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[v2,2/5] input: misc: Add IBM Operation Panel driver

Message ID 20200908200101.64974-3-eajames@linux.ibm.com
State New
Headers show
Series input: misc: Add IBM Operation Panel driver | expand

Commit Message

Eddie James Sept. 8, 2020, 8 p.m. UTC
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>
---
 MAINTAINERS                    |   1 +
 drivers/input/misc/Kconfig     |  18 ++++
 drivers/input/misc/Makefile    |   1 +
 drivers/input/misc/ibm-panel.c | 192 +++++++++++++++++++++++++++++++++
 4 files changed, 212 insertions(+)
 create mode 100644 drivers/input/misc/ibm-panel.c

Comments

Wolfram Sang Sept. 8, 2020, 8:40 p.m. UTC | #1
Hi Eddie,

> +	switch (event) {
> +	case I2C_SLAVE_STOP:
> +		command_size = 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;
> +	default:
> +		break;
> +	}

Sorry, I missed this in my last review. READ states are mandatory, so
you will need something like this:

+	case I2C_SLAVE_READ_REQUESTED:
+	case I2C_SLAVE_READ_PROCESSED:
+		*val = 0xff;
+		break;


> +	if (command_size)
> +		ibm_panel_process_command(panel, command_size);

I wondered if you could check for the correct command_size here, so no
need to call into the function when the size doesn't match?

> +       rc = i2c_slave_register(client, ibm_panel_i2c_slave_cb);
> +       if (rc) {
> +               input_unregister_device(panel->input);
> +               dev_err(&client->dev,
> +                       "Failed to register I2C slave device: %d\n", rc);

This dev_err can go. The core will print messages if something goes
wrong.

The rest looks good from an I2C point of view.

I'd think this all should go via the input tree?

Kind regards,

   Wolfram
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Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 0d83eada50e4..0f9605c4cfc6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8350,6 +8350,7 @@  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 362e8a01980c..65ab1ce7b259 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -708,6 +708,24 @@  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 a48e5f2d859d..7e9edf0a142b 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -38,6 +38,7 @@  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_IXP4XX_BEEPER)	+= ixp4xx-beeper.o
diff --git a/drivers/input/misc/ibm-panel.c b/drivers/input/misc/ibm-panel.c
new file mode 100644
index 000000000000..7b147b090c2a
--- /dev/null
+++ b/drivers/input/misc/ibm-panel.c
@@ -0,0 +1,192 @@ 
+// 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"
+
+struct ibm_panel {
+	u8 idx;
+	u8 command[11];
+	spinlock_t lock;	/* protects writes to idx and command */
+	struct input_dev *input;
+};
+
+static void ibm_panel_process_command(struct ibm_panel *panel, u8 command_size)
+{
+	u8 i;
+	u8 chksum;
+	u16 sum = 0;
+	int pressed;
+	int released;
+
+	if (command_size != sizeof(panel->command)) {
+		dev_dbg(&panel->input->dev, "command size incorrect\n");
+		return;
+	}
+
+	if (panel->command[0] != 0xff && panel->command[1] != 0xf0) {
+		dev_dbg(&panel->input->dev, "command invalid\n");
+		return;
+	}
+
+	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++;
+
+	if (chksum != panel->command[sizeof(panel->command) - 1]) {
+		dev_dbg(&panel->input->dev, "command failed checksum\n");
+		return;
+	}
+
+	released = panel->command[2] & 0x80;
+	pressed = released ? 0 : 1;
+
+	switch (panel->command[2] & 0xf) {
+	case 0:
+		input_report_key(panel->input, BTN_NORTH, pressed);
+		break;
+	case 1:
+		input_report_key(panel->input, BTN_SOUTH, pressed);
+		break;
+	case 2:
+		input_report_key(panel->input, BTN_SELECT, pressed);
+		break;
+	default:
+		dev_dbg(&panel->input->dev, "unknown command %u\n",
+			panel->command[2] & 0xf);
+		return;
+	}
+
+	input_sync(panel->input);
+}
+
+static int ibm_panel_i2c_slave_cb(struct i2c_client *client,
+				  enum i2c_slave_event event, u8 *val)
+{
+	u8 command_size = 0;
+	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:
+		command_size = 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;
+	default:
+		break;
+	}
+
+	spin_unlock_irqrestore(&panel->lock, flags);
+
+	if (command_size)
+		ibm_panel_process_command(panel, command_size);
+
+	return 0;
+}
+
+static int ibm_panel_probe(struct i2c_client *client,
+			   const struct i2c_device_id *id)
+{
+	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;
+	input_set_capability(panel->input, EV_KEY, BTN_NORTH);
+	input_set_capability(panel->input, EV_KEY, BTN_SOUTH);
+	input_set_capability(panel->input, EV_KEY, BTN_SELECT);
+
+	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) {
+		input_unregister_device(panel->input);
+		dev_err(&client->dev,
+			"Failed to register I2C slave device: %d\n", rc);
+		return rc;
+	}
+
+	return 0;
+}
+
+static int ibm_panel_remove(struct i2c_client *client)
+{
+	int rc;
+	struct ibm_panel *panel = i2c_get_clientdata(client);
+
+	rc = i2c_slave_unregister(client);
+
+	input_unregister_device(panel->input);
+
+	return rc;
+}
+
+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");