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SubjectRe: [PATCH v2 1/4] firmware: xilinx: Add sysfs interface
On Wed, Jan 08, 2020 at 03:54:20PM -0800, Jolly Shah wrote:
> From: Rajan Vaja <rajan.vaja@xilinx.com>
>
> Add Firmware-ggs sysfs interface which provides read/write
> interface to global storage registers.
>
> Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> Signed-off-by: Jolly Shah <jollys@xilinx.com>
> ---
> Changes in v2:
> - Updated Linux kernel version in documentation.
> - Used DEVICE_ATTR_* and ATTRIBUTE_GROUPS macros.
> - Free Kobject structure in case of error.
> - Resolved smatch errors.
> - Updated Signed-off-by sequence.
> ---
> Documentation/ABI/stable/sysfs-firmware-zynqmp | 50 +++++
> drivers/firmware/xilinx/Makefile | 2 +-
> drivers/firmware/xilinx/zynqmp-ggs.c | 284 +++++++++++++++++++++++++
> drivers/firmware/xilinx/zynqmp.c | 32 +++
> include/linux/firmware/xlnx-zynqmp.h | 10 +
> 5 files changed, 377 insertions(+), 1 deletion(-)
> create mode 100644 Documentation/ABI/stable/sysfs-firmware-zynqmp
> create mode 100644 drivers/firmware/xilinx/zynqmp-ggs.c
>
> diff --git a/Documentation/ABI/stable/sysfs-firmware-zynqmp b/Documentation/ABI/stable/sysfs-firmware-zynqmp
> new file mode 100644
> index 0000000..cffa2fc
> --- /dev/null
> +++ b/Documentation/ABI/stable/sysfs-firmware-zynqmp
> @@ -0,0 +1,50 @@
> +What: /sys/firmware/zynqmp/ggs*

Why are these attributes just not hanging off of the platform device for
the firmware controller? Why do you need a new subdir under "firmware"?

> +Date: January 2018
> +KernelVersion: 5.5

5.6? :)

> +Contact: "Jolly Shah" <jollys@xilinx.com>
> +Description:
> + Read/Write PMU global general storage register value,
> + GLOBAL_GEN_STORAGE{0:3}.
> + Global general storage register that can be used
> + by system to pass information between masters.
> +
> + The register is reset during system or power-on
> + resets. Three registers are used by the FSBL and
> + other Xilinx software products: GLOBAL_GEN_STORAGE{4:6}.
> +
> + Usage:
> + # cat /sys/firmware/zynqmp/ggs0
> + # echo <mask> <value> > /sys/firmware/zynqmp/ggs0
> +
> + Example:
> + # cat /sys/firmware/zynqmp/ggs0
> + # echo 0xFFFFFFFF 0x1234ABCD > /sys/firmware/zynqmp/ggs0
> +
> +Users: Xilinx
> +
> +What: /sys/firmware/zynqmp/pggs*
> +Date: January 2018
> +KernelVersion: 5.5
> +Contact: "Jolly Shah" <jollys@xilinx.com>
> +Description:
> + Read/Write PMU persistent global general storage register
> + value, PERS_GLOB_GEN_STORAGE{0:3}.
> + Persistent global general storage register that
> + can be used by system to pass information between
> + masters.
> +
> + This register is only reset by the power-on reset
> + and maintains its value through a system reset.
> + Four registers are used by the FSBL and other Xilinx
> + software products: PERS_GLOB_GEN_STORAGE{4:7}.
> + Register is reset only by a POR reset.
> +
> + Usage:
> + # cat /sys/firmware/zynqmp/pggs0
> + # echo <mask> <value> > /sys/firmware/zynqmp/pggs0
> +
> + Example:
> + # cat /sys/firmware/zynqmp/pggs0
> + # echo 0xFFFFFFFF 0x1234ABCD > /sys/firmware/zynqmp/pggs0
> +
> +Users: Xilinx
> diff --git a/drivers/firmware/xilinx/Makefile b/drivers/firmware/xilinx/Makefile
> index 875a537..1e8643c 100644
> --- a/drivers/firmware/xilinx/Makefile
> +++ b/drivers/firmware/xilinx/Makefile
> @@ -1,5 +1,5 @@
> # SPDX-License-Identifier: GPL-2.0
> # Makefile for Xilinx firmwares
>
> -obj-$(CONFIG_ZYNQMP_FIRMWARE) += zynqmp.o
> +obj-$(CONFIG_ZYNQMP_FIRMWARE) += zynqmp.o zynqmp-ggs.o
> obj-$(CONFIG_ZYNQMP_FIRMWARE_DEBUG) += zynqmp-debug.o
> diff --git a/drivers/firmware/xilinx/zynqmp-ggs.c b/drivers/firmware/xilinx/zynqmp-ggs.c
> new file mode 100644
> index 0000000..e2a6700
> --- /dev/null
> +++ b/drivers/firmware/xilinx/zynqmp-ggs.c
> @@ -0,0 +1,284 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Xilinx Zynq MPSoC Firmware layer
> + *
> + * Copyright (C) 2014-2018 Xilinx, Inc.
> + *
> + * Jolly Shah <jollys@xilinx.com>
> + * Rajan Vaja <rajanv@xilinx.com>
> + */
> +
> +#include <linux/compiler.h>
> +#include <linux/of.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/uaccess.h>
> +#include <linux/slab.h>
> +#include <linux/firmware/xlnx-zynqmp.h>
> +
> +static ssize_t read_register(char *buf, u32 ioctl_id, u32 reg)
> +{
> + int ret;
> + u32 ret_payload[PAYLOAD_ARG_CNT];
> + const struct zynqmp_eemi_ops *eemi_ops = zynqmp_pm_get_eemi_ops();
> +
> + if (IS_ERR(eemi_ops) || !eemi_ops->ioctl)
> + return -EFAULT;
> +
> + ret = eemi_ops->ioctl(0, ioctl_id, reg, 0, ret_payload);
> + if (ret)
> + return ret;
> +
> + return sprintf(buf, "0x%x\n", ret_payload[1]);
> +}
> +
> +static ssize_t write_register(const char *buf, size_t count, u32 read_ioctl,
> + u32 write_ioctl, u32 reg)
> +{
> + char *kern_buff, *inbuf, *tok;
> + long mask, value;
> + int ret;
> + u32 ret_payload[PAYLOAD_ARG_CNT];
> + const struct zynqmp_eemi_ops *eemi_ops = zynqmp_pm_get_eemi_ops();
> +
> + if (IS_ERR(eemi_ops) || !eemi_ops->ioctl)
> + return -EFAULT;
> +
> + kern_buff = kzalloc(count, GFP_KERNEL);
> + if (!kern_buff)
> + return -ENOMEM;
> +
> + ret = strlcpy(kern_buff, buf, count);
> + if (ret < 0) {
> + ret = -EFAULT;
> + goto err;
> + }
> +
> + inbuf = kern_buff;
> +
> + /* Read the write mask */
> + tok = strsep(&inbuf, " ");
> + if (!tok) {
> + ret = -EFAULT;

If you just set count to the error value, no need to test the value of
ret when you exit. Not a big deal...

> + goto err;
> + }
> +
> + ret = kstrtol(tok, 16, &mask);
> + if (ret) {
> + ret = -EFAULT;
> + goto err;
> + }
> +
> + /* Read the write value */
> + tok = strsep(&inbuf, " ");
> + if (!tok) {
> + ret = -EFAULT;
> + goto err;
> + }
> +
> + ret = kstrtol(tok, 16, &value);
> + if (ret) {
> + ret = -EFAULT;
> + goto err;
> + }
> +
> + ret = eemi_ops->ioctl(0, read_ioctl, reg, 0, ret_payload);

This feels "tricky", if you tie this to the device you have your driver
bound to, will this make it easier instead of having to go through the
ioctl callback?


> + if (ret) {
> + ret = -EFAULT;
> + goto err;
> + }
> + ret_payload[1] &= ~mask;
> + value &= mask;
> + value |= ret_payload[1];
> +
> + ret = eemi_ops->ioctl(0, write_ioctl, reg, value, NULL);
> + if (ret)
> + ret = -EFAULT;
> +
> +err:
> + kfree(kern_buff);
> + if (ret)
> + return ret;
> +
> + return count;
> +}
> +
> +/**
> + * ggs_show - Show global general storage (ggs) sysfs attribute
> + * @device: Device structure
> + * @attr: Device attribute structure
> + * @buf: Requested available shutdown_scope attributes string
> + * @reg: Register number
> + *
> + * Return:Number of bytes printed into the buffer.
> + *
> + * Helper function for viewing a ggs register value.
> + *
> + * User-space interface for viewing the content of the ggs0 register.
> + * cat /sys/firmware/zynqmp/ggs0
> + */
> +static ssize_t ggs_show(struct device *device,
> + struct device_attribute *attr,
> + char *buf,
> + u32 reg)
> +{
> + return read_register(buf, IOCTL_READ_GGS, reg);
> +}
> +
> +/**
> + * ggs_store - Store global general storage (ggs) sysfs attribute
> + * @device: Device structure
> + * @attr: Device attribute structure
> + * @buf: User entered shutdown_scope attribute string
> + * @count: Size of buf
> + * @reg: Register number
> + *
> + * Return: count argument if request succeeds, the corresponding
> + * error code otherwise
> + *
> + * Helper function for storing a ggs register value.
> + *
> + * For example, the user-space interface for storing a value to the
> + * ggs0 register:
> + * echo 0xFFFFFFFF 0x1234ABCD > /sys/firmware/zynqmp/ggs0
> + */
> +static ssize_t ggs_store(struct device *device,
> + struct device_attribute *attr,
> + const char *buf, size_t count,
> + u32 reg)
> +{
> + if (!device || !attr || !buf || !count || reg >= GSS_NUM_REGS)
> + return -EINVAL;
> +
> + return write_register(buf, count, IOCTL_READ_GGS, IOCTL_WRITE_GGS, reg);
> +}
> +
> +/* GGS register show functions */
> +#define GGS0_SHOW(N) \
> + ssize_t ggs##N##_show(struct device *device, \
> + struct device_attribute *attr, \
> + char *buf) \
> + { \
> + return ggs_show(device, attr, buf, N); \
> + }
> +
> +static GGS0_SHOW(0);
> +static GGS0_SHOW(1);
> +static GGS0_SHOW(2);
> +static GGS0_SHOW(3);
> +
> +/* GGS register store function */
> +#define GGS0_STORE(N) \
> + ssize_t ggs##N##_store(struct device *device, \
> + struct device_attribute *attr, \
> + const char *buf, \
> + size_t count) \
> + { \
> + return ggs_store(device, attr, buf, count, N); \
> + }
> +
> +static GGS0_STORE(0);
> +static GGS0_STORE(1);
> +static GGS0_STORE(2);
> +static GGS0_STORE(3);
> +
> +/**
> + * pggs_show - Show persistent global general storage (pggs) sysfs attribute
> + * @device: Device structure
> + * @attr: Device attribute structure
> + * @buf: Requested available shutdown_scope attributes string
> + * @reg: Register number
> + *
> + * Return:Number of bytes printed into the buffer.
> + *
> + * Helper function for viewing a pggs register value.
> + */
> +static ssize_t pggs_show(struct device *device,
> + struct device_attribute *attr,
> + char *buf,
> + u32 reg)
> +{
> + return read_register(buf, IOCTL_READ_PGGS, reg);
> +}
> +
> +/**
> + * pggs_store - Store persistent global general storage (pggs) sysfs attribute
> + * @device: Device structure
> + * @attr: Device attribute structure
> + * @buf: User entered shutdown_scope attribute string
> + * @count: Size of buf
> + * @reg: Register number
> + *
> + * Return: count argument if request succeeds, the corresponding
> + * error code otherwise
> + *
> + * Helper function for storing a pggs register value.
> + */
> +static ssize_t pggs_store(struct device *device,
> + struct device_attribute *attr,
> + const char *buf, size_t count,
> + u32 reg)
> +{
> + return write_register(buf, count, IOCTL_READ_PGGS,
> + IOCTL_WRITE_PGGS, reg);
> +}
> +
> +#define PGGS0_SHOW(N) \
> + ssize_t pggs##N##_show(struct device *device, \
> + struct device_attribute *attr, \
> + char *buf) \
> + { \
> + return pggs_show(device, attr, buf, N); \
> + }
> +
> +#define PGGS0_STORE(N) \
> + ssize_t pggs##N##_store(struct device *device, \
> + struct device_attribute *attr, \
> + const char *buf, \
> + size_t count) \
> + { \
> + return pggs_store(device, attr, buf, count, N); \
> + }
> +
> +/* PGGS register show functions */
> +static PGGS0_SHOW(0);
> +static PGGS0_SHOW(1);
> +static PGGS0_SHOW(2);
> +static PGGS0_SHOW(3);
> +
> +/* PGGS register store functions */
> +static PGGS0_STORE(0);
> +static PGGS0_STORE(1);
> +static PGGS0_STORE(2);
> +static PGGS0_STORE(3);
> +
> +/* GGS register attributes */
> +static DEVICE_ATTR_RW(ggs0);
> +static DEVICE_ATTR_RW(ggs1);
> +static DEVICE_ATTR_RW(ggs2);
> +static DEVICE_ATTR_RW(ggs3);
> +
> +/* PGGS register attributes */
> +static DEVICE_ATTR_RW(pggs0);
> +static DEVICE_ATTR_RW(pggs1);
> +static DEVICE_ATTR_RW(pggs2);
> +static DEVICE_ATTR_RW(pggs3);
> +
> +static struct attribute *zynqmp_ggs_attrs[] = {
> + &dev_attr_ggs0.attr,
> + &dev_attr_ggs1.attr,
> + &dev_attr_ggs2.attr,
> + &dev_attr_ggs3.attr,
> + &dev_attr_pggs0.attr,
> + &dev_attr_pggs1.attr,
> + &dev_attr_pggs2.attr,
> + &dev_attr_pggs3.attr,
> + NULL,
> +};
> +
> +ATTRIBUTE_GROUPS(zynqmp_ggs);
> +
> +int zynqmp_pm_ggs_init(struct kobject *parent_kobj)
> +{
> + return sysfs_create_group(parent_kobj, zynqmp_ggs_groups[0]);

You might be racing userspace here and loosing :(

> +}
> diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c
> index 75bdfaa..4c1117d 100644
> --- a/drivers/firmware/xilinx/zynqmp.c
> +++ b/drivers/firmware/xilinx/zynqmp.c
> @@ -473,6 +473,10 @@ static inline int zynqmp_is_valid_ioctl(u32 ioctl_id)
> case IOCTL_GET_PLL_FRAC_MODE:
> case IOCTL_SET_PLL_FRAC_DATA:
> case IOCTL_GET_PLL_FRAC_DATA:
> + case IOCTL_WRITE_GGS:
> + case IOCTL_READ_GGS:
> + case IOCTL_WRITE_PGGS:
> + case IOCTL_READ_PGGS:

Huh???

> return 1;
> default:
> return 0;
> @@ -704,6 +708,28 @@ const struct zynqmp_eemi_ops *zynqmp_pm_get_eemi_ops(void)
> }
> EXPORT_SYMBOL_GPL(zynqmp_pm_get_eemi_ops);
>
> +static int zynqmp_pm_sysfs_init(void)
> +{
> + struct kobject *zynqmp_kobj;
> + int ret;
> +
> + zynqmp_kobj = kobject_create_and_add("zynqmp", firmware_kobj);
> + if (!zynqmp_kobj) {
> + pr_err("zynqmp: Firmware kobj add failed.\n");
> + return -ENOMEM;
> + }
> +
> + ret = zynqmp_pm_ggs_init(zynqmp_kobj);
> + if (ret) {
> + kobject_put(zynqmp_kobj);
> + pr_err("%s() GGS init fail with error %d\n",
> + __func__, ret);
> + goto err;
> + }
> +err:
> + return ret;
> +}
> +
> static int zynqmp_firmware_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -751,6 +777,12 @@ static int zynqmp_firmware_probe(struct platform_device *pdev)
> /* Assign eemi_ops_table */
> eemi_ops_tbl = &eemi_ops;
>
> + ret = zynqmp_pm_sysfs_init();

See, you have a platform device, hang the attributes off of that instead
of making a kobject and detatching yourself from the global device tree!

Please redo this, I think it will make it a lot simpler and more
obvious.

thanks,

greg k-h

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