Re: [RESEND PATCH v2] coresight: change tmc from misc device to cdev device

[Mathieu Poirier <mathieu.poirier@linaro.org>]

On Thu, 13 Jan 2022 at 20:16, Jiankang Chen <jkchen@linux.alibaba.com> wrote:
>
> Hi Mathieu
>
> 在 2022/1/14 00:56, Mathieu Poirier 写道:
> > On Wed, 12 Jan 2022 at 23:12, Jay Chen <jkchen@linux.alibaba.com> wrote:
> >> Currently, there are 130 etr and etf on our machine,
> >> but the current coresight tmc driver uses misc_register
> >> to register the device, which leads to the error that
> >> the device number is not enough.
> >>
> >> coresight-tmc: probe of xxxxx failed with error -16
> >>
> >> This patch changes the device registration method
> >> to cdev's dynamic registration method to solve the
> >> problem of insufficient device numbers.
> > On December 21st you posted this patch with a "RFC V3 PATCH" tag.  On
> > January 5th you posted a new version with a simple "PATCH" tag which,
> > minutes later, was superseded by another patch labelled "RESEND
> > PATCH".  Today you're sending yet another revision labelled "RESEND
> > PATCH V2"...
> >
> > Is it a "V2" of the "RESEND PATCH" that was a new revision of the "RFC
> > V3 PATCH"?  Are you confused?  I certainly am...
> >
> this patch v2 is a new version，and it fix some bugs;
>

How can it be a V2 when a V3 has already been published?  I will not
review this patch, and even less apply it, until it is properly
labelled.

> sorry
>
> jay
>
> >> Signed-off-by: Jay Chen <jkchen@linux.alibaba.com>
> >> ---
> >>   .../hwtracing/coresight/coresight-tmc-core.c  | 103 ++++++++++++++----
> >>   drivers/hwtracing/coresight/coresight-tmc.h   |  11 +-
> >>   2 files changed, 91 insertions(+), 23 deletions(-)
> >>
> >> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
> >> index d0276af82494..0977f1ce6338 100644
> >> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
> >> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
> >> @@ -12,7 +12,6 @@
> >>   #include <linux/io.h>
> >>   #include <linux/err.h>
> >>   #include <linux/fs.h>
> >> -#include <linux/miscdevice.h>
> >>   #include <linux/mutex.h>
> >>   #include <linux/property.h>
> >>   #include <linux/uaccess.h>
> >> @@ -31,6 +30,12 @@ DEFINE_CORESIGHT_DEVLIST(etb_devs, "tmc_etb");
> >>   DEFINE_CORESIGHT_DEVLIST(etf_devs, "tmc_etf");
> >>   DEFINE_CORESIGHT_DEVLIST(etr_devs, "tmc_etr");
> >>
> >> +static DEFINE_IDA(tmc_ida);
> >> +static dev_t tmc_major;
> >> +static struct class *tmc_class;
> >> +
> >> +#define TMC_DEV_MAX    (MINORMASK + 1)
> >> +
> >>   void tmc_wait_for_tmcready(struct tmc_drvdata *drvdata)
> >>   {
> >>          struct coresight_device *csdev = drvdata->csdev;
> >> @@ -146,8 +151,10 @@ static int tmc_read_unprepare(struct tmc_drvdata *drvdata)
> >>   static int tmc_open(struct inode *inode, struct file *file)
> >>   {
> >>          int ret;
> >> -       struct tmc_drvdata *drvdata = container_of(file->private_data,
> >> -                                                  struct tmc_drvdata, miscdev);
> >> +       struct tmc_cdev *cdev = container_of(inode->i_cdev,
> >> +                                            struct tmc_cdev, cdev);
> >> +       struct tmc_drvdata *drvdata = container_of(cdev,
> >> +                                                  struct tmc_drvdata, cdev);
> >>
> >>          ret = tmc_read_prepare(drvdata);
> >>          if (ret)
> >> @@ -178,8 +185,10 @@ static ssize_t tmc_read(struct file *file, char __user *data, size_t len,
> >>   {
> >>          char *bufp;
> >>          ssize_t actual;
> >> -       struct tmc_drvdata *drvdata = container_of(file->private_data,
> >> -                                                  struct tmc_drvdata, miscdev);
> >> +       struct tmc_cdev *cdev = container_of(file->f_inode->i_cdev,
> >> +                                            struct tmc_cdev, cdev);
> >> +       struct tmc_drvdata *drvdata = container_of(cdev,
> >> +                                                  struct tmc_drvdata, cdev);
> >>          actual = tmc_get_sysfs_trace(drvdata, *ppos, len, &bufp);
> >>          if (actual <= 0)
> >>                  return 0;
> >> @@ -199,8 +208,10 @@ static ssize_t tmc_read(struct file *file, char __user *data, size_t len,
> >>   static int tmc_release(struct inode *inode, struct file *file)
> >>   {
> >>          int ret;
> >> -       struct tmc_drvdata *drvdata = container_of(file->private_data,
> >> -                                                  struct tmc_drvdata, miscdev);
> >> +       struct tmc_cdev *cdev = container_of(inode->i_cdev,
> >> +                                            struct tmc_cdev, cdev);
> >> +       struct tmc_drvdata *drvdata = container_of(cdev,
> >> +                                                  struct tmc_drvdata, cdev);
> >>
> >>          ret = tmc_read_unprepare(drvdata);
> >>          if (ret)
> >> @@ -451,6 +462,7 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
> >>   {
> >>          int ret = 0;
> >>          u32 devid;
> >> +       dev_t devt;
> >>          void __iomem *base;
> >>          struct device *dev = &adev->dev;
> >>          struct coresight_platform_data *pdata = NULL;
> >> @@ -546,14 +558,32 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
> >>                  goto out;
> >>          }
> >>
> >> -       drvdata->miscdev.name = desc.name;
> >> -       drvdata->miscdev.minor = MISC_DYNAMIC_MINOR;
> >> -       drvdata->miscdev.fops = &tmc_fops;
> >> -       ret = misc_register(&drvdata->miscdev);
> >> +       ret = ida_simple_get(&tmc_ida, 0, TMC_DEV_MAX, GFP_KERNEL);
> >> +       if (ret < 0)
> >> +               goto err_coresight_unregister;
> >> +
> >> +       cdev_init(&drvdata->cdev.cdev, &tmc_fops);
> >> +       drvdata->cdev.cdev.owner = THIS_MODULE;
> >> +       devt = MKDEV(MAJOR(tmc_major), ret);
> >> +       ret = cdev_add(&drvdata->cdev.cdev, devt, 1);
> >>          if (ret)
> >> -               coresight_unregister(drvdata->csdev);
> >> -       else
> >> +               goto err_free_tmc_ida;
> >> +
> >> +       drvdata->cdev.dev = device_create(tmc_class, NULL, devt, &drvdata->cdev, desc.name);
> >> +       if (IS_ERR(drvdata->cdev.dev)) {
> >> +               ret = PTR_ERR(drvdata->cdev.dev);
> >> +               goto err_delete_cdev;
> >> +       } else
> >>                  pm_runtime_put(&adev->dev);
> >> +
> >> +       return 0;
> >> +
> >> +err_delete_cdev:
> >> +       cdev_del(&drvdata->cdev.cdev);
> >> +err_free_tmc_ida:
> >> +       ida_simple_remove(&tmc_ida, MINOR(devt));
> >> +err_coresight_unregister:
> >> +       coresight_unregister(drvdata->csdev);
> >>   out:
> >>          return ret;
> >>   }
> >> @@ -583,13 +613,11 @@ static void tmc_shutdown(struct amba_device *adev)
> >>   static void tmc_remove(struct amba_device *adev)
> >>   {
> >>          struct tmc_drvdata *drvdata = dev_get_drvdata(&adev->dev);
> >> +       struct device *dev = drvdata->cdev.dev;
> >>
> >> -       /*
> >> -        * Since misc_open() holds a refcount on the f_ops, which is
> >> -        * etb fops in this case, device is there until last file
> >> -        * handler to this device is closed.
> >> -        */
> >> -       misc_deregister(&drvdata->miscdev);
> >> +       ida_simple_remove(&tmc_ida, MINOR(dev->devt));
> >> +       device_destroy(tmc_class, dev->devt);
> >> +       cdev_del(&drvdata->cdev.cdev);
> >>          coresight_unregister(drvdata->csdev);
> >>   }
> >>
> >> @@ -618,7 +646,42 @@ static struct amba_driver tmc_driver = {
> >>          .id_table       = tmc_ids,
> >>   };
> >>
> >> -module_amba_driver(tmc_driver);
> >> +static int __init tmc_init(void)
> >> +{
> >> +       int ret;
> >> +
> >> +       ret = alloc_chrdev_region(&tmc_major, 0, TMC_DEV_MAX, "tmc");
> >> +       if (ret < 0) {
> >> +               pr_err("tmc: failed to allocate char dev region\n");
> >> +               return ret;
> >> +       }
> >> +
> >> +       tmc_class = class_create(THIS_MODULE, "tmc");
> >> +       if (IS_ERR(tmc_class)) {
> >> +               pr_err("tmc: failed to create class\n");
> >> +               unregister_chrdev_region(tmc_major, TMC_DEV_MAX);
> >> +               return PTR_ERR(tmc_class);
> >> +       }
> >> +
> >> +       ret = amba_driver_register(&tmc_driver);
> >> +       if (ret) {
> >> +               pr_err("tmc: error registering amba driver\n");
> >> +               class_destroy(tmc_class);
> >> +               unregister_chrdev_region(tmc_major, TMC_DEV_MAX);
> >> +       }
> >> +
> >> +       return ret;
> >> +}
> >> +
> >> +static void __exit tmc_exit(void)
> >> +{
> >> +       amba_driver_unregister(&tmc_driver);
> >> +       class_destroy(tmc_class);
> >> +       unregister_chrdev_region(tmc_major, TMC_DEV_MAX);
> >> +}
> >> +
> >> +module_init(tmc_init);
> >> +module_exit(tmc_exit);
> >>
> >>   MODULE_AUTHOR("Pratik Patel <pratikp@codeaurora.org>");
> >>   MODULE_DESCRIPTION("Arm CoreSight Trace Memory Controller driver");
> >> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
> >> index 6bec20a392b3..11441c6b9c26 100644
> >> --- a/drivers/hwtracing/coresight/coresight-tmc.h
> >> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> >> @@ -7,9 +7,9 @@
> >>   #ifndef _CORESIGHT_TMC_H
> >>   #define _CORESIGHT_TMC_H
> >>
> >> +#include <linux/cdev.h>
> >>   #include <linux/dma-mapping.h>
> >>   #include <linux/idr.h>
> >> -#include <linux/miscdevice.h>
> >>   #include <linux/mutex.h>
> >>   #include <linux/refcount.h>
> >>
> >> @@ -163,11 +163,16 @@ struct etr_buf {
> >>          void                            *private;
> >>   };
> >>
> >> +struct tmc_cdev {
> >> +       struct cdev cdev;
> >> +       struct device *dev;
> >> +};
> >> +
> >>   /**
> >>    * struct tmc_drvdata - specifics associated to an TMC component
> >>    * @base:      memory mapped base address for this component.
> >>    * @csdev:     component vitals needed by the framework.
> >> - * @miscdev:   specifics to handle "/dev/xyz.tmc" entry.
> >> + * @tmc_cdev:  specifics to handle "/dev/xyz.tmc" entry.
> >>    * @spinlock:  only one at a time pls.
> >>    * @pid:       Process ID of the process being monitored by the session
> >>    *             that is using this component.
> >> @@ -191,7 +196,7 @@ struct etr_buf {
> >>   struct tmc_drvdata {
> >>          void __iomem            *base;
> >>          struct coresight_device *csdev;
> >> -       struct miscdevice       miscdev;
> >> +       struct tmc_cdev         cdev;
> >>          spinlock_t              spinlock;
> >>          pid_t                   pid;
> >>          bool                    reading;
> >> --
> >> 2.27.0
> >>

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