On Wed, Jul 24, 2019 at 11:41:10AM +0200, Greg KH wrote:

On Tue, Jul 23, 2019 at 12:51:27PM +0800, Wu Hao wrote:

quoted

This patch introduces more sysfs interfaces for Accelerated
Function Unit (AFU). These interfaces allow users to read
current AFU Power State (APx), read / clear AFU Power (APx)
events which are sticky to identify transient APx state,
and manage AFU's LTR (latency tolerance reporting).

Signed-off-by: Ananda Ravuri <redacted>
Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Wu Hao <redacted>
Acked-by: Alan Tull <atull@kernel.org>
Signed-off-by: Moritz Fischer <mdf@kernel.org>
---
v2: rebased, and remove DRV/MODULE_VERSION modifications
v3: update kernel version and date in sysfs doc
---
 Documentation/ABI/testing/sysfs-platform-dfl-port |  30 +++++
 drivers/fpga/dfl-afu-main.c                       | 137 ++++++++++++++++++++++
 drivers/fpga/dfl.h                                |  11 ++
 3 files changed, 178 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-platform-dfl-port b/Documentation/ABI/testing/sysfs-platform-dfl-port
index 6a92dda..5961fb2 100644
--- a/Documentation/ABI/testing/sysfs-platform-dfl-port
+++ b/Documentation/ABI/testing/sysfs-platform-dfl-port

@@ -14,3 +14,33 @@ Description:	Read-only. User can program different PR bitstreams to FPGA
 		Accelerator Function Unit (AFU) for different functions. It
 		returns uuid which could be used to identify which PR bitstream
 		is programmed in this AFU.
+
+What:		/sys/bus/platform/devices/dfl-port.0/power_state
+Date:		July 2019
+KernelVersion:	5.4
+Contact:	Wu Hao <hao.wu@intel.com>
+Description:	Read-only. It reports the APx (AFU Power) state, different APx
+		means different throttling level. When reading this file, it
+		returns "0" - Normal / "1" - AP1 / "2" - AP2 / "6" - AP6.
+
+What:		/sys/bus/platform/devices/dfl-port.0/ap1_event
+Date:		July 2019
+KernelVersion:	5.4
+Contact:	Wu Hao <hao.wu@intel.com>
+Description:	Read-write. Read or set 1 to clear AP1 (AFU Power State 1)
+		event. It's used to indicate transient AP1 state.

So reading the value changes the state of the system?  That's almost
always never a good idea.

Force userspace to write the value to change something.  Otherwise all
libraries that use sysfs will be accidentally changing the state of your
system without you ever knowing it.

Oh.. I think the description makes some misunderstanding here, will fix it
in the next version. This AP1/AP2 event will only be cleared by write 1 to
it, read will not change the state.

quoted

+
+What:		/sys/bus/platform/devices/dfl-port.0/ap2_event
+Date:		July 2019
+KernelVersion:	5.4
+Contact:	Wu Hao [off-list ref]
+Description:	Read-write. Read or set 1 to clear AP2 (AFU Power State 2)
+		event. It's used to indicate transient AP2 state.
+
+What:		/sys/bus/platform/devices/dfl-port.0/ltr
+Date:		July 2019
+KernelVersion:	5.4
+Contact:	Wu Hao [off-list ref]
+Description:	Read-write. Read and set AFU latency tolerance reporting value.
+		Set ltr to 1 if the AFU can tolerate latency >= 40us or set it
+		to 0 if it is latency sensitive.

diff --git a/drivers/fpga/dfl-afu-main.c b/drivers/fpga/dfl-afu-main.c
index 68b4d08..cb3f73e 100644
--- a/drivers/fpga/dfl-afu-main.c
+++ b/drivers/fpga/dfl-afu-main.c

@@ -141,8 +141,145 @@ static int port_get_id(struct platform_device *pdev)
 }
 static DEVICE_ATTR_RO(id);
 
+static ssize_t
+ltr_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct dfl_feature_platform_data *pdata = dev_get_platdata(dev);
+	void __iomem *base;
+	u64 v;
+
+	base = dfl_get_feature_ioaddr_by_id(dev, PORT_FEATURE_ID_HEADER);
+
+	mutex_lock(&pdata->lock);
+	v = readq(base + PORT_HDR_CTRL);
+	mutex_unlock(&pdata->lock);

Why do you need a lock to call readq()?  What are you protecting here?

If this code is running on 32bit machine, readq will be replaced with 2
readl operation. If that is the case, should we protect the code against
it?

quoted

+
+	return sprintf(buf, "%x\n", (u8)FIELD_GET(PORT_CTRL_LATENCY, v));
+}
+
+static ssize_t
+ltr_store(struct device *dev, struct device_attribute *attr,
+	  const char *buf, size_t count)
+{
+	struct dfl_feature_platform_data *pdata = dev_get_platdata(dev);
+	void __iomem *base;
+	u8 ltr;
+	u64 v;
+
+	if (kstrtou8(buf, 0, &ltr) || ltr > 1)
+		return -EINVAL;

Are you doing anything with this value?  If not, how about just using
the sysfs boolean read function and if it is 1, then do the clearing?

Same for all other show/store functions in here.

Sure, will fix this in the next version.

Thanks a lot for the comments.

Hao

thanks,

greg k-h