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From:   frowand.list@gmail.com
To:     Rob Herring <robh+dt@kernel.org>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        pantelis.antoniou@konsulko.com,
        Pantelis Antoniou <panto@antoniou-consulting.com>
Cc:     devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Alan Tull <atull@kernel.org>
Subject: [RFC PATCH 1/2] of: unittest: add overlay gpio test to catch gpio hog problem
Date:   Wed, 15 Jan 2020 00:47:07 -0600
Message-Id: <1579070828-18221-2-git-send-email-frowand.list@gmail.com>
In-Reply-To: <1579070828-18221-1-git-send-email-frowand.list@gmail.com>
References: <1579070828-18221-1-git-send-email-frowand.list@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Frank Rowand <frank.rowand@sony.com>

Geert reports that gpio hog nodes are not properly processed when
the gpio hog node is added via an overlay reply and provides an
RFC patch to fix the problem [1].

Add a unittest that shows the problem.  Unittest will report "1 failed"
test before applying Geert's RFC patch and "0 failed" after applying
Geert's RFC patch.

[1] https://lore.kernel.org/linux-devicetree/20191230133852.5890-1-geert+renesas@glider.be/

Signed-off-by: Frank Rowand <frank.rowand@sony.com>
---

There are checkpatch warnings.
  - The lines over 80 characters are consistent with unittest.c style
  - The undocumented compatibles are restricted to use by unittest
    and should not be documented under Documentation

This unittest was also valuable in that it allowed me to explore
possible issues related to the proposed solution to the gpio hog
problem.

 drivers/of/unittest-data/Makefile             |   8 +-
 drivers/of/unittest-data/overlay_gpio_01.dts  |  23 +++
 drivers/of/unittest-data/overlay_gpio_02a.dts |  16 ++
 drivers/of/unittest-data/overlay_gpio_02b.dts |  16 ++
 drivers/of/unittest-data/overlay_gpio_03.dts  |  23 +++
 drivers/of/unittest-data/overlay_gpio_04a.dts |  16 ++
 drivers/of/unittest-data/overlay_gpio_04b.dts |  16 ++
 drivers/of/unittest.c                         | 257 ++++++++++++++++++++++++++
 8 files changed, 374 insertions(+), 1 deletion(-)
 create mode 100644 drivers/of/unittest-data/overlay_gpio_01.dts
 create mode 100644 drivers/of/unittest-data/overlay_gpio_02a.dts
 create mode 100644 drivers/of/unittest-data/overlay_gpio_02b.dts
 create mode 100644 drivers/of/unittest-data/overlay_gpio_03.dts
 create mode 100644 drivers/of/unittest-data/overlay_gpio_04a.dts
 create mode 100644 drivers/of/unittest-data/overlay_gpio_04b.dts

diff --git a/drivers/of/unittest-data/Makefile b/drivers/of/unittest-data/Makefile
index 9b6807065827..009f4045c8e4 100644
--- a/drivers/of/unittest-data/Makefile
+++ b/drivers/of/unittest-data/Makefile
@@ -21,7 +21,13 @@ obj-$(CONFIG_OF_OVERLAY) += overlay.dtb.o \
 			    overlay_bad_add_dup_prop.dtb.o \
 			    overlay_bad_phandle.dtb.o \
 			    overlay_bad_symbol.dtb.o \
-			    overlay_base.dtb.o
+			    overlay_base.dtb.o \
+			    overlay_gpio_01.dtb.o \
+			    overlay_gpio_02a.dtb.o \
+			    overlay_gpio_02b.dtb.o \
+			    overlay_gpio_03.dtb.o \
+			    overlay_gpio_04a.dtb.o \
+			    overlay_gpio_04b.dtb.o
 
 # enable creation of __symbols__ node
 DTC_FLAGS_overlay += -@
diff --git a/drivers/of/unittest-data/overlay_gpio_01.dts b/drivers/of/unittest-data/overlay_gpio_01.dts
new file mode 100644
index 000000000000..f039e8bce3b6
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_01.dts
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_01 {
+		compatible = "unittest-gpio";
+		reg = <0>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		ngpios = <2>;
+		gpio-line-names = "line-A", "line-B";
+
+		line_b {
+			gpio-hog;
+			gpios = <2 0>;
+			input;
+			line-name = "line-B-input";
+		};
+	};
+};
diff --git a/drivers/of/unittest-data/overlay_gpio_02a.dts b/drivers/of/unittest-data/overlay_gpio_02a.dts
new file mode 100644
index 000000000000..cdafab604793
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_02a.dts
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_02 {
+		compatible = "unittest-gpio";
+		reg = <1>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		ngpios = <2>;
+		gpio-line-names = "line-A", "line-B";
+	};
+};
diff --git a/drivers/of/unittest-data/overlay_gpio_02b.dts b/drivers/of/unittest-data/overlay_gpio_02b.dts
new file mode 100644
index 000000000000..0cea0dccafba
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_02b.dts
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_02 {
+		line_a {
+			gpio-hog;
+			gpios = <1 0>;
+			input;
+			line-name = "line-A-input";
+		};
+	};
+};
diff --git a/drivers/of/unittest-data/overlay_gpio_03.dts b/drivers/of/unittest-data/overlay_gpio_03.dts
new file mode 100644
index 000000000000..1d5c680fa254
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_03.dts
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_03 {
+		compatible = "unittest-gpio";
+		reg = <0>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		ngpios = <2>;
+		gpio-line-names = "line-A", "line-B", "line-C", "line-D";
+
+		line_d {
+			gpio-hog;
+			gpios = <4 0>;
+			input;
+			line-name = "line-D-input";
+		};
+	};
+};
diff --git a/drivers/of/unittest-data/overlay_gpio_04a.dts b/drivers/of/unittest-data/overlay_gpio_04a.dts
new file mode 100644
index 000000000000..d2482cde310e
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_04a.dts
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_04 {
+		compatible = "unittest-gpio";
+		reg = <1>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		ngpios = <2>;
+		gpio-line-names = "line-A", "line-B", "line-C", "line-D";
+	};
+};
diff --git a/drivers/of/unittest-data/overlay_gpio_04b.dts b/drivers/of/unittest-data/overlay_gpio_04b.dts
new file mode 100644
index 000000000000..70ad05d759f9
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_04b.dts
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_04 {
+		line_c {
+			gpio-hog;
+			gpios = <3 0>;
+			input;
+			line-name = "line-C-input";
+		};
+	};
+};
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index 68b87587b2ef..db0a6f4103a4 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -24,6 +24,7 @@
 
 #include <linux/i2c.h>
 #include <linux/i2c-mux.h>
+#include <linux/gpio/driver.h>
 
 #include <linux/bitops.h>
 
@@ -46,6 +47,101 @@
 	failed; \
 })
 
+/*
+ * Expected message may have a message level other than KERN_INFO.
+ * Print the expected message only if the current loglevel will allow
+ * the actual message to print.
+ */
+#define EXPECT_BEGIN(level, fmt, ...) \
+	printk(level pr_fmt("EXPECT \\ : ") fmt, ##__VA_ARGS__)
+
+#define EXPECT_END(level, fmt, ...) \
+	printk(level pr_fmt("EXPECT / : ") fmt, ##__VA_ARGS__)
+
+struct unittest_gpio_dev {
+	void __iomem *base;
+	struct gpio_chip chip;
+	spinlock_t gpio_lock;
+};
+
+static int unittest_gpio_chip_request_count;
+static int unittest_gpio_probe_count;
+static int unittest_gpio_probe_pass_count;
+
+static int unittest_gpio_chip_request(struct gpio_chip *chip, unsigned int offset)
+{
+	unittest_gpio_chip_request_count++;
+
+	pr_debug("%s(): %s %d %d\n", __func__, chip->label, offset,
+		 unittest_gpio_chip_request_count);
+	return 0;
+}
+
+static int unittest_gpio_probe(struct platform_device *pdev)
+{
+	struct unittest_gpio_dev *devptr;
+	int ret;
+
+	unittest_gpio_probe_count++;
+
+	devptr = kzalloc(sizeof(*devptr), GFP_KERNEL);
+	if (!devptr)
+		return -ENOMEM;
+
+	spin_lock_init(&devptr->gpio_lock);
+
+	platform_set_drvdata(pdev, devptr);
+
+	devptr->chip.of_node = pdev->dev.of_node;
+	devptr->chip.label = "of-unittest-gpio";
+	devptr->chip.base = -1; /* dynamic allocation */
+	devptr->chip.ngpio = 5;
+	devptr->chip.request = unittest_gpio_chip_request;
+
+	ret = gpiochip_add_data(&devptr->chip, NULL);
+
+	unittest(!ret,
+		 "gpiochip_add_data() for node @%pOF failed, ret = %d\n", devptr->chip.of_node, ret);
+
+	if (!ret)
+		unittest_gpio_probe_pass_count++;
+	return ret;
+}
+
+static int unittest_gpio_remove(struct platform_device *pdev)
+{
+	struct unittest_gpio_dev *gdev = platform_get_drvdata(pdev);
+	struct device *dev = &pdev->dev;
+	struct device_node *np = pdev->dev.of_node;
+
+	dev_dbg(dev, "%s for node @%pOF\n", __func__, np);
+
+	if (!gdev)
+		return -EINVAL;
+
+	if (gdev->chip.base != -1)
+		gpiochip_remove(&gdev->chip);
+
+	platform_set_drvdata(pdev, NULL);
+	kfree(pdev);
+
+	return 0;
+}
+
+static const struct of_device_id unittest_gpio_id[] = {
+	{ .compatible = "unittest-gpio", },
+	{}
+};
+
+static struct platform_driver unittest_gpio_driver = {
+	.probe	= unittest_gpio_probe,
+	.remove	= unittest_gpio_remove,
+	.driver	= {
+		.name		= "unittest-gpio",
+		.of_match_table	= of_match_ptr(unittest_gpio_id),
+	},
+};
+
 static void __init of_unittest_find_node_by_name(void)
 {
 	struct device_node *np;
@@ -2183,6 +2279,153 @@ static inline void of_unittest_overlay_i2c_15(void) { }
 
 #endif
 
+static void __init of_unittest_overlay_gpio(void)
+{
+	int chip_request_count;
+	int probe_pass_count;
+	int ret;
+
+	/*
+	 * tests: apply overlays before registering driver
+	 * Similar to installing a driver as a module, the
+	 * driver is registered after applying the overlays.
+	 *
+	 * - apply overlay_gpio_01
+	 * - apply overlay_gpio_02a
+	 * - apply overlay_gpio_02b
+	 * - register driver
+	 *
+	 * register driver will result in
+	 *   - probe and processing gpio hog for overlay_gpio_01
+	 *   - probe for overlay_gpio_02a
+	 *   - processing gpio for overlay_gpio_02b
+	 */
+
+	probe_pass_count = unittest_gpio_probe_pass_count;
+	chip_request_count = unittest_gpio_chip_request_count;
+
+	/*
+	 * overlay_gpio_01 contains gpio node and child gpio hog node
+	 * overlay_gpio_02a contains gpio node
+	 * overlay_gpio_02b contains child gpio hog node
+	 */
+
+	unittest(overlay_data_apply("overlay_gpio_01", NULL),
+		 "Adding overlay 'overlay_gpio_01' failed\n");
+
+	unittest(overlay_data_apply("overlay_gpio_02a", NULL),
+		 "Adding overlay 'overlay_gpio_02a' failed\n");
+
+	unittest(overlay_data_apply("overlay_gpio_02b", NULL),
+		 "Adding overlay 'overlay_gpio_02b' failed\n");
+
+	/*
+	 * messages are the result of the probes, after the
+	 * driver is registered
+	 */
+
+	EXPECT_BEGIN(KERN_INFO,
+		     "GPIO line <<int>> (line-B-input) hogged as input\n");
+
+	EXPECT_BEGIN(KERN_INFO,
+		     "GPIO line <<int>> (line-A-input) hogged as input\n");
+
+	ret = platform_driver_register(&unittest_gpio_driver);
+	if (unittest(ret == 0, "could not register unittest gpio driver\n"))
+		return;
+
+	EXPECT_END(KERN_INFO,
+		   "GPIO line <<int>> (line-A-input) hogged as input\n");
+	EXPECT_END(KERN_INFO,
+		   "GPIO line <<int>> (line-B-input) hogged as input\n");
+
+	unittest(probe_pass_count + 2 == unittest_gpio_probe_pass_count,
+		 "unittest_gpio_probe() failed or not called\n");
+
+	unittest(chip_request_count + 2 == unittest_gpio_chip_request_count,
+		 "unittest_gpio_chip_request() called %d times (expected 1 time)\n",
+		 unittest_gpio_chip_request_count - chip_request_count);
+
+	/*
+	 * tests: apply overlays after registering driver
+	 *
+	 * Similar to a driver built-in to the kernel, the
+	 * driver is registered before applying the overlays.
+	 *
+	 * overlay_gpio_03 contains gpio node and child gpio hog node
+	 *
+	 * - apply overlay_gpio_03
+	 *
+	 * apply overlay will result in
+	 *   - probe and processing gpio hog.
+	 */
+
+	probe_pass_count = unittest_gpio_probe_pass_count;
+	chip_request_count = unittest_gpio_chip_request_count;
+
+	EXPECT_BEGIN(KERN_INFO,
+		     "GPIO line <<int>> (line-D-input) hogged as input\n");
+
+	/* overlay_gpio_03 contains gpio node and child gpio hog node */
+
+	unittest(overlay_data_apply("overlay_gpio_03", NULL),
+		 "Adding overlay 'overlay_gpio_03' failed\n");
+
+	EXPECT_END(KERN_INFO,
+		   "GPIO line <<int>> (line-D-input) hogged as input\n");
+
+	unittest(probe_pass_count + 1 == unittest_gpio_probe_pass_count,
+		 "unittest_gpio_probe() failed or not called\n");
+
+	unittest(chip_request_count + 1 == unittest_gpio_chip_request_count,
+		 "unittest_gpio_chip_request() called %d times (expected 1 time)\n",
+		 unittest_gpio_chip_request_count - chip_request_count);
+
+	/*
+	 * overlay_gpio_04a contains gpio node
+	 *
+	 * - apply overlay_gpio_04a
+	 *
+	 * apply the overlay will result in
+	 *   - probe for overlay_gpio_04a
+	 */
+
+	probe_pass_count = unittest_gpio_probe_pass_count;
+	chip_request_count = unittest_gpio_chip_request_count;
+
+	/* overlay_gpio_04a contains gpio node */
+
+	unittest(overlay_data_apply("overlay_gpio_04a", NULL),
+		 "Adding overlay 'overlay_gpio_04a' failed\n");
+
+	unittest(probe_pass_count + 1 == unittest_gpio_probe_pass_count,
+		 "unittest_gpio_probe() failed or not called\n");
+
+	/*
+	 * overlay_gpio_04b contains child gpio hog node
+	 *
+	 * - apply overlay_gpio_04b
+	 *
+	 * apply the overlay will result in
+	 *   - processing gpio for overlay_gpio_04b
+	 */
+
+	EXPECT_BEGIN(KERN_INFO,
+		     "GPIO line <<int>> (line-C-input) hogged as input\n");
+
+	/* overlay_gpio_04b contains child gpio hog node */
+
+	unittest(overlay_data_apply("overlay_gpio_04b", NULL),
+		 "Adding overlay 'overlay_gpio_04b' failed\n");
+
+	EXPECT_END(KERN_INFO,
+		   "GPIO line <<int>> (line-C-input) hogged as input\n");
+
+	unittest(chip_request_count + 1 == unittest_gpio_chip_request_count,
+		 "unittest_gpio_chip_request() called %d times (expected 1 time)\n",
+		 unittest_gpio_chip_request_count - chip_request_count);
+}
+
 static void __init of_unittest_overlay(void)
 {
 	struct device_node *bus_np = NULL;
@@ -2242,6 +2485,8 @@ static void __init of_unittest_overlay(void)
 	of_unittest_overlay_i2c_cleanup();
 #endif
 
+	of_unittest_overlay_gpio();
+
 	of_unittest_destroy_tracked_overlays();
 
 out:
@@ -2295,6 +2540,12 @@ struct overlay_info {
 OVERLAY_INFO_EXTERN(overlay_12);
 OVERLAY_INFO_EXTERN(overlay_13);
 OVERLAY_INFO_EXTERN(overlay_15);
+OVERLAY_INFO_EXTERN(overlay_gpio_01);
+OVERLAY_INFO_EXTERN(overlay_gpio_02a);
+OVERLAY_INFO_EXTERN(overlay_gpio_02b);
+OVERLAY_INFO_EXTERN(overlay_gpio_03);
+OVERLAY_INFO_EXTERN(overlay_gpio_04a);
+OVERLAY_INFO_EXTERN(overlay_gpio_04b);
 OVERLAY_INFO_EXTERN(overlay_bad_add_dup_node);
 OVERLAY_INFO_EXTERN(overlay_bad_add_dup_prop);
 OVERLAY_INFO_EXTERN(overlay_bad_phandle);
@@ -2319,6 +2570,12 @@ struct overlay_info {
 	OVERLAY_INFO(overlay_12, 0),
 	OVERLAY_INFO(overlay_13, 0),
 	OVERLAY_INFO(overlay_15, 0),
+	OVERLAY_INFO(overlay_gpio_01, 0),
+	OVERLAY_INFO(overlay_gpio_02a, 0),
+	OVERLAY_INFO(overlay_gpio_02b, 0),
+	OVERLAY_INFO(overlay_gpio_03, 0),
+	OVERLAY_INFO(overlay_gpio_04a, 0),
+	OVERLAY_INFO(overlay_gpio_04b, 0),
 	OVERLAY_INFO(overlay_bad_add_dup_node, -EINVAL),
 	OVERLAY_INFO(overlay_bad_add_dup_prop, -EINVAL),
 	OVERLAY_INFO(overlay_bad_phandle, -EINVAL),
-- 
Frank Rowand <frank.rowand@sony.com>