linux-kernel - [PATCH 04/12] misc: xilinx_sdfec: Add open, close and ioctl

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Message-ID: <1552997064-432700-5-git-send-email-dragan.cvetic@xilinx.com>
Date:   Tue, 19 Mar 2019 12:04:16 +0000
From:   Dragan Cvetic <dragan.cvetic@...inx.com>
To:     <arnd@...db.de>, <gregkh@...uxfoundation.org>,
        <michal.simek@...inx.com>, <linux-arm-kernel@...ts.infradead.org>
CC:     <linux-kernel@...r.kernel.org>,
        Dragan Cvetic <dragan.cvetic@...inx.com>,
        Derek Kiernan <derek.kiernan@...inx.com>
Subject: [PATCH 04/12] misc: xilinx_sdfec: Add open, close and ioctl

Add char device interface per DT node present and support
file operations:
- open(), which keeps only one open per device at a time,
- close(), which release the open for this device,
- ioctl(), which provides infrastructure for a specific driver
control.

Reviewed-by: Michal Simek <michal.simek@...inx.com>
Tested-by: Dragan Cvetic <dragan.cvetic@...inx.com>
Signed-off-by: Derek Kiernan <derek.kiernan@...inx.com>
Signed-off-by: Dragan Cvetic <dragan.cvetic@...inx.com>
---
 drivers/misc/xilinx_sdfec.c      | 79 ++++++++++++++++++++++++++++++++++++++++
 include/uapi/misc/xilinx_sdfec.h |  4 ++
 2 files changed, 83 insertions(+)

diff --git a/drivers/misc/xilinx_sdfec.c b/drivers/misc/xilinx_sdfec.c
index a52a5c6..3407de4 100644
--- a/drivers/misc/xilinx_sdfec.c
+++ b/drivers/misc/xilinx_sdfec.c
@@ -81,8 +81,87 @@ struct xsdfec_dev {
        struct xsdfec_clks clks;
 };

+static int xsdfec_dev_open(struct inode *iptr, struct file *fptr)
+{
+       struct xsdfec_dev *xsdfec;
+
+       xsdfec = container_of(iptr->i_cdev, struct xsdfec_dev, xsdfec_cdev);
+       if (!xsdfec)
+               return -EAGAIN;
+
+       /* Only one open per device at a time */
+       if (!atomic_dec_and_test(&xsdfec->open_count)) {
+               atomic_inc(&xsdfec->open_count);
+               return -EBUSY;
+       }
+
+       fptr->private_data = xsdfec;
+       return 0;
+}
+
+static int xsdfec_dev_release(struct inode *iptr, struct file *fptr)
+{
+       struct xsdfec_dev *xsdfec;
+
+       xsdfec = container_of(iptr->i_cdev, struct xsdfec_dev, xsdfec_cdev);
+       if (!xsdfec)
+               return -EAGAIN;
+
+       atomic_inc(&xsdfec->open_count);
+       return 0;
+}
+
+static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd,
+                            unsigned long data)
+{
+       struct xsdfec_dev *xsdfec = fptr->private_data;
+       void __user *arg = NULL;
+       int rval = -EINVAL;
+       int err = 0;
+
+       if (!xsdfec)
+               return rval;
+
+       if (_IOC_TYPE(cmd) != XSDFEC_MAGIC) {
+               dev_err(xsdfec->dev, "Not a xilinx sdfec ioctl");
+               return -ENOTTY;
+       }
+
+       /* check if ioctl argument is present and valid */
+       if (_IOC_DIR(cmd) != _IOC_NONE) {
+               arg = (void __user *)data;
+               if (!arg) {
+                       dev_err(xsdfec->dev,
+                               "xilinx sdfec ioctl argument is NULL Pointer");
+                       return rval;
+               }
+       }
+
+       /* Access check of the argument if present */
+       if (_IOC_DIR(cmd) & _IOC_READ)
+               err = !access_ok((void *)arg, _IOC_SIZE(cmd));
+       else if (_IOC_DIR(cmd) & _IOC_WRITE)
+               err = !access_ok((void *)arg, _IOC_SIZE(cmd));
+
+       if (err) {
+               dev_err(xsdfec->dev, "Invalid xilinx sdfec ioctl argument");
+               return -EFAULT;
+       }
+
+       switch (cmd) {
+       default:
+               /* Should not get here */
+               dev_err(xsdfec->dev, "Undefined SDFEC IOCTL");
+               break;
+       }
+       return rval;
+}
+
 static const struct file_operations xsdfec_fops = {
        .owner = THIS_MODULE,
+       .open = xsdfec_dev_open,
+       .release = xsdfec_dev_release,
+       .unlocked_ioctl = xsdfec_dev_ioctl,
 };

 static int xsdfec_clk_init(struct platform_device *pdev,
diff --git a/include/uapi/misc/xilinx_sdfec.h b/include/uapi/misc/xilinx_sdfec.h
index 5543163..5de0add 100644
--- a/include/uapi/misc/xilinx_sdfec.h
+++ b/include/uapi/misc/xilinx_sdfec.h
@@ -39,4 +39,8 @@ struct xsdfec_config {
        s32 fec_id;
 };

+/*
+ * XSDFEC IOCTL List
+ */
+#define XSDFEC_MAGIC 'f'
 #endif /* __XILINX_SDFEC_H__ */
--
2.7.4

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