media: microchip: add ISC driver as Microchip ISC

The Atmel ISC driver will be moved to staging to support old users that
are not using the media controller paradigm.
The ISC driver was converted to media controller in the public patch
series:

https://lore.kernel.org/lkml/20220503095127.48710-1-eugen.hristev@microchip.com/T/#m2c320fa8153c01379a1c35b1d90a00903949513a

However the conversion cannot be done directly as it would affect existing
users by breaking the old way of configuration for sama5d2 platforms.

After discussions with the media maintainers, the decision is to move
Atmel ISC to staging as-is, to keep the Kconfig symbols and the users
to the driver in staging. Thus, all the existing users of the non
media-controller paradigm will continue to be happy and use the old config
way.

The converted driver would support both sama5d2 and sama7g5 platforms with
media controller paradigm, but it requires userspace configuration of the
pipeline for all the pipeline modules.

In a simple configuration sensor ==> isc , the old isc driver used to call
subdev s_fmt and control the sensor directly.
This was achieved by having a lot of code inside the driver that was
querying the subdev at probe time and made a list of formats which are
usable.
Basically the user had nothing to configure, as the isc would handle
everything at the top level. This was an easy way to capture, but also came
with the drawback of lack of flexibility.
In a more complicated pipeline
 sensor ==> controller 1 ==> controller 2 ==> isc
this would not be achievable, as controller 1 and controller 2 might be
media-controller configurable, and will not propagate the formats down to
the sensor.
The new driver Microchip ISC would solve all these problems and exposes pads
entities and links to userspace.
For the ease of tracking, the patches that convert to media controller come
on top of this patch that simply readds the driver to the new location under
the new Kconfig symbols.

To differentiate between the old driver and the new driver, I have renamed
the new driver to Microchip ISC, renaming the Kconfig symbols as well, and
all the mentions inside the driver.
The only thing that remains common is the file
include/linux/atmel-isc-media.h which is the ABI for the v4l2 custom
controls that the ISC exposes.
This file is used by both driver, so I kept it as-is.
To further avoid confusion all files have been renamed and all functions
named isc_* as well.
The exported symbols have been renamed with added microchip_ prefix, to
avoid symbol duplication with the old driver, and to avoid confusion.
Other than that, I have fixed small checkpatch issues when readding the
driver.
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

MAINTAINERS

@@ -13495,6 +13495,8 @@ F:	Documentation/devicetree/bindings/media/atmel,isc.yaml
 F:	Documentation/devicetree/bindings/media/microchip,xisc.yaml
 F:	drivers/media/platform/atmel/atmel-isc*
 F:	drivers/media/platform/atmel/atmel-sama*-isc*
+F:	drivers/media/platform/microchip/microchip-isc*
+F:	drivers/media/platform/microchip/microchip-sama*-isc*
 F:	include/linux/atmel-isc-media.h
 
 MICROCHIP ISI DRIVER

drivers/media/platform/microchip/Kconfig

@@ -2,6 +2,48 @@
 
 comment "Microchip Technology, Inc. media platform drivers"
 
+config VIDEO_MICROCHIP_ISC
+	tristate "Microchip Image Sensor Controller (ISC) support"
+	depends on V4L_PLATFORM_DRIVERS
+	depends on VIDEO_DEV && COMMON_CLK
+	depends on ARCH_AT91 || COMPILE_TEST
+	select MEDIA_CONTROLLER
+	select VIDEO_V4L2_SUBDEV_API
+	select VIDEOBUF2_DMA_CONTIG
+	select REGMAP_MMIO
+	select V4L2_FWNODE
+	select VIDEO_MICROCHIP_ISC_BASE
+	help
+	   This module makes the Microchip Image Sensor Controller available
+	   as a v4l2 device.
+
+	   To compile this driver as a module, choose M here: the
+	   module will be called microchip-isc.
+
+config VIDEO_MICROCHIP_XISC
+	tristate "Microchip eXtended Image Sensor Controller (XISC) support"
+	depends on V4L_PLATFORM_DRIVERS
+	depends on VIDEO_DEV && COMMON_CLK && VIDEO_V4L2_SUBDEV_API
+	depends on ARCH_AT91 || COMPILE_TEST
+	select VIDEOBUF2_DMA_CONTIG
+	select REGMAP_MMIO
+	select V4L2_FWNODE
+	select VIDEO_MICROCHIP_ISC_BASE
+	select MEDIA_CONTROLLER
+	select VIDEO_V4L2_SUBDEV_API
+	help
+	   This module makes the Microchip eXtended Image Sensor Controller
+	   available as a v4l2 device.
+
+	   To compile this driver as a module, choose M here: the
+	   module will be called microchip-xisc.
+
+config VIDEO_MICROCHIP_ISC_BASE
+	tristate
+	default n
+	help
+	  Microchip ISC and XISC common code base.
+
 config VIDEO_MICROCHIP_CSI2DC
 	tristate "Microchip CSI2 Demux Controller"
 	depends on V4L_PLATFORM_DRIVERS

drivers/media/platform/microchip/Makefile

 # 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
 
+obj-$(CONFIG_VIDEO_MICROCHIP_ISC_BASE) += microchip-isc-common.o
+obj-$(CONFIG_VIDEO_MICROCHIP_ISC) += microchip-isc.o
+obj-$(CONFIG_VIDEO_MICROCHIP_XISC) += microchip-xisc.o
 obj-$(CONFIG_VIDEO_MICROCHIP_CSI2DC) += microchip-csi2dc.o

drivers/media/platform/microchip/microchip-isc-clk.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Microchip Image Sensor Controller (ISC) common clock driver setup
+ *
+ * Copyright (C) 2016 Microchip Technology, Inc.
+ *
+ * Author: Songjun Wu
+ * Author: Eugen Hristev <eugen.hristev@microchip.com>
+ *
+ */
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+
+#include "microchip-isc-regs.h"
+#include "microchip-isc.h"
+
+static int isc_wait_clk_stable(struct clk_hw *hw)
+{
+	struct isc_clk *isc_clk = to_isc_clk(hw);
+	struct regmap *regmap = isc_clk->regmap;
+	unsigned long timeout = jiffies + usecs_to_jiffies(1000);
+	unsigned int status;
+
+	while (time_before(jiffies, timeout)) {
+		regmap_read(regmap, ISC_CLKSR, &status);
+		if (!(status & ISC_CLKSR_SIP))
+			return 0;
+
+		usleep_range(10, 250);
+	}
+
+	return -ETIMEDOUT;
+}
+
+static int isc_clk_prepare(struct clk_hw *hw)
+{
+	struct isc_clk *isc_clk = to_isc_clk(hw);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(isc_clk->dev);
+	if (ret < 0)
+		return ret;
+
+	return isc_wait_clk_stable(hw);
+}
+
+static void isc_clk_unprepare(struct clk_hw *hw)
+{
+	struct isc_clk *isc_clk = to_isc_clk(hw);
+
+	isc_wait_clk_stable(hw);
+
+	pm_runtime_put_sync(isc_clk->dev);
+}
+
+static int isc_clk_enable(struct clk_hw *hw)
+{
+	struct isc_clk *isc_clk = to_isc_clk(hw);
+	u32 id = isc_clk->id;
+	struct regmap *regmap = isc_clk->regmap;
+	unsigned long flags;
+	unsigned int status;
+
+	dev_dbg(isc_clk->dev, "ISC CLK: %s, id = %d, div = %d, parent id = %d\n",
+		__func__, id, isc_clk->div, isc_clk->parent_id);
+
+	spin_lock_irqsave(&isc_clk->lock, flags);
+	regmap_update_bits(regmap, ISC_CLKCFG,
+			   ISC_CLKCFG_DIV_MASK(id) | ISC_CLKCFG_SEL_MASK(id),
+			   (isc_clk->div << ISC_CLKCFG_DIV_SHIFT(id)) |
+			   (isc_clk->parent_id << ISC_CLKCFG_SEL_SHIFT(id)));
+
+	regmap_write(regmap, ISC_CLKEN, ISC_CLK(id));
+	spin_unlock_irqrestore(&isc_clk->lock, flags);
+
+	regmap_read(regmap, ISC_CLKSR, &status);
+	if (status & ISC_CLK(id))
+		return 0;
+	else
+		return -EINVAL;
+}
+
+static void isc_clk_disable(struct clk_hw *hw)
+{
+	struct isc_clk *isc_clk = to_isc_clk(hw);
+	u32 id = isc_clk->id;
+	unsigned long flags;
+
+	spin_lock_irqsave(&isc_clk->lock, flags);
+	regmap_write(isc_clk->regmap, ISC_CLKDIS, ISC_CLK(id));
+	spin_unlock_irqrestore(&isc_clk->lock, flags);
+}
+
+static int isc_clk_is_enabled(struct clk_hw *hw)
+{
+	struct isc_clk *isc_clk = to_isc_clk(hw);
+	u32 status;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(isc_clk->dev);
+	if (ret < 0)
+		return 0;
+
+	regmap_read(isc_clk->regmap, ISC_CLKSR, &status);
+
+	pm_runtime_put_sync(isc_clk->dev);
+
+	return status & ISC_CLK(isc_clk->id) ? 1 : 0;
+}
+
+static unsigned long
+isc_clk_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
+{
+	struct isc_clk *isc_clk = to_isc_clk(hw);
+
+	return DIV_ROUND_CLOSEST(parent_rate, isc_clk->div + 1);
+}
+
+static int isc_clk_determine_rate(struct clk_hw *hw,
+				  struct clk_rate_request *req)
+{
+	struct isc_clk *isc_clk = to_isc_clk(hw);
+	long best_rate = -EINVAL;
+	int best_diff = -1;
+	unsigned int i, div;
+
+	for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
+		struct clk_hw *parent;
+		unsigned long parent_rate;
+
+		parent = clk_hw_get_parent_by_index(hw, i);
+		if (!parent)
+			continue;
+
+		parent_rate = clk_hw_get_rate(parent);
+		if (!parent_rate)
+			continue;
+
+		for (div = 1; div < ISC_CLK_MAX_DIV + 2; div++) {
+			unsigned long rate;
+			int diff;
+
+			rate = DIV_ROUND_CLOSEST(parent_rate, div);
+			diff = abs(req->rate - rate);
+
+			if (best_diff < 0 || best_diff > diff) {
+				best_rate = rate;
+				best_diff = diff;
+				req->best_parent_rate = parent_rate;
+				req->best_parent_hw = parent;
+			}
+
+			if (!best_diff || rate < req->rate)
+				break;
+		}
+
+		if (!best_diff)
+			break;
+	}
+
+	dev_dbg(isc_clk->dev,
+		"ISC CLK: %s, best_rate = %ld, parent clk: %s @ %ld\n",
+		__func__, best_rate,
+		__clk_get_name((req->best_parent_hw)->clk),
+		req->best_parent_rate);
+
+	if (best_rate < 0)
+		return best_rate;
+
+	req->rate = best_rate;
+
+	return 0;
+}
+
+static int isc_clk_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct isc_clk *isc_clk = to_isc_clk(hw);
+
+	if (index >= clk_hw_get_num_parents(hw))
+		return -EINVAL;
+
+	isc_clk->parent_id = index;
+
+	return 0;
+}
+
+static u8 isc_clk_get_parent(struct clk_hw *hw)
+{
+	struct isc_clk *isc_clk = to_isc_clk(hw);
+
+	return isc_clk->parent_id;
+}
+
+static int isc_clk_set_rate(struct clk_hw *hw,
+			    unsigned long rate,
+			    unsigned long parent_rate)
+{
+	struct isc_clk *isc_clk = to_isc_clk(hw);
+	u32 div;
+
+	if (!rate)
+		return -EINVAL;
+
+	div = DIV_ROUND_CLOSEST(parent_rate, rate);
+	if (div > (ISC_CLK_MAX_DIV + 1) || !div)
+		return -EINVAL;
+
+	isc_clk->div = div - 1;
+
+	return 0;
+}
+
+static const struct clk_ops isc_clk_ops = {
+	.prepare	= isc_clk_prepare,
+	.unprepare	= isc_clk_unprepare,
+	.enable		= isc_clk_enable,
+	.disable	= isc_clk_disable,
+	.is_enabled	= isc_clk_is_enabled,
+	.recalc_rate	= isc_clk_recalc_rate,
+	.determine_rate	= isc_clk_determine_rate,
+	.set_parent	= isc_clk_set_parent,
+	.get_parent	= isc_clk_get_parent,
+	.set_rate	= isc_clk_set_rate,
+};
+
+static int isc_clk_register(struct isc_device *isc, unsigned int id)
+{
+	struct regmap *regmap = isc->regmap;
+	struct device_node *np = isc->dev->of_node;
+	struct isc_clk *isc_clk;
+	struct clk_init_data init;
+	const char *clk_name = np->name;
+	const char *parent_names[3];
+	int num_parents;
+
+	if (id == ISC_ISPCK && !isc->ispck_required)
+		return 0;
+
+	num_parents = of_clk_get_parent_count(np);
+	if (num_parents < 1 || num_parents > 3)
+		return -EINVAL;
+
+	if (num_parents > 2 && id == ISC_ISPCK)
+		num_parents = 2;
+
+	of_clk_parent_fill(np, parent_names, num_parents);
+
+	if (id == ISC_MCK)
+		of_property_read_string(np, "clock-output-names", &clk_name);
+	else
+		clk_name = "isc-ispck";
+
+	init.parent_names	= parent_names;
+	init.num_parents	= num_parents;
+	init.name		= clk_name;
+	init.ops		= &isc_clk_ops;
+	init.flags		= CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;
+
+	isc_clk = &isc->isc_clks[id];
+	isc_clk->hw.init	= &init;
+	isc_clk->regmap		= regmap;
+	isc_clk->id		= id;
+	isc_clk->dev		= isc->dev;
+	spin_lock_init(&isc_clk->lock);
+
+	isc_clk->clk = clk_register(isc->dev, &isc_clk->hw);
+	if (IS_ERR(isc_clk->clk)) {
+		dev_err(isc->dev, "%s: clock register fail\n", clk_name);
+		return PTR_ERR(isc_clk->clk);
+	} else if (id == ISC_MCK) {
+		of_clk_add_provider(np, of_clk_src_simple_get, isc_clk->clk);
+	}
+
+	return 0;
+}
+
+int microchip_isc_clk_init(struct isc_device *isc)
+{
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(isc->isc_clks); i++)
+		isc->isc_clks[i].clk = ERR_PTR(-EINVAL);
+
+	for (i = 0; i < ARRAY_SIZE(isc->isc_clks); i++) {
+		ret = isc_clk_register(isc, i);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(microchip_isc_clk_init);
+
+void microchip_isc_clk_cleanup(struct isc_device *isc)
+{
+	unsigned int i;
+
+	of_clk_del_provider(isc->dev->of_node);
+
+	for (i = 0; i < ARRAY_SIZE(isc->isc_clks); i++) {
+		struct isc_clk *isc_clk = &isc->isc_clks[i];
+
+		if (!IS_ERR(isc_clk->clk))
+			clk_unregister(isc_clk->clk);
+	}
+}
+EXPORT_SYMBOL_GPL(microchip_isc_clk_cleanup);