WIP: gpio: add simple logic analyzer using pollingrenesas/topic/la-prototype-experimental

Not for upstream yet!

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

4 files changed, 212 insertions, 2 deletions

diff --git a/arch/arm64/boot/dts/renesas/salvator-common.dtsi b/arch/arm64/boot/dts/renesas/salvator-common.dtsi
index b8a7f37d289e67..a0000377de6266 100644
--- a/arch/arm64/boot/dts/renesas/salvator-common.dtsi
+++ b/arch/arm64/boot/dts/renesas/salvator-common.dtsi
@@ -110,7 +110,7 @@
 	};
 
 	logic-analyzer@pwm {
-		compatible = "logic-analyzer-irq";
+		compatible = "logic-analyzer-poll";
 
 		probe-gpios = <&gpio6 21 GPIO_OPEN_DRAIN>,
 				<&gpio6 4 GPIO_OPEN_DRAIN>;
@@ -366,7 +366,7 @@
 
 	status = "okay";
 
-	clock-frequency = <100000>;
+	clock-frequency = <400000>;
 
 	ak4613: codec@10 {
 		compatible = "asahi-kasei,ak4613";
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 1f75218ecce6d0..f9d241bb7914fe 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1631,6 +1631,9 @@ config GPIO_AGGREGATOR
 config GPIO_LOGIC_ANALYZER_IRQ
 	tristate "Simple GPIO logic analyzer IRQ"
 
+config GPIO_LOGIC_ANALYZER_POLL
+	tristate "Simple GPIO logic analyzer POLL"
+
 config GPIO_MOCKUP
 	tristate "GPIO Testing Driver"
 	select IRQ_SIM
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index b40f5573580e7d..6ef2378a9855b2 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_GPIO_ACPI)		+= gpiolib-acpi.o
 obj-$(CONFIG_GPIO_REGMAP)	+= gpio-regmap.o
 obj-$(CONFIG_GPIO_GENERIC)	+= gpio-generic.o
 obj-$(CONFIG_GPIO_LOGIC_ANALYZER_IRQ) += gpio-la-irq.o
+obj-$(CONFIG_GPIO_LOGIC_ANALYZER_POLL) += gpio-la-poll.o
 
 # directly supported by gpio-generic
 gpio-generic-$(CONFIG_GPIO_GENERIC)	+= gpio-mmio.o
diff --git a/drivers/gpio/gpio-la-poll.c b/drivers/gpio/gpio-la-poll.c
new file mode 100644
index 00000000000000..f5b2870bb29cf1
--- /dev/null
+++ b/drivers/gpio/gpio-la-poll.c
@@ -0,0 +1,206 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Simple logic analyzer using GPIOs
+ *
+ * Copyright (C) 2020 Wolfram Sang <wsa@sang-engineering.com>
+ * Copyright (C) 2020 Renesas Electronics Corporation
+ */
+
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/sizes.h>
+#include <linux/timekeeping.h>
+#include <linux/vmalloc.h>
+
+#define GPIO_LA_DEFAULT_BUF_SIZE SZ_256K
+
+struct gpio_la_poll_priv {
+	unsigned long ndelay;
+	u32 buf_idx;
+	struct debugfs_blob_wrapper blob;
+	struct gpio_descs *descs;
+	struct dentry *debug_dir, *blob_dent;
+	struct debugfs_blob_wrapper meta;
+	unsigned long gpio_delay;
+};
+
+static struct dentry *gpio_la_poll_debug_dir;
+
+static int fops_capture_set(void *data, u64 val)
+{
+	struct gpio_la_poll_priv *priv = data;
+	u8 *la_buf = priv->blob.data;
+	unsigned long state = 0;
+	int ret;
+
+	if (val) {
+		if (priv->blob_dent) {
+			debugfs_remove(priv->blob_dent);
+			priv->blob_dent = NULL;
+		}
+
+		priv->buf_idx = 0;
+
+		local_irq_disable();
+		preempt_disable_notrace();
+		while (priv->buf_idx < priv->blob.size && ret == 0) {
+			ret = gpiod_get_array_value(priv->descs->ndescs, priv->descs->desc,
+					      priv->descs->info, &state);
+			la_buf[priv->buf_idx++] = state;
+			//la_buf[priv->buf_idx++] = gpiod_get_value(priv->descs->desc[0]);
+			ndelay(priv->ndelay);
+		}
+		preempt_enable_notrace();
+		local_irq_enable();
+		if (ret)
+			pr_err("%s: couldn't read GPIOs: %d\n", __func__, ret);
+
+		priv->blob_dent = debugfs_create_blob("sample_data", 0400, priv->debug_dir, &priv->blob);
+	}
+
+	return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(fops_capture, NULL, fops_capture_set, "%llu\n");
+
+static int fops_buf_size_get(void *data, u64 *val)
+{
+	struct gpio_la_poll_priv *priv = data;
+
+	*val = priv->blob.size;
+
+	return 0;
+}
+
+static int fops_buf_size_set(void *data, u64 val)
+{
+	struct gpio_la_poll_priv *priv = data;
+	void *p;
+
+	//FIXME: locking?
+	//FIXME: sanity checks on val
+	vfree(priv->blob.data);
+	p = vzalloc(val);
+	if (!p)
+		return -ENOMEM;
+
+	priv->blob.data = p;
+	priv->blob.size = val;
+
+	return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(fops_buf_size, fops_buf_size_get, fops_buf_size_set, "%llu\n");
+
+static int gpio_la_poll_probe(struct platform_device *pdev)
+{
+	struct gpio_la_poll_priv *priv;
+	struct device *dev = &pdev->dev;
+	char *meta = NULL;
+	unsigned long state;
+	ktime_t start_time, end_time;
+	int ret, i;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	fops_buf_size_set(priv, GPIO_LA_DEFAULT_BUF_SIZE);
+
+	priv->descs = devm_gpiod_get_array(dev, "probe", GPIOD_IN);
+	if (IS_ERR(priv->descs))
+		return PTR_ERR(priv->descs);
+
+	/* artificial limit to keep 1 byte per sample */
+	if (priv->descs->ndescs > 8)
+		return -ERANGE;
+
+	for (i = 0; i < priv->descs->ndescs; i++) {
+		const char *str, *old_meta;
+
+		ret = of_property_read_string_index(pdev->dev.of_node, "probe-names",
+						    i, &str);
+		if (ret == 0) {
+			gpiod_set_consumer_name(priv->descs->desc[i], str);
+
+			old_meta = meta;
+			meta = devm_kasprintf(dev, GFP_KERNEL, "%sChannel %d: %s\n",
+					      old_meta ?: "", i, str);
+			if (!meta)
+				return -ENOMEM;
+
+			devm_kfree(dev, old_meta);
+		}
+	}
+
+	priv->debug_dir = debugfs_create_dir(dev_name(dev), gpio_la_poll_debug_dir);
+	if (IS_ERR(priv->debug_dir))
+		return PTR_ERR(priv->debug_dir);
+
+	debugfs_create_file_unsafe("buf_size", 0600, priv->debug_dir, priv, &fops_buf_size);
+	debugfs_create_file_unsafe("capture", 0600, priv->debug_dir, priv, &fops_capture);
+	debugfs_create_ulong("delay_ns_user", 0600, priv->debug_dir, &priv->ndelay);
+
+	priv->meta.data = meta;
+	priv->meta.size = strlen(meta);
+	debugfs_create_blob("meta_data", 0400, priv->debug_dir, &priv->meta);
+
+	local_irq_disable();
+	preempt_disable_notrace();
+	start_time = ktime_get();
+	for (i = 0; i < 1024 && ret == 0; i++)
+		ret = gpiod_get_array_value(priv->descs->ndescs, priv->descs->desc,
+				      priv->descs->info, &state);
+	end_time = ktime_get();
+	preempt_enable_notrace();
+	local_irq_enable();
+	if (ret) {
+		dev_err(dev, "couldn't read GPIOs: %d\n", ret);
+		return ret;
+	}
+
+	priv->gpio_delay = ktime_sub(end_time, start_time) / 1024;
+	debugfs_create_ulong("delay_ns_acquisition", 0400, priv->debug_dir, &priv->gpio_delay);
+
+	return 0;
+}
+
+static const struct of_device_id gpio_la_poll_of_match[] = {
+	{ .compatible = "logic-analyzer-poll", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, gpio_la_poll_of_match);
+
+static struct platform_driver gpio_la_poll_device_driver = {
+	.probe		= gpio_la_poll_probe,
+	//.remove	= FIXME
+	.driver		= {
+		.name	= "logic-analyzer-poll",
+		.of_match_table = gpio_la_poll_of_match,
+	}
+};
+
+static int __init gpio_la_poll_init(void)
+{
+	gpio_la_poll_debug_dir = debugfs_create_dir("simple_logic_analyzer-poll", NULL);
+	if (IS_ERR(gpio_la_poll_debug_dir))
+		return PTR_ERR(gpio_la_poll_debug_dir);
+
+	return platform_driver_register(&gpio_la_poll_device_driver);
+}
+late_initcall(gpio_la_poll_init);
+
+static void __exit gpio_la_poll_exit(void)
+{
+	platform_driver_unregister(&gpio_la_poll_device_driver);
+	debugfs_remove_recursive(gpio_la_poll_debug_dir);
+}
+module_exit(gpio_la_poll_exit);
+
+MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
+MODULE_DESCRIPTION("Simple logic analyzer using GPIOs");
+MODULE_LICENSE("GPL v2");