linux-kernel - Re: [PATCH] clk-si5341: Support NVM programming through sysfs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <160454088987.3965362.6147280271557523496@swboyd.mtv.corp.google.com>
Date:   Wed, 04 Nov 2020 17:48:09 -0800
From:   Stephen Boyd <sboyd@...nel.org>
To:     Mike Looijmans <mike.looijmans@...ic.nl>, linux-clk@...r.kernel.org
Cc:     mturquette@...libre.com, linux-kernel@...r.kernel.org,
        Mike Looijmans <mike.looijmans@...ic.nl>
Subject: Re: [PATCH] clk-si5341: Support NVM programming through sysfs

Quoting Mike Looijmans (2020-11-03 06:17:41)
> Export an attribute program_nvm_bank that when read reports the current
> bank value. To program the chip's current state into NVM, write the
> magic value 0xC7 into this attribute.
> 
> Signed-off-by: Mike Looijmans <mike.looijmans@...ic.nl>
> ---

Any chance this can be done through the nvmem framework?

>  drivers/clk/clk-si5341.c | 73 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 73 insertions(+)
> 
> diff --git a/drivers/clk/clk-si5341.c b/drivers/clk/clk-si5341.c
> index e0446e66fa64..4e025a5ea2b7 100644
> --- a/drivers/clk/clk-si5341.c
> +++ b/drivers/clk/clk-si5341.c
> @@ -1199,6 +1205,69 @@ static const struct regmap_config si5341_regmap_config = {
>         .volatile_table = &si5341_regmap_volatile,
>  };
>  
> +static ssize_t program_nvm_bank_show(struct device *dev,
> +                               struct device_attribute *attr, char *buf)
> +{
> +       struct i2c_client *client = to_i2c_client(dev);
> +       struct clk_si5341 *data = i2c_get_clientdata(client);
> +       unsigned int regval;
> +       int ret;
> +
> +       ret = regmap_read(data->regmap, SI5341_ACTIVE_NVM_BANK, &regval);
> +       if (ret)
> +               return ret;
> +
> +       return sprintf(buf, "%#x\n", regval);
> +}
> +
> +static ssize_t program_nvm_bank_store(struct device *dev,
> +       struct device_attribute *attr,
> +       const char *buf,
> +       size_t count)
> +{
> +       struct clk_si5341 *data = i2c_get_clientdata(to_i2c_client(dev));
> +       int ret;
> +       unsigned int value;
> +       unsigned int timeout;
> +
> +       ret = kstrtouint(buf, 0, &value);
> +       if (ret < 0)
> +               return ret;
> +
> +       /* Write the magic value to this attribute to program the NVM */
> +       if (value != SI5341_SI5341_NVM_WRITE_COOKIE)
> +               return -EINVAL;
> +
> +       ret = regmap_write(data->regmap, SI5341_NVM_WRITE,
> +                       SI5341_SI5341_NVM_WRITE_COOKIE);
> +       if (ret)
> +               return ret;
> +
> +       /* Wait for SI5341_DEVICE_READY register to become 0x0f */
> +       for (timeout = 10000; timeout; --timeout) {
> +               ret = regmap_read(data->regmap, SI5341_DEVICE_READY, &value);

This is regmap_read_poll_timeout()?

> +               if (ret)
> +                       return ret;
> +
> +               if (value == 0x0f)
> +                       break;
> +       }
> +
> +       return count;
> +}
> +
> +static DEVICE_ATTR_RW(program_nvm_bank);
> +
> +static struct attribute *si5341_sysfs_entries[] = {
> +       &dev_attr_program_nvm_bank.attr,
> +       NULL,
> +};
> +
> +static struct attribute_group si5341_attr_group = {
> +       .name   = NULL, /* put in device directory */
> +       .attrs  = si5341_sysfs_entries,
> +};

If not nvmem framework, then this needs to be documented in
Documentation/ABI/

> +
>  static int si5341_dt_parse_dt(struct i2c_client *client,
>         struct clk_si5341_output_config *config)
>  {
> @@ -1544,6 +1613,10 @@ static int si5341_probe(struct i2c_client *client,
>         for (i = 0; i < data->num_synth; ++i)
>                  devm_kfree(&client->dev, (void *)synth_clock_names[i]);
>  
> +       err = sysfs_create_group(&client->dev.kobj, &si5341_attr_group);
> +       if (err)
> +               dev_err(&client->dev, "failed to create sysfs entries\n");
> +

Cool, I as a user would do what in this situation? The error message
seems sort of worthless.