[PATCH v5 0/2] input: misc: Add IBM Operation Panel driver

[PATCH v5 0/2] input: misc: Add IBM Operation Panel driver

[Eddie James]

This series adds support for input from the IBM Operation Panel, which is
a simple controller with three buttons and an LCD display meant for
interacting with a server. It's connected over I2C, typically to a service
processor. This series only supports the input from the panel, in which the
panel masters the I2C bus and sends data to the host system when someone
presses a button on the controller.

Changes since v4:
 - Fix missing input include in dt binding resulting in make check failure

Changes since v3:
 - Document linux,keycodes property
 - Use linux,keycodes property to map the buttons
 - Put the checksumming in a seperate function
 - Don't do unneccessary input_unregister calls
 - Minor cleanup and add debug data to dev_dbg calls

Changes since v2:
 - Add "additionalProperties: false" to dts doc
 - Refactor switch statement in the input driver; check command size and call
   the processing function within the STOP case
 - Use a different definition name for Aspeed interrupt status mask

Changes since v1:
 - Redo DTS documentation example to use I2C_OWN_SLAVE_ADDRESS
 - Reject commands received in the input driver that are too long
 - Add a definition for the interrupt status mask in the Aspeed I2C driver
 - Use I2C_OWN_SLAVE_ADDRESS for both dts additions

Eddie James (2):
  dt-bindings: input: Add documentation for IBM Operation Panel
  input: misc: Add IBM Operation Panel driver

 .../bindings/input/ibm,op-panel.yaml          |  50 +++++
 MAINTAINERS                                   |   7 +
 drivers/input/misc/Kconfig                    |  18 ++
 drivers/input/misc/Makefile                   |   1 +
 drivers/input/misc/ibm-panel.c                | 198 ++++++++++++++++++
 5 files changed, 274 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/ibm,op-panel.yaml
 create mode 100644 drivers/input/misc/ibm-panel.c

-- 
2.31.1

[PATCH v5 1/2] dt-bindings: input: Add documentation for IBM Operation Panel

[Eddie James]

Document the bindings for the IBM Operation Panel, which provides
a simple interface to control a server. It has a display and three
buttons.
Also update MAINTAINERS for the new file.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Joel Stanley <joel@jms.id.au>
---
 .../bindings/input/ibm,op-panel.yaml          | 50 +++++++++++++++++++
 MAINTAINERS                                   |  6 +++
 2 files changed, 56 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/ibm,op-panel.yaml

diff --git a/Documentation/devicetree/bindings/input/ibm,op-panel.yaml b/Documentation/devicetree/bindings/input/ibm,op-panel.yaml
new file mode 100644
index 000000000000..29a1879e356d
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/ibm,op-panel.yaml
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/ibm,op-panel.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: IBM Operation Panel
+
+maintainers:
+  - Eddie James <eajames@linux.ibm.com>
+
+allOf:
+  - $ref: input.yaml#
+
+description: |
+  The IBM Operation Panel provides a simple interface to control the connected
+  server. It has a display and three buttons: two directional arrows and one
+  'Enter' button.
+
+properties:
+  compatible:
+    const: ibm,op-panel
+
+  reg:
+    maxItems: 1
+
+  linux,keycodes:
+    minItems: 1
+    maxItems: 3
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/i2c/i2c.h>
+    #include <dt-bindings/input/input.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        ibm-op-panel@62 {
+            compatible = "ibm,op-panel";
+            reg = <(0x62 | I2C_OWN_SLAVE_ADDRESS)>;
+            linux,keycodes = <KEY_UP>, <KEY_DOWN>, <KEY_ENTER>;
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 2180312fe0a4..4dc90f22eb54 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9642,6 +9642,12 @@ S:	Orphan
 F:	Documentation/ia64/
 F:	arch/ia64/
 
+IBM Operation Panel Input Driver
+M:	Eddie James <eajames@linux.ibm.com>
+L:	linux-input@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/input/ibm,op-panel.yaml
+
 IBM Power 842 compression accelerator
 M:	Haren Myneni <haren@us.ibm.com>
 S:	Supported
-- 
2.31.1

[PATCH v5 2/2] input: misc: Add IBM Operation Panel driver

[Eddie James]

Add a driver to get the button events from the panel and provide
them to userspace with the input subsystem. The panel is
connected with I2C and controls the bus, so the driver registers
as an I2C slave device.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com> # I2C slave parts
---
 MAINTAINERS                    |   1 +
 drivers/input/misc/Kconfig     |  18 +++
 drivers/input/misc/Makefile    |   1 +
 drivers/input/misc/ibm-panel.c | 198 +++++++++++++++++++++++++++++++++
 4 files changed, 218 insertions(+)
 create mode 100644 drivers/input/misc/ibm-panel.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 4dc90f22eb54..aec90a44c044 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9647,6 +9647,7 @@ M:	Eddie James <eajames@linux.ibm.com>
 L:	linux-input@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/input/ibm,op-panel.yaml
+F:	drivers/input/misc/ibm-panel.c
 
 IBM Power 842 compression accelerator
 M:	Haren Myneni <haren@us.ibm.com>
diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index a18ab7358d8f..8901528bbeb0 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -730,6 +730,24 @@ config INPUT_ADXL34X_SPI
 	  To compile this driver as a module, choose M here: the
 	  module will be called adxl34x-spi.
 
+config INPUT_IBM_PANEL
+	tristate "IBM Operation Panel driver"
+	depends on I2C_SLAVE || COMPILE_TEST
+	help
+	  Say Y here if you have an IBM Operation Panel connected to your system
+	  over I2C. The panel is typically connected only to a system's service
+	  processor (BMC).
+
+	  If unsure, say N.
+
+	  The Operation Panel is a controller with some buttons and an LCD
+	  display that allows someone with physical access to the system to
+	  perform various administrative tasks. This driver only supports the part
+	  of the controller that sends commands to the system.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called ibm-panel.
+
 config INPUT_IMS_PCU
 	tristate "IMS Passenger Control Unit driver"
 	depends on USB
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index 28dfc444f0a9..9eea13e98d48 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -41,6 +41,7 @@ obj-$(CONFIG_INPUT_GPIO_DECODER)	+= gpio_decoder.o
 obj-$(CONFIG_INPUT_GPIO_VIBRA)		+= gpio-vibra.o
 obj-$(CONFIG_INPUT_HISI_POWERKEY)	+= hisi_powerkey.o
 obj-$(CONFIG_HP_SDC_RTC)		+= hp_sdc_rtc.o
+obj-$(CONFIG_INPUT_IBM_PANEL)		+= ibm-panel.o
 obj-$(CONFIG_INPUT_IMS_PCU)		+= ims-pcu.o
 obj-$(CONFIG_INPUT_IQS269A)		+= iqs269a.o
 obj-$(CONFIG_INPUT_IQS626A)		+= iqs626a.o
diff --git a/drivers/input/misc/ibm-panel.c b/drivers/input/misc/ibm-panel.c
new file mode 100644
index 000000000000..c77cb9b12ebc
--- /dev/null
+++ b/drivers/input/misc/ibm-panel.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) IBM Corporation 2020
+ */
+
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/limits.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/spinlock.h>
+
+#define DEVICE_NAME		"ibm-panel"
+#define PANEL_KEYCODES_COUNT	3
+
+struct ibm_panel {
+	u8 idx;
+	u8 command[11];
+	u32 keycodes[PANEL_KEYCODES_COUNT];
+	spinlock_t lock;	/* protects writes to idx and command */
+	struct input_dev *input;
+};
+
+static u8 ibm_panel_calculate_checksum(struct ibm_panel *panel)
+{
+	u8 chksum;
+	u16 sum = 0;
+	unsigned int i;
+
+	for (i = 0; i < sizeof(panel->command) - 1; ++i) {
+		sum += panel->command[i];
+		if (sum & 0xff00) {
+			sum &= 0xff;
+			sum++;
+		}
+	}
+
+	chksum = sum & 0xff;
+	chksum = ~chksum;
+	chksum++;
+
+	return chksum;
+}
+
+static void ibm_panel_process_command(struct ibm_panel *panel)
+{
+	u8 button;
+	u8 chksum;
+
+	if (panel->command[0] != 0xff && panel->command[1] != 0xf0) {
+		dev_dbg(&panel->input->dev, "command invalid: %02x %02x\n",
+			panel->command[0], panel->command[1]);
+		return;
+	}
+
+	chksum = ibm_panel_calculate_checksum(panel);
+	if (chksum != panel->command[sizeof(panel->command) - 1]) {
+		dev_dbg(&panel->input->dev,
+			"command failed checksum: %u != %u\n", chksum,
+			panel->command[sizeof(panel->command) - 1]);
+		return;
+	}
+
+	button = panel->command[2] & 0xf;
+	if (button < PANEL_KEYCODES_COUNT) {
+		input_report_key(panel->input, panel->keycodes[button],
+				 !(panel->command[2] & 0x80));
+		input_sync(panel->input);
+	} else {
+		dev_dbg(&panel->input->dev, "unknown button %u\n",
+			button);
+	}
+}
+
+static int ibm_panel_i2c_slave_cb(struct i2c_client *client,
+				  enum i2c_slave_event event, u8 *val)
+{
+	unsigned long flags;
+	struct ibm_panel *panel = i2c_get_clientdata(client);
+
+	dev_dbg(&panel->input->dev, "event: %u data: %02x\n", event, *val);
+
+	spin_lock_irqsave(&panel->lock, flags);
+
+	switch (event) {
+	case I2C_SLAVE_STOP:
+		if (panel->idx == sizeof(panel->command))
+			ibm_panel_process_command(panel);
+		else
+			dev_dbg(&panel->input->dev,
+				"command incorrect size %u\n", panel->idx);
+		fallthrough;
+	case I2C_SLAVE_WRITE_REQUESTED:
+		panel->idx = 0;
+		break;
+	case I2C_SLAVE_WRITE_RECEIVED:
+		if (panel->idx < sizeof(panel->command))
+			panel->command[panel->idx++] = *val;
+		else
+			/*
+			 * The command is too long and therefore invalid, so set the index
+			 * to it's largest possible value. When a STOP is finally received,
+			 * the command will be rejected upon processing.
+			 */
+			panel->idx = U8_MAX;
+		break;
+	case I2C_SLAVE_READ_REQUESTED:
+	case I2C_SLAVE_READ_PROCESSED:
+		*val = 0xff;
+		break;
+	default:
+		break;
+	}
+
+	spin_unlock_irqrestore(&panel->lock, flags);
+
+	return 0;
+}
+
+static int ibm_panel_probe(struct i2c_client *client,
+			   const struct i2c_device_id *id)
+{
+	int i;
+	int rc;
+	struct ibm_panel *panel = devm_kzalloc(&client->dev, sizeof(*panel),
+					       GFP_KERNEL);
+
+	if (!panel)
+		return -ENOMEM;
+
+	panel->input = devm_input_allocate_device(&client->dev);
+	if (!panel->input)
+		return -ENOMEM;
+
+	panel->input->name = client->name;
+	panel->input->id.bustype = BUS_I2C;
+
+	rc = device_property_read_u32_array(&client->dev, "linux,keycodes",
+					    panel->keycodes,
+					    PANEL_KEYCODES_COUNT);
+	if (rc) {
+		/*
+		 * Use gamepad buttons as defaults for compatibility with
+		 * existing applications.
+		 */
+		panel->keycodes[0] = BTN_NORTH;
+		panel->keycodes[1] = BTN_SOUTH;
+		panel->keycodes[2] = BTN_SELECT;
+	}
+
+	for (i = 0; i < PANEL_KEYCODES_COUNT; ++i)
+		input_set_capability(panel->input, EV_KEY, panel->keycodes[i]);
+
+	rc = input_register_device(panel->input);
+	if (rc) {
+		dev_err(&client->dev, "Failed to register input device: %d\n",
+			rc);
+		return rc;
+	}
+
+	spin_lock_init(&panel->lock);
+
+	i2c_set_clientdata(client, panel);
+	rc = i2c_slave_register(client, ibm_panel_i2c_slave_cb);
+	if (rc)
+		dev_err(&client->dev, "Failed to register as i2c slave: %d\n",
+			rc);
+
+	return rc;
+}
+
+static int ibm_panel_remove(struct i2c_client *client)
+{
+	i2c_slave_unregister(client);
+
+	return 0;
+}
+
+static const struct of_device_id ibm_panel_match[] = {
+	{ .compatible = "ibm,op-panel" },
+	{ }
+};
+
+static struct i2c_driver ibm_panel_driver = {
+	.driver = {
+		.name = DEVICE_NAME,
+		.of_match_table = ibm_panel_match,
+	},
+	.probe = ibm_panel_probe,
+	.remove = ibm_panel_remove,
+};
+module_i2c_driver(ibm_panel_driver);
+
+MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
+MODULE_DESCRIPTION("IBM Operation Panel Driver");
+MODULE_LICENSE("GPL");
-- 
2.31.1