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Subject: Re: [PATCH V3 XRT Alveo 15/18] fpga: xrt: clock frequence counter
 platform driver
To:     Tom Rix <trix@redhat.com>, Lizhi Hou <lizhi.hou@xilinx.com>,
        <linux-kernel@vger.kernel.org>
CC:     <linux-fpga@vger.kernel.org>, <maxz@xilinx.com>,
        <sonal.santan@xilinx.com>, <michal.simek@xilinx.com>,
        <stefanos@xilinx.com>, <devicetree@vger.kernel.org>,
        <mdf@kernel.org>, <robh@kernel.org>, Max Zhen <max.zhen@xilinx.com>
References: <20210218064019.29189-1-lizhih@xilinx.com>
 <20210218064019.29189-16-lizhih@xilinx.com>
 <85c34149-ccb4-31c9-4a7d-477b30effad2@redhat.com>
From:   Lizhi Hou <lizhi.hou@xilinx.com>
Message-ID: <4dcd1a9f-1d96-6c1e-8e70-13cbc312c7b5@xilinx.com>
Date:   Fri, 12 Mar 2021 15:43:54 -0800
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Hi Tom,


On 03/06/2021 07:25 AM, Tom Rix wrote:
> On 2/17/21 10:40 PM, Lizhi Hou wrote:
>> Add clock frequence counter driver. Clock frequence counter is
>> a hardware function discovered by walking xclbin metadata. A platform
>> device node will be created for it. Other part of driver can read the
>> actual clock frequence through clock frequence counter driver.
>>
>> Signed-off-by: Sonal Santan <sonal.santan@xilinx.com>
>> Signed-off-by: Max Zhen <max.zhen@xilinx.com>
>> Signed-off-by: Lizhi Hou <lizhih@xilinx.com>
>> ---
>>   drivers/fpga/xrt/include/xleaf/clkfreq.h |  23 +++
>>   drivers/fpga/xrt/lib/xleaf/clkfreq.c     | 221 +++++++++++++++++++++++
>>   2 files changed, 244 insertions(+)
>>   create mode 100644 drivers/fpga/xrt/include/xleaf/clkfreq.h
>>   create mode 100644 drivers/fpga/xrt/lib/xleaf/clkfreq.c
>>
>> diff --git a/drivers/fpga/xrt/include/xleaf/clkfreq.h b/drivers/fpga/xrt/include/xleaf/clkfreq.h
>> new file mode 100644
>> index 000000000000..29fc45e8a31b
>> --- /dev/null
>> +++ b/drivers/fpga/xrt/include/xleaf/clkfreq.h
>> @@ -0,0 +1,23 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Header file for XRT Clock Counter Leaf Driver
>> + *
>> + * Copyright (C) 2020-2021 Xilinx, Inc.
>> + *
>> + * Authors:
>> + *   Lizhi Hou <Lizhi.Hou@xilinx.com>
>> + */
>> +
>> +#ifndef _XRT_CLKFREQ_H_
>> +#define _XRT_CLKFREQ_H_
>> +
>> +#include "xleaf.h"
>> +
>> +/*
>> + * CLKFREQ driver IOCTL calls.
>> + */
>> +enum xrt_clkfreq_ioctl_cmd {
>> +     XRT_CLKFREQ_READ = XRT_XLEAF_CUSTOM_BASE, /* See comments in xleaf.h */
>> +};
>> +
>> +#endif       /* _XRT_CLKFREQ_H_ */
>> diff --git a/drivers/fpga/xrt/lib/xleaf/clkfreq.c b/drivers/fpga/xrt/lib/xleaf/clkfreq.c
>> new file mode 100644
>> index 000000000000..2482dd2cff47
>> --- /dev/null
>> +++ b/drivers/fpga/xrt/lib/xleaf/clkfreq.c
>> @@ -0,0 +1,221 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Xilinx Alveo FPGA Clock Frequency Counter Driver
>> + *
>> + * Copyright (C) 2020-2021 Xilinx, Inc.
>> + *
>> + * Authors:
>> + *      Lizhi Hou<Lizhi.Hou@xilinx.com>
>> + */
>> +
>> +#include <linux/mod_devicetable.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/delay.h>
>> +#include <linux/device.h>
>> +#include <linux/io.h>
>> +#include "metadata.h"
>> +#include "xleaf.h"
>> +#include "xleaf/clkfreq.h"
>> +
>> +#define CLKFREQ_ERR(clkfreq, fmt, arg...)   \
>> +     xrt_err((clkfreq)->pdev, fmt "\n", ##arg)
>> +#define CLKFREQ_WARN(clkfreq, fmt, arg...)  \
>> +     xrt_warn((clkfreq)->pdev, fmt "\n", ##arg)
>> +#define CLKFREQ_INFO(clkfreq, fmt, arg...)  \
>> +     xrt_info((clkfreq)->pdev, fmt "\n", ##arg)
>> +#define CLKFREQ_DBG(clkfreq, fmt, arg...)   \
>> +     xrt_dbg((clkfreq)->pdev, fmt "\n", ##arg)
>> +
>> +#define XRT_CLKFREQ          "xrt_clkfreq"
>> +
>> +#define OCL_CLKWIZ_STATUS_MASK               0xffff
>> +
>> +#define OCL_CLKWIZ_STATUS_MEASURE_START      0x1
>> +#define OCL_CLKWIZ_STATUS_MEASURE_DONE       0x2
>> +#define OCL_CLK_FREQ_COUNTER_OFFSET  0x8
>> +#define OCL_CLK_FREQ_V5_COUNTER_OFFSET       0x10
>> +#define OCL_CLK_FREQ_V5_CLK0_ENABLED 0x10000
> Similar to earlier, OCL -> XRT_CLKFREQ
>
> Use regmap
Will change this.
>
>> +
>> +struct clkfreq {
>> +     struct platform_device  *pdev;
>> +     void __iomem            *clkfreq_base;
>> +     const char              *clkfreq_ep_name;
>> +     struct mutex            clkfreq_lock; /* clock counter dev lock */
>> +};
>> +
>> +static inline u32 reg_rd(struct clkfreq *clkfreq, u32 offset)
>> +{
>> +     return ioread32(clkfreq->clkfreq_base + offset);
>> +}
>> +
>> +static inline void reg_wr(struct clkfreq *clkfreq, u32 val, u32 offset)
>> +{
>> +     iowrite32(val, clkfreq->clkfreq_base + offset);
>> +}
>> +
>> +static u32 clkfreq_read(struct clkfreq *clkfreq)
>> +{
> failure returns 0, it would be better if -EINVAL or similar was returned.
>
> and u32 *freq added as a function parameter
Will change this.
>
>> +     u32 freq = 0, status;
>> +     int times = 10;
> 10 is a config parameter, should be a #define
Sure.
>> +
>> +     mutex_lock(&clkfreq->clkfreq_lock);
>> +     reg_wr(clkfreq, OCL_CLKWIZ_STATUS_MEASURE_START, 0);
>> +     while (times != 0) {
>> +             status = reg_rd(clkfreq, 0);
>> +             if ((status & OCL_CLKWIZ_STATUS_MASK) ==
>> +                 OCL_CLKWIZ_STATUS_MEASURE_DONE)
>> +                     break;
>> +             mdelay(1);
>> +             times--;
>> +     };
>> +     if (times > 0) {
> I do not like tristate setting, convert to if-else
Will change this.
>> +             freq = (status & OCL_CLK_FREQ_V5_CLK0_ENABLED) ?
>> +                     reg_rd(clkfreq, OCL_CLK_FREQ_V5_COUNTER_OFFSET) :
>> +                     reg_rd(clkfreq, OCL_CLK_FREQ_COUNTER_OFFSET);
>> +     }
>> +     mutex_unlock(&clkfreq->clkfreq_lock);
>> +
>> +     return freq;
>> +}
>> +
>> +static ssize_t freq_show(struct device *dev, struct device_attribute *attr, char *buf)
>> +{
>> +     struct clkfreq *clkfreq = platform_get_drvdata(to_platform_device(dev));
>> +     u32 freq;
>> +     ssize_t count;
>> +
>> +     freq = clkfreq_read(clkfreq);
> unchecked error
Will add check.
>> +     count = snprintf(buf, 64, "%d\n", freq);
> %u
Sure.
>> +
>> +     return count;
>> +}
>> +static DEVICE_ATTR_RO(freq);
>> +
>> +static struct attribute *clkfreq_attrs[] = {
>> +     &dev_attr_freq.attr,
>> +     NULL,
>> +};
>> +
>> +static struct attribute_group clkfreq_attr_group = {
>> +     .attrs = clkfreq_attrs,
>> +};
>> +
>> +static int
>> +xrt_clkfreq_leaf_ioctl(struct platform_device *pdev, u32 cmd, void *arg)
>> +{
>> +     struct clkfreq          *clkfreq;
>> +     int                     ret = 0;
>> +
>> +     clkfreq = platform_get_drvdata(pdev);
>> +
>> +     switch (cmd) {
>> +     case XRT_XLEAF_EVENT:
>> +             /* Does not handle any event. */
>> +             break;
>> +     case XRT_CLKFREQ_READ: {
> brace not needed
Will remove.
>> +             *(u32 *)arg = clkfreq_read(clkfreq);
> Unchecked error
Will add check.
>> +             break;
>> +     }
>> +     default:
>> +             xrt_err(pdev, "unsupported cmd %d", cmd);
>> +             return -EINVAL;
>> +     }
>> +
>> +     return ret;
>> +}
>> +
>> +static int clkfreq_remove(struct platform_device *pdev)
>> +{
>> +     struct clkfreq *clkfreq;
>> +
>> +     clkfreq = platform_get_drvdata(pdev);
>> +     if (!clkfreq) {
>> +             xrt_err(pdev, "driver data is NULL");
>> +             return -EINVAL;
>> +     }
>> +
>> +     platform_set_drvdata(pdev, NULL);
>> +     devm_kfree(&pdev->dev, clkfreq);
>> +
>> +     CLKFREQ_INFO(clkfreq, "successfully removed clkfreq subdev");
>> +     return 0;
>> +}
>> +
>> +static int clkfreq_probe(struct platform_device *pdev)
>> +{
>> +     struct clkfreq *clkfreq = NULL;
>> +     struct resource *res;
>> +     int ret;
>> +
>> +     clkfreq = devm_kzalloc(&pdev->dev, sizeof(*clkfreq), GFP_KERNEL);
>> +     if (!clkfreq)
>> +             return -ENOMEM;
>> +
>> +     platform_set_drvdata(pdev, clkfreq);
>> +     clkfreq->pdev = pdev;
>> +     mutex_init(&clkfreq->clkfreq_lock);
>> +
>> +     res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +     clkfreq->clkfreq_base = ioremap(res->start, res->end - res->start + 1);
>> +     if (!clkfreq->clkfreq_base) {
>> +             CLKFREQ_ERR(clkfreq, "map base %pR failed", res);
>> +             ret = -EFAULT;
>> +             goto failed;
>> +     }
>> +     clkfreq->clkfreq_ep_name = res->name;
>> +
>> +     ret = sysfs_create_group(&pdev->dev.kobj, &clkfreq_attr_group);
>> +     if (ret) {
>> +             CLKFREQ_ERR(clkfreq, "create clkfreq attrs failed: %d", ret);
>> +             goto failed;
>> +     }
>> +
>> +     CLKFREQ_INFO(clkfreq, "successfully initialized clkfreq subdev");
>> +
>> +     return 0;
>> +
>> +failed:
>> +     clkfreq_remove(pdev);
>> +     return ret;
>> +}
>> +
>> +static struct xrt_subdev_endpoints xrt_clkfreq_endpoints[] = {
>> +     {
>> +             .xse_names = (struct xrt_subdev_ep_names[]) {
>> +                     { .regmap_name = "freq_cnt" },
> name should be closer to filename, maybe 'clock_frequency' or 'clkfreq'
'freq_cnt' is from firmware metadata. I will add #define in metadata.h.

Thanks,
Lizhi
>
> Tom
>
>> +                     { NULL },
>> +             },
>> +             .xse_min_ep = 1,
>> +     },
>> +     { 0 },
>> +};
>> +
>> +static struct xrt_subdev_drvdata xrt_clkfreq_data = {
>> +     .xsd_dev_ops = {
>> +             .xsd_ioctl = xrt_clkfreq_leaf_ioctl,
>> +     },
>> +};
>> +
>> +static const struct platform_device_id xrt_clkfreq_table[] = {
>> +     { XRT_CLKFREQ, (kernel_ulong_t)&xrt_clkfreq_data },
>> +     { },
>> +};
>> +
>> +static struct platform_driver xrt_clkfreq_driver = {
>> +     .driver = {
>> +             .name = XRT_CLKFREQ,
>> +     },
>> +     .probe = clkfreq_probe,
>> +     .remove = clkfreq_remove,
>> +     .id_table = xrt_clkfreq_table,
>> +};
>> +
>> +void clkfreq_leaf_init_fini(bool init)
>> +{
>> +     if (init) {
>> +             xleaf_register_driver(XRT_SUBDEV_CLKFREQ,
>> +                                   &xrt_clkfreq_driver, xrt_clkfreq_endpoints);
>> +     } else {
>> +             xleaf_unregister_driver(XRT_SUBDEV_CLKFREQ);
>> +     }
>> +}