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

On Mon, 24 Jan 2022 at 04:00, 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.

This patch is still not labelled properly and as such being dropped.

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