[PATCH v1 1/2] PCI: Add ignore_reset sysfs interface to control whether to do device reset in PCI drivers

[Zhenguo Yao <yaozhenguo1@gmail.com>]

Some PCI devices can't do device reset in enable and disable operations.
So, and ignore_reset sysfs interface to ignore reset in those operations.
For example:

echo 1 > /sys/bus/pci/xxxx/ignore_reset

PCI drivers can ignore reset for this device based on ignore_reset.

Signed-off-by: Zhenguo Yao <yaozhenguo1@gmail.com>
---
 drivers/pci/pci-sysfs.c | 25 +++++++++++++++++++++++++
 include/linux/pci.h     |  1 +
 2 files changed, 26 insertions(+)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 7fb5cd17cc98..c2fa2ed3ae55 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -255,6 +255,30 @@ static ssize_t ari_enabled_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(ari_enabled);
 
+static ssize_t ignore_reset_show(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct pci_dev *pci_dev = to_pci_dev(dev);
+
+	return sprintf(buf, "%u\n", pci_dev->ignore_reset);
+}
+static ssize_t ignore_reset_store(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf, size_t count)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	unsigned long val;
+
+	if (kstrtoul(buf, 0, &val) < 0)
+		return -EINVAL;
+
+	pdev->ignore_reset = !!val;
+
+	return count;
+}
+static DEVICE_ATTR_RW(ignore_reset);
+
 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)
 {
@@ -618,6 +642,7 @@ static struct attribute *pci_dev_attrs[] = {
 #endif
 	&dev_attr_driver_override.attr,
 	&dev_attr_ari_enabled.attr,
+	&dev_attr_ignore_reset.attr,
 	NULL,
 };
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index cd8aa6fce204..ac026acd4572 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -508,6 +508,7 @@ struct pci_dev {
 
 	/* These methods index pci_reset_fn_methods[] */
 	u8 reset_methods[PCI_NUM_RESET_METHODS]; /* In priority order */
+	u8 ignore_reset; /* ignore reset control in driver */
 };
 
 static inline struct pci_dev *pci_physfn(struct pci_dev *dev)
-- 
2.27.0