Re: [PATCH 1/5] firmware: xilinx: Adds new eemi call for reg access

Michal Simek
2019-12-18T14:10:56Z

On 05. 12. 19 0:29, Jolly Shah wrote:
> From: Rajan Vaja <rajan.vaja@xilinx.com>
>
> This patch adds new EEMI call which is used for CSU/PMU register
> access from linux.
>
> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
> Signed-off-by: Jolly Shah <jolly.shah@xilinx.com>
> ---
> drivers/firmware/xilinx/zynqmp.c | 183 +++++++++++++++++++++++++++++++++++
> include/linux/firmware/xlnx-zynqmp.h | 9 ++
> 2 files changed, 192 insertions(+)
>
> diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c
> index fd3d837..56431ad 100644
> --- a/drivers/firmware/xilinx/zynqmp.c
> +++ b/drivers/firmware/xilinx/zynqmp.c
> @@ -24,6 +24,8 @@
> #include <linux/firmware/xlnx-zynqmp.h>
> #include "zynqmp-debug.h"
>
> +static unsigned long register_address;
> +
> static const struct zynqmp_eemi_ops *eemi_ops_tbl;
>
> static const struct mfd_cell firmware_devs[] = {
> @@ -664,6 +666,26 @@ static int zynqmp_pm_set_requirement(const u32 node, const u32 capabilities,
> qos, ack, NULL);
> }
>
> +/**
> + * zynqmp_pm_config_reg_access - PM Config API for Config register access
> + * @register_access_id: ID of the requested REGISTER_ACCESS
> + * @address: Address of the register to be accessed
> + * @mask: Mask to be written to the register
> + * @value: Value to be written to the register
> + * @out: Returned output value
> + *
> + * This function calls REGISTER_ACCESS to configure CSU/PMU registers.
> + *
> + * Return: Returns status, either success or error+reason
> + */
> +
> +static int zynqmp_pm_config_reg_access(u32 register_access_id, u32 address,
> + u32 mask, u32 value, u32 *out)
> +{
> + return zynqmp_pm_invoke_fn(PM_REGISTER_ACCESS, register_access_id,
> + address, mask, value, out);
> +}
> +
> static const struct zynqmp_eemi_ops eemi_ops = {
> .get_api_version = zynqmp_pm_get_api_version,
> .get_chipid = zynqmp_pm_get_chipid,
> @@ -687,6 +709,7 @@ static const struct zynqmp_eemi_ops eemi_ops = {
> .set_requirement = zynqmp_pm_set_requirement,
> .fpga_load = zynqmp_pm_fpga_load,
> .fpga_get_status = zynqmp_pm_fpga_get_status,
> + .register_access = zynqmp_pm_config_reg_access,
> };
>
> /**
> @@ -704,6 +727,160 @@ const struct zynqmp_eemi_ops *zynqmp_pm_get_eemi_ops(void)
> }
> EXPORT_SYMBOL_GPL(zynqmp_pm_get_eemi_ops);
>
> +/**
> + * config_reg_store - Write config_reg sysfs attribute
> + * @kobj: Kobject structure
> + * @attr: Kobject attribute structure
> + * @buf: User entered health_status attribute string
> + * @count: Buffer size
> + *
> + * User-space interface for setting the config register.
> + *
> + * To write any CSU/PMU register
> + * echo <mask> <values> > /sys/firmware/zynqmp/config_reg
> + * Usage:
> + * echo 0x345AB234 0xFFFFFFFF 0x1234ABCD > /sys/firmware/zynqmp/config_reg
> + *
> + * To Read any CSU/PMU register, write address to the variable like below
> + * echo > /sys/firmware/zynqmp/config_reg
> + *
> + * Return: count argument if request succeeds, the corresponding error
> + * code otherwise
> + */
> +static ssize_t config_reg_store(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + const char *buf, size_t count)
> +{
> + char *kern_buff, *inbuf, *tok;
> + unsigned long address, value, mask;
> + int ret;
> +
> + kern_buff = kzalloc(count, GFP_KERNEL);
> + if (!kern_buff)
> + return -ENOMEM;
> +
> + ret = strlcpy(kern_buff, buf, count);
> + if (ret < 0) {
> + ret = -EFAULT;
> + goto err;
> + }

Greg: What's the recommended way how to parse parameters via sysfs?
I see that kstrndup is used for cloning buffer instead of kzalloc
followed by strchr and sscanf.

> +
> + inbuf = kern_buff;
> +
> + /* Read the addess */

typo here.

> + tok = strsep(&inbuf, " ");
> + if (!tok) {
> + ret = -EFAULT;
> + goto err;
> + }
> + ret = kstrtol(tok, 16, &address);
> + if (ret) {
> + ret = -EFAULT;
> + goto err;
> + }
> + /* Read the write value */
> + tok = strsep(&inbuf, " ");
> + /*
> + * If parameter provided is only address, then its a read operation.
> + * Store the address in a global variable and retrieve whenever
> + * required.
> + */
> + if (!tok) {
> + register_address = address;
> + goto err;
> + }
> + register_address = address;
> +
> + ret = kstrtol(tok, 16, &mask);
> + if (ret) {
> + ret = -EFAULT;
> + goto err;
> + }
> + tok = strsep(&inbuf, " ");
> + if (!tok) {
> + ret = -EFAULT;
> + goto err;
> + }
> + ret = kstrtol(tok, 16, &value);
> + if (!tok) {
> + ret = -EFAULT;
> + goto err;
> + }
> + ret = zynqmp_pm_config_reg_access(CONFIG_REG_WRITE, address,
> + mask, value, NULL);
> + if (ret)
> + pr_err("unable to write value to %lx\n", value);
> +err:
> + kfree(kern_buff);
> + if (ret)
> + return ret;
> + return count;
> +}
> +
> +/**
> + * config_reg_show - Read config_reg sysfs attribute
> + * @kobj: Kobject structure
> + * @attr: Kobject attribute structure
> + * @buf: User entered health_status attribute string
> + *
> + * User-space interface for getting the config register.
> + *
> + * To Read any CSU/PMU register, write address to the variable like below
> + * echo > /sys/firmware/zynqmp/config_reg
> + *
> + * Then Read the address using below command
> + * cat /sys/firmware/zynqmp/config_reg
> + *
> + * Return: number of chars written to buf.
> + */
> +static ssize_t config_reg_show(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + char *buf)
> +{
> + int ret;
> + u32 ret_payload[PAYLOAD_ARG_CNT];
> +
> + ret = zynqmp_pm_config_reg_access(CONFIG_REG_READ, register_address,
> + 0, 0, ret_payload);
> + if (ret)
> + return ret;
> +
> + return sprintf(buf, "0x%x\n", ret_payload[1]);
> +}
> +
> +static struct kobj_attribute zynqmp_attr_config_reg =
> + __ATTR_RW(config_reg);

use DEVICE_ATTR_RW() instead

> +
> +static struct attribute *attrs[] = {
> + &zynqmp_attr_config_reg.attr,
> + NULL,
> +};

> +
> +static const struct attribute_group attr_group = {
> + .attrs = attrs,
> + NULL,
> +};

ATTRIBUTE_GROUPS instead.

> +
> +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 = sysfs_create_group(zynqmp_kobj, &attr_group);
> + if (ret) {
> + pr_err("%s() sysfs creation fail with error %d\n",
> + __func__, ret);

if you fail here you should free kobject_put(zynqmp_kobj);

> + }
> +
> + return ret;
> +}
> +
> static int zynqmp_firmware_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -748,6 +925,12 @@ static int zynqmp_firmware_probe(struct platform_device *pdev)
> /* Assign eemi_ops_table */
> eemi_ops_tbl = &eemi_ops;
>
> + ret = zynqmp_pm_sysfs_init();
> + if (ret) {
> + pr_err("%s() sysfs init fail with error %d\n", __func__, ret);
> + return ret;
> + }
> +
> zynqmp_pm_api_debugfs_init();
>
> ret = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE, firmware_devs,
> diff --git a/include/linux/firmware/xlnx-zynqmp.h b/include/linux/firmware/xlnx-zynqmp.h
> index df366f1..55561d0 100644
> --- a/include/linux/firmware/xlnx-zynqmp.h
> +++ b/include/linux/firmware/xlnx-zynqmp.h
> @@ -77,6 +77,8 @@ enum pm_api_id {
> PM_CLOCK_GETRATE,
> PM_CLOCK_SETPARENT,
> PM_CLOCK_GETPARENT,
> + /* PM_REGISTER_ACCESS API */
> + PM_REGISTER_ACCESS = 52,
> };
>
> /* PMU-FW return status codes */
> @@ -261,6 +263,11 @@ enum tap_delay_type {
> PM_TAPDELAY_OUTPUT,
> };
>
> +enum pm_register_access_id {
> + CONFIG_REG_WRITE,
> + CONFIG_REG_READ,
> +};
> +
> /**
> * struct zynqmp_pm_query_data - PM query data
> * @qid: query ID
> @@ -305,6 +312,8 @@ struct zynqmp_eemi_ops {
> const u32 capabilities,
> const u32 qos,
> const enum zynqmp_pm_request_ack ack);
> + int (*register_access)(u32 register_access_id, u32 address,
> + u32 mask, u32 value, u32 *out);
> };
>
> int zynqmp_pm_invoke_fn(u32 pm_api_id, u32 arg0, u32 arg1,
>