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Date: Thu, 13 Jan 2022 14:06:00 +0800
From: Jiankang Chen <jkchen@...ux.alibaba.com>
To: mathieu.poirier@...aro.org, suzuki.poulose@....com,
leo.yan@...aro.org, alexander.shishkin@...ux.intel.com,
linux-arm-kernel@...ts.infradead.org, coresight@...ts.linaro.org,
linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH] coresight: change tmc from misc device to cdev
device
hi all
在 2022/1/5 10:38, Jay Chen 写道:
> 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.
>
> Signed-off-by: Jay Chen <jkchen@...ux.alibaba.com>
> ---
> .../hwtracing/coresight/coresight-tmc-core.c | 91 +++++++++++++++----
> drivers/hwtracing/coresight/coresight-tmc.h | 11 ++-
> 2 files changed, 82 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
> index d0276af82494..55a131c059fe 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;
> @@ -147,7 +152,7 @@ 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);
> +
I found a mistake in this place. I'll revise it again;
sorry
> struct tmc_drvdata, cdev);
>
> ret = tmc_read_prepare(drvdata);
> if (ret)
> @@ -179,7 +184,7 @@ 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_drvdata, cdev);
> actual = tmc_get_sysfs_trace(drvdata, *ppos, len, &bufp);
> if (actual <= 0)
> return 0;
> @@ -200,7 +205,7 @@ 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_drvdata, cdev);
>
> ret = tmc_read_unprepare(drvdata);
> if (ret)
> @@ -451,6 +456,7 @@ 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 +552,32 @@ 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 +607,11 @@ 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 +640,42 @@ 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@...eaurora.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;
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