Re: [PATCH 08/18] media: platform: microchip: Add new histogram submodule

From: Balakrishnan Sambath <redacted>

Add new histogram submodule driver to export raw histogram statistics
and data to userspace.

Signed-off-by: Balakrishnan Sambath <redacted>
---
 drivers/media/platform/microchip/Kconfig      |   2 +
 drivers/media/platform/microchip/Makefile     |   2 +-
 .../platform/microchip/microchip-isc-stats.c  | 549 ++++++++++++++++++
 .../media/platform/microchip/microchip-isc.h  |  24 +
 4 files changed, 576 insertions(+), 1 deletion(-)
 create mode 100644 drivers/media/platform/microchip/microchip-isc-stats.c

diff --git a/drivers/media/platform/microchip/Kconfig b/drivers/media/platform/microchip/Kconfig
index 4734ecced029..2864a57e2ff4 100644
--- a/drivers/media/platform/microchip/Kconfig
+++ b/drivers/media/platform/microchip/Kconfig

@@ -10,6 +10,7 @@ config VIDEO_MICROCHIP_ISC
 	select MEDIA_CONTROLLER
 	select VIDEO_V4L2_SUBDEV_API
 	select VIDEOBUF2_DMA_CONTIG
+	select VIDEOBUF2_VMALLOC
 	select REGMAP_MMIO
 	select V4L2_FWNODE
 	select VIDEO_MICROCHIP_ISC_BASE

@@ -26,6 +27,7 @@ config VIDEO_MICROCHIP_XISC
 	depends on VIDEO_DEV && COMMON_CLK
 	depends on ARCH_AT91 || COMPILE_TEST
 	select VIDEOBUF2_DMA_CONTIG
+	select VIDEOBUF2_VMALLOC
 	select REGMAP_MMIO
 	select V4L2_FWNODE
 	select VIDEO_MICROCHIP_ISC_BASE

diff --git a/drivers/media/platform/microchip/Makefile b/drivers/media/platform/microchip/Makefile
index bd8d6e779c51..94c64d3d242c 100644
--- a/drivers/media/platform/microchip/Makefile
+++ b/drivers/media/platform/microchip/Makefile

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 microchip-isc-objs = microchip-sama5d2-isc.o
 microchip-xisc-objs = microchip-sama7g5-isc.o
-microchip-isc-common-objs = microchip-isc-base.o microchip-isc-clk.o microchip-isc-scaler.o
+microchip-isc-common-objs = microchip-isc-base.o microchip-isc-clk.o microchip-isc-scaler.o microchip-isc-stats.o
 
 obj-$(CONFIG_VIDEO_MICROCHIP_ISC_BASE) += microchip-isc-common.o
 obj-$(CONFIG_VIDEO_MICROCHIP_ISC) += microchip-isc.o

diff --git a/drivers/media/platform/microchip/microchip-isc-stats.c b/drivers/media/platform/microchip/microchip-isc-stats.c
new file mode 100644
index 000000000000..d7813c9d95ac
--- /dev/null
+++ b/drivers/media/platform/microchip/microchip-isc-stats.c

@@ -0,0 +1,549 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Microchip ISC Driver - Statistics Subdevice
+ * Raw Histogram Export for Userspace Applications
+ *
+ * Copyright (C) 2025 Microchip Technology Inc.
+ *
+ * Author: Balakrishnan Sambath <balakrishnan.s@microchip.com>
+ */
+
+#include <linux/clk.h>
+#include <media/v4l2-common.h>
+#include <media/v4l2-event.h>
+#include <media/v4l2-ioctl.h>
+#include <media/videobuf2-core.h>
+#include <media/videobuf2-vmalloc.h>
+#include "microchip-isc-regs.h"
+#include "microchip-isc.h"
+
+#define ISC_STATS_DEV_NAME	"microchip-isc_stats"
+#define ISC_STATS_MIN_BUFS	2
+#define ISC_STATS_MAX_BUFS	8
+
+/**
+ * struct isc_stat_buffer - Raw histogram statistics buffer structure
+ * @frame_number: Sequential frame number from capture
+ * @timestamp: Frame capture timestamp in nanoseconds
+ * @meas_type: Bitmask of measurement types available (ISC_CIF_ISP_STAT_*)
+ * @hist: Array of histogram data for each Bayer channel
+ * @hist.hist_bins: Raw 512-bin histogram data from hardware
+ * @hist.hist_min: Minimum pixel value observed in channel
+ * @hist.hist_max: Maximum pixel value observed in channel
+ * @hist.total_pixels: Total number of pixels processed in channel
+ * @valid_channels: Bitmask indicating which Bayer channels contain valid data
+ * @bayer_pattern: Current Bayer pattern configuration (CFA_BAYCFG_*)
+ * @reserved: Padding for future expansion and alignment
+ *
+ * This structure contains raw, unprocessed histogram data from the ISC
+ * hardware for all four Bayer channels (GR, R, GB, B). No algorithmic
+ * processing is performed - data is exported directly from hardware
+ * registers for userspace processing applications.
+ */
+struct isc_stat_buffer {
+	u32 frame_number;
+	u64 timestamp;