[RFC] fpga: dfl: a prototype uio driver

[trix@redhat.com]

From: Tom Rix <trix@redhat.com>

From [PATCH 0/2] UIO support for dfl devices
https://lore.kernel.org/linux-fpga/1602828151-24784-1-git-send-email-yilun.xu@intel.com/

Here is an idea to have uio support with no driver override.

This makes UIO the primary driver interface because every feature
will have one and makes the existing platform driver interface
secondary.  There will be a new burden for locking write access when
they compete.

Example shows finding the fpga's temperture.

Signed-off-by: Tom Rix <trix@redhat.com>
---
 drivers/fpga/dfl-fme-main.c |  9 +++-
 drivers/fpga/dfl-uio.c      | 96 +++++++++++++++++++++++++++++++++++++
 drivers/fpga/dfl.c          | 44 ++++++++++++++++-
 drivers/fpga/dfl.h          |  9 ++++
 uio.c                       | 56 ++++++++++++++++++++++
 5 files changed, 212 insertions(+), 2 deletions(-)
 create mode 100644 drivers/fpga/dfl-uio.c
 create mode 100644 uio.c

diff --git a/drivers/fpga/dfl-fme-main.c b/drivers/fpga/dfl-fme-main.c
index 037dc4f946f0..3323e90a18c4 100644
--- a/drivers/fpga/dfl-fme-main.c
+++ b/drivers/fpga/dfl-fme-main.c
@@ -709,12 +709,18 @@ static int fme_probe(struct platform_device *pdev)
 	if (ret)
 		goto dev_destroy;
 
-	ret = dfl_fpga_dev_ops_register(pdev, &fme_fops, THIS_MODULE);
+	ret = dfl_fpga_dev_feature_init_uio(pdev, DFH_TYPE_FIU);
 	if (ret)
 		goto feature_uinit;
 
+	ret = dfl_fpga_dev_ops_register(pdev, &fme_fops, THIS_MODULE);
+	if (ret)
+		goto feature_uinit_uio;
+
 	return 0;
 
+feature_uinit_uio:
+	dfl_fpga_dev_feature_uinit_uio(pdev, DFH_TYPE_FIU);
 feature_uinit:
 	dfl_fpga_dev_feature_uinit(pdev);
 dev_destroy:
@@ -726,6 +732,7 @@ exit:
 static int fme_remove(struct platform_device *pdev)
 {
 	dfl_fpga_dev_ops_unregister(pdev);
+	dfl_fpga_dev_feature_uinit_uio(pdev, DFH_TYPE_FIU);
 	dfl_fpga_dev_feature_uinit(pdev);
 	fme_dev_destroy(pdev);
 
diff --git a/drivers/fpga/dfl-uio.c b/drivers/fpga/dfl-uio.c
new file mode 100644
index 000000000000..7610ee0b19dc
--- /dev/null
+++ b/drivers/fpga/dfl-uio.c
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * prototype dfl uio driver
+ *
+ * Copyright Tom Rix 2020
+ */
+#include <linux/module.h>
+#include "dfl.h"
+
+static irqreturn_t dfl_uio_handler(int irq, struct uio_info *info)
+{
+	return IRQ_HANDLED;
+}
+
+static int dfl_uio_mmap(struct uio_info *info, struct vm_area_struct *vma)
+{
+	int ret = -ENODEV;
+	return ret;
+}
+
+static int dfl_uio_open(struct uio_info *info, struct inode *inode)
+{
+	int ret = -ENODEV;
+	struct dfl_feature *feature = container_of(info, struct dfl_feature, uio);
+	if (feature->dev)
+		mutex_lock(&feature->lock);
+
+	ret = 0;
+	return ret;
+}
+
+static int dfl_uio_release(struct uio_info *info, struct inode *inode)
+{
+	int ret = -ENODEV;
+	struct dfl_feature *feature = container_of(info, struct dfl_feature, uio);
+	if (feature->dev)
+		mutex_unlock(&feature->lock);
+
+	ret = 0;
+	return ret;
+}
+
+static int dfl_uio_irqcontrol(struct uio_info *info, s32 irq_on)
+{
+	int ret = -ENODEV;
+	return ret;
+}
+
+int dfl_uio_add(struct dfl_feature *feature)
+{
+	struct uio_info *uio = &feature->uio;
+	struct resource *res =
+		&feature->dev->resource[feature->resource_index];
+	int ret = 0;
+
+	uio->name = kasprintf(GFP_KERNEL, "dfl-uio-%llx", feature->id);
+	if (!uio->name) {
+		ret = -ENOMEM;
+		goto exit;
+	}
+
+	uio->version = "0.1";
+	uio->mem[0].memtype = UIO_MEM_PHYS;
+	uio->mem[0].addr = res->start & PAGE_MASK;
+	uio->mem[0].offs = res->start & ~PAGE_MASK;
+	uio->mem[0].size = (uio->mem[0].offs + resource_size(res)
+			    + PAGE_SIZE - 1) & PAGE_MASK;
+	/* How are nr_irqs > 1 handled ??? */
+	if (feature->nr_irqs == 1)
+		uio->irq = feature->irq_ctx[0].irq;
+	uio->handler = dfl_uio_handler;
+	//uio->mmap = dfl_uio_mmap;
+	uio->open = dfl_uio_open;
+	uio->release = dfl_uio_release;
+	uio->irqcontrol = dfl_uio_irqcontrol;
+
+	ret = uio_register_device(&feature->dev->dev, uio);
+	if (ret)
+		goto err_register;
+
+exit:
+	return ret;
+err_register:
+	kfree(uio->name);
+	goto exit;
+}
+EXPORT_SYMBOL_GPL(dfl_uio_add);
+
+int dfl_uio_remove(struct dfl_feature *feature)
+{
+	uio_unregister_device(&feature->uio);
+	kfree(feature->uio.name);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dfl_uio_remove);
+
diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index 1305be48037d..af2cd3d1b5f6 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c
@@ -603,6 +603,7 @@ static int dfl_feature_instance_init(struct platform_device *pdev,
 	}
 
 	feature->ops = drv->ops;
+	mutex_init(&feature->lock);
 
 	return ret;
 }
@@ -663,10 +664,51 @@ exit:
 }
 EXPORT_SYMBOL_GPL(dfl_fpga_dev_feature_init);
 
+int dfl_fpga_dev_feature_init_uio(struct platform_device *pdev, int dfh_type) {
+	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
+	struct dfl_feature *feature;
+	int ret;
+
+	dfl_fpga_dev_for_each_feature(pdata, feature) {
+		if (dfh_type == DFH_TYPE_FIU) {
+			if (feature->id == FEATURE_ID_FIU_HEADER ||
+			    feature->id == FEATURE_ID_AFU)
+			    continue;
+
+			ret = dfl_uio_add(feature);
+			if (ret)
+				goto exit;
+		}
+	}
+
+	return 0;
+exit:
+	dfl_fpga_dev_feature_uinit_uio(pdev, dfh_type);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dfl_fpga_dev_feature_init_uio);
+
+int dfl_fpga_dev_feature_uinit_uio(struct platform_device *pdev, int dfh_type) {
+	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
+	struct dfl_feature *feature;
+	int ret = 0;
+
+	dfl_fpga_dev_for_each_feature(pdata, feature) {
+		if (dfh_type == DFH_TYPE_FIU) {
+			if (feature->id == FEATURE_ID_FIU_HEADER ||
+			    feature->id == FEATURE_ID_AFU)
+				continue;
+
+			ret |= dfl_uio_remove(feature);
+		}
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dfl_fpga_dev_feature_uinit_uio);
+
 static void dfl_chardev_uinit(void)
 {
 	int i;
-
 	for (i = 0; i < DFL_FPGA_DEVT_MAX; i++)
 		if (MAJOR(dfl_chrdevs[i].devt)) {
 			unregister_chrdev_region(dfl_chrdevs[i].devt,
diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
index a85d1cd7a130..fde0fc902d4d 100644
--- a/drivers/fpga/dfl.h
+++ b/drivers/fpga/dfl.h
@@ -26,6 +26,7 @@
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/uuid.h>
+#include <linux/uio_driver.h>
 #include <linux/fpga/fpga-region.h>
 
 /* maximum supported number of ports */
@@ -232,6 +233,7 @@ struct dfl_feature_irq_ctx {
  * struct dfl_feature - sub feature of the feature devices
  *
  * @dev: ptr to pdev of the feature device which has the sub feature.
+ * @uio: uio interface for feature.
  * @id: sub feature id.
  * @index: unique identifier for an sub feature within the feature device.
  *	   It is possible that multiply sub features with same feature id are
@@ -248,6 +250,8 @@ struct dfl_feature_irq_ctx {
  */
 struct dfl_feature {
 	struct platform_device *dev;
+	struct uio_info uio;
+	struct mutex lock; /* serialize dev and uio */
 	u64 id;
 	int index;
 	int resource_index;
@@ -360,6 +364,11 @@ void dfl_fpga_dev_feature_uinit(struct platform_device *pdev);
 int dfl_fpga_dev_feature_init(struct platform_device *pdev,
 			      struct dfl_feature_driver *feature_drvs);
 
+int dfl_fpga_dev_feature_init_uio(struct platform_device *pdev, int dfh_type);
+int dfl_fpga_dev_feature_uinit_uio(struct platform_device *pdev, int dfh_type);
+int dfl_uio_add(struct dfl_feature *feature);
+int dfl_uio_remove(struct dfl_feature *feature);
+
 int dfl_fpga_dev_ops_register(struct platform_device *pdev,
 			      const struct file_operations *fops,
 			      struct module *owner);
diff --git a/uio.c b/uio.c
new file mode 100644
index 000000000000..50210aab4822
--- /dev/null
+++ b/uio.c
@@ -0,0 +1,56 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdint.h>
+
+int main()
+{
+	int fd;
+	uint64_t *ptr;
+	unsigned page_size=sysconf(_SC_PAGESIZE);
+	struct stat sb;
+
+	/*
+	 * this is fid 1, thermal mgt
+	 * ex/ 
+	 * # cat /sys/class/hwmon/hwmon3/temp1_input
+	 * 39000
+	 */
+	fd = open("/dev/uio0", O_RDONLY|O_SYNC);
+	if (fd < 0) {
+		perror("uio open:");
+		return errno;
+	}
+
+	ptr = (uint64_t *) mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);
+	if (!ptr) {
+		perror("uio mmap:");
+	} else {
+
+		/* from dfl-fme-main.c :
+		 * 
+		 * #define FME_THERM_RDSENSOR_FMT1	0x10
+		 * #define FPGA_TEMPERATURE	GENMASK_ULL(6, 0)
+		 *
+		 * case hwmon_temp_input:
+		 * v = readq(feature->ioaddr + FME_THERM_RDSENSOR_FMT1);
+		 * *val = (long)(FIELD_GET(FPGA_TEMPERATURE, v) * 1000);
+		 * break;
+		 */
+		uint64_t v = ptr[2];
+		v &= (1 << 6) -1;
+		v *= 1000;
+		printf("Temperature %d\n", v);
+	    
+		munmap(ptr, page_size);
+	}
+	if (close(fd))
+		perror("uio close:");
+
+	return errno;
+}
-- 
2.18.4