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Date: Wed, 5 Jan 2022 10:16:31 +0800
From: Jiankang Chen <jkchen@...ux.alibaba.com>
To: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: 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, zhangliguang@...ux.alibaba.com
Subject: Re: [RFC V3 PATCH] coresight: change tmc from misc device to cdev
device
Hi Mathieu:
I will resend the patch again
tks
jay
在 2022/1/4 02:28, Mathieu Poirier 写道:
> Good day Jay,
>
> For your next iteration, please remove the "RFC" from the patch title, we are
> well pass that now.
>
> On Tue, Dec 21, 2021 at 08:04:37PM +0800, Jay Chen 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 is much better.
>
>> Signed-off-by: Jay Chen <jkchen@...ux.alibaba.com>
>> ---
>> .../hwtracing/coresight/coresight-tmc-core.c | 91 +++++++++++++++----
>> drivers/hwtracing/coresight/coresight-tmc.h | 10 +-
>> 2 files changed, 83 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
>> index d0276af82494..0d51071e9f88 100644
>> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
>> @@ -31,6 +31,12 @@ 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 +153,7 @@ 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);
>> + struct tmc_drvdata, cdev);
>>
>> ret = tmc_read_prepare(drvdata);
>> if (ret)
>> @@ -179,7 +185,7 @@ 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 +206,7 @@ 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 +457,7 @@ 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 +553,32 @@ 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 +608,11 @@ 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, dev->devt);
> 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 +641,43 @@ 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");
>> + ret = PTR_ERR(tmc_class);
>> + unregister_chrdev_region(tmc_major, TMC_DEV_MAX);
>> + return ret;
> You can simply 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..b65ac363f9e4 100644
>> --- a/drivers/hwtracing/coresight/coresight-tmc.h
>> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
>> @@ -7,6 +7,7 @@
>> #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>
> miscdevice.h can likely be removed in both .c and .h files.
>
> Thanks,
> Mathieu
>
>> @@ -163,11 +164,16 @@ 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 +197,7 @@ 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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