linux-kernel - Re: [PATCH 2/2] nvmem: imx-ocotp-ele: Support accessing controller for i.MX9

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Message-ID: <20241213041100.GA6948@localhost.localdomain>
Date: Fri, 13 Dec 2024 12:11:00 +0800
From: Peng Fan <peng.fan@....nxp.com>
To: Frank Li <Frank.li@....com>
Cc: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, devicetree@...r.kernel.org,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH 2/2] nvmem: imx-ocotp-ele: Support accessing controller
 for i.MX9

On Thu, Dec 12, 2024 at 12:45:48PM -0500, Frank Li wrote:
>On Thu, Dec 12, 2024 at 04:24:42PM +0800, Peng Fan (OSS) wrote:
>> From: Peng Fan <peng.fan@....com>
>>
>> i.MX9 OCOTP supports a specific peripheral or function being fused
>> which means disabled, so
>>  - Introduce ocotp_access_gates to be container of efuse gate info
>>  - Iterate each node under '/soc' to check accessing permission. If not
>>    allowed to be accessed, detach the node
>>
>> Signed-off-by: Peng Fan <peng.fan@....com>
>> ---
>>  drivers/nvmem/imx-ocotp-ele.c | 187 +++++++++++++++++++++++++++++++++++++++++-
>>  1 file changed, 186 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/nvmem/imx-ocotp-ele.c b/drivers/nvmem/imx-ocotp-ele.c
>> index ca6dd71d8a2e29888c6e556aaea116c1a967cb5f..542539b86efd2d38be2903c1d0ea72f918ff5b75 100644
>> --- a/drivers/nvmem/imx-ocotp-ele.c
>> +++ b/drivers/nvmem/imx-ocotp-ele.c
>> @@ -5,6 +5,8 @@
>>   * Copyright 2023 NXP
>>   */
>>
>> +#include <dt-bindings/nvmem/fsl,imx93-ocotp.h>
>> +#include <dt-bindings/nvmem/fsl,imx95-ocotp.h>
>>  #include <linux/device.h>
>>  #include <linux/io.h>
>>  #include <linux/module.h>
>> @@ -27,6 +29,7 @@ struct ocotp_map_entry {
>>  };
>>
>>  struct ocotp_devtype_data {
>> +	const struct ocotp_access_gates *access_gates;
>>  	u32 reg_off;
>>  	char *name;
>>  	u32 size;
>> @@ -36,11 +39,26 @@ struct ocotp_devtype_data {
>>  	struct ocotp_map_entry entry[];
>>  };
>>
>> +#define OCOTP_MAX_NUM_GATE_WORDS 4
>> +#define IMX93_OCOTP_NUM_GATES 17
>> +#define IMX95_OCOTP_NUM_GATES 36
>> +
>> +struct ocotp_access_gates {
>> +	u32 num_words;
>> +	u32 words[OCOTP_MAX_NUM_GATE_WORDS];
>> +	u32 num_gates;
>> +	struct access_gate {
>> +		u32 word;
>> +		u32 mask;
>> +	} gates[];
>> +};
>> +
>>  struct imx_ocotp_priv {
>>  	struct device *dev;
>>  	void __iomem *base;
>>  	struct nvmem_config config;
>>  	struct mutex lock;
>> +	u32 value[OCOTP_MAX_NUM_GATE_WORDS];
>>  	const struct ocotp_devtype_data *data;
>>  };
>>
>> @@ -131,6 +149,100 @@ static void imx_ocotp_fixup_dt_cell_info(struct nvmem_device *nvmem,
>>  	cell->read_post_process = imx_ocotp_cell_pp;
>>  }
>>
>> +static int imx_ele_ocotp_check_access(struct platform_device *pdev, u32 id)
>> +{
>> +	struct imx_ocotp_priv *priv = platform_get_drvdata(pdev);
>> +	const struct ocotp_access_gates *access_gates = priv->data->access_gates;
>> +	u32 word, mask;
>> +
>> +	if (id >= access_gates->num_gates) {
>> +		dev_err(&pdev->dev, "Index %d too large\n", id);
>> +		return -EACCES;
>> +	}
>> +
>> +	word = access_gates->gates[id].word;
>> +	mask = access_gates->gates[id].mask;
>> +
>> +	dev_dbg(&pdev->dev, "id:%d word:%d mask:0x%08x\n", id, word, mask);
>> +	/* true means not allow access */
>> +	if (priv->value[word] & mask)
>> +		return -EACCES;
>> +
>> +	return 0;
>> +}
>> +
>> +static int imx_ele_ocotp_grant_access(struct platform_device *pdev, struct device_node *parent)
>> +{
>> +	struct device_node *child;
>> +	struct device *dev = &pdev->dev;
>> +
>> +	for_each_available_child_of_node(parent, child) {
>> +		struct of_phandle_iterator it;
>> +		int err;
>> +		u32 id;
>> +
>> +		of_for_each_phandle(&it, err, child, "access-controllers",
>> +				    "#access-controller-cells", 0) {
>> +			struct of_phandle_args provider_args;
>> +			struct device_node *provider = it.node;
>> +
>> +			if (err) {
>> +				dev_err(dev, "Unable to get access-controllers property for node %s\n, err: %d",
>> +					child->full_name, err);
>> +				of_node_put(provider);
>> +				return err;
>> +			}
>> +
>> +			/* Only support one cell */
>> +			if (of_phandle_iterator_args(&it, provider_args.args, 1) != 1) {
>> +				dev_err(dev, "wrong args count\n");
>> +				return -EINVAL;
>> +			}
>> +
>> +			id = provider_args.args[0];
>> +
>> +			dev_dbg(dev, "Checking node: %s gate: %d\n", child->full_name, id);
>> +
>> +			if (imx_ele_ocotp_check_access(pdev, id)) {
>> +				of_detach_node(child);
>> +				dev_err(dev, "%s: Not granted, device driver will not be probed\n",
>> +					child->full_name);
>> +			}
>> +		}
>> +
>> +		imx_ele_ocotp_grant_access(pdev, child);
>> +	}
>
>Does it mean ocopt driver have to probe before other driver probe?

Yes. devlink could make sure ocotp being probed before other drivers which
needs access control check.

Regards,
Peng.

>
>Frank
>