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Date:   Mon, 2 Jul 2018 18:26:49 +0200
From:   Jiri Pirko <jiri@resnulli.us>
To:     Andreas =?iso-8859-1?Q?F=E4rber?= <afaerber@suse.de>
Cc:     netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org,
        Jian-Hong Pan <starnight@g.ncu.edu.tw>,
        Marcel Holtmann <marcel@holtmann.org>,
        "David S . Miller" <davem@davemloft.net>,
        Matthias Brugger <mbrugger@suse.com>,
        Janus Piwek <jpiwek@arroweurope.com>,
        Michael =?iso-8859-1?Q?R=F6der?= <michael.roeder@avnet.eu>,
        Dollar Chen <dollar.chen@wtmec.com>,
        Ken Yu <ken.yu@rakwireless.com>
Subject: Re: [RFC net-next 08/15] net: lora: sx1276: Add debugfs
Message-ID: <20180702162649.GC2737@nanopsycho.orion>
References: <20180701110804.32415-1-afaerber@suse.de>
 <20180701110804.32415-9-afaerber@suse.de>
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Sun, Jul 01, 2018 at 01:07:57PM CEST, afaerber@suse.de wrote:
>Allow some interactive inspection at runtime via debugfs.
>
>Signed-off-by: Andreas F?rber <afaerber@suse.de>
>---
> drivers/net/lora/sx1276.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 132 insertions(+)
>
>diff --git a/drivers/net/lora/sx1276.c b/drivers/net/lora/sx1276.c
>index d6732111247a..1072019cfcc1 100644
>--- a/drivers/net/lora/sx1276.c
>+++ b/drivers/net/lora/sx1276.c
>@@ -5,6 +5,7 @@
>  * Copyright (c) 2016-2018 Andreas F?rber
>  */
> 
>+#include <linux/debugfs.h>
> #include <linux/delay.h>
> #include <linux/lora.h>
> #include <linux/module.h>
>@@ -61,6 +62,8 @@ struct sx1276_priv {
> 
> 	struct workqueue_struct *wq;
> 	struct work_struct tx_work;
>+
>+	struct dentry *debugfs;
> };
> 
> static int sx1276_read_single(struct spi_device *spi, u8 reg, u8 *val)
>@@ -416,6 +419,128 @@ static const struct net_device_ops sx1276_netdev_ops =  {
> 	.ndo_start_xmit = sx1276_loradev_start_xmit,
> };
> 
>+static ssize_t sx1276_freq_read(struct file *file, char __user *user_buf,
>+				 size_t count, loff_t *ppos)
>+{
>+	struct net_device *netdev = file->private_data;
>+	struct sx1276_priv *priv = netdev_priv(netdev);
>+	struct spi_device *spi = priv->spi;
>+	ssize_t size;
>+	char *buf;
>+	int ret;
>+	u8 msb, mid, lsb;
>+	u32 freq_xosc;
>+	unsigned long long frf;
>+
>+	ret = of_property_read_u32(spi->dev.of_node, "clock-frequency", &freq_xosc);
>+	if (ret)
>+		return 0;
>+
>+	mutex_lock(&priv->spi_lock);
>+
>+	ret = sx1276_read_single(spi, REG_FRF_MSB, &msb);
>+	if (!ret)
>+		ret = sx1276_read_single(spi, REG_FRF_MID, &mid);
>+	if (!ret)
>+		ret = sx1276_read_single(spi, REG_FRF_LSB, &lsb);
>+
>+	mutex_unlock(&priv->spi_lock);
>+
>+	if (ret)
>+		return 0;
>+
>+	frf = freq_xosc;
>+	frf *= ((ulong)msb << 16) | ((ulong)mid << 8) | lsb;
>+	frf /= (1 << 19);
>+
>+	buf = kasprintf(GFP_KERNEL, "%llu\n", frf);
>+	if (!buf)
>+		return 0;
>+
>+	size = simple_read_from_buffer(user_buf, count, ppos, buf, strlen(buf));
>+	kfree(buf);
>+
>+	return size;
>+}
>+
>+static const struct file_operations sx1276_freq_fops = {
>+	.owner = THIS_MODULE,
>+	.open = simple_open,
>+	.read = sx1276_freq_read,
>+};
>+
>+static ssize_t sx1276_state_read(struct file *file, char __user *user_buf,
>+				 size_t count, loff_t *ppos)
>+{
>+	struct net_device *netdev = file->private_data;
>+	struct sx1276_priv *priv = netdev_priv(netdev);
>+	struct spi_device *spi = priv->spi;
>+	ssize_t size;
>+	char *buf;
>+	int len = 0;
>+	int ret;
>+	u8 val;
>+	bool lora_mode = true;
>+	const int max_len = 4096;
>+
>+	buf = kzalloc(max_len, GFP_KERNEL);
>+	if (!buf)
>+		return 0;
>+
>+	mutex_lock(&priv->spi_lock);
>+
>+	ret = sx1276_read_single(spi, REG_OPMODE, &val);
>+	if (!ret) {
>+		len += snprintf(buf + len, max_len - len, "RegOpMode = 0x%02x\n", val);
>+		lora_mode = (val & REG_OPMODE_LONG_RANGE_MODE) != 0;
>+	}
>+
>+	ret = sx1276_read_single(spi, REG_FRF_MSB, &val);
>+	if (!ret)
>+		len += snprintf(buf + len, max_len - len, "RegFrMsb = 0x%02x\n", val);
>+	ret = sx1276_read_single(spi, REG_FRF_MID, &val);
>+	if (!ret)
>+		len += snprintf(buf + len, max_len - len, "RegFrMid = 0x%02x\n", val);
>+	ret = sx1276_read_single(spi, REG_FRF_LSB, &val);
>+	if (!ret)
>+		len += snprintf(buf + len, max_len - len, "RegFrLsb = 0x%02x\n", val);
>+
>+	ret = sx1276_read_single(spi, REG_PA_CONFIG, &val);
>+	if (!ret)
>+		len += snprintf(buf + len, max_len - len, "RegPaConfig = 0x%02x\n", val);
>+
>+	if (lora_mode) {
>+		ret = sx1276_read_single(spi, LORA_REG_IRQ_FLAGS_MASK, &val);
>+		if (!ret)
>+			len += snprintf(buf + len, max_len - len, "RegIrqFlagsMask = 0x%02x\n", val);
>+
>+		ret = sx1276_read_single(spi, LORA_REG_IRQ_FLAGS, &val);
>+		if (!ret)
>+			len += snprintf(buf + len, max_len - len, "RegIrqFlags = 0x%02x\n", val);
>+
>+		ret = sx1276_read_single(spi, LORA_REG_SYNC_WORD, &val);
>+		if (!ret)
>+			len += snprintf(buf + len, max_len - len, "RegSyncWord = 0x%02x\n", val);
>+	}
>+
>+	ret = sx1276_read_single(spi, REG_PA_DAC, &val);
>+	if (!ret)
>+		len += snprintf(buf + len, max_len - len, "RegPaDac = 0x%02x\n", val);
>+
>+	mutex_unlock(&priv->spi_lock);
>+
>+	size = simple_read_from_buffer(user_buf, count, ppos, buf, len);
>+	kfree(buf);
>+
>+	return size;
>+}
>+
>+static const struct file_operations sx1276_state_fops = {
>+	.owner = THIS_MODULE,
>+	.open = simple_open,
>+	.read = sx1276_state_read,
>+};
>+
> static int sx1276_probe(struct spi_device *spi)
> {
> 	struct net_device *netdev;
>@@ -566,6 +691,10 @@ static int sx1276_probe(struct spi_device *spi)
> 		return ret;
> 	}
> 
>+	priv->debugfs = debugfs_create_dir(dev_name(&spi->dev), NULL);
>+	debugfs_create_file("state", S_IRUGO, priv->debugfs, netdev, &sx1276_state_fops);
>+	debugfs_create_file("frequency", S_IRUGO, priv->debugfs, netdev, &sx1276_freq_fops);

Hmm. These look like useful information not only for debugging. I think
it would be worth to expose these via some standard uapi. Like generic
netlink, similar to nl80211


>+
> 	dev_info(&spi->dev, "SX1276 module probed (SX%d)", model);
> 
> 	return 0;
>@@ -574,6 +703,9 @@ static int sx1276_probe(struct spi_device *spi)
> static int sx1276_remove(struct spi_device *spi)
> {
> 	struct net_device *netdev = spi_get_drvdata(spi);
>+	struct sx1276_priv *priv = netdev_priv(netdev);
>+
>+	debugfs_remove_recursive(priv->debugfs);
> 
> 	unregister_loradev(netdev);
> 	free_loradev(netdev);
>-- 
>2.16.4
>