input: misc: Add IBM Operation Panel driver

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 <[email protected]>

Reviewed-by Joel Stanley <[email protected]>

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 <[email protected]>

Reviewed-by Joel Stanley <[email protected]>

---
 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

MAINTAINERS +1 -0

index 28408d29d873..5429da957a1a 100644
@@ -8351,6 +8351,7 @@ M:	Eddie James <[email protected]>
 L:	linux-input at 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 <[email protected]>

drivers/input/misc/Kconfig +18 -0

index 362e8a01980c..65ab1ce7b259 100644
@@ -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

drivers/input/misc/Makefile +1 -0

index a48e5f2d859d..7e9edf0a142b 100644
@@ -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

drivers/input/misc/ibm-panel.c new file +37 -0

new file mode 100644
index 000000000000..7329f4641636
@@ -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) {

drivers/input/misc/ibm-panel.c new file +74 -0

+
+	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;

drivers/input/misc/ibm-panel.c new file +4 -0

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

drivers/input/misc/ibm-panel.c new file +4 -0

+		return rc;
+	}
+
+	return 0;

drivers/input/misc/ibm-panel.c new file +20 -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 <[email protected]>");
+MODULE_DESCRIPTION("IBM Operation Panel Driver");
+MODULE_LICENSE("GPL");

Signature · 1 line

2.26.2

Mask the IRQ status to only the bits that the driver checks. This prevents excessive driver warnings when operating in slave mode when additional bits are set that the driver doesn't handle.

Signed-off-by Eddie James <[email protected]>

Reviewed-by Tao Ren <[email protected]>

Quoted 6 lines · Eddie James

Mask the IRQ status to only the bits that the driver checks. This prevents excessive driver warnings when operating in slave mode when additional bits are set that the driver doesn't handle.

Signed-off-by Eddie James <[email protected]>

Reviewed-by Tao Ren <[email protected]>

I reconsidered and applied it now because this helps whenever slave mode is used. So, applied to for-current, thanks!

Mask the IRQ status to only the bits that the driver checks. This prevents excessive driver warnings when operating in slave mode when additional bits are set that the driver doesn't handle.

Signed-off-by Eddie James <[email protected]>

Reviewed-by Tao Ren <[email protected]>

drivers/i2c/busses/i2c-aspeed.c +1 -1

 #define ASPEED_I2CD_INTR_SDA_DL_TIMEOUT                        BIT(14)
 #define ASPEED_I2CD_INTR_BUS_RECOVER_DONE              BIT(13)
 #define ASPEED_I2CD_INTR_SLAVE_MATCH                   BIT(7)

@@ -604,6 +605,7 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
        writel(irq_received & ~ASPEED_I2CD_INTR_RX_DONE,
               bus->base + ASPEED_I2C_INTR_STS_REG);
        readl(bus->base + ASPEED_I2C_INTR_STS_REG);
+       irq_received &= ASPEED_I2CD_INTR_RECV_MASK;
        irq_remaining = irq_received;
 
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
--

2.26.2

Quoted 6 lines · Eddie James

Mask the IRQ status to only the bits that the driver checks. This prevents excessive driver warnings when operating in slave mode when additional bits are set that the driver doesn't handle.

Signed-off-by Eddie James <[email protected]>

Reviewed-by Tao Ren <[email protected]>

Sorry, looks like I didn't get my comment in in time.

Looks good in principle. One minor comment below:

Quoted 4 lines

---
  drivers/i2c/busses/i2c-aspeed.c | 2 ++
  1 file changed, 2 insertions(+)

drivers/i2c/busses/i2c-aspeed.c line 72

Quoted 9 lines

drivers/i2c/busses/i2c-aspeed.c +1 -0

index 31268074c422..724bf30600d6 100644
@@ -69,6 +69,7 @@
   * These share bit definitions, so use the same values for the enable &
   * status bits.
   */
+#define ASPEED_I2CD_INTR_RECV_MASK                     0xf000ffff

Could we define ASPEED_I2CD_INTR_RECV_MASK to be ASPEED_I2CD_INTR_ALL ?

Quoted 15 lines

drivers/i2c/busses/i2c-aspeed.c +1 -1

  #define ASPEED_I2CD_INTR_SDA_DL_TIMEOUT                        BIT(14)
  #define ASPEED_I2CD_INTR_BUS_RECOVER_DONE              BIT(13)
  #define ASPEED_I2CD_INTR_SLAVE_MATCH                   BIT(7)

@@ -604,6 +605,7 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
         writel(irq_received & ~ASPEED_I2CD_INTR_RX_DONE,
                bus->base + ASPEED_I2C_INTR_STS_REG);
         readl(bus->base + ASPEED_I2C_INTR_STS_REG);
+       irq_received &= ASPEED_I2CD_INTR_RECV_MASK;
         irq_remaining = irq_received;
 
  #if IS_ENABLED(CONFIG_I2C_SLAVE)
--

2.26.2

Set I2C bus 0 to multi-master mode and add the panel device that will register as a slave.

Signed-off-by Eddie James <[email protected]>

Reviewed-by Joel Stanley <[email protected]>

---
 arch/arm/boot/dts/aspeed-bmc-opp-tacoma.dts | 7 +++++++
 1 file changed, 7 insertions(+)

arch/arm/boot/dts/aspeed-bmc-opp-tacoma.dts +7 -1

index 5f4ee67ac787..4d070d6ba09f 100644
@@ -4,6 +4,7 @@
 
 #include "aspeed-g6.dtsi"
 #include <dt-bindings/gpio/aspeed-gpio.h>
+#include <dt-bindings/i2c/i2c.h>
 #include <dt-bindings/leds/leds-pca955x.h>
 
 / {

@@ -438,7 +439,13 @@ aliases {
 };
 
 &i2c0 {
+       multi-master;
        status = "okay";
+
+       ibm-panel at 62 {
+               compatible = "ibm,op-panel";
+               reg = <(0x62 | I2C_OWN_SLAVE_ADDRESS)>;
+       };
 };
 
 &i2c1 {
--

2.26.2

Set I2C bus 7 to multi-master mode and add the panel device that will register as a slave.

Signed-off-by Eddie James <[email protected]>

Reviewed-by Joel Stanley <[email protected]>

---
 arch/arm/boot/dts/aspeed-bmc-ibm-rainier.dts | 7 +++++++
 1 file changed, 7 insertions(+)

arch/arm/boot/dts/aspeed-bmc-ibm-rainier.dts +7 -1

index b94421f6cbd5..50d528444f5d 100644
@@ -4,6 +4,7 @@
 
 #include "aspeed-g6.dtsi"
 #include <dt-bindings/gpio/aspeed-gpio.h>
+#include <dt-bindings/i2c/i2c.h>
 #include <dt-bindings/leds/leds-pca955x.h>
 
 / {

@@ -698,6 +699,7 @@ eeprom at 53 {
 };
 
 &i2c7 {
+       multi-master;
        status = "okay";
 
        si7021-a20 at 20 {

@@ -831,6 +833,11 @@ gpio at 15 {
                };
        };
 
+       ibm-panel at 62 {
+               compatible = "ibm,op-panel";
+               reg = <(0x62 | I2C_OWN_SLAVE_ADDRESS)>;
+       };
+
        dps: dps310 at 76 {
                compatible = "infineon,dps310";
                reg = <0x76>;
--

2.26.2