HID: Intel-thc-hid: Intel-thc: Introduce interrupt delay control

This patch adds support for a new feature, named "Interrupt Delay",
allowing driver to set a specific delay time for next interrupt
detection. It gives driver a capability to control THC waiting time for
the next interrupt, to reduce the likelihood of spurious readings.

APIs added:
- thc_i2c_set_rx_int_delay(): Set I2C Rx input interrupt delay value
- thc_i2c_rx_int_delay_enable(): Enable or disable I2C Rx interrupt delay

As this interrupt delay feature is only applicable to RxDMA and must
remain disabled during SWDMA operations, it also involves a change
in SWDMA code to record the max input size control feature state
before SWDMA and restore the state after SWDMA.

Signed-off-by: Even Xu <even.xu@intel.com>
Tested-by: Chong Han <chong.han@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

1 files changed, 71 insertions, 0 deletions

diff --git a/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dev.c b/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dev.c
index 8fc6e8484cd8..6f2263869b20 100644
--- a/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dev.c
+++ b/drivers/hid/intel-thc-hid/intel-thc/intel-thc-dev.c
@@ -2,6 +2,7 @@
 /* Copyright (c) 2024 Intel Corporation */
 
 #include <linux/bitfield.h>
+#include <linux/math.h>
 #include <linux/regmap.h>
 
 #include "intel-thc-dev.h"
@@ -1640,6 +1641,76 @@ int thc_i2c_rx_max_size_enable(struct thc_device *dev, bool enable)
 }
 EXPORT_SYMBOL_NS_GPL(thc_i2c_rx_max_size_enable, "INTEL_THC");
 
+/**
+ * thc_i2c_set_rx_int_delay - Set I2C Rx input interrupt delay value
+ * @dev: The pointer of THC private device context
+ * @delay_us: Interrupt delay value, unit is us
+ *
+ * Set @delay_us for I2C RxDMA input interrupt delay feature.
+ *
+ * Return: 0 on success, other error codes on failure.
+ */
+int thc_i2c_set_rx_int_delay(struct thc_device *dev, u32 delay_us)
+{
+	u32 val;
+	int ret;
+
+	if (!dev)
+		return -EINVAL;
+
+	if (!delay_us)
+		return -EOPNOTSUPP;
+
+	ret = regmap_read(dev->thc_regmap, THC_M_PRT_SW_SEQ_STS_OFFSET, &val);
+	if (ret)
+		return ret;
+
+	/* THC hardware counts at 10us unit */
+	val |= FIELD_PREP(THC_M_PRT_SPI_ICRRD_OPCODE_I2C_INTERVAL, DIV_ROUND_UP(delay_us, 10));
+
+	ret = regmap_write(dev->thc_regmap, THC_M_PRT_SPI_ICRRD_OPCODE_OFFSET, val);
+	if (ret)
+		return ret;
+
+	dev->i2c_int_delay_us = delay_us;
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(thc_i2c_set_rx_int_delay, "INTEL_THC");
+
+/**
+ * thc_i2c_rx_int_delay_enable - Enable I2C Rx interrupt delay
+ * @dev: The pointer of THC private device context
+ * @enable: Enable interrupt delay or not
+ *
+ * Enable or disable I2C RxDMA input interrupt delay feature.
+ * Input interrupt delay can only be enabled after interrupt delay value
+ * was set by thc_i2c_set_rx_int_delay().
+ *
+ * Return: 0 on success, other error codes on failure.
+ */
+int thc_i2c_rx_int_delay_enable(struct thc_device *dev, bool enable)
+{
+	u32 mask = THC_M_PRT_SPI_ICRRD_OPCODE_I2C_INTERVAL_EN;
+	u32 val = enable ? mask : 0;
+	int ret;
+
+	if (!dev)
+		return -EINVAL;
+
+	if (!dev->i2c_int_delay_us)
+		return -EOPNOTSUPP;
+
+	ret = regmap_write_bits(dev->thc_regmap, THC_M_PRT_SPI_ICRRD_OPCODE_OFFSET, mask, val);
+	if (ret)
+		return ret;
+
+	dev->i2c_int_delay_en = enable;
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(thc_i2c_rx_int_delay_enable, "INTEL_THC");
+
 MODULE_AUTHOR("Xinpeng Sun <xinpeng.sun@intel.com>");
 MODULE_AUTHOR("Even Xu <even.xu@intel.com>");