[PATCH V1] Input: synaptics-rmi4- Add a new feature for Forcepad.

[Marge Yang <marge.yang@tw.synaptics.com>]

From: Marge Yang <Marge.Yang@tw.synaptics.com>

Forcepad devices will use F21, for click simulation
due to lack of a metal button, so we add F21 support
to make forcepad support click function.

Signed-off-by: Marge Yang <Marge.Yang@tw.synaptics.com>
---
 drivers/input/rmi4/Kconfig      |   8 ++
 drivers/input/rmi4/Makefile     |   1 +
 drivers/input/rmi4/rmi_bus.c    |   3 +
 drivers/input/rmi4/rmi_driver.h |   5 ++
 drivers/input/rmi4/rmi_f21.c    | 126 ++++++++++++++++++++++++++++++++
 5 files changed, 143 insertions(+)
 create mode 100644 drivers/input/rmi4/rmi_f21.c

diff --git a/drivers/input/rmi4/Kconfig b/drivers/input/rmi4/Kconfig
index c0163b983ce6..086013be6a64 100644
--- a/drivers/input/rmi4/Kconfig
+++ b/drivers/input/rmi4/Kconfig
@@ -82,6 +82,14 @@ config RMI4_F12
 	  touchpads. For sensors that support relative pointing, F12 also
 	  provides mouse input.
 
+config RMI4_F21
+	bool "RMI4 Function 21 (PRESSURE)"
+	help
+	  Say Y here if you want to add support for RMI4 function 21.
+
+	  Function 21 provides buttons/pressure for RMI4 devices. This includes
+	  support for buttons/pressure on PressurePad.
+
 config RMI4_F30
 	bool "RMI4 Function 30 (GPIO LED)"
 	help
diff --git a/drivers/input/rmi4/Makefile b/drivers/input/rmi4/Makefile
index 02f14c846861..484b97eca025 100644
--- a/drivers/input/rmi4/Makefile
+++ b/drivers/input/rmi4/Makefile
@@ -8,6 +8,7 @@ rmi_core-$(CONFIG_RMI4_2D_SENSOR) += rmi_2d_sensor.o
 rmi_core-$(CONFIG_RMI4_F03) += rmi_f03.o
 rmi_core-$(CONFIG_RMI4_F11) += rmi_f11.o
 rmi_core-$(CONFIG_RMI4_F12) += rmi_f12.o
+rmi_core-$(CONFIG_RMI4_F21) += rmi_f21.o
 rmi_core-$(CONFIG_RMI4_F30) += rmi_f30.o
 rmi_core-$(CONFIG_RMI4_F34) += rmi_f34.o rmi_f34v7.o
 rmi_core-$(CONFIG_RMI4_F3A) += rmi_f3a.o
diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c
index 3aee04837205..47fe7a88c92b 100644
--- a/drivers/input/rmi4/rmi_bus.c
+++ b/drivers/input/rmi4/rmi_bus.c
@@ -360,6 +360,9 @@ static struct rmi_function_handler *fn_handlers[] = {
 #ifdef CONFIG_RMI4_F12
 	&rmi_f12_handler,
 #endif
+#ifdef CONFIG_RMI4_F21
+	&rmi_f21_handler,
+#endif
 #ifdef CONFIG_RMI4_F30
 	&rmi_f30_handler,
 #endif
diff --git a/drivers/input/rmi4/rmi_driver.h b/drivers/input/rmi4/rmi_driver.h
index 3bfe9013043e..18fdf2a166d5 100644
--- a/drivers/input/rmi4/rmi_driver.h
+++ b/drivers/input/rmi4/rmi_driver.h
@@ -115,6 +115,10 @@ static inline int rmi_f03_overwrite_button(struct rmi_function *fn,
 static inline void rmi_f03_commit_buttons(struct rmi_function *fn) {}
 #endif
 
+#ifdef CONFIG_RMI4_F21
+int rmi_f21_report_pressure(struct rmi_function *fn, int i);
+#endif
+
 #ifdef CONFIG_RMI4_F34
 int rmi_f34_create_sysfs(struct rmi_device *rmi_dev);
 void rmi_f34_remove_sysfs(struct rmi_device *rmi_dev);
@@ -133,6 +137,7 @@ extern struct rmi_function_handler rmi_f01_handler;
 extern struct rmi_function_handler rmi_f03_handler;
 extern struct rmi_function_handler rmi_f11_handler;
 extern struct rmi_function_handler rmi_f12_handler;
+extern struct rmi_function_handler rmi_f21_handler;
 extern struct rmi_function_handler rmi_f30_handler;
 extern struct rmi_function_handler rmi_f34_handler;
 extern struct rmi_function_handler rmi_f3a_handler;
diff --git a/drivers/input/rmi4/rmi_f21.c b/drivers/input/rmi4/rmi_f21.c
new file mode 100644
index 000000000000..93ef2331ed16
--- /dev/null
+++ b/drivers/input/rmi4/rmi_f21.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2012-2025 Synaptics Incorporated
+ */
+
+#include <linux/kernel.h>
+#include <linux/rmi.h>
+#include <linux/input.h>
+#include <linux/slab.h>
+#include "rmi_driver.h"
+
+#define RMI_f21_INPUT_REPORT_DATA_SIZE	6
+#define RMI_F21_INPUT_REPORT_FORCE_CLICK_OFFSET	5
+#define RMI_F21_TABLE_FORCE_CLICK_OFFSET	8
+#define RMI_f21_FORCE_CLICK			0x01
+#define RMI_f21_DATA_REGS_MAX_SIZE	19
+#define RMI_f21_FORCEPAD_BUTTON_COUNT	1
+
+struct f21_data {
+	/* Query Data */
+	u8 data_regs[RMI_f21_DATA_REGS_MAX_SIZE];
+	u8 input_report_data[RMI_f21_INPUT_REPORT_DATA_SIZE];
+	struct input_dev *input;
+	u16 key_code;
+};
+
+static irqreturn_t rmi_f21_attention(int irq, void *ctx)
+{
+	struct rmi_function *fn = ctx;
+	struct f21_data *f21 = dev_get_drvdata(&fn->dev);
+	struct rmi_driver_data *drvdata = dev_get_drvdata(&fn->rmi_dev->dev);
+	int error;
+	bool pressed;
+
+	if (drvdata->attn_data.data) {
+		if (drvdata->attn_data.size < RMI_f21_INPUT_REPORT_DATA_SIZE) {
+			dev_warn(&fn->dev, "f21 interrupted, but data is missing\n");
+			return IRQ_HANDLED;
+		}
+		memcpy(f21->input_report_data, drvdata->attn_data.data, RMI_f21_INPUT_REPORT_DATA_SIZE);
+		drvdata->attn_data.data += RMI_f21_INPUT_REPORT_DATA_SIZE;
+		drvdata->attn_data.size -= RMI_f21_INPUT_REPORT_DATA_SIZE;
+
+		pressed = !!(f21->input_report_data[RMI_F21_INPUT_REPORT_FORCE_CLICK_OFFSET] &
+					RMI_f21_FORCE_CLICK);
+	} else {
+		error = rmi_read_block(fn->rmi_dev, fn->fd.data_base_addr,
+					f21->data_regs, RMI_f21_DATA_REGS_MAX_SIZE);
+		if (error) {
+			dev_err(&fn->dev, "%s: Failed to read f21 data registers: %d\n",
+				__func__, error);
+			return IRQ_RETVAL(error);
+		}
+		pressed = !!(f21->data_regs[RMI_F21_TABLE_FORCE_CLICK_OFFSET] &
+					RMI_f21_FORCE_CLICK);
+	}
+
+	input_report_key(f21->input, f21->key_code, pressed);
+
+	return IRQ_HANDLED;
+}
+
+static int rmi_f21_config(struct rmi_function *fn)
+{
+	struct f21_data *f21 = dev_get_drvdata(&fn->dev);
+	struct rmi_driver *drv = fn->rmi_dev->driver;
+
+	if (!f21)
+		return 0;
+
+	drv->set_irq_bits(fn->rmi_dev, fn->irq_mask);
+
+	return 0;
+}
+
+static int rmi_f21_initialize(struct rmi_function *fn, struct f21_data *f21)
+{
+	struct input_dev *input = f21->input;
+	unsigned int button = BTN_LEFT;
+
+	f21->key_code = button;
+	input_set_capability(input, EV_KEY, f21->key_code);
+	input->keycode = &(f21->key_code);
+	input->keycodesize = sizeof(f21->key_code);
+	input->keycodemax = RMI_f21_FORCEPAD_BUTTON_COUNT;
+
+	__set_bit(INPUT_PROP_BUTTONPAD, input->propbit);
+
+	return 0;
+}
+
+static int rmi_f21_probe(struct rmi_function *fn)
+{
+	struct rmi_device *rmi_dev = fn->rmi_dev;
+	struct rmi_driver_data *drv_data = dev_get_drvdata(&rmi_dev->dev);
+	struct f21_data *f21;
+	int error;
+
+	if (!drv_data->input) {
+		dev_info(&fn->dev, "f21: no input device found, ignoring\n");
+		return -ENXIO;
+	}
+
+	f21 = devm_kzalloc(&fn->dev, sizeof(*f21), GFP_KERNEL);
+	if (!f21)
+		return -ENOMEM;
+
+	f21->input = drv_data->input;
+
+	error = rmi_f21_initialize(fn, f21);
+	if (error)
+		return error;
+
+	dev_set_drvdata(&fn->dev, f21);
+	return 0;
+}
+
+struct rmi_function_handler rmi_f21_handler = {
+	.driver = {
+		.name = "rmi4_f21",
+	},
+	.func = 0x21,
+	.probe = rmi_f21_probe,
+	.config = rmi_f21_config,
+	.attention = rmi_f21_attention,
+};
-- 
2.43.0