
> > ---
> >   MAINTAINERS                                  |   1 +
> >   drivers/input/touchscreen/Kconfig            |  12 +
> >   drivers/input/touchscreen/Makefile           |   1 +
> >   drivers/input/touchscreen/touchnetix_axiom.c | 664 +++++++++++++++++++
> >   4 files changed, 678 insertions(+)
> >   create mode 100644 drivers/input/touchscreen/touchnetix_axiom.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 4752d8436dbb..337ddac6c74b 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -21436,6 +21436,7 @@ M:      Kamel Bouhara <kamel.bouhara@bootlin.com>
> >   L:     linux-input@vger.kernel.org
> >   S:     Maintained
> >   F:     Documentation/devicetree/bindings/input/touchscreen/touchnetix,ax54a.yaml
> > +F:     drivers/input/touchscreen/touchnetix_axiom.c
> >
> >   THUNDERBOLT DMA TRAFFIC TEST DRIVER
> >   M:     Isaac Hazan <isaac.hazan@intel.com>
> > diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> > index e3e2324547b9..f36bee8d8696 100644
> > --- a/drivers/input/touchscreen/Kconfig
> > +++ b/drivers/input/touchscreen/Kconfig
> > @@ -803,6 +803,18 @@ config TOUCHSCREEN_MIGOR
> >            To compile this driver as a module, choose M here: the
> >            module will be called migor_ts.
> >
> > +config TOUCHSCREEN_TOUCHNETIX_AXIOM
> > +       tristate "TouchNetix AXIOM based touchscreen controllers"
> > +       depends on I2C
> > +       help
> > +         Say Y here if you have a axiom touchscreen connected to
> > +         your system.
> > +
> > +         If unsure, say N.
> > +
> > +         To compile this driver as a module, choose M here: the
> > +         module will be called axiom.
> > +
> >   config TOUCHSCREEN_TOUCHRIGHT
> >          tristate "Touchright serial touchscreen"
> >          select SERIO
> > diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> > index 62bd24f3ac8e..8e32a2df5e18 100644
> > --- a/drivers/input/touchscreen/Makefile
> > +++ b/drivers/input/touchscreen/Makefile
> > @@ -88,6 +88,7 @@ obj-$(CONFIG_TOUCHSCREEN_SUR40)               += sur40.o
> >   obj-$(CONFIG_TOUCHSCREEN_SURFACE3_SPI) += surface3_spi.o
> >   obj-$(CONFIG_TOUCHSCREEN_TI_AM335X_TSC)        += ti_am335x_tsc.o
> >   obj-$(CONFIG_TOUCHSCREEN_TOUCHIT213)   += touchit213.o
> > +obj-$(CONFIG_TOUCHSCREEN_TOUCHNETIX_AXIOM)     += touchnetix_axiom.o
> >   obj-$(CONFIG_TOUCHSCREEN_TOUCHRIGHT)   += touchright.o
> >   obj-$(CONFIG_TOUCHSCREEN_TOUCHWIN)     += touchwin.o
> >   obj-$(CONFIG_TOUCHSCREEN_TS4800)       += ts4800-ts.o
> > diff --git a/drivers/input/touchscreen/touchnetix_axiom.c b/drivers/input/touchscreen/touchnetix_axiom.c
> > new file mode 100644
> > index 000000000000..cbb5525b83f5
> > --- /dev/null
> > +++ b/drivers/input/touchscreen/touchnetix_axiom.c
> > @@ -0,0 +1,664 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * TouchNetix axiom Touchscreen Driver
> > + *
> > + * Copyright (C) 2020-2023 TouchNetix Ltd.
> > + *
> > + * Author(s): Bart Prescott <bartp@baasheep.co.uk>
> > + *            Pedro Torruella <pedro.torruella@touchnetix.com>
> > + *            Mark Satterthwaite <mark.satterthwaite@touchnetix.com>
> > + *            Hannah Rossiter <hannah.rossiter@touchnetix.com>
> > + *            Kamel Bouhara <kamel.bouhara@bootlin.com>
> > + *
> > + */
> > +#include <linux/bitfield.h>
> > +#include <linux/crc16.h>
> > +#include <linux/delay.h>
> > +#include <linux/device.h>
> > +#include <linux/gpio/consumer.h>
> > +#include <linux/i2c.h>
> > +#include <linux/input.h>
> > +#include <linux/input/mt.h>
> > +#include <linux/input/touchscreen.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/regmap.h>
> > +
> > +#include <asm/unaligned.h>
> > +#define AXIOM_PROX_LEVEL               -128
> > +#define AXIOM_DMA_OPS_DELAY_USEC       250
> > +/*
> > + * Register group u31 has 2 pages for usage table entries.
> > + */
> > +#define AXIOM_U31_MAX_USAGES           0xff
> > +#define AXIOM_U31_BYTES_PER_USAGE      6
> > +#define AXIOM_U31_PAGE0_LENGTH         0x0C
> > +#define AXIOM_U31_BOOTMODE_MASK                BIT(7)
> > +#define AXIOM_U31_DEVID_MASK           GENMASK(14, 0)
> > +
> > +#define AXIOM_MAX_REPORT_LEN           0x7f
> > +
> > +#define AXIOM_CMD_HEADER_READ_MASK     BIT(15)
> > +#define AXIOM_U41_MAX_TARGETS          10
> > +
> > +#define AXIOM_U46_AUX_CHANNELS         4
> > +#define AXIOM_U46_AUX_MASK             GENMASK(11, 0)
> > +
> > +#define AXIOM_COMMS_MAX_USAGE_PAGES    3
> > +#define AXIOM_COMMS_PAGE_SIZE          256
> > +#define AXIOM_COMMS_REPORT_LEN_MASK    GENMASK(6, 0)
> > +
> > +#define AXIOM_REPORT_USAGE_ID          0x34
> > +#define AXIOM_DEVINFO_USAGE_ID         0x31
> > +#define AXIOM_USAGE_2HB_REPORT_ID      0x01
> > +#define AXIOM_USAGE_2AUX_REPORT_ID     0x46
> > +#define AXIOM_USAGE_2DCTS_REPORT_ID    0x41
> > +
> > +#define AXIOM_PAGE_OFFSET_MASK         GENMASK(6, 0)
> > +
> > +struct axiom_devinfo {
> > +       __le16 device_id;
> > +       u8 fw_minor;
> > +       u8 fw_major;
> > +       u8 fw_info_extra;
> > +       u8 tcp_revision;
> > +       u8 bootloader_fw_minor;
> > +       u8 bootloader_fw_major;
> > +       __le16 jedec_id;
> > +       u8 num_usages;
> > +} __packed;
> > +
> > +/*
> > + * Describes parameters of a specific usage, essentially a single element of
> > + * the "Usage Table"
> > + */
> > +struct axiom_usage_entry {
> > +       u8 id;
> > +       u8 is_report;
> > +       u8 start_page;
> > +       u8 num_pages;
> > +};
> > +
> > +/*
> > + * Represents state of a touch or target when detected prior to a touch (eg.
> > + * hover or proximity events).
> > + */
> > +enum axiom_target_state {
> > +       AXIOM_TARGET_STATE_NOT_PRESENT = 0,
> > +       AXIOM_TARGET_STATE_PROX = 1,
> > +       AXIOM_TARGET_STATE_HOVER = 2,
> > +       AXIOM_TARGET_STATE_TOUCHING = 3,
> > +};
> > +
> > +struct axiom_u41_target {
> > +       enum axiom_target_state state;
> > +       u16 x;
> > +       u16 y;
> > +       s8 z;
> > +       bool insert;
> > +       bool touch;
> > +};
> > +
> > +struct axiom_target_report {
> > +       u8 index;
> > +       u8 present;
> > +       u16 x;
> > +       u16 y;
> > +       s8 z;
> > +};
> > +
> > +struct axiom_cmd_header {
> > +       __le16 target_address;
> > +       __le16 length;
> > +} __packed;
> > +
> > +struct axiom_data {
> > +       struct axiom_devinfo devinfo;
> > +       struct device *dev;
> > +       struct gpio_desc *reset_gpio;
> > +       struct i2c_client *client;
> > +       struct input_dev *input_dev;
> > +       u32 max_report_len;
> > +       u8 rx_buf[AXIOM_COMMS_MAX_USAGE_PAGES * AXIOM_COMMS_PAGE_SIZE];
> > +       struct axiom_u41_target targets[AXIOM_U41_MAX_TARGETS];
> > +       struct axiom_usage_entry usage_table[AXIOM_U31_MAX_USAGES];
> > +       bool usage_table_populated;
> > +       struct regulator *vdda;
> > +       struct regulator *vddi;
> > +       struct regmap *regmap;
> > +       struct touchscreen_properties   prop;
> > +};
> > +
> > +static const struct regmap_config axiom_i2c_regmap_config = {
> > +       .reg_bits = 32,
> > +       .reg_format_endian = REGMAP_ENDIAN_LITTLE,
> > +       .val_bits = 8,
> > +       .val_format_endian = REGMAP_ENDIAN_LITTLE,
> > +};
> > +
> > +/*
> > + * axiom devices are typically configured to report touches at a rate
> > + * of 100Hz (10ms) for systems that require polling for reports.
> > + * When reports are polled, it will be expected to occasionally
> > + * observe the overflow bit being set in the reports.
> > + * This indicates that reports are not being read fast enough.
> > + */
> > +#define POLL_INTERVAL_DEFAULT_MS 10
> > +
> > +/* Translate usage/page/offset triplet into physical address. */
> > +static u16 axiom_usage_to_target_address(struct axiom_data *ts, u8 usage, u8 page,
> > +                                        char offset)
> > +{
> > +       /* At the moment the convention is that u31 is always at physical address 0x0 */
> > +       if (!ts->usage_table_populated) {
> > +               if (usage == AXIOM_DEVINFO_USAGE_ID)
> > +                       return ((page << 8) + offset);
> > +               else
> > +                       return 0xffff;
> > +       }
> > +
> > +       if (page >= ts->usage_table[usage].num_pages) {
> > +               dev_err(ts->dev, "Invalid usage table! usage: u%02x, page: %02x, offset: %02x\n",
> > +                       usage, page, offset);
> > +               return 0xffff;
> > +       }
> > +
> > +       return ((ts->usage_table[usage].start_page + page) << 8) + offset;
> > +}
> > +
> > +static int axiom_read(struct axiom_data *ts, u8 usage, u8 page, void *buf, u16 len)
> > +{
> > +       struct axiom_cmd_header cmd_header;
> > +       int ret;
> > +
> > +       cmd_header.target_address = cpu_to_le16(axiom_usage_to_target_address(ts, usage, page, 0));
> > +       cmd_header.length = cpu_to_le16(len | AXIOM_CMD_HEADER_READ_MASK);
> > +
> > +       __le32 preamble = get_unaligned_le32((u8 *)&cmd_header);
> > +
> > +       ret = regmap_write(ts->regmap, preamble, 0);
> > +       if (ret) {
> > +               dev_err(ts->dev, "failed to write preamble, error %d\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       ret = regmap_raw_read(ts->regmap, 0, buf, len);
> > +       if (ret) {
> > +               dev_err(ts->dev, "failed to read target address %04x, error %d\n",
> > +                       cmd_header.target_address, ret);
> > +               return ret;
> > +       }
> > +
> > +       /* Wait device's DMA operations */
> > +       usleep_range(AXIOM_DMA_OPS_DELAY_USEC, AXIOM_DMA_OPS_DELAY_USEC + 50);
> > +
> > +       return 0;
> > +}
> > +
> > +/*
> > + * One of the main purposes for reading the usage table is to identify
> > + * which usages reside at which target address.
> > + * When performing subsequent reads or writes to AXIOM, the target address
> > + * is used to specify which usage is being accessed.
> > + * Consider the following discovery code which will build up the usage table.
> > + */
> > +static u32 axiom_populate_usage_table(struct axiom_data *ts)
> > +{
> > +       struct axiom_usage_entry *usage_table;
> > +       u8 *rx_data = ts->rx_buf;
> > +       u32 max_report_len;
> please force initialization of max_report_len to 0.

Fixed, thanks !

> > +       u32 usage_id;
> > +       int error;
> > +
> > +       usage_table = ts->usage_table;
> > +
> > +       /* Read the second page of usage u31 to get the usage table */
> > +       error = axiom_read(ts, AXIOM_DEVINFO_USAGE_ID, 1, rx_data,
> > +                          (AXIOM_U31_BYTES_PER_USAGE * ts->devinfo.num_usages));
> > +
> > +       if (error)
> > +               return error;
> > +
> > +       for (usage_id = 1; usage_id < AXIOM_U31_MAX_USAGES; usage_id++) {
>
> usage_id should start at 0, since it's used to compute the offset in the
> page 1 of u31.
> if you start with usage_id=1, then whatever is the 1st usage of the
> usage table gets jumped out...

You're right, first usage id is u01, I think that's what induced my
mistake here.

> also, you should stop the loop at num_usages, otherwise you're going to
> read garbage after the end of rx_data buffer...
> this garbage would end up in wrong computation of max_report_len then in
> failure of reading any touch report.
>

Reading num_usages is indeed a more clever choice here, thanks again !

> > +               u16 offset = (usage_id * AXIOM_U31_BYTES_PER_USAGE);
> > +               u8 id = rx_data[offset + 0];
> > +               u8 start_page = rx_data[offset + 1];
> > +               u8 num_pages = rx_data[offset + 2];
> > +               u32 max_offset = ((rx_data[offset + 3] & AXIOM_PAGE_OFFSET_MASK) + 1) * 2;
> > +
> > +               if (!num_pages)
> > +                       usage_table[id].is_report = true;
> please add an else statement to set is_report to false.

Fixed in v7, thanks.

> > +
> > +               /* Store the entry into the usage table */
> > +               usage_table[id].id = id;
> > +               usage_table[id].start_page = start_page;
> > +               usage_table[id].num_pages = num_pages;
> > +
> > +               dev_dbg(ts->dev, "Usage u%02x Info: %*ph\n", id, AXIOM_U31_BYTES_PER_USAGE,
> > +                       &rx_data[offset]);
> > +
> > +               /* Identify the max report length the module will receive */
> > +               if (usage_table[id].is_report && max_offset > max_report_len)
> > +                       max_report_len = max_offset;
> > +       }
> > +
> > +       ts->usage_table_populated = true;
> > +
> > +       return max_report_len;
> > +}
> > +
> > +static int axiom_discover(struct axiom_data *ts)
> > +{
> > +       int error;
> > +
> > +       /*
> > +        * Fetch the first page of usage u31 to get the
> > +        * device information and the number of usages
> > +        */
> > +       error = axiom_read(ts, AXIOM_DEVINFO_USAGE_ID, 0, &ts->devinfo, AXIOM_U31_PAGE0_LENGTH);
> > +       if (error)
> > +               return error;
> > +
> > +       dev_dbg(ts->dev, "  Boot Mode      : %s\n",
> > +               FIELD_GET(AXIOM_U31_BOOTMODE_MASK,
> > +                         le16_to_cpu(ts->devinfo.device_id)) ? "BLP" : "TCP");
> > +       dev_dbg(ts->dev, "  Device ID      : %04lx\n",
> > +               FIELD_GET(AXIOM_U31_DEVID_MASK, le16_to_cpu(ts->devinfo.device_id)));
> > +       dev_dbg(ts->dev, "  Firmware Rev   : %02x.%02x\n", ts->devinfo.fw_major,
> > +               ts->devinfo.fw_minor);
> > +       dev_dbg(ts->dev, "  Bootloader Rev : %02x.%02x\n", ts->devinfo.bootloader_fw_major,
> > +               ts->devinfo.bootloader_fw_minor);
> > +       dev_dbg(ts->dev, "  FW Extra Info  : %04x\n", ts->devinfo.fw_info_extra);
> > +       dev_dbg(ts->dev, "  Silicon        : %04x\n", le16_to_cpu(ts->devinfo.jedec_id));
> > +       dev_dbg(ts->dev, "  Number usages        : %04x\n", ts->devinfo.num_usages);
> > +
> > +       ts->max_report_len = axiom_populate_usage_table(ts);
> > +       if (!ts->max_report_len || !ts->devinfo.num_usages ||
> > +           ts->max_report_len > AXIOM_MAX_REPORT_LEN) {
> > +               dev_err(ts->dev, "Invalid report length or usages number");
> > +               return -EINVAL;
> > +       }
> > +
> > +       dev_dbg(ts->dev, "Max Report Length: %u\n", ts->max_report_len);
> > +
> > +       return 0;
> > +}
> > +
> > +/*
> > + * Support function to axiom_process_u41_report.
> > + * Generates input-subsystem events for every target.
> > + * After calling this function the caller shall issue
> > + * a Sync to the input sub-system.
> > + */
> > +static bool axiom_process_u41_report_target(struct axiom_data *ts,
> > +                                           struct axiom_target_report *target)
> > +{
> > +       struct input_dev *input_dev = ts->input_dev;
> > +       struct axiom_u41_target *target_prev_state;
> > +       enum axiom_target_state current_state;
> > +       int slot;
> > +
> > +       /* Verify the target index */
> > +       if (target->index >= AXIOM_U41_MAX_TARGETS) {
> > +               dev_err(ts->dev, "Invalid target index! %u\n", target->index);
> > +               return false;
> > +       }
> > +
> > +       target_prev_state = &ts->targets[target->index];
> > +
> > +       current_state = AXIOM_TARGET_STATE_NOT_PRESENT;
> > +
> > +       if (target->present) {
> > +               if (target->z >= 0)
> > +                       current_state = AXIOM_TARGET_STATE_TOUCHING;
> > +               else if (target->z > AXIOM_PROX_LEVEL && target->z < 0)
> > +                       current_state = AXIOM_TARGET_STATE_HOVER;
> > +               else if (target->z == AXIOM_PROX_LEVEL)
> > +                       current_state = AXIOM_TARGET_STATE_PROX;
> > +       }
> > +
> > +       if (target_prev_state->state == current_state &&
> > +           target_prev_state->x == target->x &&
> > +           target_prev_state->y == target->y &&
> > +           target_prev_state->z == target->z)
> > +               return false;
> > +
> > +       slot = target->index;
> > +
> > +       dev_dbg(ts->dev, "U41 Target T%u, slot:%u present:%u, x:%u, y:%u, z:%d\n",
> > +               target->index, slot, target->present,
> > +               target->x, target->y, target->z);
> > +
> > +       switch (current_state) {
> > +       case AXIOM_TARGET_STATE_NOT_PRESENT:
> > +       case AXIOM_TARGET_STATE_PROX:
> > +               if (!target_prev_state->insert)
> > +                       break;
> > +               target_prev_state->insert = false;
> > +               input_mt_slot(input_dev, slot);
> > +
> > +               if (!slot)
> > +                       input_report_key(input_dev, BTN_TOUCH, 0);
> > +
> > +               input_mt_report_slot_inactive(input_dev);
> > +               /*
> > +                * make sure the previous coordinates are
> > +                * all off screen when the finger comes back
> > +                */
> > +               target->x = 65535;
> > +               target->y = 65535;
> > +               target->z = AXIOM_PROX_LEVEL;
> > +               break;
> > +       case AXIOM_TARGET_STATE_HOVER:
> > +       case AXIOM_TARGET_STATE_TOUCHING:
> > +               target_prev_state->insert = true;
> > +               input_mt_slot(input_dev, slot);
> > +               input_report_abs(input_dev, ABS_MT_TRACKING_ID, slot);
> > +               input_report_abs(input_dev, ABS_MT_POSITION_X, target->x);
> > +               input_report_abs(input_dev, ABS_MT_POSITION_Y, target->y);
> > +
> > +               if (current_state == AXIOM_TARGET_STATE_TOUCHING) {
> > +                       input_report_abs(input_dev, ABS_MT_DISTANCE, 0);
> > +                       input_report_abs(input_dev, ABS_DISTANCE, 0);
> > +                       input_report_abs(input_dev, ABS_MT_PRESSURE, target->z);
> > +                       input_report_abs(input_dev, ABS_PRESSURE, target->z);
> > +               } else {
> > +                       input_report_abs(input_dev, ABS_MT_DISTANCE, -target->z);
> > +                       input_report_abs(input_dev, ABS_DISTANCE, -target->z);
> > +                       input_report_abs(input_dev, ABS_MT_PRESSURE, 0);
> > +                       input_report_abs(input_dev, ABS_PRESSURE, 0);
> > +               }
> > +
> > +               if (!slot)
> > +                       input_report_key(input_dev, BTN_TOUCH, (current_state ==
> > +                                        AXIOM_TARGET_STATE_TOUCHING));
> > +               break;
> > +       default:
> > +               break;
> > +       }
> > +
> > +       target_prev_state->state = current_state;
> > +       target_prev_state->x = target->x;
> > +       target_prev_state->y = target->y;
> > +       target_prev_state->z = target->z;
> > +
> > +       return true;
> > +}
> > +
> > +/*
> > + * U41 is the output report of the 2D CTS and contains the status of targets
> > + * (including contacts and pre-contacts) along with their X,Y,Z values.
> > + * When a target has been removed (no longer detected),
> > + * the corresponding X,Y,Z values will be zeroed.
> > + */
> > +static bool axiom_process_u41_report(struct axiom_data *ts, u8 *rx_buf)
> > +{
> > +       struct axiom_target_report target;
> > +       bool update_done = false;
> > +       u16 target_status;
> > +       int i;
> > +
> > +       target_status = get_unaligned_le16(rx_buf + 1);
> > +
> > +       for (i = 0; i < AXIOM_U41_MAX_TARGETS; i++) {
> > +               u8 *target_step = &rx_buf[i * 4];
> > +
> > +               target.index = i;
> > +               target.present = ((target_status & (1 << i)) != 0) ? 1 : 0;
> > +               target.x = get_unaligned_le16(target_step + 3);
> > +               target.y = get_unaligned_le16(target_step + 5);
> > +               target.z = (s8)(rx_buf[i + 43]);
> > +               update_done |= axiom_process_u41_report_target(ts, &target);
> > +       }
> > +
> > +       return update_done;
> > +}
> > +
> > +/*
> > + * U46 report contains a low level measurement data generated by the capacitive
> > + * displacement sensor (CDS) algorithms from the auxiliary channels.
> > + * This information is useful when tuning multi-press to assess mechanical
> > + * consistency in the unit's construction.
> > + */
> > +static void axiom_process_u46_report(struct axiom_data *ts, u8 *rx_buf)
> > +{
> > +       struct input_dev *input_dev = ts->input_dev;
> > +       u32 event_value;
> > +       u16 aux_value;
> > +       int i;
> > +
> > +       for (i = 0; i < AXIOM_U46_AUX_CHANNELS; i++) {
> > +               u8 *target_step = &rx_buf[i * 2];
> > +
> > +               aux_value = get_unaligned_le16(target_step + 1) & AXIOM_U46_AUX_MASK;
> > +               event_value = (i << 16) | (aux_value);
> > +               input_event(input_dev, EV_MSC, MSC_RAW, event_value);
> > +       }
> > +}
> > +
> > +/*
> > + * Validates the crc and demultiplexes the axiom reports to the appropriate
> > + * report handler
> > + */
> > +static int axiom_handle_events(struct axiom_data *ts)
> > +{
> > +       struct input_dev *input_dev = ts->input_dev;
> > +       u8 *report_data = ts->rx_buf;
> > +       struct device *dev = ts->dev;
> > +       u16 crc_report;
> > +       u16 crc_calc;
> > +       int error;
> > +       u8 len;
> > +
> > +       error = axiom_read(ts, AXIOM_REPORT_USAGE_ID, 0, report_data, ts->max_report_len);
> > +       if (error)
> > +               return error;
> > +
> > +       len = (report_data[0] & AXIOM_COMMS_REPORT_LEN_MASK) << 1;
> > +       if (len <= 2) {
> > +               dev_err(dev, "Zero length report discarded.\n");
> > +               return -ENODATA;
> > +       }
> > +
> > +       /* Validate the report CRC */
> > +       u8 *crc_bytes = &report_data[len];
> > +
> > +       crc_report = get_unaligned_le16(crc_bytes - 2);
> > +       /* Length is in 16 bit words and remove the size of the CRC16 itself */
> > +       crc_calc = crc16(0, report_data, (len - 2));
> > +
> > +       if (crc_calc != crc_report) {
> > +               dev_err(dev,
> > +                       "CRC mismatch! Expected: %#x, Calculated CRC: %#x.\n",
> > +                       crc_report, crc_calc);
> > +               return -EINVAL;
> > +       }
> > +
> > +       switch (report_data[1]) {
> > +       case AXIOM_USAGE_2DCTS_REPORT_ID:
> > +               if (axiom_process_u41_report(ts, &report_data[1])) {
> > +                       input_mt_sync_frame(input_dev);
> > +                       input_sync(input_dev);
> > +               }
> > +               break;
> > +
> > +       case AXIOM_USAGE_2AUX_REPORT_ID:
> > +               /* This is an aux report (force) */
> > +               axiom_process_u46_report(ts, &report_data[1]);
> > +               input_mt_sync(input_dev);
> > +               input_sync(input_dev);
> > +               break;
> > +
> > +       case AXIOM_USAGE_2HB_REPORT_ID:
> > +               /* This is a heartbeat report */
> > +               break;
> > +       default:
> > +               return -EINVAL;
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +static void axiom_i2c_poll(struct input_dev *input_dev)
> > +{
> > +       struct axiom_data *ts = input_get_drvdata(input_dev);
> > +
> > +       axiom_handle_events(ts);
> > +}
> > +
> > +static irqreturn_t axiom_irq(int irq, void *dev_id)
> > +{
> > +       struct axiom_data *ts = dev_id;
> > +
> > +       axiom_handle_events(ts);
> > +
> > +       return IRQ_HANDLED;
> > +}
> > +
> > +static void axiom_reset(struct gpio_desc *reset_gpio)
> > +{
> > +       gpiod_set_value_cansleep(reset_gpio, 1);
> > +       usleep_range(1000, 2000);
> > +       gpiod_set_value_cansleep(reset_gpio, 0);
> > +       msleep(110);
> > +}
> > +
> > +static int axiom_i2c_probe(struct i2c_client *client)
> > +{
> > +       u32 poll_interval = POLL_INTERVAL_DEFAULT_MS;
> > +       struct device *dev = &client->dev;
> > +       struct input_dev *input_dev;
> > +       struct axiom_data *ts;
> > +       u32 startup_delay_ms;
> > +       int target;
> > +       int error;
> > +
> > +       ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
> > +       if (!ts)
> > +               return -ENOMEM;
> > +
> > +       i2c_set_clientdata(client, ts);
> > +       ts->client = client;
> > +       ts->dev = dev;
> > +
> > +       ts->regmap = devm_regmap_init_i2c(client, &axiom_i2c_regmap_config);
> > +       error = PTR_ERR_OR_ZERO(ts->regmap);
> > +       if (error) {
> > +               dev_err(dev, "Failed to initialize regmap: %d\n", error);
> > +               return error;
> > +       }
> > +
> > +       ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> > +       if (IS_ERR(ts->reset_gpio))
> > +               return dev_err_probe(dev, PTR_ERR(ts->reset_gpio), "failed to get reset GPIO\n");
> > +
> > +       if (ts->reset_gpio)
> > +               axiom_reset(ts->reset_gpio);
> > +
> > +       ts->vddi = devm_regulator_get_optional(dev, "vddi");
> > +       if (!IS_ERR(ts->vddi)) {
> > +               error = devm_regulator_get_enable(dev, "vddi");
> > +               if (error)
> > +                       return dev_err_probe(&client->dev, error,
> > +                                            "Failed to enable vddi regulator\n");
> > +       }
> > +
> > +       ts->vdda = devm_regulator_get_optional(dev, "vdda");
> > +       if (!IS_ERR(ts->vdda)) {
> > +               error = devm_regulator_get_enable(dev, "vdda");
> > +               if (error)
> > +                       return dev_err_probe(&client->dev, error,
> > +                                            "Failed to enable vdda regulator\n");
> > +               if (!device_property_read_u32(dev, "startup-time-ms", &startup_delay_ms))
> > +                       msleep(startup_delay_ms);
> > +       }
> > +
> > +       error = axiom_discover(ts);
> > +       if (error)
> > +               return dev_err_probe(dev, error, "Failed touchscreen discover\n");
> > +
> > +       input_dev = devm_input_allocate_device(ts->dev);
> > +       if (!input_dev)
> > +               return -ENOMEM;
> > +
> > +       input_dev->name = "TouchNetix axiom Touchscreen";
> > +       input_dev->phys = "input/axiom_ts";
> > +
> > +       input_set_abs_params(input_dev, ABS_MT_POSITION_X, 0, 65535, 0, 0);
> > +       input_set_abs_params(input_dev, ABS_MT_POSITION_Y, 0, 65535, 0, 0);
> > +       input_set_abs_params(input_dev, ABS_MT_TOOL_TYPE, 0, MT_TOOL_MAX, 0, 0);
> > +       input_set_abs_params(input_dev, ABS_MT_DISTANCE, 0, 127, 0, 0);
> > +       input_set_abs_params(input_dev, ABS_MT_PRESSURE, 0, 127, 0, 0);
> > +
> > +       touchscreen_parse_properties(input_dev, true, &ts->prop);
> > +
> > +       /* Registers the axiom device as a touchscreen instead of a mouse pointer */
> > +       error = input_mt_init_slots(input_dev, AXIOM_U41_MAX_TARGETS, INPUT_MT_DIRECT);
> > +       if (error)
> > +               return error;
> > +
> > +       /* Enables the raw data for up to 4 force channels to be sent to the input subsystem */
> > +       set_bit(EV_REL, input_dev->evbit);
> > +       set_bit(EV_MSC, input_dev->evbit);
> > +       /* Declare that we support "RAW" Miscellaneous events */
> > +       set_bit(MSC_RAW, input_dev->mscbit);
> > +
> > +       ts->input_dev = input_dev;
> > +       input_set_drvdata(ts->input_dev, ts);
> > +
> > +       /* Ensure that all reports are initialised to not be present. */
> > +       for (target = 0; target < AXIOM_U41_MAX_TARGETS; target++)
> > +               ts->targets[target].state = AXIOM_TARGET_STATE_NOT_PRESENT;
> > +
> > +       error = input_register_device(input_dev);
> > +       if (error)
> > +               return dev_err_probe(ts->dev, error,
> > +                                    "Could not register with Input Sub-system.\n");
> > +
> > +       error = devm_request_threaded_irq(dev, client->irq, NULL,
> > +                                         axiom_irq, IRQF_ONESHOT, dev_name(dev), ts);
> > +       if (error) {
> > +               dev_info(dev, "Request irq failed, falling back to polling mode");
> > +
> > +               error = input_setup_polling(input_dev, axiom_i2c_poll);
> > +               if (error)
> > +                       return dev_err_probe(ts->dev, error, "Unable to set up polling mode\n");
> > +
> > +               if (!device_property_read_u32(ts->dev, "poll-interval", &poll_interval))
> > +                       input_set_poll_interval(input_dev, poll_interval);
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +static const struct i2c_device_id axiom_i2c_id_table[] = {
> > +       { "ax54a" },
> > +       { },
> > +};
> > +MODULE_DEVICE_TABLE(i2c, axiom_i2c_id_table);
> > +
> > +static const struct of_device_id axiom_i2c_of_match[] = {
> > +       { .compatible = "touchnetix,ax54a", },
> > +       { }
> > +};
> > +MODULE_DEVICE_TABLE(of, axiom_i2c_of_match);
> > +
> > +static struct i2c_driver axiom_i2c_driver = {
> > +       .driver = {
> > +                  .name = "axiom",
> > +                  .of_match_table = axiom_i2c_of_match,
> > +       },
> > +       .id_table = axiom_i2c_id_table,
> > +       .probe = axiom_i2c_probe,
> > +};
> > +module_i2c_driver(axiom_i2c_driver);
> > +
> > +MODULE_AUTHOR("Bart Prescott <bartp@baasheep.co.uk>");
> > +MODULE_AUTHOR("Pedro Torruella <pedro.torruella@touchnetix.com>");
> > +MODULE_AUTHOR("Mark Satterthwaite <mark.satterthwaite@touchnetix.com>");
> > +MODULE_AUTHOR("Hannah Rossiter <hannah.rossiter@touchnetix.com>");
> > +MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
> > +MODULE_DESCRIPTION("TouchNetix axiom touchscreen I2C bus driver");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.25.1
> >
>

--
Kamel Bouhara, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com