[RFC V2 PATCH] coresight: change tmc from misc device to cdev device
Mathieu Poirier
mathieu.poirier at linaro.org
Fri Dec 17 09:15:13 PST 2021
Good day Jay,
On Fri, Dec 17, 2021 at 11:42:08AM +0800, Jay Chen wrote:
> From: root <root at localhost.localdomain>
>
> For coresight in the server scenario, if there are too many
> funnel (about 130) and tmc (about 130) peripherals, the error
> of insufficient device numbers will occur by misc device
>
Why is the changelog mention funnels when they have nothing to do with misc
devices?
> Signed-off-by: root <root at localhost.localdomain>
> ---
> .../hwtracing/coresight/coresight-tmc-core.c | 84 +++++++++++++++----
> drivers/hwtracing/coresight/coresight-tmc.h | 10 ++-
> 2 files changed, 75 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
> index d0276af82494..03b114c0616a 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
> @@ -31,6 +31,11 @@ DEFINE_CORESIGHT_DEVLIST(etb_devs, "tmc_etb");
> DEFINE_CORESIGHT_DEVLIST(etf_devs, "tmc_etf");
> DEFINE_CORESIGHT_DEVLIST(etr_devs, "tmc_etr");
>
> +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);
> + 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)
> @@ -449,8 +454,9 @@ static u32 tmc_etr_get_max_burst_size(struct device *dev)
>
> static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
> {
> - int ret = 0;
> + int ret = 0, tmc_num = 0;
> u32 devid;
> + dev_t devt;
> void __iomem *base;
> struct device *dev = &adev->dev;
> struct coresight_platform_data *pdata = NULL;
> @@ -546,14 +552,26 @@ 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);
> - if (ret)
> + tmc_num = etb_devs.nr_idx + etf_devs.nr_idx +
> + etr_devs.nr_idx;
Humm... This is turning out to be a lot worse than expected. Please use an IDA,
the same way the rpmsg_char driver does.
> +
> + cdev_init(&drvdata->cdev.cdev, &tmc_fops);
> + drvdata->cdev.cdev.owner = THIS_MODULE;
> + devt = MKDEV(MAJOR(tmc_major), tmc_num - 1);
> + ret = cdev_add(&drvdata->cdev.cdev, devt, 1);
> + if (ret) {
> coresight_unregister(drvdata->csdev);
> - else
> + goto out;
> + }
> +
> + 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);
> + cdev_del(&drvdata->cdev.cdev);
> + coresight_unregister(drvdata->csdev);
> + } else
> pm_runtime_put(&adev->dev);
> +
> out:
> return ret;
> }
> @@ -584,12 +602,8 @@ static void tmc_remove(struct amba_device *adev)
> {
> struct tmc_drvdata *drvdata = dev_get_drvdata(&adev->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);
> + device_destroy(tmc_class, drvdata->cdev.dev->devt);
> + cdev_del(&drvdata->cdev.cdev);
> coresight_unregister(drvdata->csdev);
> }
>
> @@ -618,7 +632,43 @@ 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("failed to create tmc class\n");
> + ret = PTR_ERR(tmc_class);
> + unregister_chrdev_region(tmc_major, TMC_DEV_MAX);
> + return ret;
> + }
> +
> + 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 at 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..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>
> @@ -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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