Re: [PATCH 3/4] nvmem: ocotp: handle too early calls into ocotp driver gracefully

[Marco Felsch <m.felsch@pengutronix.de>]

On 23-07-26, Ahmad Fatoum wrote:
> HAB code calls into OCOTP driver by relying on a global imx_ocotp
> variable that's populated on driver probe.
> 
> For board code that calls a HAB function to early, this may end up
> dereferencing a NULL pointer, so let's return -EPROBE_DEFER in that
> case or if deep probe is enabled, just probe the OCOTP directly.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  drivers/clk/imx/clk-vf610.c |  5 ++++-
>  drivers/nvmem/ocotp.c       | 41 +++++++++++++++++++++++++++++++++++--
>  include/mach/imx/ocotp.h    |  2 +-
>  3 files changed, 44 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clk/imx/clk-vf610.c b/drivers/clk/imx/clk-vf610.c
> index 89899e0dc9b4..112f64df9b74 100644
> --- a/drivers/clk/imx/clk-vf610.c
> +++ b/drivers/clk/imx/clk-vf610.c
> @@ -568,13 +568,16 @@ static int vf610_switch_cpu_clock_to_400mhz(void)
>  static int vf610_switch_cpu_clock(void)
>  {
>  	int ret;
> -	bool sense_enable;
> +	int sense_enable;
>  	uint32_t speed_grading;
>  
>  	if (!of_machine_is_compatible("fsl,vf610"))
>  		return 0;
>  
>  	sense_enable = imx_ocotp_sense_enable(true);
> +	if (sense_enable < 0)
> +		return sense_enable;
> +
>  	ret = imx_ocotp_read_field(VF610_OCOTP_SPEED_GRADING, &speed_grading);
>  	imx_ocotp_sense_enable(sense_enable);
>  	if (ret < 0)
> diff --git a/drivers/nvmem/ocotp.c b/drivers/nvmem/ocotp.c
> index 8ba7a8af5da5..c22e5d9585fa 100644
> --- a/drivers/nvmem/ocotp.c
> +++ b/drivers/nvmem/ocotp.c
> @@ -14,6 +14,7 @@
>   */
>  
>  #include <common.h>
> +#include <deep-probe.h>
>  #include <driver.h>
>  #include <malloc.h>
>  #include <xfuncs.h>
> @@ -497,11 +498,17 @@ static void imx_ocotp_field_decode(uint32_t field, unsigned *word,
>  	*mask = GENMASK(width, 0);
>  }
>  
> +static int imx_ocotp_ensure_probed(void);

Nit: Move the function definition here?

Regards,
  Marco

>  int imx_ocotp_read_field(uint32_t field, unsigned *value)
>  {
>  	unsigned word, bit, mask, val;
>  	int ret;
>  
> +	ret = imx_ocotp_ensure_probed();
> +	if (ret)
> +		return ret;
> +
>  	imx_ocotp_field_decode(field, &word, &bit, &mask);
>  
>  	ret = imx_ocotp_reg_read(imx_ocotp, word, &val);
> @@ -524,6 +531,10 @@ int imx_ocotp_write_field(uint32_t field, unsigned value)
>  	unsigned word, bit, mask;
>  	int ret;
>  
> +	ret = imx_ocotp_ensure_probed();
> +	if (ret)
> +		return ret;
> +
>  	imx_ocotp_field_decode(field, &word, &bit, &mask);
>  
>  	value &= mask;
> @@ -541,14 +552,27 @@ int imx_ocotp_write_field(uint32_t field, unsigned value)
>  
>  int imx_ocotp_permanent_write(int enable)
>  {
> +	int ret;
> +
> +	ret = imx_ocotp_ensure_probed();
> +	if (ret)
> +		return ret;
> +
>  	imx_ocotp->permanent_write_enable = enable;
>  
>  	return 0;
>  }
>  
> -bool imx_ocotp_sense_enable(bool enable)
> +int imx_ocotp_sense_enable(bool enable)
>  {
> -	const bool old_value = imx_ocotp->sense_enable;
> +	bool old_value;
> +	int ret;
> +
> +	ret = imx_ocotp_ensure_probed();
> +	if (ret)
> +		return ret;
> +
> +	old_value = imx_ocotp->sense_enable;
>  	imx_ocotp->sense_enable = enable;
>  	return old_value;
>  }
> @@ -994,6 +1018,19 @@ static __maybe_unused struct of_device_id imx_ocotp_dt_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(of, imx_ocotp_dt_ids);
>  
> +static int imx_ocotp_ensure_probed(void)
> +{
> +	if (!imx_ocotp && deep_probe_is_supported()) {
> +		int ret;
> +
> +		ret = of_devices_ensure_probed_by_dev_id(imx_ocotp_dt_ids);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return imx_ocotp ? 0 : -EPROBE_DEFER;
> +}
> +
>  static struct driver imx_ocotp_driver = {
>  	.name	= "imx_ocotp",
>  	.probe	= imx_ocotp_probe,
> diff --git a/include/mach/imx/ocotp.h b/include/mach/imx/ocotp.h
> index 7c72edfb22a7..5f7b88f716a7 100644
> --- a/include/mach/imx/ocotp.h
> +++ b/include/mach/imx/ocotp.h
> @@ -35,7 +35,7 @@
>  int imx_ocotp_read_field(uint32_t field, unsigned *value);
>  int imx_ocotp_write_field(uint32_t field, unsigned value);
>  int imx_ocotp_permanent_write(int enable);
> -bool imx_ocotp_sense_enable(bool enable);
> +int imx_ocotp_sense_enable(bool enable);
>  
>  static inline u64 imx_ocotp_read_uid(void __iomem *ocotp)
>  {
> -- 
> 2.39.2
> 
> 
>