Message-ID: <a75310be-da16-8b8e-90a8-3a15ef8b735d@xilinx.com>
Date:   Wed, 18 Dec 2019 15:10:33 +0100
From:   Michal Simek <michal.simek@...inx.com>
To:     Jolly Shah <jolly.shah@...inx.com>, ard.biesheuvel@...aro.org,
        mingo@...nel.org, gregkh@...uxfoundation.org,
        matt@...eblueprint.co.uk, sudeep.holla@....com,
        hkallweit1@...il.com, keescook@...omium.org,
        dmitry.torokhov@...il.com, michal.simek@...inx.com
Cc:     rajanv@...inx.com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Rajan Vaja <rajan.vaja@...inx.com>
Subject: Re: [PATCH 1/5] firmware: xilinx: Adds new eemi call for reg access

On 05. 12. 19 0:29, Jolly Shah wrote:
> From: Rajan Vaja <rajan.vaja@...inx.com>
> 
> This patch adds new EEMI call which is used for CSU/PMU register
> access from linux.
> 
> Signed-off-by: Michal Simek <michal.simek@...inx.com>
> Signed-off-by: Rajan Vaja <rajan.vaja@...inx.com>
> Signed-off-by: Jolly Shah <jolly.shah@...inx.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 <address> <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 <address> > /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 <address> > /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,
> 

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