Hi Eddie,
On Wed, Sep 09, 2020 at 03:30:56PM -0500, Eddie James wrote:
> 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 <eaja...@linux.ibm.com>
> Reviewed-by: Joel Stanley <j...@jms.id.au>
> ---
> MAINTAINERS | 1 +
> drivers/input/misc/Kconfig | 18 ++++
> drivers/input/misc/Makefile | 1 +
> drivers/input/misc/ibm-panel.c | 189 +++++++++++++++++++++++++++++++++
> 4 files changed, 209 insertions(+)
> create mode 100644 drivers/input/misc/ibm-panel.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 28408d29d873..5429da957a1a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8351,6 +8351,7 @@ M: Eddie James <eaja...@linux.ibm.com>
> L: linux-in...@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 <ha...@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..7329f4641636
> --- /dev/null
> +++ b/drivers/input/misc/ibm-panel.c
> @@ -0,0 +1,189 @@
> +// 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 i;
> + u8 chksum;
> + u16 sum = 0;
> + int pressed;
> + int released;
> +
> + 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++;
Maybe move checksum calculation into a separate function?
> +
> + 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;
pressed = !(panel->command[2] & BIT(7));
or "pressed = !released;" if you want to keep both.
> +
> + 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)
> +{
> + 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 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);
North/South/Select are gamepad buttons, not general purpose ones. I
think you should not hard-code keymap in the driver, but rather use
device property to specify keymap that makes sense for the particular
board's application.
> +
> + 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);
You are using devm, there is no need to manually unregister input
device.
> + 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);
This is not needed.
> +
> + return rc;
The remove operation is not reversible, so there is no need to return
error here. Just log en error if i2c_slave_unregister() fails if you
want, and 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 <eaja...@linux.ibm.com>");
> +MODULE_DESCRIPTION("IBM Operation Panel Driver");
> +MODULE_LICENSE("GPL");
> --
> 2.26.2
>
Thanks.
--
Dmitry
